Silva Fennica

article id 23074, category Editorial

Christian Kanzian. (2023). Are productivity studies in forest operations old fashioned and no more publishable? Silva Fennica vol. 57 no. 3 article id 23074. https://doi.org/10.14214/sf.23074

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Kanzian, Department of Forest and Soil Sciences, Institute of Forest Engineering, University of Natural Resources and Life Sciences, Vienna (BOKU), Peter-Jordan-Strasse 82, 1190 Vienna, Austria https://orcid.org/0000-0002-1198-9788 E-mail: christian.kanzian@boku.ac.at

article id 288, category Special section

Björn Berg, Per Gundersen, Cecilia Akselsson, Maj-Britt Johansson, Åke Nilsson, Lars Vesterdal. (2007). Carbon sequestration rates in Swedish forest soils – a comparison of three approaches. Silva Fennica vol. 41 no. 3 article id 288. https://doi.org/10.14214/sf.288

Keywords: carbon sequestration; stable humus; forest floor C; litter decomposition; limit value

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Carbon sequestration rates in forest soil can be estimated using the concept of calculable stable remains in decomposing litter. In a case study of Swedish forest land we estimated C-sequestration rates for the two dominant tree species in the forest floor on top of the mineral soil. Carbon sequestration rates were upscaled to the forested land of Sweden with 23 x 10⁶ ha with Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (Karst.) L.). Two different theoretical approaches, based on limit-value for litter decomposition and N-balance for vegetation and SOM gave rates of the same magnitude. For the upscaling, using these methods, 17 000 grids of 5 x 5 km were used.

The ‘limit-value approach’ gave a sequestration of 4.8 10⁶ tons of C, annually sequestered in the forest floor, with an average of 180 kg C ha^–1 yr^–1 and a range from 40 to 410 kg C ha^–1 yr^–1. The ‘N-balance approach’ gave an average value of c. 96 kg ha^–1 yr^–1 and a range from –60 to 360 kg ha^–1 yr^–1. A method based on direct measurements of changes in humus depth over 40 years, combined with C analyses gave an average rate that was not very different from the calculated rates, viz. c. 180 kg ha^–1 yr^–1 and a range from –20 to 730 kg ha^–1 yr^–1. These values agree with forest floor C sequestration rate based on e.g. sampling of chronsequences but differ from CO₂ balance measurements.

The three approaches showed different patterns over the country and regions with high and low carbon sequestration rates that were not always directly related to climate.

Berg, Dept. of Forest Ecology, University of Helsinki, Finland (present address: Dipartimento Biologia Strutturale e Funzionale, Complesso Universitario, Monte S. Angelo, Napoli, Italy E-mail: bjorn.berg@helsinki.fi
Gundersen, Forest & Landscape Denmark, University of Copenhagen, Denmark E-mail: pg@nn.dk
Akselsson, Swedish Environmental Research Institute, IVL, Gothenburg, Sweden E-mail: ca@nn.se
Johansson, Department of Forest Soils, SLU, Uppsala, Sweden E-mail: mbj@nn.se
Nilsson, Department of Forest Soils, SLU, Uppsala, Sweden E-mail: an@nn.se
Vesterdal, Forest & Landscape Denmark, University of Copenhagen, Denmark E-mail: lv@nn.dk

article id 23067, category Climate resilient and sustainable forest management – Research article

Lucas N. López, Hanne K. Sjølie, Abbas Nabhani, Francisco X. Aguilar. (2024). Impacts of biodiversity and carbon policies on the management of Norwegian forest and its ecosystem services. Silva Fennica vol. 58 no. 4 article id 23067. https://doi.org/10.14214/sf.23067

Keywords: simulation; optimization; site productivity; bio-economic modeling; NorFor; regional impacts; TreeSim

Highlights: National-level biodiversity and carbon forest sector policies modelled in a simulation-optimization framework; Impacts of policies on management along site productivity gradients estimated; Policies vary in impact across productivity gradients with regional implications.

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Measures to enhance boreal forests’ biodiversity and climate change mitigation potential are high on the policy agenda. Site productivity influences management, ecological attributes, and economic outcomes. However, national-level analyses of management implementation in response to policies considering site productivity are lacking. We analyzed impacts of a carbon policy (Carb), a biodiversity policy (Bio) and a combined biodiversity and carbon policy (BioCarb) in Norway using a simulation-optimization framework, assessing impacts on forest management, timber harvest, ecological attributes, and carbon fluxes until year 2140. Management alternatives were simulated in the single-tree simulator TreeSim before being fed into a market model NorFor to compare policy outcomes to a business-as-usual (BAU) scenario. All policies led to decreased harvests. Old forests expanded from the current 3% to cover 21% or more of the productive forest area in all scenarios. Impacts of policies depended on site productivity. On low-productive land, management under Bio mirrored BAU, while the Carb and BioCarb policies yielded more set-asides. On high-productive land, management intensity under the Carb policy was similar to BAU but the Bio and BioCarb policies resulted in more set-asides and more old forest. Thus, on low-productive land, the carbon policy showed to have the strongest impact on forest management, while on high-productive land, the biodiversity policy had the strongest impact. With geographical site-productivity gradients, the two policies exhibited different regional effects. The study shows that ex-ante analyses with appropriate tools can provide relevant information of multiple consequences beyond the stated aims which should be considered in policy design.

López, Inland Norway University of Applied Sciences, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, P.O. Box 2400, Koppang, Norway https://orcid.org/0009-0006-6860-3408 E-mail: lucas.lopez@inn.no
Sjølie, Inland Norway University of Applied Sciences, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, P.O. Box 2400, Koppang, Norway https://orcid.org/0000-0001-8099-3521 E-mail: hanne.sjolie@inn.no
Nabhani, Inland Norway University of Applied Sciences, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, P.O. Box 2400, Koppang, Norway E-mail: abbas.nabhani@inn.no
Aguilar, Swedish University of Agricultural Sciences, Department of Forest Economics, SE-901 83 Umeå, Sweden E-mail: francisco.aguilar@slu.se

article id 25036, category Research article

Juha Kaitera, Tuula Piri, Minna Männistö, Sanna Vinblad, Heli Väätäjä, Kari Mäkitalo. (2026). Dogs can detect the rust fungus Cronartium pini in the forest. Silva Fennica vol. 60 no. 1 article id 25036. https://doi.org/10.14214/sf.25036

Keywords: Pinus sylvestris; Scots pine blister rust; alternate hosts; canine; resin-top disease; scent detection

Highlights: Dogs identified Cronartium pini spores, fruit bodies and young and old lesions; Dogs identified both heteroecious and autoecious Cronartium pini; Dogs identified Cronartium pini at the early epidemical stage of the disease; Dogs identified Cronartium pini from latent infections in alive shoots.

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Cronartium pini (Willd.) Jørst. is a major rust pathogen that kills especially Scots pine (Pinus sylvestris L.). Early diagnosis of the pathogen would reduce significant losses in managed forest productivity. Dogs (Canis lupus familiaris L.) with their accurate sense of smell have potential to detect forest pathogens at an early stage before they cause significant losses in forests. In this study, we tested in northern Finland whether trained volunteer dog-handler teams could identify infected wood, fruit bodies, spores or mycelia of C. pini in vitro and in vivo to facilitate early disease diagnosis. Volunteer dog-handler teams were able to indicate C. pini spores, fruit bodies and both fresh and old rust lesions on Scots pine including alive shoots, where the rust was present yet as latent. Five dogs out of five detected in vitro C. pini (both life-cycle forms), with 51% mean sensitivity and 58% mean precision. Four dogs out of four detected in vivo the autoecious life-cycle form of C. pini, with 95% mean sensitivity and 89% mean precision. In in vivo detection of the heteroecious life cycle form on pine, two dogs out of two performed with 78% mean sensitivity (100% precision). For identifying C. pini on alternate hosts in vivo, the mean sensitivity was 58% (precision 100%). Trained dog-handler pairs show promise as an aid in searching for C. pini especially in Scots pine stands at their early epidemical stage, but further testing is needed.

Kaitera, Natural Resources Institute Finland (Luke), Paavo Havaksen tie 3, FI-90570 Oulu, Finland https://orcid.org/0000-0003-2549-7001 E-mail: juha.kaitera@luke.fi
Piri, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0001-8690-3726 E-mail: tuula.piri@luke.fi
Männistö, Natural Resources Institute Finland (Luke), Ounasjoentie 6, FI-96200 Rovaniemi, Finland https://orcid.org/0000-0001-9390-1104 E-mail: minna.mannisto@luke.fi
Vinblad, Lapland University of Applied Sciences, Jokiväylä 11 C, FI-96300 Rovaniemi, Finland https://orcid.org/0009-0009-1131-6143 E-mail: sanna.vinblad@lapinamk.fi
Väätäjä, Lapland University of Applied Sciences, Jokiväylä 11 C, FI-96300 Rovaniemi, Finland https://orcid.org/0000-0003-3324-9497 E-mail: heli.vaataja@lapinamk.fi
Mäkitalo, Natural Resources Institute Finland (Luke), Ounasjoentie 6, FI-96200 Rovaniemi, Finland E-mail: kari.makitalo@luke.fi

article id 25018, category Research article

Erik Arvidsson, Anders Rowell, Linnea Hansson, Håkan Lideskog, Mikael Rönnqvist. (2026). Comparison of manual and automated coverage path planning for mechanized forest regeneration. Silva Fennica vol. 60 no. 1 article id 25018. https://doi.org/10.14214/sf.25018

Keywords: site preparation; planting; mechanization; automation; precision forestry; routing

Highlights: Automated coverage path planners TerraTrail and Pathfinder outperform manual operators driving the PlantMax planting machine in coverage across all test sites; Pathfinder demonstrated the shortest path lengths, especially in constrained environments, with up to 14% shorter paths compared to manual planning; The study emphasizes the potential of autonomous path planning systems to reduce labor dependency, enhance sustainability, and improve the efficiency of forest regeneration operations; The automated planners effectively accounted for vehicle constraints such as terrain and soil moisture conditions, optimizing routes for more efficient regeneration.

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In Finland and Scandinavia, even-aged forest management predominates, often including mechanical site preparation and manual planting. Growing labor shortages and increased demand for sustainability have driven interest in mechanized and autonomous planting systems. This study evaluates two automated Coverage Path Planners (CPP), Pathfinder and TerraTrail, developed to optimize planting routes for mechanized forest regeneration. Their performance is compared to the routes of the manually operated mechanized planting machine, PlantMax. Three operational sites in Sweden, representing varied terrain and hydrological conditions are evaluated. The evaluation focuses on coverage, Euclidean and Dubins path lengths. Both CPPs incorporate Digital Elevation Models (DEM), Depth-to-Water (DTW) maps and vehicle-specific kinematics to generate planting routes. Two scenarios are evaluated: one where the CPPs neglect the DTW map, and another where the CPPs are constrained to avoid DTW values below 0.3 m. Results show that automated CPPs achieve 15–19% higher coverage than manual planning on average. Pathfinder showed similar normalized path lengths in an unconstrained scenario as the manual operator, but 14% shorter in the constrained environment. TerraTrail shows 7% longer normalized path lengths in an unconstrained scenario, while the constrained scenario shows similar path lengths as the manual operator. These findings emphasize the potential of deploying automated CPP systems to enhance precision, sustainability, and labor efficiency of silvicultural operations. The CPPs support both autonomous deployment and decision support tool for operators. Further refinement, including combining both CPPs to leverage the best functions of each, along with reversible path planning, could enhance their value in forestry practices.

Arvidsson, Luleå University of Technology (LTU), SE-971 87 Luleå, Sweden https://orcid.org/0000-0001-7679-0203 E-mail: erik.arvidsson@ltu.se
Rowell, Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden https://orcid.org/0009-0000-2810-1434 E-mail: anders.rowell@skogforsk.se
Hansson, Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden https://orcid.org/0000-0002-9788-1734 E-mail: linnea.hansson@skogforsk.se
Lideskog, Luleå University of Technology (LTU), SE-971 87 Luleå, Sweden https://orcid.org/0000-0002-9862-828X E-mail: hakan.lideskog@ltu.se
Rönnqvist, Université Laval, 1065, avenue de la Médecine, Local 1504, Québec G1V 0A6, Canada https://orcid.org/0000-0002-1940-6129 E-mail: mikael.ronnqvist@gmc.ulaval.ca

article id 25012, category Research article

Heikki Astola, Annika Kangas, Francesco Minunno, Matti Mõttus. (2026). Emulating a forest growth and productivity model with deep learning. Silva Fennica vol. 60 no. 1 article id 25012. https://doi.org/10.14214/sf.25012

Keywords: carbon balance; simulation; machine learning; climate scenarios; digital twins; forest variables; time series prediction

Highlights: Emulating the operation of analytical forest growth models is feasible using state-of-the-art machine learning methods; Long term prediction of forest growth and carbon balance variables were produced with low bias accumulation when compared to the reference model; The methods tested offer means for long time span simulations of large areas with a high spatial resolution.

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We studied the possibility of replacing a complex forest growth and productivity model with a deep learning model with sufficient accuracy. We used three different neural network architectures for emulating the prediction task of the PREBASSO (Mäkelä 1997; Minunno et al. 2016) forest growth model: 1) Recurrent Neural Network (RNN) Encoder-decoder network, 2) RNN encoder network, and 3) Transformer encoder network. The PREBASSO forest growth model was used to produce 25-year predictions for forest variables: tree height, stem diameter, basal area, and the carbon balance variables: net primary production (NPP), gross primary production per tree layer (GPP), net ecosystem exchange (NEE) and gross growth (GGR) to train the machine learning models. The Finnish Forest Centre provided the data for 29 619 field inventory plots in continental Finland that were used as the initial state of the forest sites to be simulated. Climate data downloaded from Copernicus Climate Data Store were used to provide realistic climate scenarios. We emphasized the importance of low bias in long term predictions and set the goal for the emulator prediction relative bias to be within ±2%. The RNN encoder model produced the best results with the mean of the yearly bias values within the specified ±2% limit over the 25-year prediction period. The study shows that emulating the operation of analytical forest growth models is feasible using state-of-the-art machine learning methods and indicates the potential of using such emulators for producing long time span simulations for e.g. digital twins.

Astola, VTT Technical Research Centre of Finland, Tekniikantie 1, 02150 Espoo, Finland https://orcid.org/0000-0003-4989-9910 E-mail: heikki.astola@gmail.com
Kangas, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, Yliopistokatu 6, 80100 Joensuu, Finland https://orcid.org/0000-0002-8637-5668 E-mail: annika.kangas@luke.fi
Minunno, Yucatrote, Rua António Gavina L49, 8600-214 Luz, Lagos, Portugal https://orcid.org/0000-0002-7658-6402 E-mail: francesco.minunno@helsinki.fi
Mõttus, VTT Technical Research Centre of Finland, Tekniikantie 1, 02150 Espoo, Finland https://orcid.org/0000-0002-2745-1966 E-mail: Matti.Mottus@vtt.fi

article id 25001, category Research article

Katri Rusanen, Teppo Hujala, Jouni Pykäläinen. (2026). “We are already in the frontline” – Sustainable value creation and entrepreneurial orientation in forest-based small and medium-sized enterprises. Silva Fennica vol. 60 no. 1 article id 25001. https://doi.org/10.14214/sf.25001

Keywords: forest-based sector; sustainability transition; sustainable business model; sustainable entrepreneurship; value creation

Highlights: Sustainability transitions call for new types of businesses and value creation; Sustainability-oriented forest-based SMEs providing various services were studied; Operating environment and entrepreneurial orientation of companies shape how sustainable value is created with and for stakeholders; There is resistance from the operating environment towards sustainability-oriented businesses; System-level changes and sustainability-oriented entrepreneurship are interconnected and support each other.

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Sustainability challenges such as climate change and biodiversity loss have a great impact on the operating environment of companies. Business actors have increasingly sought answers to these challenges. A range of innovations, technologies and business models have been developed. Little is however known about those companies and entrepreneurs that strive for solving sustainability challenges. Sustainability-oriented entrepreneurship has interested researchers for a while. Nevertheless, studies have not thoroughly focused on forest-based services and related business models and value creation. This multiple case study investigates how the operating environment and entrepreneurial orientation are entailed in sustainability-pursuant value creation. We interviewed nine sustainability-oriented small and medium-sized enterprises providing forest-based services. The results indicate that the companies feature several entrepreneurial capabilities that enable them creating sustainable value. They are positively oriented towards future and consider their business as a solution to focal sustainability challenges. The companies’ operating environment can support the emergence and long-term development of sustainability-oriented businesses and innovations, and hence collaboration with stakeholders is essential for sustainable value creation. However, the established forest-based sector and existing support system have created tensions for the development of the sustainability-oriented businesses. The companies strive actively for making an impact on their operating environment to create sustainable value with and for their stakeholders. This study advances empirical research on sustainable value creation and entrepreneurship. Overall, this paper suggests that sustainability-oriented entrepreneurs need more collaboration and support for scaling up the solving of sustainability challenges.

Rusanen, School of Forest Sciences, Faculty of Science, Forestry and Technology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-1705-5561 E-mail: katri.rusanen@uef.fi
Hujala, School of Forest Sciences, Faculty of Science, Forestry and Technology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0002-7905-7602 E-mail: teppo.hujala@uef.fi
Pykäläinen, School of Forest Sciences, Faculty of Science, Forestry and Technology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-3427-9954 E-mail: jouni.pykalainen@uef.fi

article id 25032, category Research article

Annastina Saari, Marjo Palviainen, Mikko T. Niemi, Annamari Laurén. (2025). Impacts of reduced ditch network maintenance and ditch shallowing on ecosystem services of peatland forests in Finland. Silva Fennica vol. 59 no. 3 article id 25032. https://doi.org/10.14214/sf.25032

Keywords: stand growth; drainage; carbon balance; water table; ecosystem modelling; nutrient export load

Highlights: Effects of ditch shallowing on ecosystem services depend on latitude, site type and tree species; Ditch shallowing increased ecosystem carbon sinks; If the initial ditch depth was 0.6 m and deeper, stand volume growth mainly increased in Southern Finland; Ditch shallowing had the largest benefits for all studied ecosystem services when the initial ditch depth was 0.9 m.

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According to the 13th Finnish National Forest Inventory, 0.8 Mha of drained peatland forests require ditch network maintenance (DNM). The annual DNM area has decreased radically during the past ten years, leading to gradual shallowing of ditches and rise of water table (WT) in peatland forests. To study the impacts of ditch shallowing on ecosystem services, we applied Peatland Simulator SUSI for 20 average peatland forests representing four different geographical regions in Finland. The simulation period was 20 years and the initial ditch depths were set to 0.3 m, 0.6 m and 0.9 m. The study included drained peatland forest site types from nutrient rich to nutrient poor, with main species as Scots pine (Pinus sylvestris L.) or Norway spruce (Picea abies (L.) Karst.). We studied how ditch shallowing affected stand volume growth, ecosystem and soil carbon (C) balances, and nitrogen (N) and phosphorus (P) export loads to water courses in different peatland sites. The results showed that due to ditch shallowing, the ecosystem C sinks increased in most sites when the initial ditch depth was 0.6 m or 0.9 m. Ditch shallowing generally increased stand volume growth in Southern Finland when the initial ditch depth was 0.6 m or 0.9 m. Regardless of the location and initial ditch depth, ditch shallowing decreased N and P exports, and soil C emissions. The study calls for new water management guidelines for drained forested peatlands in Finland.

Saari, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland https://orcid.org/0009-0001-5931-4210 E-mail: annastina.saari@helsinki.fi
Palviainen, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland https://orcid.org/0000-0001-9963-4748 E-mail: marjo.palviainen@helsinki.fi
Niemi, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland https://orcid.org/0000-0003-0461-3667 E-mail: mikko.t.niemi@helsinki.fi
Laurén, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland; Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0002-6835-9568 E-mail: annamari.lauren@helsinki.fi

article id 25021, category Research article

Taru Rikkonen, Ville Hallikainen, Minna Turunen, Pasi Rautio. (2025). Pendulous lichen colonization in small gap openings can enable a resource continuum for reindeer. Silva Fennica vol. 59 no. 3 article id 25021. https://doi.org/10.14214/sf.25021

Keywords: continuous cover forestry; forestry; uneven-aged forestry; multiple use of forests; reindeer husbandry; land use conflicts; small gap cutting

Highlights: Pendulous lichens successfully colonized seedlings in small gap openings; Colonization was most successful in the smallest gaps (d = 20 m) and near gap edges; Higher seedling density and greater seedling height increased the probability of lichen colonization; Pendulous lichens on adjacent mature trees promoted colonization within gaps; Small gap cutting can facilitate the coexistence of commercial forestry and reindeer husbandry.

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In northern Finland, continuous cover forestry (CCF), has been introduced to better reconcile multiple land uses, including commercial forestry and reindeer husbandry. We studied how small gap cutting, a CCF method, can facilitate the colonization of pendulous lichens (Alectoria sp., Bryoria sp., and Usnea sp.), a bottle-neck resource for reindeer (Rangifer tarandus tarandus), into harvested areas. To assess the potential for balancing between forestry and reindeer husbandry, we investigated the colonization success of pendulous lichen on seedlings within the gaps created ten years before onset of our study in a pine-dominated boreal forest in central Finnish Lapland. The study included three gap sizes (diameters 20, 40, and 80 m) in xeric and sub-xeric sites, arranged in six randomized blocks, with 18 replicates per each gap size. Additionally, we examined the influence of gaps on the abundance of pendulous lichens in mature trees in the surrounding forest. Our results indicate that pendulous lichens colonized the smallest gaps (d = 20 m) efficiently, while colonization success declined as gap size increased. Colonization was strongly associated with seedling density, as a higher number of seedlings within gaps increased the probability of lichen colonized seedlings. The highest colonization rates occurred near gap edges, with lower colonization in the center. Furthermore, seedling height positively influenced colonization, and the presence of pendulous lichens on adjacent mature trees enhanced seedling colonization within gaps. However, we also observed that gap edges significantly reduced the amount of pendulous lichens on mature trees.

Rikkonen, Natural Resources Institute Finland (Luke), Ounasjoentie 6, FI-96200 Rovaniemi, Finland; Arctic Centre, University of Lapland, POB 122, FI-96101 Rovaniemi, Finland https://orcid.org/0000-0002-7352-5241 E-mail: taru.rikkonen@luke.fi
Hallikainen, Natural Resources Institute Finland (Luke), Ounasjoentie 6, FI-96200 Rovaniemi, Finland https://orcid.org/0000-0001-5384-8265 E-mail: ext.ville.hallikainen@luke.fi
Turunen, Arctic Centre, University of Lapland, POB 122, FI-96101 Rovaniemi, Finland https://orcid.org/0000-0002-3425-6472 E-mail: minna.turunen@ulapland.fi
Rautio, Natural Resources Institute Finland (Luke), Ounasjoentie 6, FI-96200 Rovaniemi, Finland https://orcid.org/0000-0003-0559-7531 E-mail: pasi.rautio@luke.fi

article id 25011, category Research article

Tuomas Niinistö, Perttu Anttila, Janne Kaseva, Lauri Sikanen, Kalle Kärhä, Johanna Routa. (2025). Energy wood flows and the operational environment of supply chains in finland: insights from a supplier survey. Silva Fennica vol. 59 no. 3 article id 25011. https://doi.org/10.14214/sf.25011

Keywords: bioenergy; forest chips; energy transition; energy wood procurement; wood fuel supply

Highlights: Most of the consumed energy wood is sourced within 100 km of the plant; Energy wood transport distance increases with the higher consumption level of plant; Industrial roundwood could cover 25–33% of roundwood burned; Most of the stumps are sourced from land-use change areas; Economic viability of harvesting small-diameter trees should be increased to divert energy wood harvesting to young forests.

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Energy wood supply has faced significant challenges in Finland in recent years. While forest chip consumption has increased, the cessation of wood imports from Russia has added pressure on the use of domestic forest resources. This study examined the status of energy wood supply to heat-only and combined heat and power (CHP) plants from the perspective of energy wood suppliers. The survey-based study particularly focused on energy wood transport distances, the origin of delivered energy wood, and the proportion of various assortments. The operational environment, including wood fuel storage capacity and policy impacts, was also investigated. The results indicate that most energy wood consumed as forest chips was sourced less than 100 km from the consumer plant. However, these transport distances depended on annual forest chip consumption at the delivery point plant. Notably, energy wood was supplemented by roundwood that otherwise would have been suitable for processing in the forest industry; the proportion of that was 25–33% of all roundwood delivered. The results of this study also highlighted the visible role of land-use change areas, especially for stump sourcing, while imported wood accounted for only a small fraction of the supply. In conclusion, to reduce the burning of industrial roundwood and to divert energy wood harvesting to young commercial forests, policy should place greater emphasis on the economic viability of harvesting small-diameter trees for energy production. Furthermore, uncertainty in the operational environment, caused by policy changes, should be mitigated.

Niinistö, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0009-0006-2645-0095 E-mail: tuomas.niinisto@luke.fi
Anttila, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0002-6131-392X E-mail: perttu.anttila@luke.fi
Kaseva, Natural Resources Institute Finland (Luke), Tietotie 4, FI-31600 Jokioinen, Finland https://orcid.org/0000-0002-8167-5434 E-mail: janne.kaseva@luke.fi
Sikanen, Natural Resources Institute Finland (Luke), Yliopistokatu 6b, FI-80100 Joensuu, Finland https://orcid.org/0000-0001-6368-2879 E-mail: lauri.sikanen@luke.fi
Kärhä, School of Forest Sciences, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland E-mail: kalle.karha@uef.fi
Routa, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0001-7225-1798 E-mail: johanna.routa@luke.fi

article id 24072, category Research article

Atte Kumpu, Mikko Peltoniemi, Martin Forsius, Annikki Mäkelä. (2025). Soil carbon and nitrogen in unmanaged forests in Southern and Eastern Finland. Silva Fennica vol. 59 no. 3 article id 24072. https://doi.org/10.14214/sf.24072

Keywords: Norway spruce; boreal forest; mineral soil layer; organic soil layer

Highlights: Unmanaged forest soils store more carbon and nitrogen than managed forest soils; In unmanaged forest soils the carbon and nitrogen storages remain stable over time.

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Soils have an essential role in ecosystem carbon balance. The soils of natural-like old unmanaged forests have been studied less than those of managed stands. In this study, we collected soil core samples and measured the soil carbon and nitrogen content of 27 old unmanaged forest soils in Southern and Eastern Finland. The results were compared against existing data from managed stands of similar site types. The data was also compared with earlier soil measurements from the same sites to look for any significant changes. The analysis resulted in an average of 2.58, 2.44 and 1.62 kg m^-2 of soil carbon and 0.087, 0.097 and 0.074 kg m^-2 of nitrogen in the organic layer, 0–10 cm of mineral soil layer and 10–20 cm of mineral soil layer, respectively. Carbon contents in the mineral soil layers were higher in unmanaged forests than in managed forests, but not in the organic-layer. Similarly for nitrogen, there was a significant difference between the unmanaged forests and the managed stands for both mineral soil layers, but not for the organic layer. There were no significant changes in soil carbon or nitrogen contents between the old and new measurements in the old unmanaged forests. The results align with the assumption that carbon and nitrogen content are higher in unmanaged forests than in managed forests due to their higher litter input on average, and more stable and cooler conditions. This means that old unmanaged forests have an important role as carbon storage and that the carbon storage is stable.

Kumpu, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland https://orcid.org/0000-0001-9547-1697 E-mail: atte.kumpu@helsinki.fi
Peltoniemi, Natural Resources Institute Finland (Luke); Bioeconomy and environment, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: mikko.peltoniemi@luke.fi
Forsius, Finnish Environment Institute (Syke), Nature solutions, Latokartanonkaari 11, FI-00790 Helsinki, Finland https://orcid.org/0000-0003-0125-5120 E-mail: martin.forsius@syke.fi
Mäkelä, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland https://orcid.org/0000-0001-9633-7350 E-mail: annikki.makela@helsinki.fi

article id 24064, category Research article

Mikko Hyppönen, Ville Hallikainen, Urban Bergsten, Hans Winsa, Jari Miina, Sauli Valkonen, Pekka Helenius, Esko Jaskari, Pasi Rautio. (2025). Is it possible to extend the season for direct seeding of Scots pine and lodgepole pine in northern Fennoscandia? Silva Fennica vol. 59 no. 3 article id 24064. https://doi.org/10.14214/sf.24064

Keywords: Pinus sylvestris; Pinus contorta; artificial regeneration; autumn direct seeding; generalized linear mixed effects models

Highlights: Scots pine and lodgepole pine were direct seeded during June–November in a six-year experiment in Finnish Lapland; Both early summer and late autumn as well as early winter were appropriate periods for the successful seeding of both species; Seeding in late summer and early autumn (August and September) was much less successful for Scots pine; For lodgepole pine seeding time, site quality or cold-wet treatment of seeds were not critical for the seedling emergence or survival.

Abstract | Full text in HTML | Full text in PDF | Author Info

The aim of this study was to experimentally test the most favourable seeding times for Scots pine (Pinus sylvestris L.), and to compare Scots pine and lodgepole pine (Pinus contorta Douglas ex Loudon) in respect to suitable seeding times and site factors. The experimental area was located in Sodankylä, Central Finnish Lapland. Generalized linear mixed effects models with binomial distribution assumption were applied to model the presence or absence of a seedling at a seeding point. The study shows that in addition to spring and early summer, direct seeding of Scots pine can also be carried out during late autumn or even early winter (October and November) in northern Fennoscandia. On the contrary, seeding in late summer and early autumn (August and September) is much less successful and cannot be recommended as such, but can be used if the amount of seeding material is increased to compensate the loss. There is more flexibility for lodgepole pine for which the proper seeding period seems to be from spring through to late autumn. Whether lodgepole pine seeds were stratified or not had no statistically significant effect on regeneration success. Our results clearly indicate that lodgepole pine is less susceptible to unfavourable site and soil factors than Scots pine. Our results give support to extend the period of direct seeding from the present early summer to another period in late autumn and even early winter.

Hyppönen, Natural Resources Institute Finland (Luke), Ounasjoentie 6, FI-96200 Rovaniemi, Finland E-mail: mikkokthypponen@gmail.com
Hallikainen, Natural Resources Institute Finland (Luke), Ounasjoentie 6, FI-96200 Rovaniemi, Finland https://orcid.org/0000-0001-5384-8265 E-mail: ext.ville.hallikainen@luke.fi
Bergsten, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences (SLU), Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: burskog@gmail.com
Winsa, Natural Resources Institute Finland (Luke), Ounasjoentie 6, FI-96200 Rovaniemi, Finland E-mail: hans.winsa@gmail.com
Miina, Natural Resources Institute Finland (Luke), Yliopistokatu 6 B, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-8639-4383 E-mail: jari.miina@luke.fi
Valkonen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790, Helsinki, Finland https://orcid.org/0000-0002-2879-4821 E-mail: sauli.valkonen@luke.fi
Helenius, Natural Resources Institute Finland (Luke), Tietotie 4, FI-31600 Jokioinen, Finland E-mail: psjhelenius@elisanet.fi
Jaskari, Natural Resources Institute Finland (Luke), Ounasjoentie 6, FI-96200 Rovaniemi, Finland E-mail: ejaskari@gmail.com
Rautio, Natural Resources Institute Finland (Luke), Ounasjoentie 6, FI-96200 Rovaniemi, Finland https://orcid.org/0000-0003-0559-7531 E-mail: pasi.rautio@luke.fi

article id 25013, category Research article

Binod Kafle, Ville Kankare, Harri Kaartinen, Kari Väätäinen, Heikki Hyyti, Tamas Faitli, Juha Hyyppä, Antero Kukko, Kalle Kärhä. (2025). Assessing the consistency of low vegetation characteristics estimated using harvester, handheld, and drone light detection and ranging (LiDAR) systems. Silva Fennica vol. 59 no. 2 article id 25013. https://doi.org/10.14214/sf.25013

Keywords: biodiversity; harvester; wood harvesting; dense area for games; drone laser scanning (DLS); handheld mobile laser scanning (HMLS); point cloud

Highlights: Harvester-mounted LiDAR consistently estimated low vegetation height and volume comparable to handheld and drone LiDAR; Enhancing LiDAR range could improve harvester LiDAR efficiency, reducing processing time and increasing accuracy beyond 20 m.

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Evaluating the potential of a harvester-mounted LiDAR system in monitoring biodiversity indicators such as low vegetation during forest harvesting could enhance sustainable forest management and habitat conservation including dense forest areas for game. However, there is a lack of understanding on the capabilities and limitations of these systems to detect low vegetation characteristics. To address this knowledge gap, this study investigated the performance of a harvester-mounted LiDAR system for measuring low vegetation (height <5 m) attributes in a boreal forest in Finland, by comparing it with handheld mobile laser scanning (HMLS) and drone laser scanning (DLS) systems. LiDAR point cloud data was collected in September 2023 to quantify the low vegetation height (maximum, mean, and percentiles), volume (voxel-based and mean height-based) and cover (grid method). Depending on the system, LiDAR point cloud data was collected either before (HMLS and DLS), during (harvester LiDAR) or after (HMLS and DLS) harvesting operations. A total of 46 fixed-sized (5 m × 5 m) grid cells were studied and analyzed. Results showed harvester-mounted LiDAR provided consistent estimates with HMLS and DLS for maximum height, 99th height percentile, and volume across various grids (5 cm, 10 cm, 20 cm) and voxel (20 cm) sizes. High correlation was observed between the systems used for these attributes. This study demonstrated that harvester-mounted LiDAR is comparable to HMLS and DLS for assessing low vegetation height and volume. The findings could assist forest harvester operators in identifying potential low vegetation and dense areas for conservation and game management.

Kafle, School of Forest Sciences, University of Eastern Finland (UEF), Yliopistokatu 7, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-0744-3480 E-mail: binod.kafle@uef.fi
Kankare, Department of Geography and Geology, University of Turku, FI-20014 Turun yliopisto, Finland https://orcid.org/0000-0001-6038-1579 E-mail: viveka@utu.fi
Kaartinen, Department of Remote Sensing and Photogrammetry, Finnish Geospatial Research Institute (FGI), Opastinsilta 12 C, FI-00520 Helsinki, Finland https://orcid.org/0000-0002-4796-3942 E-mail: harri.kaartinen@nls.fi
Väätäinen, Natural Resources Institute Finland (Luke), Yliopistokatu 6 B, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-6886-0432 E-mail: kari.vaatainen@luke.fi
Hyyti, Department of Remote Sensing and Photogrammetry, Finnish Geospatial Research Institute (FGI), Opastinsilta 12 C, FI-00520 Helsinki, Finland https://orcid.org/0000-0003-4664-6221 E-mail: heikki.hyyti@nls.fi
Faitli, Department of Remote Sensing and Photogrammetry, Finnish Geospatial Research Institute (FGI), Opastinsilta 12 C, FI-00520 Helsinki, Finland https://orcid.org/0000-0001-5334-5537 E-mail: tamas.faitli@nls.fi
Hyyppä, Department of Remote Sensing and Photogrammetry, Finnish Geospatial Research Institute (FGI), Opastinsilta 12 C, FI-00520 Helsinki, Finland E-mail: juha.coelasr@gmail.com
Kukko, Department of Remote Sensing and Photogrammetry, Finnish Geospatial Research Institute (FGI), Opastinsilta 12 C, FI-00520 Helsinki, Finland https://orcid.org/0000-0002-3841-6533 E-mail: antero.kukko@nls.fi
Kärhä, School of Forest Sciences, University of Eastern Finland (UEF), Yliopistokatu 7, FI-80101 Joensuu, Finland E-mail: kalle.karha@uef.fi

article id 25003, category Research article

Lennart Noordermeer, Terje Gobakken, Johannes Breidenbach, Rune Eriksen, Erik Næsset, Hans Ole Ørka, Ole M. Bollandsås. (2025). Effects of sample tree selection and calculation methods on the accuracy of field plot values in area-based forest inventories. Silva Fennica vol. 59 no. 2 article id 25003. https://doi.org/10.14214/sf.25003

Keywords: forest inventory methods; field plot accuracy; height-diameter modeling; sample tree selection

Highlights: Retaining field-measured heights of sample trees improved accuracies of plot values; Selecting sample trees with probability proportional to basal area was recommended; The number of sample trees and sample tree selection method impacted accuracies; The choice of calculation method had a strong influence on accuracies of plot values.

Abstract | Full text in HTML | Full text in PDF | Author Info

Accurate field plot data on forest attributes are crucial in area-based forest inventories assisted by airborne laser scanning, providing an essential reference for calibrating predictive models. This study assessed how sample tree selection methods and plot data calculation methods affect the accuracy of field plot values of timber volume, Lorey’s mean height, and dominant height. We used data obtained from 12 420 circular sample plots of 250 m², measured as part of the Norwegian national forest inventory and 45 local forest management inventories. We applied Monte Carlo simulations by which we tested various numbers of sample trees, methods to select sample trees, and methods to calculate plot-level values from tree-level measurements. Accuracies of plot values were statistically significantly affected by the number of sample trees, sample tree selection method, and calculation method. Obtained values of root mean square error ranged from 5% to 16% relative to the mean observed values, across the factors studied. Accuracy improved with increasing numbers of sample trees for all forest attributes. We obtained greatest accuracies by selecting sample trees with a probability proportional to basal area, and by retaining field-measured heights for sample trees and using heights predicted with a height-diameter model for non-sample trees. This study highlights the importance of appropriate sample tree selection methods and calculation methods in obtaining accurate field plot data in area-based forest inventories.

Noordermeer, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0002-8840-0345 E-mail: lennart.noordermeer@nmbu.no
Gobakken, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0001-5534-049X E-mail: terje.gobakken@nmbu.no
Breidenbach, Division of Forest and Forest Resources, Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, NO-1431 Ås, Norway E-mail: johannes.breidenbach@nibio.no
Eriksen, Division of Forest and Forest Resources, Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, NO-1431 Ås, Norway E-mail: rune.eriksen@nibio.no
Næsset, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway E-mail: erik.naesset@nmbu.no
Ørka, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway E-mail: hans-ole.orka@nmbu.no
Bollandsås, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0002-1231-7692 E-mail: ole.martin.bollandsas@nmbu.no

article id 24046, category Research article

Līga Liepa, Zigmārs Rendenieks, Edgars Dubrovskis, Lāsma Freimane, Inga Straupe, Āris Jansons. (2025). Patterns of short-term vegetation recovery after a fire in protected Scots pine forests of hemiboreal Latvia. Silva Fennica vol. 59 no. 1 article id 24046. https://doi.org/10.14214/sf.24046

Keywords: succession; fire disturbance; plant functional traits; post-fire regeneration; protected forests

Highlights: We observed more rapid vegetation recovery at the ground level, but the dominance increased more steadily at herb and tree layers; We found the highest species diversity at the herb layer during the third (middle-aged stands) and fourth (over-mature stands) years after fire disturbance; From regenerating tree species, only Populus tremula in over-mature stands showed a decline in projective cover during the four studied years.

Abstract | Full text in HTML | Full text in PDF | Author Info

Wildfires as natural disturbances have had important impacts on terrestrial ecosystems, including forests. We studied patterns of short-term vegetation recovery after surface fire in protected hemiboreal Pinus sylvestris L.-dominated forest. Our study was carried out near Stikli village in Western Latvia. Seven forest stands – middle-age and over-mature were sampled on nutrient-poor and mesic soils. Forest fire occurred in the summer of 2018 and covered 1440 ha of forested area. In each stand we established 16 sample plots (1 m × 1 m) in a radial pattern from the center. Every summer from 2019 till 2022 we surveyed these sample plots – recorded projective cover (%) and identified Ellenberg indicator values and species traits – plant strategy groups (C-S-R after Grime), Raunkiær life history forms and habitat types. Additionally, the occurrence of specialized fire-adapted plants was recorded. In total we identified 15 species in the ground layer, 47 species in the herbaceous layer, and 9 regenerating tree species. The colonization at the ground layer was the most rapid (projective cover increased overall by 67% in middle-aged stands and by 82% in over-mature stands). Species diversity was the highest at the herb layer during the third (middle-aged stands) and fourth (over-mature stands) after fire disturbance but showed overall declining trends. Betula spp. and Populus tremula L.-dominated regenerating tree species. The dominance of fire-adapted species declined rapidly after the fire except for moss Polytrichum spp. Overall, hemiboreal over-mature stands demonstrated higher vegetation cover and more rapid rate of initial colonization compared to middle-aged stands.

Liepa, Latvian State Forest Research Institute “Silava”, Rīgas street 111, LV-2169, Salaspils, Latvia; Latvian University of Life Sciences and Technologies, Faculty of Forest and Environmental Sciences, Akadēmijas street 11, LV-3001, Jelgava, Latvia https://orcid.org/0000-0002-8270-6722 E-mail: liga.liepa@outlook.com
Rendenieks, Latvian State Forest Research Institute “Silava”, Rīgas street 111, LV-2169, Salaspils, Latvia https://orcid.org/0000-0002-3511-1486 E-mail: zigmars.rendenieks@silava.lv
Dubrovskis, Latvian University of Life Sciences and Technologies, Faculty of Forest and Environmental Sciences, Akadēmijas street 11, LV-3001, Jelgava, Latvia https://orcid.org/0000-0003-0810-5651 E-mail: edgars.dubrovskis@lbtu.lv
Freimane, Latvian University of Life Sciences and Technologies, Faculty of Forest and Environmental Sciences, Akadēmijas street 11, LV-3001, Jelgava, Latvia E-mail: lasma.freimane@lbtu.lv
Straupe, Latvian University of Life Sciences and Technologies, Faculty of Forest and Environmental Sciences, Akadēmijas street 11, LV-3001, Jelgava, Latvia https://orcid.org/0000-0002-2098-7194 E-mail: inga.straupe@lbtu.lv
Jansons, Latvian State Forest Research Institute “Silava”, Rīgas street 111, LV-2169, Salaspils, Latvia https://orcid.org/0000-0001-7981-4346 E-mail: aris.jansons@silava.lv

article id 24041, category Research article

Johanna Jetsonen, Annamari Laurén, Heli Peltola, Katariina Laurén, Samuli Launiainen, Marjo Palviainen. (2025). Volume growth responses of Scots pine and Norway spruce to nitrogen fertilization: quantitative synthesis of fertilization experiments in Finland. Silva Fennica vol. 59 no. 1 article id 24041. https://doi.org/10.14214/sf.24041

Keywords: precipitation; growth response; mineral soils; site fertility

Highlights: Volume growth responses increased linearly with the applied nitrogen (N) dose up to 200 kg N ha^–1; Precipitation, site fertility, and time since fertilization affected the growth responses; Volume growth response to nitrogen fertilization was larger for Scots pine than for Norway spruce; Results can support planning of environmentally responsible and economically viable precision fertilization.

Abstract | Full text in HTML | Full text in PDF | Author Info

The effects of nitrogen (N) fertilization on tree growth have been studied widely in boreal forests in Finland, but a quantitative synthesis is still lacking. We performed a quantitative synthesis on volume growth responses to N fertilization in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands in experiments established on mineral soils across Finland. Our study employed findings of 9 published studies including 108 Scots pine and 57 Norway spruce observations covering a wide range of N fertilization treatments, as well as forest stand- and climatic conditions. Based on these observations, we built linear mixed models to describe the N fertilization-induced annual volume growth response of Scots pine and Norway spruce stands. Our models showed that the N dose was the best predictor for volume growth response, and the growth response increased linearly with increasing N dose for both tree species. The volume growth responses also increased along with an increase in mean annual precipitation. The annual volume growth response decreased with the time since fertilization. For Scots pine, the best model also contained site fertility; increase in site fertility increased the volume growth response. These findings emphasize the need for site-specific precision fertilization schemes to sustainably improve growth and carbon sequestration of boreal forests.

Jetsonen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Finland https://orcid.org/0009-0006-4878-8951 E-mail: johanna.jetsonen@helsinki.fi
Laurén, Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Finland; Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0002-6835-9568 E-mail: annamari.lauren@helsinki.fi
Peltola, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-1384-9153 E-mail: heli.peltola@uef.fi
Laurén, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland; University of Helsinki, Faculty of Medicine, Haartmaninkatu 8, 00290 Helsinki, Finland https://orcid.org/0009-0009-4677-9826 E-mail: katariina.lauren@helsinki.fi
Launiainen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, 00790 Helsinki, Finland https://orcid.org/0000-0001-6611-6573 E-mail: samuli.launiainen@luke.fi
Palviainen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Finland https://orcid.org/0000-0001-9963-4748 E-mail: marjo.palviainen@helsinki.fi

article id 24026, category Research article

Olli Muhonen, Heli Peltola, Annamari Laurén, Veli-Pekka Ikonen, Juha Nevalainen, Laura Pikkarainen, Antti Kilpeläinen, Samuli Launiainen, Marjo Palviainen. (2025). Spatial evenness of fertilization and short-term volume growth responses of Scots pine and Norway spruce to fertilization intensity. Silva Fennica vol. 59 no. 1 article id 24026. https://doi.org/10.14214/sf.24026

Keywords: Pinus sylvestris; boreal forest; Picea abies; stand growth; forest fertilization; upland forests; nitrogen fertilizer dose

Highlights: Differences between the target and the measured fertilizer doses were in a range of 3–22% for fertilization treatments in Scots pine and Norway spruce study sites; The volume growth response was affected by the initial basal area and fertilization dose; The fertilization dose correlated with nitrogen concentrations in needles and soil organic (humus) layer and volume growth.

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We studied the spatial evenness of nitrogen (N) fertilizer and the effects of fertilization intensity on the short-term volume growth responses in two ground-fertilized Scots pine and two airborne-fertilized Norway spruce study sites on mesic (Myrtillus-type) upland forests in Eastern Finland. We also studied the relationships between measured fertilizer dose, N concentrations in the needles and soil organic (humus) layer, and volume growth of the trees. In each study site, we established three replicate 1 ha blocks for each fertilization treatment (0, 150 and 200 kg N ha^–1). Each block contained three 200 m² circular plots. The spatial evenness of the fertilizer was measured using textile funnels. The height, breast height diameter and vitality of the trees were measured annually. The nutrient concentrations in the needles and humus layer were measured once. Differences between the target and measured fertilizer doses were 3–10% for Scots pine and 11–22% for Norway spruce. At the Scots pine and Norway spruce sites, the volume growth was 0.4–2.1 and 1.8–2.6 m³ ha^–1 a^–1 higher with fertilization, respectively. The fertilizer dose correlated with the N concentrations in the needles and humus layer, and volume growth. Significant volume growth responses to the fertilization (p < 0.05) were found only in the Scots pine at Ilomantsi, possibly due to variations in the initial volume and the fertilizer dose realized between and within treatments. We expect that the differences in volume growth responses between fertilization treatments will increase over time.

Muhonen, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, FI-80101 Joensuu, Finland https://orcid.org/0009-0007-4051-8567 E-mail: ollmu@uef.fi
Peltola, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-1384-9153 E-mail: heli.peltola@uef.fi
Laurén, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, FI-80101 Joensuu, Finland; University of Helsinki, Department of Forest Sciences, Latokartanonkaari 7, FI-00014 Helsinki, Finland https://orcid.org/0000-0002-6835-9568 E-mail: annamari.lauren@helsinki.fi
Ikonen, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-1732-2922 E-mail: veli-pekka.ikonen@uef.fi
Nevalainen, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, FI-80101 Joensuu, Finland https://orcid.org/0009-0000-2972-4385 E-mail: juha.hs.nevalainen@gmail.com
Pikkarainen, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, FI-80101 Joensuu, Finland https://orcid.org/0000-0001-5301-3639 E-mail: laura.pikkarainen@uef.fi
Kilpeläinen, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-4299-0578 E-mail: antti.kilpelainen@uef.fi
Launiainen, Natural Resources Institute Finland, Bioeconomy and Environment, Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0001-6611-6573 E-mail: samuli.launiainen@luke.fi
Palviainen, University of Helsinki, Department of Forest Sciences, Latokartanonkaari 7, FI-00014 Helsinki, Finland https://orcid.org/0000-0001-9963-4748 E-mail: marjo.palviainen@helsinki.fi

article id 23080, category Research article

Irene Kuhmonen, Annukka Näyhä, Miisa Solaranta, Janne Keränen. (2024). Can small and medium-sized companies increase the value added from wood-based side streams? Silva Fennica vol. 58 no. 5 article id 23080. https://doi.org/10.14214/sf.23080

Keywords: circular bioeconomy; dynamic capabilities; forest-based sector; strategic niche management; sustainability transition; wood-based SMEs

Highlights: Upgrading the use of wood-based side streams is necessary for circular bioeconomy; Small and medium-sized companies offer innovative solutions for using wood-based side streams; Companies utilizing the side streams host a variety of dynamic capabilities; Strong technological orientation reduces horizontal networking among innovative small and medium-sized companies; The forest-based regime resists the spread of innovations aiming for higher value added.

Abstract | Full text in HTML | Full text in PDF | Author Info

One of the central goals of circular bioeconomy in the Finnish forest-based sector is upgrading the use of wood-based materials, especially wood-based side streams, to higher value-added products. However, despite these ambitions, most wood-based side streams are used in energy production. Within the forest-based sector, innovative solutions for higher value-added production of wood-based side streams are being developed within small and medium-sized companies (SMEs). Therefore, to promote the process of upscaling these solutions, understanding the success of these companies is pivotal. For this end, we conducted a qualitative study with 10 forest-based SMEs utilizing wood-based side streams to understand both the internal and external factors affecting their ability to scale up their business models. By applying the dynamic capabilities approach from management research and the strategic niche management approach from sociotechnical transition studies, we found that even though the companies are internally well positioned to succeed in their growth aspirations, they face barriers from the dominant forest-based regime. The studied SMEs are facing a mismatch between their own business models and the rules and operating principles of the forest-based sector based on linear economy. Overcoming these barriers and challenging the dominant structures within the Finnish forest-based regime would require joint efforts from the companies. However, the companies have a strong technological orientation, which makes them hesitant with regard to horizontal networking. They also operate in diverse markets, making it difficult for them to find common ground. As a result, the pressure for systemic transformation within the forest-based sector remains nominal.

Kuhmonen, University of Jyväskylä, School of Business and Economics, P.O. Box 35, FI-40014 University of Jyväskylä, Finland https://orcid.org/0000-0002-1407-8349 E-mail: irene.a.kuhmonen@jyu.fi
Näyhä, University of Jyväskylä, School of Business and Economics, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: annukka.nayha@jyu.fi
Solaranta, University of Jyväskylä, School of Business and Economics, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: miisa.solaranta@gmail.com
Keränen, VTT Technical Research Centre of Finland Ltd, P.O. Box 1603, FI-40101 Jyväskylä, Finland https://orcid.org/0000-0002-5626-2929 E-mail: janne.keranen@vtt.fi

article id 23035, category Research article

Venla Wallius, Janni Kunttu, Elias Hurmekoski, Teppo Hujala, Anders Q. Nyrud, Hans F. Hoen. (2024). Attractiveness of wood-frame multi-storey buildings in seven European countries: consumer segmentation and the effect of fire safety information. Silva Fennica vol. 58 no. 5 article id 23035. https://doi.org/10.14214/sf.23035

Keywords: wood construction; consumer perceptions; consumer segmentation; fire safety

Highlights: There are significant differences in the perceived attractiveness of wooden multi-storey construction between consumer segments; According to the survey results, young consumers living in urban areas have the most interest in wooden multi-storey construction; Targeted marketing efforts are needed to inform potential consumers of wooden multi-storey construction.

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Wooden construction has the potential to contribute to climate change mitigation, and it is being promoted by the EU and national governments. However, several market barriers to wood-frame multi-storey building (WMSB), have been recognized, including obstacles in national building codes, lack of expertise in wood construction, and material durability concerns among end-users as well as other technical aspects. Given that increased wood construction is a target, understanding consumer perceptions of WMSB is crucial. In this study, consumer attitudes on WMSB were studied through consumer segmentation relying on demographic attributes. Further, the effect of providing fire safety information was explored. To this end, an online survey was deployed in seven European countries, with 7007 responses. The results show that in general, the awareness and attractiveness of WMSB is low amongst European consumers. Out of all respondents, 46% had not heard of WMSB before and only 12% stated that they are interested in the subject and know something about it, showing a clear lack of information and awareness within the general public. Significant differences in the perceived attractiveness of wooden multi-storey construction between consumer segments exist, with younger consumers and urban consumers being more attracted to living in WMSB than older or rural consumers. Fire safety was an important attribute affecting overall attractiveness, yet updated information regarding fire safety and control in WMSBs had a small but statistically significant negative effect on the perceived attractiveness. The results indicate that targeted marketing efforts are needed to inform potential consumers of WMSB and aspects related to fire safety effectively.

Wallius, European Forest Institute, Yliopistokatu 6 B, FI-80100, Joensuu, Finland; Jyväskylä University School of Business and Economics, P.O. Box 35, FI-40014 University of Jyväskylä, Finland https://orcid.org/0000-0003-2576-9994 E-mail: venla.j.wallius@jyu.fi
Kunttu, University of Helsinki, Department of Forest Sciences, P.O. Box 4, FI-00014 University of Helsinki, Finland https://orcid.org/0000-0002-7298-3363 E-mail: janni.kunttu@helsinki.fi
Hurmekoski, University of Helsinki, Department of Forest Sciences, P.O. Box 4, FI-00014 University of Helsinki, Finland https://orcid.org/0000-0001-8717-7287 E-mail: elias.hurmekoski@helsinki.fi
Hujala, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0002-7905-7602 E-mail: teppo.hujala@uef.fi
Nyrud, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: anders.qvale.nyrud@nmbu.no
Hoen, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: hans.hoen@nmbu.no

article id 24011, category Research article

Alexander Kaulen, Benjamin Engler, Thomas Purfürst. (2024). Net carbon storage of supplied timber in highly mechanized timber harvest. Silva Fennica vol. 58 no. 4 article id 24011. https://doi.org/10.14214/sf.24011

Keywords: carbon balance; emissions; forest machine data; forestry technique; timber supply chain; traceability

Highlights: CO₂ emissions from timber supply comprise only 1.5–5% of the CO₂ stored in wood; Distance to the mill has the greatest influence on CO₂ emissions; Successful application by combining a few variable parameters from forest machine data with constant parameters to create a net carbon storage of the supplied timber; Simple presentation of the net CO₂ storage capacity of wood can influence policy positively.

Abstract | Full text in HTML | Full text in PDF | Author Info

Highly mechanized timber harvesting and timber logistics emit CO₂. In turn, the provided timber stores CO₂ from the atmosphere as biogenic carbon. This basic assumption resulted in the calculation of net carbon storage of supplied timber. For this, we first developed a formula that represents the carbon content of freshly harvested timber. Coniferous wood contains about 734 kg CO₂ m^-3 and deciduous wood about 1000 CO₂ m^-3. Contrary to this, CO₂ emissions from trucks, harvesters, and forwarders were calculated using the variable parameters for actual diesel consumption and the distance to the sawmill and constant parameters for the transport of the machine to the stand, lubricants, transport of operators, loading, and fabrication, supply, and maintenance. The method was tested on an actual harvest. The principal findings are that the method is practical, the net carbon storage of the supplied timber is reduced by 1.5% to 5% by harvesting and transport activities, and timber logistics is the largest contributor to emissions. The CO₂ emissions for harvesters and forwarders are about 4 kg CO₂ m^-3, and for downstream timber logistics across all assortments and distances is 11 kg CO₂ m^-3. We conclude that the emissions are low, vis-a-vis the storage capacity. Emissions and a standardized calculation model are imperative. The model developed here for mapping the net carbon storage of roundwood highlights the climate protection performance of timber and contributes to optimizing climate-friendly timber supply chains.

Kaulen, KWF - Kuratorium für Waldarbeit und Forsttechnik e.V., Spremberger Straße 1, 64823 Groß-Umstadt, Germany; University of Freiburg, Chair of Forest Operations, Werthmannstr. 6, 79085 Freiburg, Germany https://orcid.org/0009-0006-2633-8132 E-mail: alexander.kaulen@kwf-online.de
Engler, University of Freiburg, Chair of Forest Operations, Werthmannstr. 6, 79085 Freiburg, Germany https://orcid.org/0000-0003-2104-8209 E-mail: benjamin.engler@foresteng.uni-freiburg.de
Purfürst, University of Freiburg, Chair of Forest Operations, Werthmannstr. 6, 79085 Freiburg, Germany https://orcid.org/0000-0001-9661-0193 E-mail: thomas.purfuerst@foresteng.uni-freiburg.de

article id 23077, category Research article

Timo Domisch, Saija Huuskonen, Juho Matala, Ari Nikula. (2024). Interactive effects of moose browsing and stand composition on the development of mixed species seedling stands. Silva Fennica vol. 58 no. 4 article id 23077. https://doi.org/10.14214/sf.23077

Keywords: boreal forest; tree species; Alces alces; ungulates; moose damage; mixed stands; meta-analysis

Highlights: We conducted meta-analyses assessing effect sizes of moose exclusion on seedling density and height, as well as regressions between stand density and deciduous seedling proportion and effect sizes; The more deciduous trees in a seedling stand, the smaller was the fencing effect, but at some point, the conifer seedling growth was impaired by too many deciduous seedlings. At the same time, the protective fencing effect increased with stand density; An appropriate deciduous admixture in conifer-dominated mixed seedling stands seems to improve moose damage tolerance.

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The moose (Alces alces L.), a common large herbivore in the boreal region, impairs forest regeneration by browsing on tree seedlings and saplings. Moose prefer deciduous species, but during winter more coniferous seedlings are used. We used meta-analyses, separately for deciduous and coniferous seedlings, for evaluating whether excluding moose browsing affected seedling density and height. In addition, we compared (1) deciduous seedling proportion, (2) stand density, (3) elapsed time from fencing and (4) estimated moose density with moose exclusion effect sizes. Fencing had a positive effect on coniferous seedling height. With more deciduous trees in a seedling stand, the fencing effect for both seedling height and density of coniferous seedlings decreased. On the other hand, the fencing effects increased with denser stands. At some point effect sizes turned to negative, and conifer species varied in their response to browsing. This implies that deciduous seedlings can protect conifers from browsing by moose up to some mixing ratio, but when deciduous seedling densities are too high, their negative effect increases, presumably through increased competition. Our results suggest that a moderate deciduous admixture in conifer-dominated mixed seedling stands can decrease moose damage but also underline the significance of timely silvicultural measures to minimize the negative effects of excessive deciduous seedlings and too dense stands. Due to differences in coniferous and deciduous species, as well as their compositions and amounts in studied experiments, more studies adjusted to local conditions are still needed to give exact measures for silvicultural recommendations.

Domisch, Natural Resources Institute Finland (Luke), Natural Resources, Yliopistokatu 6B, FI-80100 Joensuu, Finland https://orcid.org/0000-0001-7026-1087 E-mail: timo.domisch@luke.fi
Huuskonen, Natural Resources Institute Finland (Luke), Natural Resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: saija.huuskonen@luke.fi
Matala, Natural Resources Institute Finland (Luke), Natural Resources, Yliopistokatu 6B, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-5867-5057 E-mail: juho.matala@luke.fi
Nikula, Natural Resources Institute Finland (Luke), Natural Resources, Ounasjoentie 6, FI-96200 Rovaniemi, Finland https://orcid.org/0000-0001-8372-8440 E-mail: ari.nikula@luke.fi

article id 23018, category Research article

Anssi Ahtikoski, Kari Väätäinen, Perttu Anttila, Juha Laitila, Antti Mutanen, Jari Lindblad, Lauri Sikanen, Johanna Routa. (2024). The effects of the EU’s forest-related policies on harvesting costs in Finland. Silva Fennica vol. 58 no. 3 article id 23018. https://doi.org/10.14214/sf.23018

Keywords: forests; scenario approach; harvesting costs; directives and regulations; EU legislation; structural systems analysis

Highlights: The EU’s forest-related policies set direct and indirect limitations on the harvesting operations and operating environment; The effect on harvesting costs of Directives and Regulations depends on the magnitude of policy implementation; In a high-impact scenario, harvesting costs could increase by as much as 18% from the current level of costs.

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The EU’s influence on national forest policies is growing, and the implementation of forest-related policies proposed by the Commission will affect the practice of forestry in Europe. For instance, the Nature Restoration Law sets concrete areal goals for restoring forest ecosystems and for conservation, the Deforestation Regulation requires meticulous tracking of wood’s origin, and the renewed Renewable Energy Directive (RED III) sets new criteria to sustainable forest biomass procurement. So far there have been no studies that have looked into the impacts from the economic and operational point of view. In this study, structural systems analysis was first performed to discover the relevant variables (and their functioning) associated with the roundwood harvesting operations and the operating environment. A scenario approach was then applied to capture the potential levels of implementation of the EU’s forest-related policies. Finally, using different scenarios (low-, moderate- and high-impact) and a systems analysis framework, the impact of alternative levels of implementation was quantified in terms of harvesting costs, measured in € m^–3. The results indicate that with the low- and moderate-impact scenarios the harvesting costs would increase by less than 10% from the current levels in three different regions in Finland. Such an increase (less than 10%) could be tolerated over a period of a few years, but a sudden increase is likely to lead to challenges to the running of businesses. With the high-impact scenario the harvesting costs would increase by between 15% and 18%, depending on the region. This magnitude of increase (of approximately a sixth) corresponds to a severe change in the roundwood harvesting operations and operating environment.

Ahtikoski, Natural Resources Institute Finland (Luke), Tekniikankatu 1, FI-33720 Tampere, Finland https://orcid.org/0000-0003-1658-3813 E-mail: anssi.ahtikoski@luke.fi
Väätäinen, Natural Resources Institute Finland (Luke), Yliopistonkatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-6886-0432 E-mail: kari.vaatainen@luke.fi
Anttila, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0002-6131-392X E-mail: perttu.anttila@luke.fi
Laitila, Natural Resources Institute Finland (Luke), Yliopistonkatu 6, FI-80100 Joensuu, Finland E-mail: juha.laitila@luke.fi
Mutanen, Natural Resources Institute Finland (Luke), Yliopistonkatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0003-0533-9356 E-mail: antti.mutanen@luke.fi
Lindblad, Natural Resources Institute Finland (Luke), Yliopistonkatu 6, FI-80100 Joensuu, Finland https://orcid.org/0009-0003-6766-6587 E-mail: jari.lindblad@luke.fi
Sikanen, Natural Resources Institute Finland (Luke), Yliopistonkatu 6, FI-80100 Joensuu, Finland E-mail: lauri.sikanen@luke.fi
Routa, Natural Resources Institute Finland (Luke), Yliopistonkatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0001-7225-1798 E-mail: johanna.routa@luke.fi

article id 23029, category Research article

Amira Fetouab, Nicole J. Fenton, Nelson Thiffault, Martin Barrette. (2024). Planting density and mechanical site preparation effects on understory composition, functional diversity and planted black spruce growth in boreal forests. Silva Fennica vol. 58 no. 2 article id 23029. https://doi.org/10.14214/sf.23029

Keywords: silviculture; paludification; reforestation; plantation establishment; community ecology; functional ecology

Highlights: Mechanical site preparation and planting density interacted to influence understory diversity and composition in plowed plots; Careful logging alone resulted in higher density of naturally established conifers; Planting density and site preparation alone had no effect on tree height and diameter; Findings provide insights for managing paludified forests and enhancing forest ecosystem functions.

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Mechanical site preparation (MSP) is used prior to planting to control competing vegetation and enhance soil conditions, particularly in areas prone to paludification. Tree planting density can be adapted to the management context and objectives, as it influences yield and wood quality. However, the combined effects of MSP and planting density on understory vegetation composition, functional traits, and diversity remain uncertain. We thus conducted a study in the Clay Belt region of northwestern Quebec, Canada. After careful logging, the study area was divided into nine sites, each receiving one of three treatments: plowing, disc trenching, or no preparation. Sites were further divided into two, with black spruce (Picea mariana [Mill.] Britton, Sterns & Poggenb.) seedlings planted at either a low planting density of 1100 seedlings ha^-1 or a high planting density of 2500 seedlings ha^-1. After nine years, we assessed understory composition, diversity, key functional traits, sapling density and growth of planted trees. Careful logging alone led to a higher density of naturally established conifers compared to plowing or disc trenching. The interaction between planting density and MSP significantly influenced understory diversity and composition in plowed plots. Understory composition was affected by the soil C/N ratio, coniferous species, and deciduous species density. The growth of black spruce was notably enhanced with higher planting density in the plow treatment only. Neither planting density nor MSP alone affected tree height and diameter. Our results suggest that combining plowing with high-density planting can enhance stand growth and improve forest productivity. These findings guide future research on paludified forests.

Fetouab, Institute for Forest Research and Centre for Forest Research, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada E-mail: amira.fetouab@uqat.ca
Fenton, Institute for Forest Research and Centre for Forest Research, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada https://orcid.org/0000-0002-3782-2361 E-mail: nicole.fenton@uqat.ca
Thiffault, Institute for Forest Research and Centre for Forest Research, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada; Canadian Wood Fibre Centre, Natural Resources Canada, 1055 du P.E.P.S, P.O. Box 10380, Sainte-Foy Stn, Québec, QC G1V 4C7, Canada https://orcid.org/0000-0003-2017-6890 E-mail: nelson.thiffault@canada.ca
Barrette, Institute for Forest Research and Centre for Forest Research, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada; Direction de la recherche forestière, Ministère des Ressources naturelles et des Forêts, 2700 rue Einstein, Québec, QC G1P 3W8, Canada https://orcid.org/0000-0001-5937-382X E-mail: martin.barrette@mffp.gouv.qc.ca

article id 23072, category Research article

Matti Haapanen. (2024). Realised genetic gains from past Finnish silver birch seed orchards. Silva Fennica vol. 58 no. 1 article id 23072. https://doi.org/10.14214/sf.23072

Keywords: Betula pendula; seed orchards; genetic gain; forest reproductive materials

Highlights: Seed orchard materials generally outperformed unimproved trees in all growth and quality traits, but individual seed orchards showed substantial performance variability; Realised gains in stem volume and forking showed an increasing temporal trend, whereas gains in branch quality were positive and steady; Gains in stem volume and branch quality trade off slightly; The bi-clonal seed orchard variety “JR-2” emerged as the best overall performer across all the seed orchards, whereas the older variety “JR-1” was mediocre; An alternative statistical concept, D-value, was introduced to compare levels of genetic gains for different scaled, normally distributed traits.

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Genetic gains realised through silver birch (Betula pendula Roth) seed orchards were studied using data from common-garden trials established at 34 sites in southern and central Finland. The test materials include seedlots representing 19 commercial seed orchards that operated between 1972 and 2009, and 21 natural stands. All the trials were assessed for several growth and quality traits between the ages of 9 and 24. Realised gains were estimated based on univariate linear mixed models with corrections for latitudinal seed transfer effects. Overall, seed orchard materials outperformed unimproved reference materials in all the traits but results for individual seed orchards varied substantially. Stem volume gains ranged from 1.0% to 31.1%. Improved trees had, on average, 6.8% (up to 26.7%) fewer ramicorn branches and 16.2% (up to 57.6%) fewer forks than unimproved trees. Branch and overall quality showed consistently positive gains. More recently established seed orchards performed better than older ones, and seed orchards with fewer clones outperformed those with dozens of clones. "JR-1" and "JR-2" bi-clonal seed orchards fared differently, with "JR-1" showing modest genetic gains and "JR-2" emerging as the top overall performer across all seed orchards. An alternative statistical concept, the D-value, was utilised to assess the magnitude of genetic gain for different scaled, normally distributed traits. Average D-values implied a similar level of improvement for stem volume, branch quality, and forking, and a smaller gain for stem slenderness and the number of ramicorn branches. The results for individual seed orchards suggest a slight trade-off between stem volume growth and branch quality.

Haapanen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, 00790 Helsinki, Finland https://orcid.org/0000-0003-3294-501X E-mail: matti.haapanen@luke.fi

article id 23032, category Research article

Maria Anna Gartner, Matthias Kaltenbrunner, Manfred Gronalt. (2024). Dynamic box assignment planning in log yards. Silva Fennica vol. 58 no. 1 article id 23032. https://doi.org/10.14214/sf.23032

Keywords: storage assignment; seasonality; binary integer program; optimisation model; sawmill storage

Highlights: Seasonal change of assortments calls for dynamic box assignment planning in log yards; Multi-period planning better suited for dynamic problem, however period per period planning improves with decreasing capacity on the log yard; Rearrangement of assortment amounts to 8–11% of total transportation distance (loaded travelled distances of transportation vehicle); Considering separate box allocation (storage and ejection), which results in double stage planning of box allocation, benefits most if 10% additional volume may be cut in to clear the box.

Abstract | Full text in HTML | Full text in PDF | Author Info

The situation on the log yard changes seasonally and also over the years. The quantities of assortments to be stored, their number and also the type of wood can change. To respond to this, we have developed a dynamic log yard planning model for assigning roundwood to specific ejection boxes and storage areas in order to minimise the overall transport distances of the loaded transportation vehicles on the log yard, including any possible re-allocation of assortments. The study centres on the log yard of a medium-sized hardwood sawmill in Europe, with actual cutting data from a six-month period. We are comparing a multi-period binary integer program with a model that operates on a period per period basis and a solution approach that splits the problem into two subproblems and solves them sequentially. The models undergo testing with decreasing space capacities at the storage boxes on the log yard and are compared. If capacity is continuously decreasing from 100% to 80%, then period per period planning is on average 13% worse than multi-period planning. We also investigate how the solutions change when twice as many or half as many assortments are stored at the log yard. In addition, we study how much the solutions improve when logs can be removed from the storage boxes to clear them and release them for other material in the following period.

Gartner, University of Natural Resources and Life Sciences, Department of Economics and Social Sciences, Institute of Production and Logistics, Feistmantelstrasse 4, 1180 Vienna, Austria https://orcid.org/0000-0001-8547-718X E-mail: maria.gartner@boku.ac.at
Kaltenbrunner, improvem GmbH, Holzinnovationszentrum 1a, 8740 Zeltweg, Austria https://orcid.org/0000-0002-1178-0087 E-mail: matthias.kaltenbrunner@improvem.at
Gronalt, University of Natural Resources and Life Sciences, Department of Economics and Social Sciences, Institute of Production and Logistics, Feistmantelstrasse 4, 1180 Vienna, Austria https://orcid.org/0000-0003-0944-4911 E-mail: manfred.gronalt@boku.ac.at

article id 23040, category Research article

Jānis Liepiņš, Ieva Jaunslaviete, Kaspars Liepiņš, Līga Jansone, Roberts Matisons, Andis Lazdiņš, Āris Jansons. (2023). Effect of stem rot on wood basic density, carbon, and nitrogen content of living deciduous trees in hemiboreal forests. Silva Fennica vol. 57 no. 3 article id 23040. https://doi.org/10.14214/sf.23040

Keywords: wood specific gravity; birch; climate change mitigation; biomass estimation; alder; aspen; wood decay

Highlights: Stem rot significantly reduces the basic density of wood and increases its nitrogen content in living deciduous trees, while the carbon content appears irresponsive; The effect of the distance from the pith on the basic density and nitrogen content of wood varies, depending on presence of discoloration or decomposition in the wood.

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While numerous studies have focused on analyzing various aspects of the carbon (C) budget in forests, there appears to be a lack of comprehensive assessments specifically addressing the impact of stem rot on the C budget of broadleaf tree species, especially in old-growth forests where stem rot is prevalent. One of the main challenges in accurately quantifying C losses caused by stem rot is the lack of precise data on the basic density and C content of decayed wood, which are crucial for converting decayed wood volume into biomass and C stocks. Using linear mixed-effects models, we examine the variability of wood basic density, C content, and nitrogen (N) content. Discolored and decomposed wood was collected from the stems of 136 living deciduous trees common in hemiboreal forests in Latvia. Our research indicates a noticeable reduction in the wood basic density, coupled with an increase in the N content within the stem wood throughout the decomposition process in birch (Betula spp.), European aspen (Populus tremula L.), grey alder (Alnus incana (L.) Moench), and common alder (Alnus glutinosa (L.) Gaertn.). While aspen wood showed a decreasing trend in C content as decay progressed, a pairwise comparison test revealed no significant differences in C content between discolored and decomposed wood for the studied species, unlike the findings for basic density and N content. This study emphasizes the need to account for stem rot in old-growth forest carbon budgets, especially in broadleaf species, and calls for more research on stem rot-induced carbon losses.

Liepiņš, Latvian State Forest Research Institute “Silava,” Rigas Street 111, LV-2169 Salaspils, Latvia https://orcid.org/0000-0003-3030-1122 E-mail: janis.liepins@silava.lv
Jaunslaviete, Latvian State Forest Research Institute “Silava,” Rigas Street 111, LV-2169 Salaspils, Latvia https://orcid.org/0009-0000-7322-2729 E-mail: ieva.jaunslaviete@silava.lv
Liepiņš, Latvian State Forest Research Institute “Silava,” Rigas Street 111, LV-2169 Salaspils, Latvia https://orcid.org/0000-0002-1179-8586 E-mail: kaspars.liepins@silava.lv
Jansone, Latvian State Forest Research Institute “Silava,” Rigas Street 111, LV-2169 Salaspils, Latvia https://orcid.org/0000-0003-2748-3797 E-mail: liga.jansone@silava.lv
Matisons, Latvian State Forest Research Institute “Silava,” Rigas Street 111, LV-2169 Salaspils, Latvia E-mail: roberts.matisons@silava.lv
Lazdiņš, Latvian State Forest Research Institute “Silava,” Rigas Street 111, LV-2169 Salaspils, Latvia https://orcid.org/0000-0002-7169-2011 E-mail: andis.lazdins@silava.lv
Jansons, Latvian State Forest Research Institute “Silava,” Rigas Street 111, LV-2169 Salaspils, Latvia https://orcid.org/0000-0001-7981-4346 E-mail: aris.jansons@silava.lv

article id 23024, category Research article

Anu Laakkonen, Katri Rusanen, Teppo Hujala, Mika Gabrielsson, Jouni Pykäläinen. (2023). Implications of the sustainability transition on the industry value creation logic – case of Finnish pulp and paper industry. Silva Fennica vol. 57 no. 3 article id 23024. https://doi.org/10.14214/sf.23024

Keywords: forest industry; business transformation; circular bioeconomy; sustainable business

Highlights: Global change drivers are inducing a sustainability transition to a circular bioeconomy; Established industries need to reconfigure their value creation logic; A document analysis investigated pulp and paper industry’s communicated value creation logic; An interdisciplinary approach helps to understand a changing business environment; Recognition of a socio-economic-technological-environmental system is needed.

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Global economic, social and environmental change drivers have tremendous effects on the dynamic and nested business environment calling for a sustainability transition to a circular bioeconomy. The transition will pressurise established industries to alter their value creation logic to consider sustainability holistically. The study follows a case study research strategy and investigates how an established Finnish pulp and paper industry reconfigures its communicated value creation logic. The findings of a qualitative document analysis suggest that the pulp and paper industry has started to explore new sustainable path-breaking innovations and create a common development agenda, which has resulted in incremental adaptations in the value creation logic. However, the industry’s narrative of already being sustainable has hampered the reconfiguration and stabilisation of the adapted value creation logic. From a theoretical perspective, adopting an interdisciplinary and systemic perspective is necessary to understand the changing business environment. From a managerial perspective, cross-sectoral collaboration and including perspectives of different actors can help in creating a holistically sustainable value creation logic.

Laakkonen, School of Forest Sciences, Faculty of Science, Forestry and Technology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland; Department of Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Finland https://orcid.org/0000-0002-6384-7773 E-mail: anu.laakkonen@uef.fi
Rusanen, School of Forest Sciences, Faculty of Science, Forestry and Technology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-1705-5561 E-mail: katri.rusanen@uef.fi
Hujala, School of Forest Sciences, Faculty of Science, Forestry and Technology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0002-7905-7602 E-mail: teppo.hujala@uef.fi
Gabrielsson, Department of Marketing, Hanken School of Economics, P.O. Box 479, FI-00101, Helsinki, Finland; UEF Business School, Faculty of Social Sciences and Business Studies, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland https://orcid.org/0000-0002-0633-6918 E-mail: mika.gabrielsson@uef.fi
Pykäläinen, School of Forest Sciences, Faculty of Science, Forestry and Technology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: jouni.pykalainen@uef.fi

article id 23004, category Research article

Per Nordin, Erika Olofsson, Karin Hjelm. (2023). Within-site adaptation: growth and mortality of Norway spruce, Scots pine and silver birch seedlings in different planting positions across a soil moisture gradient. Silva Fennica vol. 57 no. 3 article id 23004. https://doi.org/10.14214/sf.23004

Keywords: regeneration; microsite; decision making; mounding; planting; depth-to-water

Highlights: A soil moisture map could be used to support the choice of planting position for different soil moisture conditions; Mounds reduced mortality rates for conifers when conditions were wet, but at drier conditions differences between planting positions were small; Contradictory, silver birch had higher survival in lower planting positions compared with mounds; Height and diameter were higher in mounds for conifers, but only small differences occurred between planting positions for silver birch.

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Adapting to site conditions is a central part of forest regeneration and can be done through selection of different planting positions. Requirements are tree species specific, and the use of soil moisture maps could be a way to support decision making in forest regeneration planning. At two experimental sites with varying soil moisture conditions in southern Sweden Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and silver birch (Betula pendula Roth) seedlings were planted in four different planting positions following mounding site preparation; Depression, Hinge, Mound and Unscarified. Soil moisture estimates were obtained from a high-resolution depth-to-water raster for each planting spot. The effect of soil moisture, planting position and their interactions on mortality, height and diameter was evaluated for each tree species. In wet conditions mounds proved to be the best option to minimize seedling mortality for conifers, but with decreasing soil moisture, differences between the planting positions decreased. Birch on the other hand had the greatest survival in the hinge. The coniferous species displayed increased height and diameter when planted in mounds independent of the soil moisture conditions, whereas silver birch was less dependent on a specific planting position. Results from this study shows that a soil moisture map can explain mortality, height and diameter and thus can be a useful tool when choosing planting position in different soil moisture conditions.

Nordin, pcSKOG, Grisslevägen 15, 227 32 Lund, Sweden https://orcid.org/0000-0002-2156-6615 E-mail: per.nordin@skogforsk.se
Olofsson, Linnaeus University, Department of Forestry and Wood Technology, 351 95 Växjö, Sweden https://orcid.org/0000-0001-5844-6775 E-mail: erika.olofsson@lnu.se
Hjelm, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, Box 190, 234 22 Lomma, Sweden https://orcid.org/0000-0002-6144-8250 E-mail: karin.hjelm@slu.se

article id 23003, category Research article

Olli-Pekka Tikkanen, Ilari Lehtonen. (2023). Changing climatic drivers of European spruce bark beetle outbreaks: a comparison of locations around the Northern Baltic Sea. Silva Fennica vol. 57 no. 3 article id 23003. https://doi.org/10.14214/sf.23003

Keywords: climate change; temperature sum; precipitation; Ips typographus; hydrothermic index

Highlights: Temperatures in the Northern Baltic Sea area will reach new and higher levels in all studied climate change scenarios, speeding up the development of the European spruce bark beetle; Unless greenhouse gas emissions are reduced rapidly, more frequent droughts will facilitate spruce bark beetle outbreaks, especially in Sweden and, to a lesser extent, in Estonia and in Southern Finland.

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European spruce bark beetle (Ips typographus [L.]; SBB) damage has reached extreme and unprecedented levels in East Central Sweden, likely driven by increasing temperatures and severe drought due to climate change. However, SBB outbreaks have been less severe on the eastern side of the Baltic Sea, in Estonia and Finland, than in Sweden. This study investigated how precipitation, temperature sum, and droughts (hydrothermic index) have varied in land areas surrounding the Baltic Sea. We studied past meteorological observations from 1950 to 1999. We modeled the effect of climate change on precipitation and temperature using three representative concentration pathway (RCP) scenarios for greenhouse gas emissions (RCP2.6, RCP4.5, and RCP8.5) and multiple (17–23) climate models. Future climate projections (up to 2100) were made for Southeastern Estonia, Southern Finland, and East Central Sweden. Weather data showed that temperature sums had been high and droughts severe in the 2010s, particularly in East Central Sweden, where SBB outbreaks have been a more significant problem than on the eastern shores of the Baltic Sea. Future climate projections suggest that increases in temperature sum will further enhance SBB reproduction, especially in the RCP4.5 and RCP8.5 scenarios. In all climate change scenarios, drought continues to be a problem in East Central Sweden, potentially facilitating SBB outbreaks. In addition, moderate and severe droughts may become more frequent in Southeastern Estonia and Southern Finland if climate change proceeds as predicted in the RCP4.5 or RCP8.5 scenarios.

Tikkanen, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0002-3875-2772 E-mail: Olli-Pekka.Tikkanen@uef.fi
Lehtonen, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland https://orcid.org/0000-0001-7317-9580 E-mail: Ilari.Lehtonen@fmi.fi

article id 22013, category Research article

Bodil Häggström, Reimo Lutter, Tomas Lundmark, Fredrik Sjödin, Annika Nordin. (2023). Effect of arginine-phosphate addition on early survival and growth of Scots pine, Norway spruce and silver birch. Silva Fennica vol. 57 no. 2 article id 22013. https://doi.org/10.14214/sf.22013

Keywords: Pinus sylvestris; Betula pendula; Picea abies; forest regeneration; seedling growth; seedling survival; arginine

Highlights: Arginine-phosphate addition (APA) represents a potential tool to aid regeneration of planted trees, especially to increase survival of Scots pine seedlings on sites where susceptible to pests;Effects of APA however varies between different sites.

Abstract | Full text in HTML | Full text in PDF | Author Info

Applying arginine-phosphate (AP) to tree seedlings at planting is a novel silvicultural practice in Northern Europe to improve the success of forest regeneration. We present three case-studies of the potential advantages of adding AP at planting on the establishment and damage susceptibility of seedlings in pure and mixed plantings of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst. ) and silver birch (Betula pendula Roth) over two years in the field. Location of study sites were in southern (S), northeastern (NE) and northwestern (NW) Sweden. The main agents of damage were pine weevil (Hylobius abietis L.) on conifers at the south site, browsing of birch at all sites and browsing/other top damage to conifers at the north sites. The effect of adding AP varied between the sites. It was positive for survival of pine at site S, despite considerable damage by pine weevil. However, at the S site more of the surviving spruce and birch were browsed when treated with AP. At the NE site AP-treatment had positive effects on conifer growth. At the NW site adding AP positively affected survival and growth of all three species, and AP-treated seedlings of all species were less browsed than untreated seedlings. AP treatment presents a potential tool to improve the success of forest regeneration, especially when establishing pine stands in south Sweden.

Häggström, Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden https://orcid.org/0000-0002-7738-5493 E-mail: bodil.haggstrom@slu.se
Lutter, Institute of Forestry and Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51006, Estonia https://orcid.org/0000-0001-5847-4282 E-mail: reimo.lutter@emu.ee
Lundmark, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden https://orcid.org/0000-0003-2271-3469 E-mail: tomas.lundmark@slu.se
Sjödin, Unit for field-based forest research, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden E-mail: fredrik.sjodin@slu.se
Nordin, Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden https://orcid.org/0000-0002-5765-3550 E-mail: annika.nordin@slu.se

article id 22014, category Research article

Nea Kuusinen, Aarne Hovi, Miina Rautiainen. (2023). Estimation of boreal forest floor lichen cover using hyperspectral airborne and field data. Silva Fennica vol. 57 no. 1 article id 22014. https://doi.org/10.14214/sf.22014

Keywords: remote sensing; Cladonia; spectroscopy

Highlights: A pilot study on estimating forest floor lichen cover from hyperspectral data; Multiple endmember spectral mixture analysis applied to field and airborne data; Accuracy of lichen cover estimates was good; Tree cover and presence of dwarf shrubs may influence lichen cover estimation.

Abstract | Full text in HTML | Full text in PDF | Author Info

Lichens are sensitive to competition from vascular plants, intensive silviculture, pollution and reindeer and caribou grazing, and can therefore serve as indicators of environmental changes. Hyperspectral remote sensing data has been proved promising for estimation of plant diversity, but its potential for forest floor lichen cover estimation has not yet been studied. In this study, we investigated the use of hyperspectral data in estimating ground lichen cover in boreal forest stands in Finland. We acquired airborne and in situ hyperspectral data of lichen-covered forest plots, and applied multiple endmember spectral mixture analysis to estimate the fractional cover of ground lichens in these plots. Estimation of lichen cover based on in situ spectral data was very accurate (coefficient of determination (r²) 0.95, root mean square error (RMSE) 6.2). Estimation of lichen cover based on airborne data, on the other hand, was fairly good (r² 0.77, RMSE 11.7), but depended on the choice of spectral bands. When the hyperspectral data were resampled to the spectral resolution of Sentinel-2, slightly weaker results were obtained. Tree canopy cover near the flight plots was weakly related to the difference between estimated and measured lichen cover. The results also implied that the presence of dwarf shrubs could influence the lichen cover estimates.

Kuusinen, Department of Built Environment, School of Engineering, Aalto University, P.O. Box 14100, FI-00076 Aalto, Finland https://orcid.org/0000-0002-8063-1739 E-mail: nea.kuusinen@aalto.fi
Hovi, Department of Built Environment, School of Engineering, Aalto University, P.O. Box 14100, FI-00076 Aalto, Finland https://orcid.org/0000-0002-4384-5279 E-mail: aarne.hovi@aalto.fi
Rautiainen, Department of Built Environment, School of Engineering, Aalto University, P.O. Box 14100, FI-00076 Aalto, Finland https://orcid.org/0000-0002-6568-3258 E-mail: miina.a.rautiainen@aalto.fi

article id 22007, category Research article

Ilkka Korpela, Antti Polvivaara, Saija Papunen, Laura Jaakkola, Noora Tienaho, Johannes Uotila, Tuomas Puputti, Aleksi Flyktman. (2023). Airborne dual-wavelength waveform LiDAR improves species classification accuracy of boreal broadleaved and coniferous trees. Silva Fennica vol. 56 no. 4 article id 22007. https://doi.org/10.14214/sf.22007

Keywords: crown modeling; laser scanning; photogrammetry; individual tree detection; Scandinavia

Highlights: First study to assess dual-wavelength waveform data in tree species identification; New findings regarding waveform features of previously unstudied species; Waveform features correlated with tree size displaying wavelength- and species-specific differences linked to bark reflectance, height growth rate and foliage density; Effects by pulse length and beam divergence are highlighted.

Abstract | Full text in HTML | Full text in PDF | Author Info

Tree species identification constitutes a bottleneck in remote sensing applications. Waveform LiDAR has been shown to offer potential over discrete-return observations, and we assessed if the combination of two-wavelength waveform data can lead to further improvements. A total of 2532 trees representing seven living and dead conifer and deciduous species classes found in Hyytiälä forests in southern Finland were included in the experiments. LiDAR data was acquired by two single-wavelength sensors. The 1064-nm and 1550-nm data were radiometrically corrected to enable range-normalization using the radar equation. Pulses were traced through the canopy, and by applying 3D crown models, the return waveforms were assigned to individual trees. Crown models and a terrain model enabled a further split of the waveforms to strata representing the crown, understory and ground segments. Different geometric and radiometric waveform attributes were extracted per return pulse and aggregated to tree-level mean and standard deviation features. We analyzed the effect of tree size on the features, the correlation between features and the between-species differences of the waveform features. Feature importance for species classification was derived using F-test and the Random Forest algorithm. Classification tests showed significant improvement in overall accuracy (74→83% with 7 classes, 88→91% with 4 classes) when the 1064-nm and 1550-nm features were merged. Most features were not invariant to tree size, and the dependencies differed between species and LiDAR wavelength. The differences were likely driven by factors such as bark reflectance, height growth induced structural changes near the treetop as well as foliage density in old trees.

Korpela, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland 0000-0002-1665-3984 E-mail: ilkka.korpela@helsinki.fi
Polvivaara, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: –
Papunen, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland 0000-0001-5383-4314 E-mail: saija.papunen@outlook.com
Jaakkola, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: laura.jaakkola@helsinki.fi
Tienaho, University of Eastern Finland, Faculty of Science and Forestry, P.O. Box 111, FI-80101 Joensuu, Finland 0000-0002-6574-5797 E-mail: noora.tienaho@uef.fi
Uotila, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: johannes.uotila@helsinki.fi
Puputti, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland 0000-0003-1972-1636 E-mail: tuomas.puputti@helsinki.fi
Flyktman, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland 0000-0002-5235-317X E-mail: aleksi.flyktman@helsinki.fi

article id 10757, category Research article

Silvana M.J. Sione, Silvia G. Ledesma, Pablo G. Aceñolaza, Marcelo G. Wilson. (2022). Biomass Carbon and Nitrogen allocation in different tree species: do tree compartments and size affect C:N relationship? Silva Fennica vol. 56 no. 4 article id 10757. https://doi.org/10.14214/sf.10757

Keywords: Neltuma nigra; Neltuma affinis; Vachellia caven; biomass compartments; C:N ratio; native forests

Highlights: C:N relationship variations in biomass compartments were positively correlated with N concentration and did not exhibit significant association with C; C:N ratios differed significantly among species and compartments; Only in Neltuma affinis and Vachellia caven stems C:N relationship differed among tree size.

Abstract | Full text in HTML | Full text in PDF | Author Info

Tree carbon (C) and nitrogen (N) concentrations and C:N ratio are critical for understanding the elemental compositions of forests, N use efficiency, productivity and the biogeochemical cycles. We evaluate differences in C and N allocation among biomass compartments of three N‑fixing tree species of Espinal Argentine eco-region; the scaling relationship between C and N and the C:N ratio variation among compartments and tree size. Neltuma affinis (Spreng.) C.E. Hughes & G.P. Lewis, Neltuma nigra (Griseb.) C.E. Hughes & G.P. Lewis and Vachellia caven (Molina) Seigler & Ebinger plants (n = 30 for each species) were felled, grouped by stem basal diameter-based size classes and partitioned into 3 biomass compartments: stem (st), large branches (lb) and small branches + leaves, flowers and fruits (sbl). C and N concentrations were markedly influenced by species and biomass compartments. In general, sbl compartment presented more N than the st and lb, while C concentrations in Neltuma stems were the highest. Overall, no isometric C–N scaling relationships were found in different compartments. C:N variations in compartments were positively correlated with N concentrations but did not exhibit any significant association with C concentrations. C:N ratios differed significantly among species and biomass compartments. The C:N ratio for compartments ranked in an order of st > lb > sbl. C:N ratio variability in sbl was the least. Only in N. affinis and V. caven stems C:N relationship differed among tree size. Our results provide evidence of the importance of using in situ C and N concentration per main tree species and biomass compartments, to more accurate estimates of C and N stocks.

Sione, National University of Entre Ríos, Faculty of Agricultural Sciences, Ruta 11 Km 10,5 (3101) Oro Verde, Entre Ríos, Argentina; CICyTTP-CONICET (National Research and Technological Investigation Council), Materi y España (3105) Diamante, Entre Ríos, Argentina https://orcid.org/0000-0002-2119-0363 E-mail: silvana.sione@fca.uner.edu.ar
Ledesma, National University of Entre Ríos, Faculty of Agricultural Sciences, Ruta 11 Km 10,5 (3101) Oro Verde, Entre Ríos, Argentina https://orcid.org/0000-0002-9264-1766 E-mail: silvia.ledesma@fca.uner.edu.ar
Aceñolaza, National University of Entre Ríos, Faculty of Agricultural Sciences, Ruta 11 Km 10,5 (3101) Oro Verde, Entre Ríos, Argentina; CICyTTP-CONICET (National Research and Technological Investigation Council), Materi y España (3105) Diamante, Entre Ríos, Argentina https://orcid.org/0000-0002-5033-3466 E-mail: pablo.acenolaza@fca.uner.edu.ar
Wilson, National University of Entre Ríos, Faculty of Agricultural Sciences, Ruta 11 Km 10,5 (3101) Oro Verde, Entre Ríos, Argentina https://orcid.org/0000-0002-1214-1041 E-mail: wilson.marcelo@inta.gob.ar

article id 10676, category Research article

Eva Ring, Fredrik Johansson, Claudia von Brömssen, Isabelle Bergkvist. (2022). A snapshot of forest buffers near streams, ditches, and lakes on forest land in Sweden – lessons learned. Silva Fennica vol. 56 no. 4 article id 10676. https://doi.org/10.14214/sf.10676

Keywords: forestry; conifer; harvest; lake; riparian; stream; watercourse

Highlights: Forest buffers were inventoried on 174 harvested and site-prepared compartments bordering surface water in Sweden; Buffers with 100% shoreline coverage were present beside all 16 lakes and 55% of the natural or modified stream reaches; Judging streams´ character from field inspection of individual reaches alone proved difficult on forest land affected by historic drainage activities.

Abstract | Full text in HTML | Full text in PDF | Author Info

Forest buffers beside surface water can mitigate negative effects of logging. To gain more information on buffer implementation in operational forestry, forest buffers were inventoried during 2018 on 174 harvested and site-prepared compartments traversed by or bordering streams, ditches and lakes in three regions across Sweden 2–4 years after clearcutting. Most of the inventoried stream and ditch reaches were ≤5 m wide. The water reaches were categorized as lakes (n = 16), natural streams (n = 50), modified streams (n = 21) or ditches (n = 87). Forest buffers with 100% shoreline coverage were present along all lake reaches and 55% and 10% of the natural or modified stream and ditch reaches, respectively. Buffers were absent beside 14% of the natural or modified stream reaches and 61% of the ditch reaches. Lake reaches had significantly wider buffers on average than ditch reaches and natural or modified stream reaches. The mean (SE) buffer widths beside lakes, natural or modified stream reaches and ditch reaches across all three regions and shoreline coverage classes were 12 (1.1), 6.6 (0.6) and 1.5 (0.5) m, respectively. The character of the local stream networks (natural or modified streams or ditches) containing each inventoried reach, were assessed using map information and the reaches´ field classifications. This illustrated the difficulty of judging a streams´ character based solely on field inspections of individual reaches on forest land where historic drainage activities have been performed. We recommend that also upstream and downstream conditions should be considered when planning environmental measures to protect surface water bodies.

Ring, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-8962-9811 E-mail: eva.ring@skogforsk.se
Johansson, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden E-mail: fredrik.johansson@skogforsk.se
von Brömssen, Department of energy and technology, Division of applied statistics and mathematics, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden https://orcid.org/0000-0002-1452-8696 E-mail: Claudia.von.Bromssen@slu.se
Bergkvist, Mellanskog, Uppsala Science Park, Box 127, 751 04 Uppsala, Sweden E-mail: isabelle.bergkvist@mellanskog.se

article id 10755, category Research article

Rikard Jonsson, Lotta Woxblom, Rolf Björheden, Eva-Maria Nordström, Bosko Blagojevic, Ola Lindroos. (2022). Analysis of decision-making processes for strategic technology investments in Swedish large-scale forestry. Silva Fennica vol. 56 no. 3 article id 10755. https://doi.org/10.14214/sf.10755

Keywords: information needs; qualitative analysis; harwarder; forest technology development; semi-structured interviews; unstructured decision processes

Highlights: When making development decisions, respondents representing six relatively large users of forest technology aimed to maximize economic criteria without falling below threshold values for criteria such as operator well-being, soil rutting, and wood value; Collaboration between users, manufacturers, and researchers was found to be important; Decision-making could be improved by using tools such as problem-structuring methods, simulations, and optimization.

Abstract | Full text in HTML | Full text in PDF | Author Info

Technological development gives forest companies opportunities to maintain competitiveness in the highly cost-sensitive market for forest products. However, no previous studies have examined the technological development decisions made by forest companies or the support tools used when making them. We therefore aimed to describe and analyze 1) the processes used when making such decisions, 2) the associated decision situations, and 3) the use of and need for decision support tools in these processes, with a harwarder concept as case. Semi-structured interviews were conducted with respondents from six forestry organizations. Two theoretical frameworks were used to analyze the interviews, one for unstructured decision processes and one for decision situations. The respondents’ descriptions of their decision processes were consistent with those observed in other industries, and it was shown that decision-making could potentially be improved by investing more resources into diagnosing the problem at hand. The main objective in decision-making was to maximize economic criteria while satisfying threshold requirements relating to criteria such as operator well-being, soil rutting, and wood value. When facing large uncertainties, interviewees preferred to gather data through operational trials and/or scientific studies. If confronted with large uncertainties that could not be reduced, they proceeded with development only if the potential gains exceeded the estimated uncertainties, and implemented innovations in a stepwise manner. These results indicate a need for greater use of existing decision-support tools such as problem-structuring methods to enable more precise diagnoses, simulations to better understand new innovations, and optimization to better evaluate their theoretical large-scale potential.

Jonsson, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: rikard.jonsson@skogforsk.se
Woxblom, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: lotta.woxblom@skogforsk.se
Björheden, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: rolf.bjorheden@skogforsk.se
Nordström, Swedish University of Agricultural Sciences, Department of Forest Resource Management, SE-901 83 Umeå, Sweden E-mail: eva-maria.nordstrom@slu.se
Blagojevic, University of Novi Sad, Department of Water Management, Trg D. Obradovica 8, 21000 Novi Sad, Serbia E-mail: bosko.blagojevic@polj.edu.rs
Lindroos, Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83 Umeå, Sweden E-mail: ola.lindroos@slu.se

article id 10712, category Research article

Kenneth Olofsson, Johan Holmgren. (2022). Co-registration of single tree maps and data captured by a moving sensor using stem diameter weighted linking. Silva Fennica vol. 56 no. 3 article id 10712. https://doi.org/10.14214/sf.10712

Keywords: airborne laser scanning; terrestrial laser scanning; field plot; mobile laser scanning; simultaneous location and mapping; stem map

Highlights: A stem diameter weighted linking algorithm for tree maps was introduced which improves linking accuracy; A new simultaneous location and mapping-based co-registration method for stem maps measured with moving sensors was introduced that operates with high linking accuracy.

Abstract | Full text in HTML | Full text in PDF | Author Info

A new method for the co-registration of single tree data in forest stands and forest plots applicable to static as well as dynamic data capture is presented. This method consists of a stem diameter weighted linking algorithm that improves the linking accuracy when operating on diverse diameter stands with stem position errors in the single tree detectors. A co-registration quality metric threshold, Q_T, is also introduced which makes it possible to discriminate between correct and incorrect stem map co-registrations with high probability (>99%). These two features are combined to a simultaneous location and mapping-based co-registration method that operates with high linking accuracy and that can handle sensors with drifting errors and signal bias. A test with simulated data shows that the method has an 89.35% detection rate. The statistics of different settings in a simulation study are presented, where the effect of stem density and position errors were investigated. A test case with real sensor data from a forest stand shows that the average nearest neighbor distances decreased from 1.90 m to 0.51 m, which indicates the feasibility of this method.

Olofsson, Section of Forest Remote Sensing, Department of Forest Resource Management, Swedish University of Agricultural Sciences, Umeå, Sweden https://orcid.org/0000-0002-2836-2316 E-mail: kenneth.olofsson@slu.se
Holmgren, Section of Forest Remote Sensing, Department of Forest Resource Management, Swedish University of Agricultural Sciences, Umeå, Sweden https://orcid.org/0000-0002-7112-8015 E-mail: johan.holmgren@slu.se

article id 10660, category Research article

Åsa Gustafsson, Jimmy Johansson. (2022). Identifying present drivers of product development and describing roles of identified actors primarily affecting the development of harvesters: a multiple-case study. Silva Fennica vol. 56 no. 3 article id 10660. https://doi.org/10.14214/sf.10660

Keywords: forest operations; logging contractor; industry driver; interview; softwood lumber supply chain

Highlights: Legislators, logging contractors, and expert and research organizations are present drivers of product development of harvesters; They appear to prioritize meeting legal regulations and lowering costs for logging contractors as they outline requirements for manufacturing harvesters.

Abstract | Full text in HTML | Full text in PDF | Author Info

Forest operations involve several different actors. Each actor imposes their own requirements on the harvester in relation to their differing roles in the industry, whether they are concerned with the harvester itself, information, environmental concerns, etc. The manufacturers of harvesters need to meet the requirements imposed by multiple actors, among them logging contractors, whose survival depends on their harvesters. This paper aims to identify the present drivers of product development and describe the roles of the actors who have been identified as those currently affecting the development of harvesters. A multiple-case study of harvester manufacturers was conducted. In total, 4 cases were studied. Each case was comprised of five interviewees: two from each harvesting manufacturer, two logging contractors, and one dealer. Following 20 interviews and 3 validation interviews (with experts from both the industry and academia), the paper concludes that the present drivers of product development of harvesters are legislators, logging contractors, and expert and research organizations. Harvester manufacturers appear to develop harvesters aligned with requirements coming from both logging contractors and legislators. Logging contractors are the primary customers, and they prioritize requirements that reduce cost and improve work environments. Legislators, and expert and research organizations are supporting development in relation to current regulations.

Gustafsson, Department of Accounting and Logistics, Linnaeus University, Universitetsplatsen 1, 352 52 Växjö, Sweden E-mail: asa.gustafsson@lnu.se
Johansson, Department of Forestry and Wood Technology, Linnaeus University, 391 82 Kalmar, Sweden E-mail: jimmy.johansson@lnu.se

article id 10707, category Research article

Martin Goude, Urban Nilsson, Euan Mason, Giulia Vico. (2022). Comparing basal area growth models for Norway spruce and Scots pine dominated stands. Silva Fennica vol. 56 no. 2 article id 10707. https://doi.org/10.14214/sf.10707

Keywords: Pinus sylvestris; basal area; Picea abies; National Forest Inventory; regression; difference equation; long-term experiment

Highlights: Models were developed that predict basal area growth for Scot pine and Norway spruce stands in Sweden; There were no apparent differences in the ability to predict basal area development between a linear regression model for basal area growth or a compatible growth and yields model for basal area; The model based on data from the 80s had similar performance as the models with data from the 2000s, showing that both can reliably be used to predict forest development.

Abstract | Full text in HTML | Full text in PDF | Author Info

Models that predict forest development are essential for sustainable forest management. Constructing growth models via regression analysis or fitting a family of sigmoid equations to construct compatible growth and yield models are two ways these models can be developed. In this study, four species-specific models were developed and compared. A compatible growth and yield stand basal area model and a five-year stand basal area growth model were developed for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.). The models were developed using data from permanent inventory plots from the Swedish national forest inventory and long-term experiments. The species-specific models were compared, using independent data from long-term experiments, with a stand basal area growth model currently used in the Swedish forest planning system Heureka (Elfving model). All new models had a good, relatively unbiased fit. There were no apparent differences between the models in their ability to predict basal area development, except for the slightly worse predictions for the Norway spruce growth model. The lack of difference in the model comparison showed that despite the simplicity of the compatible growth and yield models, these models could be recommended, especially when data availability is limited. Also, despite using more and newer data for model development in this study, the currently used Elfving model was equally good at predicting basal area. The lack of model difference indicate that future studies should instead focus on model development for heterogeneous forests which are common but lack in growth and yield modelling research.

Goude, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, SE-230 53 Alnarp, Sweden https://orcid.org/0000-0002-2179-292X E-mail: martin.goude@slu.se
Nilsson, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, SE-230 53 Alnarp, Sweden E-mail: urban.nilsson@slu.se
Mason, School of Forestry, University of Canterbury, Private Bag 4800, Christchurch, New Zealand E-mail: euan.mason@canterbury.ac.nz
Vico, Department of Crop Production Ecology, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden E-mail: giulia.vico@slu.se

article id 10627, category Research article

Christian Kuehne, J. Paul McLean, Kobra Maleki, Clara Antón-Fernández, Rasmus Astrup. (2022). A stand-level growth and yield model for thinned and unthinned even-aged Scots pine forests in Norway. Silva Fennica vol. 56 no. 1 article id 10627. https://doi.org/10.14214/sf.10627

Keywords: Pinus sylvestris; mortality; volume growth; seemingly unrelated regression; production forestry; system of equations

Highlights: The presented growth and yield model consists of component equations for dominant height, stem density, total basal area, and total stem volume; The component equations were fitted simultaneously using seemingly unrelated regression; The model is capable to forecast and compare outcomes of varying thinning regimes; The new component equations better represent the improved growing conditions for Scots pine in Norway.

Abstract | Full text in HTML | Full text in PDF | Author Info

Management of Scots pine (Pinus sylvestris L.) in Norway requires a forest growth and yield model suitable for describing stand dynamics of even-aged forests under contemporary climatic conditions with and without the effects of silvicultural thinning. A system of equations forming such a stand-level growth and yield model fitted to long-term experimental data is presented here. The growth and yield model consists of component equations for (i) dominant height, (ii) stem density (number of stems per hectare), (iii) total basal area, (iv) and total stem volume fitted simultaneously using seemingly unrelated regression. The component equations for stem density, basal area, and volume include a thinning modifier to forecast stand dynamics in thinned stands. It was shown that thinning significantly increased basal area and volume growth while reducing competition related mortality. No significant effect of thinning was found on dominant height. Model examination by means of various fit statistics indicated no obvious bias and improvement in prediction accuracy in comparison to existing models in general. An application of the developed stand-level model comparing different management scenarios exhibited plausible long-term behavior and we propose this is therefore suitable for national deployment.

Kuehne, Norwegian Institute of Bioeconomy Research, Division of Forestry and Forest Resources, P.O. Box 115, NO-1431 Ås, Norway E-mail: christian.kuehne@nibio.no
McLean, Norwegian Institute of Bioeconomy Research, Division of Forestry and Forest Resources, P.O. Box 115, NO-1431 Ås, Norway E-mail: paul.mclean@nibio.no
Maleki, Norwegian Institute of Bioeconomy Research, Division of Forestry and Forest Resources, P.O. Box 115, NO-1431 Ås, Norway E-mail: kobra.maleki@nibio.no
Antón-Fernández, Norwegian Institute of Bioeconomy Research, Division of Forestry and Forest Resources, P.O. Box 115, NO-1431 Ås, Norway E-mail: clara.anton.fernandez@nibio.no
Astrup, Norwegian Institute of Bioeconomy Research, Division of Forestry and Forest Resources, P.O. Box 115, NO-1431 Ås, Norway E-mail: rasmus.astrup@nibio.no

article id 10608, category Research article

Lennart Noordermeer, Erik Næsset, Terje Gobakken. (2022). Effects of harvester positioning errors on merchantable timber volume predicted and estimated from airborne laser scanner data in mature Norway spruce forests. Silva Fennica vol. 56 no. 1 article id 10608. https://doi.org/10.14214/sf.10608

Keywords: forest inventory; ALS; forest harvester; GNSS; precision forestry

Highlights: Timber volume was estimated using harvester and airborne laser scanner (ALS) data acquired with different scanners over eight years; The year of ALS acquisition did not have a significant effect on errors in timber volume estimates; Accuracies of timber volume estimates decreased significantly with increasing levels of positioning error; When using inaccurately positioned harvester data, larger grid cells are beneficial.

Abstract | Full text in HTML | Full text in PDF | Author Info

Newly developed positioning systems in cut-to-length harvesters enable georeferencing of individual trees with submeter accuracy. Together with detailed tree measurements recorded during processing of the tree, georeferenced harvester data are emerging as a valuable tool for forest inventory. Previous studies have shown that harvester data can be linked to airborne laser scanner (ALS) data to estimate a range of forest attributes. However, there is little empirical evidence of the benefits of improved positioning accuracy of harvester data. The two objectives of this study were to (1) assess the accuracy of timber volume estimation using harvester data and ALS data acquired with different scanners over multiple years and (2) assess how harvester positioning errors affect merchantable timber volume predicted and estimated from ALS data. We used harvester data from 33 commercial logging operations, comprising 93 731 harvested stems georeferenced with sub-meter accuracy, as plot-level training data in an enhanced area-based inventory approach. By randomly altering the tree positions in Monte Carlo simulations, we assessed how prediction and estimation errors were influenced by different combinations of simulated positioning errors and grid cell sizes. We simulated positioning errors of 1, 2, …, 15 m and used grid cells of 100, 200, 300 and 400 m². Values of root mean square errors obtained for cell-level predictions of timber volume differed significantly for the different grid cell sizes. The use of larger grid cells resulted in a greater accuracy of timber volume predictions, which were also less affected by positioning errors. Accuracies of timber volume estimates at logging operation level decreased significantly with increasing levels of positioning error. The results highlight the benefit of accurate positioning of harvester data in forest inventory applications. Further, the results indicate that when estimating timber volume from ALS data and inaccurately positioned harvester data, larger grid cells are beneficial.

Noordermeer, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway E-mail: lennart.noordermeer@nmbu.no
Næsset, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway E-mail: erik.naesset@nmbu.no
Gobakken, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway E-mail: terje.gobakken@nmbu.no

article id 10598, category Research article

Argo Orumaa, Kajar Köster, Arvo Tullus, Tea Tullus, Marek Metslaid. (2022). Forest fires have long-term effects on the composition of vascular plants and bryophytes in Scots pine forests of hemiboreal Estonia. Silva Fennica vol. 56 no. 1 article id 10598. https://doi.org/10.14214/sf.10598

Keywords: disturbance; bryophytes; understorey vegetation; vascular plants; hemiboreal forest; fire chronosequence; wildfire

Highlights: We recorded 31 vascular plant and 39 bryophyte species in a chronosequence of Scots pine stands with 12–183 years since fire; Time since fire affected the compositional patterns of vascular plants and bryophytes; The richness of liverworts was higher in recently burned stands due to the presence of Cephaloziella spp.; The richness of dwarf-shrubs increased with longer period since fire.

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Since fire frequency is expected to increase globally due to climate change, it is important to understand its effects on forest ecosystems. We studied the long-term patterns in species diversity, cover and composition of vascular plants and bryophytes after forest fire and the site-related factors behind them. Research was carried out in northwestern Estonia, using a chronosequence of Scots pine (Pinus sylvestris L.) stands, located on nutrient poor sandy soils, where fires had occurred 12, 23, 38, 69, 80 and 183 years ago. In every stand three 100 m² vegetation plots were established to collect floristic and environmental information. The effects on floristic characteristics of time since fire, light, and soil variables were evaluated with linear mixed models, followed by backward variable selection. Compositional variation was analysed with non-metric multidimensional scaling, Multi-response Permutation Procedures, and Indicator Species Analysis. Altogether, 31 vascular plant and 39 bryophyte species were found in vegetation plots. The cover of the vascular plant and bryophyte layers increased with a longer time since fire. Soil and light variables impacted the richness of several vascular plant and bryophyte groups, whereas only the richness of liverworts and dwarf-shrubs correlated with time since fire. Considerable compositional differences were observed in vascular plant and bryophyte assemblages between recently vs. long-time ago burned stands. To conclude, time since fire significantly impacted compositional patterns of vascular plants and bryophytes in pine forests on nutrient poor soils, although time-related trends in species richness were less evident.

Orumaa, Institute of Forestry and Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, 51006, Tartu, Estonia E-mail: argo.orumaa@emu.ee
Köster, Department of Environmental and Biological Sciences, University of Eastern Finland, PO Box 111 (Yliopistokatu 7), 80130, Joensuu, Finland E-mail: kajar.koster@helsinki.fi
Tullus, Department of Botany, Institute of Ecology and Earth Sciences, University of Tartu, Lai 40, Tartu, 51003, Estonia E-mail: arvo.tullus@ut.ee
Tullus, Institute of Forestry and Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, 51006, Tartu, Estonia E-mail: tea.tullus@emu.ee
Metslaid, Institute of Forestry and Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, 51006, Tartu, Estonia E-mail: marek.metslaid@emu.ee

article id 10544, category Research article

Lars Sprengel, Heinrich Spiecker, Shuirong Wu. (2022). Two subject specific modelling approaches to construct base-age invariant polymorphic site index curves with varying asymptotes. Silva Fennica vol. 56 no. 1 article id 10544. https://doi.org/10.14214/sf.10544

Keywords: generalized algebraic difference approach; stem analysis; dummy variable approach; gnls; nonlinear mixed-effects models; nlme; Zhongtiaoshan forest region

Highlights: Base-age invariant families of height growth curves with polymorphism and varying asymptotes are presented for the seven economically most important tree species in Zhongtiaoshan forest region, China; The nonlinear fixed-effects approach outperforms the nonlinear mixed-effects approach according to the AIC, but according to RMSE and bias these results are not fully supported.

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For constructing growth and yield models the concept of site index as measure of productivity is crucial. Here, we use nonlinear mixed-effects models (NLME) with random individual effects and nonlinear models with dummy variables as fixed individual effects (NLFE) to fit mechanistic growth functions to stem analysis data of the economically most important tree species in Zhongtiaoshan forest region, China. The Richards and Lundqvist function are formulated into five dynamic equations (R1, R2, L1, L2 and L3) applying the generalized algebraic difference approach (GADA), which inherit polymorphism, varying asymptotes and base-age invariance. According to Akaike information criterion the R1 model as NLFE fits height growth data of Pinus tabuliformis Carrière, Pinus armandii Franch., Quercus liaotungensis Koidz., Quercus aliena Blume and Betula platyphylla Sukaczev best, while for Quercus variabilis Blume R2 as NLFE fits height growth data best. For Larix principis-rupprechtii Mayr L1 as NLME has been selected as best model, as R1 and R2 both as NLFE and NLME are not extrapolating the comparably short length of height growth data well enough. However, according to the root mean square error and bias differences between model fits of both the selected equation and the chosen model fitting approach are not so clear. Presented families of height growth curves serve as planning tools to identify site index and therefore assess productivity of forest stands in the studied region. A direct comparison of the productivity of forest stands of the same tree species is possible due to base-age invariance of the selected models.

Sprengel, Chair of Forest Growth and Dendroecology, Albert-Ludwigs-University Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany https://orcid.org/0000-0002-6332-7911 E-mail: lars.sprengel@iww.uni-freiburg.de
Spiecker, Chair of Forest Growth and Dendroecology, Albert-Ludwigs-University Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany E-mail: instww@uni-freiburg.de
Wu, Research Institute of Forest Policy and Information, Chinese Academy of Forestry, No. 1 Dongxiaofu, Haidian District, Beijing 100091, China E-mail: shuirongwu@126.com

article id 10520, category Research article

Shaoqin Yang, Lita Yi, Nuonan Ye, Mengyuan Wu, Meihua Liu. (2022). Spatial pattern dynamics of Cyclobalanopsis myrsinifolia in mixed broad-leaved forests on Tianmu Mountain, eastern China, 1996–2012. Silva Fennica vol. 56 no. 1 article id 10520. https://doi.org/10.14214/sf.10520

Keywords: forest dynamics; spatial distribution; East Asia; evergreen and deciduous broad-leaved mixed forests

Highlights: Spatial distribution pattern monitoring of Cyclobalanopsis myrsinifolia was performed over 16 years in a 1 ha plot; The importance value of C. myrsinifolia decreased between 1996 and 2012; The spatial distribution pattern changed at a spatial scale of 0–25 m; The drivers of the variation in spatial distribution were intra- and interspecific mutual relationships.

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Studies of the spatial patterns of dominant plant species may provide significant insights into processes and mechanisms that maintain stand stability. This study was performed in a permanent 1 ha plot in evergreen and deciduous broad-leaved mixed forests on Tianmu Mountain. Based on two surveys (1996 and 2012), the dynamics of the spatial distribution pattern of the dominant population (Cyclobalanopsis myrsinifolia (Blume) Oersted) and the intra- and interspecific relationships between C. myrsinifolia and other dominant species populations were analyzed using Ripley’s K(r) function. We identified the importance value of a species in a community, which is the sum of the relative density, relative frequency, and relative dominance. The drivers of spatial distribution variation and the maintenance mechanisms of the forest were discussed. The results showed that the importance value of C. myrsinifolia within the community decreased over the past 16 years. The C. myrsinifolia population exhibited a significantly aggregated distribution within a spatial scale of 0–25 m in 1996 whereas it changed to a random distribution at scales larger than 5.5 m in 2012. From 1996 to 2012, the spatial distribution patterns between C. myrsinifolia and Cyclocarya paliurus (Batal.) Iljinsk. and between C. myrsinifolia and Cunninghamia lanceolata (Lamb.) Hook did not change significantly. In 1996, C. myrsinifolia and Daphniphyllum macropodum Miq. were positively associated at the scale of 0–25 m; this relationship was strongly significant at the scale of 6–10 m. However, there was no association between the populations of two species in terms of the spatial distribution at the scale of 0–25 m in 2012. Our findings indicate that the drivers of variation in the spatial distribution of the C. myrsinifolia population were intra- and interspecific mutual relationships as well the seed-spreading mechanism of this species.

Yang, Zhejiang Forest Resources Monitoring Center, Hangzhou 310020, China E-mail: 20080095@zafu.edu.cn
Yi, School of Forestry and Biotechnology, Zhejiang A & F University, Lin’an 311300, China E-mail: yilita@zafu.edu.cn
Ye, School of Forestry and Biotechnology, Zhejiang A & F University, Lin’an 311300, China E-mail: 542243187@qq.com
Wu, School of Forestry and Biotechnology, Zhejiang A & F University, Lin’an 311300, China E-mail: 326585523@qq.com
Liu, School of Forestry and Biotechnology, Zhejiang A & F University, Lin’an 311300, China E-mail: mhliu@zafu.edu.cn

article id 10512, category Research article

Mateusz Liziniewicz, Ignacio Barbeito, Andis Zvirgzdins, Lars-Göran Stener, Pentti Niemistö, Nils Fahlvik, Ulf Johansson, Bo Karlsson, Urban Nilsson. (2022). Production of genetically improved silver birch plantations in southern and central Sweden. Silva Fennica vol. 56 no. 1 article id 10512. https://doi.org/10.14214/sf.10512

Keywords: Betula pendula; planting; generalized algebraic difference approach; genetic gain; stand basal area starting function

Highlights: The basal area development of genetically improved birch in Sweden was modeled using a generalized algebraic difference approach; The best model fit, both graphically and statistically was delivered by the Korf base model; The analysis of realized gain trial showed a stability of relative differences in basal area between tested genotypes.

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Investing in planting genetically improved silver birch (Betula pendula Roth) in Swedish plantations requires understanding how birch stands will develop over their entire rotation. Previous studies have indicated relatively low production of birch compared to Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). This could result from using unrepresentative basic data, collected from unimproved, naturally-regenerated birch (Betula spp.) growing on inventory plots often located in coniferous stands. The objective of this study was to develop a basal area development function of improved silver birch and evaluate production over a full rotation period. We used data from 52 experiments including planted silver birch of different genetic breeding levels in southern and central Sweden. The experimental plots were established on fertile forest sites and on former agricultural lands, and were managed with different numbers of thinnings and basal area removal regimes. The model best describing total stand basal area development was a dynamic equation derived from the Korf base model. The analysis of the realized gain trial for birch showed a good stability of the early calculated relative differences in basal area between tested genotypes over time. Thus, the relative difference in basal area might be with cautious used as representation of the realized genetic gain. On average forest sites in southern Sweden, improved and planted silver birch could produce between 6–10.5 m³ ha^–1 year^–1, while on fertile agriculture land the average productivity might be higher, especially with material coming from the improvement program. The performed analysis provided a first step toward predicting the effects of genetic improvement on total volume production and profitability of silver birch. However, more experiments are needed to set up the relative differences between different improved material.

Liziniewicz, The Forestry Research Institute of Sweden, Ekebo, SE-268 90 Svalöv, Sweden E-mail: mateusz.liziniewicz@skogforsk.se
Barbeito, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Alnarp, Sweden; Université de Lorraine, AgroParisTech, INRAE, UMR Silva, Nancy, France E-mail: ignacio.barbeito@slu.se
Zvirgzdins, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Box 49, 23053 Alnarp, Sweden E-mail: andis.zvirgzdins@slu.se
Stener, The Forestry Research Institute of Sweden, Ekebo, SE-268 90 Svalöv, Sweden E-mail: lg.stener@telia.com
Niemistö, Natural Resources In-stitute Finland (Luke), Natural resources, Seinäjoki, Finland E-mail: pentti.niemisto@luke.fi
Fahlvik, The Forestry Research Institute of Sweden, Ekebo, SE-268 90 Svalöv, Sweden E-mail: nils.fahlvik@skogforsk.se
Johansson, Tönnersjöheden Experimental Forest, SLU, Simlångsdalen, Sweden E-mail: ulf.johansson@slu.se
Karlsson, The Forestry Research Institute of Sweden, Ekebo, SE-268 90 Svalöv, Sweden E-mail: curly.birch@gmail.com
Nilsson, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Box 49, 23053 Alnarp, Sweden E-mail: urban.nilsson@slu.se

article id 10326, category Research article

Per K. Rørstad, Birger Solberg, Erik Trømborg. (2022). Can we detect regional differences in econometric analyses of the Norwegian timber supply? Silva Fennica vol. 56 no. 1 article id 10326. https://doi.org/10.14214/sf.10326

Keywords: econometric specification test; panel data analysis; price elasticities; volume elasticities

Highlights: The first difference econometric specification yields better overall fit than fixed and random effects models; Using region specific price elasticities improve the fit for fixed and random effects models; Statistically significant different price elasticities are found in 12 out of total 15 pairs of regions; Western Norway has particularly high growing stock volume elasticities and low short-term price elasticities.

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Forestry and forest industries are important for regional income and employment in Norway as well as in most North European countries, but few studies exist about factors affecting the timber supply at regional level. The main objective of this study is to estimate aggregated regional timber supply elasticities for six regions in Norway. Thereby we also test for regional differences, focusing on wood prices, standing stock volume and interest rate as explanatory variables. We have used three different statistical models (fixed and random effects panel models and first difference models) on regional data from the Norwegian forest inventory on standing volume and official statistics on harvested volumes, interest rate and prices of sawlogs and pulpwood for the period 1996–2016. Statistically significant different price elasticities are found in 12 out of total 15 pairs of regions. The price elasticity was lower and the volume elasticity higher in the western region compared to the other regions. The first difference models are best with respect to specification tests. The use of region specific price elasticities gives slightly better fit for the panel data models than using a uniform price parameter. The results show that the econometric specification influence the parameter values, and it is thus complicated to directly compare results in different timber supply studies. Regional differences in timber supply are important to consider.

Rørstad, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway E-mail: per.kristian.rorstad@nmbu.no
Solberg, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway E-mail: birger.solberg@nmbu.no
Trømborg, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway E-mail: erik.tromborg@nmbu.no

article id 10605, category Research article

Charlotta Harju, Katja Lähtinen. (2021). Perceptions of wooden interior product quality – insights on sustainability views among Finnish consumers. Silva Fennica vol. 55 no. 5 article id 10605. https://doi.org/10.14214/sf.10605

Keywords: wood products; consumer behavior; perceived quality; sociodemographic variables; sustainable consumption

Highlights: The quality indicators of wooden interior products can be grouped into four factors relating to products’ environmental friendliness, fit with lifestyle and home design, visual and tactile attractiveness, and technical solidity, which are in multiple ways connected with sustainability; The sociodemographic background of the respondents was found to be linked with consumer scores for those factors; Wooden interior products should be designed to meet different types of product quality expectations in the home environment.

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Evaluation of product attributes and the overall quality significantly affect consumer purchasing decisions. Previous studies on wooden products have mostly addressed wood product quality from technical viewpoints, while largely disregarding environmental, social, and economic aspects in the assessments. Therefore, knowledge on how sustainability aspects are evaluated as a feature of wood product quality is narrow. This study investigated consumer perceptions of different quality indicators (i.e., quality cues and attributes) of wooden interior products with a special focus on sustainability and value chain phases. In addition, the connections between consumers’ sociodemographic background and their perceptions of the quality features of wooden interior products were evaluated. The material of the study was based on data gathered in 2018 with a postal survey sent to 1000 people living in Finland with a response rate of 25.6%. As methods of analysis, exploratory factor analysis, the Mann-Whitney U test, and the Kruskall-Wallis test were utilized. The results show that the quality indicators of wooden interior products can be grouped into four factors relating to products’ environmental friendliness, fit with lifestyle and home design, visual and tactile attractiveness, and technical solidity, which are in multiple ways connected with sustainability. The sociodemographic background of the respondents was found to be linked with consumer scores for those factors. Engaging consumers in sustainable consumption choices requires providing them with information on wooden product value chains that meets their individual needs in relation to their existing knowledge of those issues and individual values.

Harju, University of Vaasa, School of Marketing and Communication, P.O. Box 700, FI-65200 Vaasa, Finland https://orcid.org/0000-0002-0432-2598 E-mail: charlotta.harju@uwasa.fi
Lähtinen, Natural Resources Institute Finland (Luke), Bioeconomy and Environment Unit, P.O. Box 2, FI-00790 Helsinki, Finland https://orcid.org/0000-0001-6260-5062 E-mail: katja.lahtinen@luke.fi

article id 10573, category Research article

Jari Miina, Inka Bohlin, Torgny Lind, Jonas Dahlgren, Kari Härkönen, Tuula Packalen, Anne Tolvanen. (2021). Lessons learned from assessing the cover and yield of bilberry and lingonberry using the national forest inventories in Finland and Sweden. Silva Fennica vol. 55 no. 5 article id 10573. https://doi.org/10.14214/sf.10573

Keywords: forest management planning; berry models; field measurements; predictions

Highlights: Model-based predictions of the berry yields of an average crop year are produced using the Finnish National Forest Inventory (NFI); Inventory-based estimates of seasonal berry yields are produced using the Swedish NFI observations; The inventory-based method provides seasonal estimates, whereas models can be utilised to integrate vegetation cover and berry yields in numerical multi-objective forest planning.

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Bilberry (Vaccinium myrtillus L.) and lingonberry (V. vitis-idaea L.) can be a part of healthy diet and are important for many animals. Two approaches are described to assessing their vegetation cover and berry yield via national forest inventory (NFI) observations. The aim was to provide estimates and predictions of the abundance and yield of the species at regional and national levels in Finland and Sweden. In Finland, the model-based predictions are used in evaluating the impacts of cutting intensity on forest berries needed in forest-related decision making. In Sweden, seasonal inventory-based estimates are used to evaluate the annual national and regional berry yields, and in a forecasting system aimed at large public and berry enterprises. Based on the NFI sample plots measured between 2014 and 2018, the total annual yields are estimated to be 208 Mkg of bilberry and 246 Mkg of lingonberry on productive forest land (increment at least 1 m³ ha^–1 year^–1) in Finland, and 336 and 382 Mkg respectively in Sweden (average of NFI inventories in 2015–2019). The predicted development of berry yields is related to the intensity of cuttings in alternative forest management scenarios: lower removals favoured bilberry, and higher removals lingonberry. The model-based method describes the effects of stand development and management on berry yields, whereas the inventory-based method can calibrate seasonal estimates through field observations. In providing spatially and timely more accurate information concerning seasonal berry yields, an assessment of berry yields should involve the elements of both inventory-based and model-based approaches described in this study.

Miina, Natural Resources Institute Finland (Luke), Yliopistokatu 6 B, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-8639-4383 E-mail: jari.miina@luke.fi
Bohlin, Swedish University of Agricultural sciences (SLU), Department of Forest Resource Management, Skogsmarksgränd, S-901 83 Umeå, Sweden E-mail: inka.bohlin@slu.se
Lind, Swedish University of Agricultural sciences (SLU), Department of Forest Resource Management, Skogsmarksgränd, S-901 83 Umeå, Sweden E-mail: torgny.lind@slu.se
Dahlgren, Swedish University of Agricultural sciences (SLU), Department of Forest Resource Management, Skogsmarksgränd, S-901 83 Umeå, Sweden E-mail: jonas.dahlgren@slu.se
Härkönen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: kari.harkonen@luke.fi
Packalen, Natural Resources Institute Finland (Luke), Yliopistokatu 6 B, FI-80100 Joensuu, Finland; Ministry of Agriculture and Forestry of Finland, P.O. Box 30, FI-00023 Government, Finland E-mail: tuula.packalen@mmm.fi
Tolvanen, Natural Resources Institute Finland (Luke), Paavo Havaksentie 3, FI-90014 University of Oulu, Finland E-mail: anne.tolvanen@luke.fi

article id 10525, category Research article

Markus Melin, Tiina Ylioja, Leena Aarnio, Katri Hamunen, Seppo Nevalainen, Antti Pouttu, Heli Viiri. (2021). Emergence levels of pine shoot beetles from roundwood piles of Scots pine and the cascading damage in the surrounding forests. Silva Fennica vol. 55 no. 5 article id 10525. https://doi.org/10.14214/sf.10525

Keywords: forest management; forestry; Tomicus piniperda; Tomicus minor; roundwood; legislation; timber storage

Highlights: Emerged pine shoot beetles were counted from piles of harvested Scots pine, and the shoot damage in the surrounding forests was measured; Damage was noticeable up to a distance of 40–60 m, being more severe near large piles; For piles smaller than 50 m³ the level of damage (fallen shoots) was mainly below known thresholds for growth losses; Logs with harvester-damaged bark were significantly less colonized by the beetles.

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Bark beetles are amongst the most aggressive pest agents of coniferous forests. Due to this, many boreal countries have designated laws aiming to lower the risk of bark beetle epidemics. Finland’s forest legislation has pre-emptive measures targeted against bark beetles, and for Scots pine (Pinus sylvestris L.), the law concerns pine shoot beetles (Tomicus spp.). This study used data collected around 25 piles of Scots pine roundwood that were harvested in the winter but left in the forest until the following November. Thus, the pine shoot beetles were able to use the piles for breeding. We assessed the number of emerged insects from the piles and the cascading damage they caused in the surrounding forests. All roundwood piles, regardless of their volume, were used by the beetles for breeding. Highest densities of beetle exit holes were found from the parts of the log with thick and intact bark. If the bark of the log was damaged by the harvester head, the number of beetles decreased significantly. Depending on the volume of the roundwood pile, the cascading damage (fallen shoots) was noticeable up to ca. 40–60 m from the roundwood pile. Storing of piles smaller than 50 m³ did not cause excess damage. The number of fallen shoots per tree was generally below the known thresholds for when growth losses can occur. However, the study was conducted in mature forests, and it can be assumed that the recorded damage levels would severely affect the growth of young pines, raising the question of where to store the roundwood. As with other bark beetles, the role of Tomicus beetles as damage agents may change in the future, but based on this as well as past studies, the species can be viewed as a notable damage agents only around long-term wood storage sites in the current northern conditions.

Melin, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6b, FI-80100 Joensuu, Finland E-mail: markus.melin@luke.fi
Ylioja, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: tiina.ylioja@luke.fi
Aarnio, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: leena.aarnio@luke.fi
Hamunen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6b, FI-80100 Joensuu, Finland E-mail: katri.hamunen@luke.fi
Nevalainen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6b, FI-80100 Joensuu, Finland E-mail: seppo.nevalainen@gmail.com
Pouttu, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: antti.pouttu@kolumbus.fi
Viiri, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6b, FI-80100 Joensuu, Finland; UPM-Kymmene Oyj, UPM Forest, Peltokatu 26 C, PL 85, FI-33100, Tampere, Finland E-mail: heli.viiri@upm.com

article id 10528, category Research article

Jaana Luoranen, Heli Viiri. (2021). Comparison of the planting success and risks of pine weevil damage on mineral soil and drained peatland sites three years after planting. Silva Fennica vol. 55 no. 4 article id 10528. https://doi.org/10.14214/sf.10528

Keywords: survival; planting; mechanical site preparation; ground vegetation; forest regeneration; Hylobius abietis

Highlights: The planting success was poorer on peatland sites than on mineral soil; Dense ground vegetation cover is more probable on peatland than on mineral soil; No differences in pine weevil feeding damage on mineral soil and peatland were found; Cultivated mineral soil reduced the vegetation cover, feeding damage and seedling mortality.

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Over 20% of regeneration operations will be on drained peatland in the next decade in Finland. There are only a few studies comparing the planting success and the risk of pine weevil (Hylobius abetis (L.) feeding damage on mineral soil and drained peatland. Thirty sites planted with Norway spruce (Picea abies (L.) H. Karst.) container seedlings in 2009 in Southern and Central Finland were inventoried three growing seasons after planting. Prediction models for the probability of survival, pine weevil damage and the presence of ground vegetation cover were done separately for peatland and mineral soil sites. The planting success was 17% lower on peatland sites (1379 surviving seedlings ha^–1) than on mineral soil (1654 seedlings ha^–1). The factors explaining the survival were the ground vegetation cover and type of the planting spot on the peatland, and the ground vegetation cover on mineral soil. On mineral soil, 76% of the planting spots were on cultivated mineral soil while on peatland only 28% of the seedlings were planted on similar spots. There were also fewer seedlings that were surrounded by dense ground vegetation on mineral soil (4%) than on peatland (14%). Pine weevil feeding damage did not differ significantly on peatland (23%) or mineral soil (18%). The more time there was from clear-cutting, the more the probability of pine weevil feeding damage was reduced on both soil classes. Additionally, cover vegetation in the vicinity of the seedlings increased on mineral soil. Cultivated planting spots, especially those covered by mineral soil, prevented pine weevil feeding and reduced the harmful effects of vegetation on the seedlings both on mineral soil and peatland.

Luoranen, Natural Recourses Institute Finland (Luke), Production systems, Juntintie 154, FI-77600 Suonenjoki, Finland https://orcid.org/0000-0002-6970-2030 E-mail: jaana.luoranen@luke.fi
Viiri, UPM Forest, Peltokatu 26 C, P.O. Box 85, FI-33100 Tampere, Finland https://orcid.org/0000-0003-3952-9481 E-mail: heli.viiri@upm.com

article id 10515, category Research article

Alwin A. Hardenbol, Anton Kuzmin, Lauri Korhonen, Pasi Korpelainen, Timo Kumpula, Matti Maltamo, Jari Kouki. (2021). Detection of aspen in conifer-dominated boreal forests with seasonal multispectral drone image point clouds. Silva Fennica vol. 55 no. 4 article id 10515. https://doi.org/10.14214/sf.10515

Keywords: Populus tremula; deciduous trees; mixed forest; protected areas; tree species classification; unmanned aerial vehicles

Highlights: Four boreal tree species (Scots pine, Norway spruce, birches and European aspen) classified with an overall accuracy of 95%; Presence of European aspen detected with excellent accuracy (UA: 97%, PA: 96%); Late spring is the best time for species classification by remote sensing; Best time to separate aspen from birch was when birch had leaves, but aspen did not.

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Current remote sensing methods can provide detailed tree species classification in boreal forests. However, classification studies have so far focused on the dominant tree species, with few studies on less frequent but ecologically important species. We aimed to separate European aspen (Populus tremula L.), a biodiversity-supporting tree species, from the more common species in European boreal forests (Pinus sylvestris L., Picea abies [L.] Karst., Betula spp.). Using multispectral drone images collected on five dates throughout one thermal growing season (May–September), we tested the optimal season for the acquisition of mono-temporal data. These images were collected from a mature, unmanaged forest. After conversion into photogrammetric point clouds, we segmented crowns manually and automatically and classified the species by linear discriminant analysis. The highest overall classification accuracy (95%) for the four species as well as the highest classification accuracy for aspen specifically (user’s accuracy of 97% and a producer’s accuracy of 96%) were obtained at the beginning of the thermal growing season (13 May) by manual segmentation. On 13 May, aspen had no leaves yet, unlike birches. In contrast, the lowest classification accuracy was achieved on 27 September during the autumn senescence period. This is potentially caused by high intraspecific variation in aspen autumn coloration but may also be related to our date of acquisition. Our findings indicate that multispectral drone images collected in spring can be used to locate and classify less frequent tree species highly accurately. The temporal variation in leaf and canopy appearance can alter the detection accuracy considerably.

Hardenbol, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0002-0615-505X E-mail: alwin.hardenbol@uef.fi
Kuzmin, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland; University of Eastern Finland, Department of Geographical and Historical Studies, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: anton.kuzmin@uef.fi
Korhonen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: lauri.korhonen@uef.fi
Korpelainen, University of Eastern Finland, Department of Geographical and Historical Studies, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: pasi.korpelainen@uef.fi
Kumpula, University of Eastern Finland, Department of Geographical and Historical Studies, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: timo.kumpula@uef.fi
Maltamo, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: matti.maltamo@uef.fi
Kouki, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: jari.kouki@uef.fi

article id 10449, category Research article

Emanuel Strieder, Sonja Vospernik. (2021). Intra-annual diameter growth variation of six common European tree species in pure and mixed stands. Silva Fennica vol. 55 no. 4 article id 10449. https://doi.org/10.14214/sf.10449

Keywords: growing season; climate effects; dendrometer; logistic model; mixing effect; seasonal growth; social tree position

Highlights: 244 intra-annual growth patterns of six tree species on five sites in mixed and corresponding pure stands were analyzed; Humid sites showed a longer growing season than dry sites; Deciduous species showed an earlier growth culmination than conifer species; Mixture effects were both positive and negative and clearly differed between years, indicating that climate alters mixture effects.

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Studies of intra-annual growth are particularly useful for understanding tree growth because of their high temporal resolution. This study was performed in Austria and included hourly band dendrometer data of 244 annual tree recordings from six tree species (Picea abies (L.) Karst., Pinus sylvestris L., Larix decidua Mill., Abies alba Mill., Fagus sylvatica L., Quercus spp. (Quercus petraea (Matt.) Liebl., Quercus robur L.) sampled on five sites with contrasting site conditions in pure and mixed stands and on trees of different social position. Measurements encompassed 1–7 years. Cumulative diameter increment was modelled by logistic mixed-effects models with random effects at the tree and year level. The results showed large differences in seasonal growth patterns between sites, with a clearly shorter growing season at the drier sites. Species specific response on dry sites could be linked to drought characteristics, whereas response on more humid sites was related to light requirements or successional status. The deciduous trees showed earlier growth culmination and shorter growing periods than the evergreen species. Individual tree growth of Quercus spp., P. abies, and F. sylvatica was positively affected by mixture whereas L. decidua, P. sylvestris and A. alba showed no or adverse mixture effects. Mixture effects differed between years and social position. Furthermore, increment culmination was earlier in mixed stands, but shifts were minor. Tree growth differed by social position with dominant trees showing the largest increment and the longest growth duration, with shifts in tree growth patterns due to social position being as large as those between different sites.

Strieder, Boku, University of Natural Resources and Life Sciences Vienna, Department of Forest- and Soil Sciences, Institute of Forest Growth, Peter-Jordan-Str. 82, A-1190 Vienna, Austria https://orcid.org/0000-0001-6398-8536 E-mail: emanuel.strieder@students.boku.ac.at
Vospernik, Boku, University of Natural Resources and Life Sciences Vienna, Department of Forest- and Soil Sciences, Institute of Forest Growth, Peter-Jordan-Str. 82, A-1190 Vienna, Austria http://orcid.org/0000-0002-4201-6444 E-mail: sonja.vospernik@boku.ac.at

article id 10244, category Research article

Hans Ole Ørka, Endre H. Hansen, Michele Dalponte, Terje Gobakken, Erik Næsset. (2021). Large-area inventory of species composition using airborne laser scanning and hyperspectral data. Silva Fennica vol. 55 no. 4 article id 10244. https://doi.org/10.14214/sf.10244

Keywords: airborne laser scanning; Dirichlet regression; hyperspectral; species proportions; species-specific forest inventory

Highlights: A methodology for using hyperspectral data in the area-based approach is presented; Hyperspectral data produced satisfactory results for species composition in 90% of the cases; Parametric Dirichlet regression is an applicable method to predicting species proportions; Normalization and a tree-based selection of pixels provided the overall best results; Both visible to near-infrared and shortwave-infrared sensors gave acceptable results.

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Tree species composition is an essential attribute in stand-level forest management inventories and remotely sensed data might be useful for its estimation. Previous studies on this topic have had several operational drawbacks, e.g., performance studied at a small scale and at a single tree-level with large fieldwork costs. The current study presents the results from a large-area inventory providing species composition following an operational area-based approach. The study utilizes a combination of airborne laser scanning and hyperspectral data and 97 field sample plots of 250 m² collected over 350 km² of productive forest in Norway. The results show that, with the availability of hyperspectral data, species-specific volume proportions can be provided in operational forest management inventories with acceptable results in 90% of the cases at the plot level. Dominant species were classified with an overall accuracy of 91% and a kappa-value of 0.73. Species-specific volumes were estimated with relative root mean square differences of 34%, 87%, and 102% for Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and deciduous species, respectively. A novel tree-based approach for selecting pixels improved the results compared to a traditional approach based on the normalized difference vegetation index.

Ørka, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0002-7492-8608 E-mail: hans-ole.orka@nmbu.no
Hansen, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway; Norwegian Forest Extension Institute, Honnevegen 60, NO-2836 Biri, Norway https://orcid.org/0000-0001-5174-4497 E-mail: eh@skogkurs.no
Dalponte, Department of Sustainable Agro-ecosystems and Bioresources, Research and Innovation Centre, Fondazione E. Mach, Via E. Mach 1, 38010 San Michele all’Adige, TN, Italy https://orcid.org/0000-0001-9850-8985 E-mail: michele.dalponte@fmach.it
Gobakken, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0001-5534-049X E-mail: terje.gobakken@nmbu.no
Næsset, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: erik.naesset@nmbu.no

article id 10545, category Research article

Karol Tomczak, Tomczak Arkadiusz, Bartłomiej Naskrent, Tomasz Jelonek. (2021). The radial gradient of moisture content of silver birch wood in different seasons. Silva Fennica vol. 55 no. 3 article id 10545. https://doi.org/10.14214/sf.10545

Keywords: birch; Betula pendula; wood properties; living trees; seasonal changes; trunk cross section

Highlights: Seasonal variation in moisture content is significant, the greatest moisture content of wood was recorded in winter, and the lowest in summer; The greatest moisture content on cross-section was observed near to the pith, and lower values near to the bark; From environmental perspective results of this study may have an impact for log transport planning, weight-scaling systems, lumber drying.

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Silver birch (Betula pendula Roth) is classified in diffuse-porous wood category. In this case structure of wood tissue is quite similar across whole cross-sectional area. The aim of this study was to analyse cross-section variability of moisture content (MC) of growing silver birch wood, significant hardwood species in Polish forests. Investigations were performed on 120 model trees. In the trunk of each model tree, an increment core was collected at breast height. Samples were collected of 30 different trees in four different seasons. The greatest MC was observed during winter, lowest MC in summer. Differences in MC were statistically significant only between winter versus spring, summer, and autumn. Distribution of MC on cross-section was similar in each season. The greatest average value was observed close to pith, then it was decreasing in bark direction. The greatest difference between observed in spring – 19.51% (p < 0.05) and lowest in autumn – 4.66%. Distribution of green density (GD) on cross section was inverse proportional to MC value. Variations in GD and MC are relevant for log transport planning, weight-scaling systems, lumber drying and dynamic assessment of stiffness. Therefore, from an environmental loss perspective, it is important to determine changes in MC and GD across the year.

Tomczak, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0001-5192-0294 E-mail: karol.tomczak@up.poznan.pl
Arkadiusz, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0003-1140-8282 E-mail: arkadiusz.tomczak@up.poznan.pl
Naskrent, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0002-0756-4162 E-mail: bartlomiej.naskrent@up.poznan.pl
Jelonek, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0001-9558-9951 E-mail: tomasz.jelonek@up.poznan.pl

article id 10503, category Research article

Katja Lähtinen, Liina Häyrinen, Anders Roos, Anne Toppinen, Francisco X. Aguilar Cabezas, Bo J. Thorsen, Teppo Hujala, Anders Q. Nyrud, Hans F. Hoen. (2021). Consumer housing values and prejudices against living in wooden homes in the Nordic region. Silva Fennica vol. 55 no. 2 article id 10503. https://doi.org/10.14214/sf.10503

Keywords: housing markets; industrial building; structural material; sustainable urbanization; timber structures; urban construction; value expectations

Highlights: Consumers in the Nordic region are similar in their housing value expectations and prejudices against building with wood; Physical properties of houses seem to be less important as constituents of housing value for the consumers compared to intangible factors related to lifestyles and milieus; Urban consumers are the most prejudiced against wood building, and thus supply of homes meeting their value expectations is of a critical importance for sustainable urbanization.

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So far, consumer housing values have not been addressed as factors affecting the market diffusion potential of multi-storey wood building (MSWB). To fill the void, this study addresses different types of consumer housing values in Denmark, Finland, Norway, and Sweden (i.e., Nordic region), and whether they affect the likelihood of prejudices against building with wood in the housing markets. The data collected in 2018 from 2191 consumers in the Nordic region were analyzed with exploratory factor analysis and logistic binary regression analysis. According to the results, consumers’ perceptions on ecological sustainability, material usage and urban lifestyle were similar in all countries, while country-specific differences were detected for perceptions on aesthetics and natural milieus. In all countries, appreciating urban lifestyle and living in attractive neighborhoods with good reputation increased the likelihood of prejudices against wood building, while appreciation of aesthetics and natural milieus decreased the likelihood of prejudices. In strengthening the demand for MSWB and sustainable urbanization through actions in businesses (e.g., branding) and via public policy support (e.g., land zoning), few messages derive from the results. In all, abreast with the already existing knowledge on the supply side factors (e.g., wood building innovations), more customized information is needed on the consumer-driven issues affecting the demand potential of MSWB in the housing markets. This would enable, e.g., both enhancing the supply of wooden homes for consumers appreciating urban lifestyle and neighborhoods and fortifying positive image of wood among consumers especially appreciating good architecture and pleasant environmental milieus.

Lähtinen, Vaasan yliopisto/Seinäjoen yliopistokeskus E-mail: katja.lahtinen@luke.fi
Häyrinen, Natural Resources Institute Finland (Luke), Bioeconomy and Environment Unit, P.O. Box 2, FI-00790 Helsinki, Finland E-mail: liina.hayrinen@luke.fi
Roos, Sveriges lantbruksuniversitet (SLU), Department of Forest Economics, Box 7060, SE-750 07 Uppsala, Sweden E-mail: anders.roos@slu.se
Toppinen, University of Helsinki, Department of Forest Sciences/Helsinki Institute of Sustainability Science (HELSUS), P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: anne.toppinen@helsinki.fi
Aguilar Cabezas, Sveriges lantbruksuniversitet (SLU), Department of Forest Economics, SE-901 83 Umeå, Sweden E-mail: francisco.aguilar@slu.se
Thorsen, University of Copenhagen, Department of Food and Resource Economics, Rolighedsvej 23, DK-1958 Frederiksberg C, DenmarkBo Jellesmark Thorsen E-mail: bjt@ifro.ku.dk
Hujala, University of Eastern Finland (UEF), Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, 80101 FI-Joensuu, Finland E-mail: teppo.hujala@uef.fi
Nyrud, Norwegian University of Life Sciences (NMBU), Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: anders.qvale.nyrud@nmbu.no
Hoen, Norwegian University of Life Sciences (NMBU), Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: hans.hoen@nmbu.no

article id 10483, category Research article

Māra Kitenberga, Guntars Šņepsts, Jānis Vuguls, Didzis Elferts, Ieva Jaunslaviete, Āris Jansons. (2021). Tree- and stand-scale factors shape the probability of wind damage to birch in hemiboreal forests. Silva Fennica vol. 55 no. 2 article id 10483. https://doi.org/10.14214/sf.10483

Keywords: stem breakage; Betula pendula; snapping height; stem damage; stem fracture; tree stability

Highlights: Prior stem and root damage significantly increased the probability of birch being wind-damaged; Trees with a high slenderness ratio had a lower relative snapping height; The snapping height was significantly negatively affected by the prior stem and root damage.

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Strong wind is the major natural disturbance in European forests, that periodically causes tremendous damages to forestry. Yet, factors that affect the probability of wind damage for birch (Betula pendula Roth and B. pubescens Ehrh.), the most common deciduous tree species in hemiboreal forests, are studied scarcely. This study aimed to assess the effects of several tree- and stand-scale variables on the probability of wind damage to birch using data from the Latvian National Forest Inventory (2004–2018), and determine individual tree characteristics that affect the height of the stem breakage. The data analysis was done using the Bayesian binary logistic generalized linear mixed-effects model and a linear mixed-effects model. The probability of wind damage significantly increased by stand age, basal area, and slenderness ratio. Trees with prior damage had a significantly higher probability (odds ratio 4.32) for wind damage. For wind-damaged trees, the snapping height was significantly decreased by an increase in the slenderness ratio (p = 0.03) and prior damage (p = 0.003). Previously damaged trees were more frequently (73%) snapped in the lowest 40% of tree height than trees without prior damage (54%). The probability of wind damage is largely set by factors related to the selection of site, species composition, and rotation. The damage probability could be decreased by management measures that lower competition within the stand with particular regard to preserving intact remaining trees during these manipulations. Factors that reduce the probability of the damage simultaneously increase the snapping height, emphasizing their relevance for mitigation of the wind damages.

Kitenberga, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia https://orcid.org/0000-0002-6192-988X E-mail: mara.kitenberga@silava.lv
Šņepsts, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia E-mail: guntars.snepsts@silava.lv
Vuguls, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia E-mail: janis.vuguls@silava.lv
Elferts, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia; Faculty of Biology, University of Latvia, Jelgavas Street 1, LV–1004, Rīga, Latvia https://orcid.org/0000-0002-9401-1231 E-mail: didzis.elferts@lu.lv
Jaunslaviete, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia E-mail: ieva.jaunslaviete@silava.lv
Jansons, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia https://orcid.org/0000-0001-7981-4346 E-mail: aris.jansons@silava.lv

article id 10447, category Research article

Marian Schönauer, Stephan Hoffmann, Martin Nolte, Dirk Jaeger. (2021). Evaluation of a new pruning and tending system for young stands of Douglas fir. Silva Fennica vol. 55 no. 2 article id 10447. https://doi.org/10.14214/sf.10447

Keywords: thinning; time study; Pseudotsuga menziesii; body posture; heart rate; OWAS; physical workload; young stand

Highlights: Electric pruning shears combined with workflow re-organization reduced time demand for pruning; Thinning by chainsaw was more productive than using the clearing saw Husqvarna 535FBX, which on the other hand showed lower physical workload; Overall cost savings through the use of the new system were quantified at 6%.

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In Germany, management restrictions for Norway spruce (Picea abies (L.) H. Karst.) due to climate change lead to increasing interest in Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) as a potential substituting species. However, Douglas fir requires cost-intensive silvicultural treatments, such as periodic thinnings and, in particular, pruning. In order to improve the efficiency of such treatments, a new tending system with an adapted two-step work system was analyzed. The new system, using electric pruning shears and the backpack clearing saw Husqvarna 535FBX ‘Spacer’, was compared to the conventional three-step work system, using handsaw and chainsaw and characterized by tree selection previously conducted as an independent work step. Time and motion studies to determine productivity and costs, as well as ergonomic analysis through heart rate measurements and posture analysis were conducted. Overall, the new system was found to be more productive and to have lower costs, with 8.9 trees per scheduled system hour (4.17 € tree^–1), compared to the conventional system with 8.1 trees per scheduled system hour (4.44 € tree^–1). Ergonomic improvements with the new system could be mainly observed during the felling of competing trees, when the level of heart rate reserve was reduced by 9.3 percent points, compared to the conventional system. However, significant advantages in reducing unfavorable body postures expected for the ‘Spacer’ could not be confirmed. Since time savings within the new system were mainly attributed to the adaptation of workflow and the use of the electric shears during pruning, it should be considered to replace the ‘Spacer’ within the new system by light chainsaws for best results under the conditions investigated.

Schönauer, Department of Forest Work Science and Engineering, University of Göttingen, Göttingen/Germany E-mail: marian.schoenauer@uni-goettingen.de
Hoffmann, Department of Forest Work Science and Engineering, University of Göttingen, Göttingen/Germany; School of Forestry, University of Canterbury, Christchurch/New Zealand https://orcid.org/0000-0002-8077-967X E-mail: stephan.hoffmann@uni-goettingen.de
Nolte, Forest Education Center FBZ / State Enterprise Forestry and Timber NRW, Arnsberg/Germany E-mail: Martin.Nolte@wald-und-holz.nrw.de
Jaeger, Department of Forest Work Science and Engineering, University of Göttingen, Göttingen/Germany E-mail: dirk.jaeger@uni-goettingen.de

article id 10446, category Research article

Juha Kaitera, Tuomas Kauppila, Jarkko Hantula. (2021). Assessment of the potential of Norway-spruce-seed-orchard associated plants to serve as alternate hosts of Thekopsora areolata. Silva Fennica vol. 55 no. 2 article id 10446. https://doi.org/10.14214/sf.10446

Keywords: Picea abies; cherry-spruce rust; epidemics; rust diseases; Prunus; heteroecism

Highlights: Prunus is the only alternate host of cherry-spruce rust identified in this study; Cherry-spruce rust does not infect plants that belong to common ground vegetation flora in Finnish Norway spruce seed orchards; Spores from different Finnish cherry-spruce rust populations are similarly pathogenic on Prunus; Disease control should be focused only on Prunus in seed orchards.

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The alternate host range of cherry-spruce rust is poorly studied although such information could be important in protecting spruce seed orchards from infections. Pathogenicity of cherry-spruce rust, Thekopsora areolata (Fr.) Magnus, was investigated on potential alternate host species in a greenhouse and in a laboratory in Finland. Five common species of Ericaceae, Vaccinium myrtillus L., V. uliginosum L., V. vitis-idaea L., Empetrum nigrum L. and Arctostaphylos uva-ursi (L.) Spreng, were inoculated in the greenhouse using aeciospores from seven Norway spruce [Picea abies (L.) H. Karst.] seed orchards suffering from T. areolata in 2018. In addition, young detached leaves of Vaccinium spp. and 17 other plant species of ground vegetation from eight Norway spruce seed orchards were inoculated with aeciospores from six seed orchards in the laboratory in 2019. Also, young leaves of Prunus padus L. trees growing within the seed orchards or close to them were inoculated as controls. None of the inoculated leaves of the potential alternate hosts formed uredinia either in the greenhouse or in the laboratory. In contrast, leaves of P. padus from the seed orchards were infected by the six spore sources from six seed orchards and produced uredinia. As T. areolata spores were able to infect only P. padus, but not the other tested species belonging to ground flora, it was concluded that T. areolata disperses only via Prunus spp. in Finnish seed orchards.

Kaitera, Natural Resources Institute Finland (Luke), Natural Resources, FI-90570 Oulu, Finland E-mail: juha.kaitera@luke.fi
Kauppila, Botanical Gardens, University of Oulu, FI-90014 Oulu, Finland E-mail: tuomas.kauppila@oulu.fi
Hantula, Natural Resources Institute Finland (Luke), Natural Resources, FI-00790 Helsinki, Finland E-mail: jarkko.hantula@luke.fi

article id 10409, category Research article

Noé Dumas, Mathieu Dassot, Jonathan Pitaud, Jérôme Piat, Lucie Arnaudet, Claudine Richter, Catherine Collet. (2021). Four-year-performance of oak and pine seedlings following mechanical site preparation with lightweight excavators. Silva Fennica vol. 55 no. 2 article id 10409. https://doi.org/10.14214/sf.10409

Keywords: vegetation control; reforestation; seedling growth; seedling survival

Highlights: Mechanical site preparation (MSP) with lightweight excavators controls highly competitive plant species (Molinia caerulea, Pteridium aquilinum) much more efficiently than MSP with conventional methods; This MSP approach improves four-year survival and growth of pine seedlings, but it is less evident for oak seedlings.

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Mechanical site preparation methods that used tools mounted on lightweight excavators and that provided localised intensive preparation were tested in eight experimental sites across France where the vegetation was dominated either by Molinia caerulea (L.) Moench or Pteridium aquilinum (L.) Kuhn. Two lightweight tools (Deep Scarifier: DS; Deep Scarifier followed by Multifunction Subsoiler: DS+MS) were tested in pine (Pinus sylvestris L., Pinus nigra var. corsicana (Loudon) Hyl. or Pinus pinaster Aiton) and oak (Quercus petraea (Matt.) Liebl. or Quercus robur L.) plantations. Regional methods commonly used locally (herbicide, disk harrow, mouldboard plow) and experimental methods (repeated herbicide application; untreated control) were used as references in the experiments. Neighbouring vegetation cover, seedling survival, height and basal diameter were assessed over three to five years after plantation. For pines growing in M. caerulea, seedling diameter after four years was 37% and 98% greater in DS and DS+MS, respectively, than in the untreated control. For pines growing in P. aquilinum, it was 62% and 107% greater in the same treatments. For oak, diameter was only 4% and 15% greater in M. caerulea, and 13% and 25% greater in P. aquilinum, in the same treatments. For pines, the survival rate after four years was 26% and 32% higher in M. caerulea and 64% and 70% higher in P. aquilinum, in the same treatments. For oak, it was 3% and 29% higher in M. caerulea and 37% and 31% higher in P. aquilinum. Herbicide, when applied for three or four years after planting, provided the best growth performances for pines growing in M. caerulea and P. aquilinum and for oaks growing in P. aquilinum. For these species and site combinations, DS+MS and DS treatments reduced the neighbouring vegetation cover for one to four years following site preparation.

Dumas, Université de Lorraine, AgroParisTech, INRAE, UMR Silva, 54000 Nancy, France E-mail: noe.dumas@inrae.fr
Dassot, EcoSustain, Environmental Engineering Office, Research and Development, 31, rue de Volmerange, 57330 Kanfen, France; Institut National de l’Information Géographique et Forestière, 1 rue des Blanches Terres, 54250 Champigneulles, France E-mail: mathieu.dassot@ign.fr
Pitaud, Office National des Forêts, Département Recherche Développement et Innovation, route d’Amance, 54280 Champenoux, France E-mail: jonathan.pitaud@onf.fr
Piat, Office National des Forêts, Département Recherche Développement et Innovation, 3 rue du petit château, 60200 Compiègne, France E-mail: jerome.piat@onf.fr
Arnaudet, Office National des Forêts, Département Recherche Développement et Innovation, 100 boulevard de la Salle, 45760 Boigny-sur-Bionne, France E-mail: lucie.arnaudet@onf.fr
Richter, Office National des Forêts, Département Recherche Développement et Innovation, Boulevard de Constance, 77300 Fontainebleau, France E-mail: claudine.richter@onf.fr
Collet, Université de Lorraine, AgroParisTech, INRAE, UMR Silva, 54000 Nancy, France https://orcid.org/0000-0003-0861-7796 E-mail: catherine.collet@inrae.fr

article id 10444, category Research article

Risto Kalliola, Timo Saarinen, Niko Tanski. (2021). Seasonal variations of foliar element distributions of silver birch in different habitats. Silva Fennica vol. 55 no. 1 article id 10444. https://doi.org/10.14214/sf.10444

Keywords: foliar nutrients; Betula pendula; deciduous tree; drought injury; element mapping; X-ray fluorescence

Highlights: Detailed mapping using micro X-ray fluorescence showed element variations in a seasonal cohort of silver birch leaves in six different habitats; Seasonal changes occurred in most of the ten studied nutrient elements; Different habitats showed unique seasonal development patterns in specific elements; Element distributions within individual leaf blades were variable; Phenotypic plasticity of foliar nutrients supports adaptation to patchy environments.

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Novel information on silver birch (Betula pendula Roth) foliar element contents and their seasonal, between-habitat and leaf level variations are provided by applying fine-scaled element mapping with micro X-ray fluorescence. In the monthly leaf samples collected from May to October from six different habitats, pairwise scatter plots and Spearman’s rank correlations showed statistically significant positive correlations between Si, Al and Fe, and covariations between also many other pairs of elements. Of the ten elements studied, seven showed statistically significant changes in their average levels between May and June. The contents of P, S and K decreased in most habitats during the later season, whereas Ca and in some habitats also Mn and Zn increased. Comparing habitats, trees in the limestone habitat had relatively low content of Mg, strongly increasing levels of P until the late season, and high content of Ca and Fe. Other habitats also revealed distinctive particularities in their foliar elements, such as a high relative content of S and a low content of Ca at the seashore. Mn was high in three habitats, possibly due to bedrock characteristics. Except for P, the contents of all elements diverged between the midrib and other leaf areas. Zn content was particularly high in the leaf veins. Mn levels were highest at the leaf margins, indicating a possible sequestration mechanism for this potentially harmful element. Si may help to alleviate the metallic toxicities of Al and Fe. Because the growing season studied was dry, some trees developed symptoms of drought stress. The injured leaf parts had reduced levels of P, S and K, suggesting translocation of these nutrients before permanent damage.

Kalliola, Department of geography and geology, University of Turku, FI-20014 Turku, Finland https://orcid.org/0000-0003-2454-8217 E-mail: risto.kalliola@utu.fi
Saarinen, Department of geography and geology, University of Turku, FI-20014 Turku, Finland E-mail: tijusa@utu.fi
Tanski, Department of geography and geology, University of Turku, FI-20014 Turku, Finland E-mail: niko.tanski@utu.fi

article id 10391, category Research article

Victoria A.M. Poljatschenko, Lauri T. Valsta. (2021). Carbon emissions displacement effect of Finnish mechanical wood products by dominant tree species in a set of wood use scenarios. Silva Fennica vol. 55 no. 1 article id 10391. https://doi.org/10.14214/sf.10391

Keywords: avoided emissions; mechanical forest industry; substitution effect; wooden construction

Highlights: Wood product consumption patterns are combined with production-based displacement factors to estimate displacement factors for logs by tree species; The main tree species in Finland have somewhat unequal displacement factors; Historical and projected wood use scenarios show large variation in the levels of avoided emissions between individual years and scenarios.

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The carbon emissions displacement effect of Finnish logs for mechanical wood products by dominant tree species (Scots pine, Pinus sylvestris L.; Norway spruce, Picea abies (L.) H. Karst.; Birch, Betula spp.) was assessed by combining information from previous studies of current consumption patterns with displacement factors (DF) for structural construction, non-structural construction, and energy usage. We did not conduct additional life cycle analyses compared to the current literature. Our aim was to identify the factors that most extensively influence the displacement effect and to estimate the overall climate effect of Finnish logs in light of current production levels of mechanical forest industry. The analyses were based on information from both statistics and proprietary sources. Contrary to previous studies, we provide DFs by main tree species in Finland, which has been an unidentified area of research to date. Additionally, we apply a more detailed classification of structural and non-structural wood products. This study did not include effects on the forest carbon sink, as they depend case-wise on forest resources and forest management. According to our results, with current production and consumption trends, the average displacement effects for domestic Scots pine, Norway spruce, and birch logs were 1.28, 1.16, and 1.43 Mg C/Mg C, respectively. The corresponding overall annual displacement effect caused by the current production of sawn wood and wood-based panels was 12.3 Tg CO₂ for Finland for the BAU scenario and varied between 8.6 and 16.3 Tg CO₂ depending on the wood use scenario.

Poljatschenko, Simosol Oy, Hämeenkatu 10, FI-11100 Riihimäki, Finland E-mail: victoria.poljatschenko@simosol.fi
Valsta, Department of Forest Sciences, University of Helsinki, Latokartanonkaari 7, FI-00014 University of Helsinki, Finland E-mail: lauri.valsta@helsinki.fi

article id 10396, category Research article

Agnese Gailīte, Anita Gaile, Dainis E. Ruņģis. (2020). Genetic diversity and structure of wild Vaccinium populations - V. myrtillus, V. vitis-idaea and V. uliginosum in the Baltic States. Silva Fennica vol. 54 no. 5 article id 10396. https://doi.org/10.14214/sf.10396

Keywords: molecular markers; bilberries; bog bilberries; chloroplast SSR; in situ conservation; lingonberries; nuclear SSR

Highlights: Wild Vaccinium species were studied using EST-SSR and chloroplast SSR markers; Populations were moderately genetically differentiated, but without higher order clustering of groups of populations; Genetic diversity of populations growing under different management regimes was similar; Selection of populations for in situ conservation should focus on rare genotypes, more differentiated populations and geographic coverage.

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Vaccinium myrtillus L., V. vitis-idaea L. and V. uliginosum L. belong to the genus Vaccinium. These wild species are widely distributed and ecologically important within the Baltic countries but they have not been extensively studied using molecular markers. EST-SSR and cpSSR markers were used to investigate the population structure and genetic diversity of these species to obtain information useful for the development of in situ conservation strategies. Wild Vaccinium species populations are moderately genetically differentiated, with some populations more highly differentiated, but without higher order clustering of groups of populations, indicating that there are no dispersal barriers for these species within the Baltic countries. Genetic diversity of populations growing in protected areas, managed forests and intensively utilised public recreational areas is similar. The results from this study can be utilised for the selection of populations for the in situ conservation of the studied Vaccinium species. In addition, complementary ex situ conservation strategies can be used for the preservation of rare varieties (e.g. V. myrtillus var. leucocarpum).

Gailīte, Genetic Resource Centre, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, Salaspils, Latvia, LV-2169 E-mail: agnese.gailite@silava.lv
Gaile, Genetic Resource Centre, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, Salaspils, Latvia, LV-2169 E-mail: anita.gaile@silava.lv
Ruņģis, Genetic Resource Centre, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, Salaspils, Latvia, LV-2169 https://orcid.org/0000-0001-5173-2912 E-mail: dainis.rungis@silava.lv

article id 10369, category Research article

Tiina Laine, Ville Kankaanhuhta, Juho Rantala, Timo Saksa. (2020). Effects of spot mounding and inverting on growth of conifers, exposed mineral soil and natural birch regeneration. Silva Fennica vol. 54 no. 5 article id 10369. https://doi.org/10.14214/sf.10369

Keywords: boreal forest; regeneration; site preparation; mounding; young stand management

Highlights: There were 21% fewer naturally regenerated birches ha^–1 in inverted areas (22 951) compared to spot mounded areas (29 086); Spot mounding exposed slightly, but not statistically significantly, larger area of mineral soil than inverting; There was no difference in seedling mortality or growth between the site preparation methods.

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In Nordic forests, consistent evidence about better seedling survival rate and increased growth due to site preparation have been obtained in numerous studies. Proper site preparation method can reduce costs of the whole regeneration chain through its effects on survival of planted seedlings, abundance of natural regeneration and competition in early stand development. This study compared the natural regeneration of birches (silver birch (Betula pendula Roth) and downy birch (B. pubescens Ehrh.)), amount of exposed mineral soil, and growth of planted seedlings between spot mounding and inverting site preparation methods. Present study was conducted in eight forest stands established in 2012 or 2015. Even though difference was not statistically significant, inverting exposed less mineral soil than spot mounding and thus reduced the natural regeneration of birch seedlings by 6135 seedlings ha^–1 compared to spot mounding. However, the variation between regeneration areas was remarkable. There was no difference in seedling mortality or growth between the site preparation methods. In order to achieve high growth of conifers, moderate amount of exposed mineral soil and thus less naturally regenerated birch, inverting should be favored over spot mounding.

Laine, Metsä Group, P.O. Box 208, FI-70101 Kuopio, Finland E-mail: tiina.laine@metsagroup.com
Kankaanhuhta, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: ville.kankaanhuhta@luke.fi
Rantala, Metsä Group, P.O. Box 10, FI-02020 METSÄ, Finland E-mail: juho.rantala@metsagroup.com
Saksa, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: timo.saksa@luke.fi

article id 10351, category Research article

Karol Bronisz, Michał Zasada. (2020). Taper models for black locust in west Poland. Silva Fennica vol. 54 no. 5 article id 10351. https://doi.org/10.14214/sf.10351

Keywords: taper; Robinia pseudoacacia; mixed-effects models; section diameter over and under bark; volume prediction

Highlights: Seven taper models with different numbers of estimated parameters were analysed; Section diameter and volume was modelled using fixed and mixed-effects modelling approaches; The variable-form taper model with eight estimated parameters fitted the data the best; The lowest error for volume prediction was achieved for the fixed-effects taper model.

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The diameter at any point on a stem and tree volume are some of the most important types of information used in forest management planning. One of the methods to predict the diameter at any point on a stem is to develop taper models. Black locust (Robinia pseudoacacia L.) occurs in almost all forests in Poland, with the largest concentration in the western part of the country. Using empirical data obtained from 13 black locust stands (48 felled trees), seven taper models with different numbers of estimated parameters were analysed for section diameters both over and under bark using fixed and mixed-effects modelling approaches. Assuming a lack of additional measurements, the best fitted taper models were used for the prediction of over bark volume using both methods. The predicted volume was compared with the results from different volume equations available for black locust. The variable-form taper model with eight estimated parameters fitted the data the best. The lowest root mean square error for volume prediction was achieved for the elaborated fixed-effects taper model (0.0476), followed by the mixed-effects taper model (0.0489). At the same time, the difference between the volume relative errors achieved based on the taper models does not differ significantly from the results obtained using the volume equations already available for black locust (two of the three analysed).

Bronisz, Institute of Forest Sciences, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, PL 02-776 Warsaw, Poland E-mail: karol.bronisz@wl.sggw.pl
Zasada, Institute of Forest Sciences, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, PL 02-776 Warsaw, Poland https://orcid.org/0000-0002-4881-296X E-mail: Michal.Zasada@wl.sggw.pl

article id 10334, category Research article

Annija Kārkliņa, Guntis Brūmelis, Iluta Dauškane, Didzis Elferts, Lāsma Freimane, Māra Kitenberga, Zane Lībiete, Roberts Matisons, Āris Jansons. (2020). Effect of salvage-logging on post-fire tree establishment and ground cover vegetation in semi-natural hemiboreal forests. Silva Fennica vol. 54 no. 5 article id 10334. https://doi.org/10.14214/sf.10334

Keywords: management; forest fire; natural disturbance; legacies; understory vegetation

Highlights: Effect of salvage logging on post-fire understory vegetation was assessed; Effect of salvage logging differed depending on forest types; In dry-poor stands, Calluna vulgaris was hindering other plant species; In wet stands, logging had positive effect on understory vegetation diversity; Salvage logging enhanced the effect of natural disturbance in dry-rich stands.

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Fire is a common disturbance in boreal forests causing changes in biological diversity at various spatial scales. In the past 100 years, forest management has limited fire outbreaks, but in the future, the fire-affected forest area is expected to increase in many regions due to climate change. Burned forests are typically salvage-logged, but the effect of this type of management versus natural regeneration on biological diversity is not well understood, particularly the mid-term effect to tree establishment and understory vegetation composition and diversity. Various management methods were used after a large fire in 1992 in a peatland-forest complex and neighbouring managed forests, which created an experimental setup for study of the effect of management after fire in the Sliteres National park, northwestern Latvia. Understory vegetation was described in plots using a design of four forest and three management types: natural regeneration (unmanaged) and managed sites with salvage logging followed by no further human intervention and salvage logging with planting. Post-fire management had different effect in each forest type. Species richness was higher in forest types with salvage logging than in natural regenerated sites on rich wet and rich dry forest types, but not for the poor forest types. Tree regeneration was generally greater in salvage-logged stands, but differed between forest types. Species composition was related to tree regeneration and canopy openness. In contrast to other studies, salvage logging had a positive mid-term effect to ground vegetation diversity and tree establishment in the studied stands, implying potential for concomitant management and conservation of ground cover vegetation in semi-natural stands.

Kārkliņa, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: annija.karklina@silava.lv
Brūmelis, University of Latvia, Faculty of Biology, Jelgavas street 1, LV-1004, Riga, Latvia E-mail: guntis.brumelis@lu.lv
Dauškane, University of Latvia, Faculty of Biology, Jelgavas street 1, LV-1004, Riga, Latvia E-mail: iluta.dauskane@lu.lv
Elferts, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia; University of Latvia, Faculty of Biology, Jelgavas street 1, LV-1004, Riga, Latvia E-mail: didzis.elferts@lu.lv
Freimane, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: lasma.freimane@silava.lv
Kitenberga, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: mara.kitenberga@silava.lv
Lībiete, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: zane.libiete@silava.lv
Matisons, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: robism@inbox.lv
Jansons, Latvian State Forest Research Institute “Silava”, 111 Rigas Street, LV-2169, Salaspils, Latvia E-mail: aris.jansons@silava.lv

article id 10291, category Research article

Sakari Tuominen, Andras Balazs, Annika Kangas. (2020). Comparison of photogrammetric canopy models from archived and made-to-order aerial imagery in forest inventory. Silva Fennica vol. 54 no. 5 article id 10291. https://doi.org/10.14214/sf.10291

Keywords: distribution; prediction; forest resources; mapping; aerial imaging; digital stereo-photogrammetry

Highlights: Two photogrammetric canopy models were tested in forest inventory: one based on archived standard aerial imagery acquired for ortho-mosaic production and another based on stereo-photogrammetrically oriented aerial imaging adjusted for stereo-photogrammetric canopy modelling; Both data sets were tested in the estimation of forest variables; Despite the differences in imaging parameters, there was little difference in their performance in predicting the forest inventory variables.

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In remote sensing-based forest inventories 3D point cloud data, such as acquired from airborne laser scanning, are well suited for estimating the volume of growing stock and stand height, but tree species recognition often requires additional optical imagery. A combination of 3D data and optical imagery can be acquired based on aerial imaging only, by using stereo photogrammetric 3D canopy modeling. The use of aerial imagery is well suited for large-area forest inventories, due to low costs, good area coverage and temporally rapid cycle of data acquisition. Stereo-photogrammetric canopy modeling can also be applied to previously acquired imagery, such as for aerial ortho-mosaic production, assuming that the imagery has sufficient stereo overlap. In this study we compared two stereo-photogrammetric canopy models combined with contemporary satellite imagery in forest inventory. One canopy model was based on standard archived imagery acquired primarily for ortho-mosaic production, and another was based on aerial imagery whose acquisition parameters were better oriented for stereo-photogrammetric canopy modeling, including higher imaging resolution and greater stereo-coverage. Aerial and satellite data were tested in the estimation of growing stock volume, volumes of main tree species, basal area and diameter and height. Despite the better quality of the latter canopy model, the difference of the accuracy of the forest estimates based on the two different data sets was relatively small for most variables (differences in RMSEs were 0–20%, depending on variable). However, the estimates based on stereo-photogrammetrically oriented aerial data retained better the original variation of the forest variables present in the study area.

Tuominen, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: sakari.tuominen@luke.fi
Balazs, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: andras.balazs@luke.fi
Kangas, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: annika.kangas@luke.fi

article id 10375, category Research article

Amy Wotherspoon, Nelson Thiffault, Robert L. Bradley. (2020). Resource availability and physiological response of black spruce to scarification in two climatic regions of Québec (Canada). Silva Fennica vol. 54 no. 4 article id 10375. https://doi.org/10.14214/sf.10375

Keywords: Picea mariana; foliar δ18O; foliar δ13C; needle gas exchange; photosynthetic nitrogen use efficiency; water use efficiency

Highlights: Mechanical scarification of clearcut sites in two climatic regions maintained high growth rates of regenerating black spruce 18 years after treatment; In both regions, scarification reduced soil moisture and increased water use efficiency; In the cooler-humid region, scarification improved soil nitrogen mineralization.

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Scarification is a mechanical site preparation technique designed to create microsites that will favor the growth of planted tree seedlings after clearcutting. However, the positive growth response of black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.) to scarification varies across different sites. We hypothesized that this was due to different forms of physiological stress induced by different climates or by the severity of competition from ericaceous shrubs. We thus compared the effects of scarification on black spruce needle gas exchange and other foliar properties, as well as on indices of soil water and nitrogen availability, in relatively warm-dry (Abitibi) vs. cool-humid (Côte-Nord) climates in the province of Québec (Canada). We found a similar positive effect of scarification on tree height in Abitibi and Côte-Nord. Scarification reduced soil moisture in both climatic regions, but increased soil N mineralization in Côte-Nord only. Accordingly, scarification increased the instantaneous water use efficiency in both climate regions, but decreased photosynthetic N use efficiency in Côte-Nord only. In both regions, we found a positive relationship between foliar δ¹⁸O and δ¹³C on scarified plots, providing further evidence that increased growth due to scarification depends on a decrease in stomatal conductance. We conclude that scarification increases total evapotranspiration of trees evenly across the east-to-west moisture gradient in the province of Québec, but also improves long-term soil nutritional quality in a cooler-humid climate.

Wotherspoon, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, J1K 2R1, Canada E-mail: amy.wotherspoon@usherbrooke.ca
Thiffault, Canadian Wood Fibre Centre, Canadian Forest Service, Natural Resources Canada, 1055 du. P.E.P.S., P.O. Box 10380, Québec, G1V 4C7, Canada E-mail: nelson.thiffault@canada.ca
Bradley, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, J1K 2R1, Canada E-mail: robert.bradley@usherbrooke.ca

article id 10370, category Research article

Juha Lappi, Timo Pukkala. (2020). Analyzing ingrowth using zero-inflated negative binomial models. Silva Fennica vol. 54 no. 4 article id 10370. https://doi.org/10.14214/sf.10370

Keywords: regeneration; continuous cover forestry; count data; generalized linear model; overdispersion; right-censoring

Highlights: Models were developed to describe ingrowth in national forest inventory data; The data were more dispersed than Poisson data and included many zeros; Fixed-effects models had larger zero-inflation probability and overdispersion parameter than mixed-effect models; Mixed-effects models had larger likelihood than fixed-effects models but provided biased predictions; Prediction of right-censored ingrowth may be useful owing to large overdispersion.

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Ingrowth is an important element of stand dynamics in several silvicultural systems, especially in continuous cover forestry. Earlier predictive models for ingrowth in Finnish forests are few and not based on up-to-date statistical methods. Ingrowth is here defined as the number of trees over 1.3 m entering a plot. This study developed new ingrowth models for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and birch (Betula pendula Roth and B. pubescens Ehrh.) using data from the permanent sample plots of the Finnish national forest inventory. The data were over-dispersed compared to a Poisson process and had many zeros. Therefore, a zero-inflated negative binomial model was used. The total and species-specific stand basal areas, temperature sum and fertility class were used as predictors in the ingrowth models. Both fixed-effects and mixed-effects models were fitted. The mixed-effects model versions included random plot effects. The mixed-effects models had larger likelihoods but provided biased predictions. Also censored prediction was considered where only a certain maximum number of ingrowth trees were accepted for a plot. The models predicted most pine ingrowth in pine-dominated stands on sub-xeric and xeric sites where stand basal area was low. The predicted amount of spruce ingrowth was maximized when the basal area of spruce was 13 m² ha^–1. Increasing temperature sum increased spruce ingrowth. Predicted birch ingrowth decreased with increasing stand basal area and towards low fertility classes. An admixture of pine increased the predicted amount of spruce ingrowth.

Lappi, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: juha.lappi.sjk@gmail.com
Pukkala, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: timo.pukkala@uef.fi

article id 10347, category Research article

Matti Katila, Tuomas Rajala, Annika Kangas. (2020). Assessing local trends in indicators of ecosystem services with a time series of forest resource maps. Silva Fennica vol. 54 no. 4 article id 10347. https://doi.org/10.14214/sf.10347

Keywords: National Forest Inventory; satellite images; k-nearest neighbour estimation; Landsat; Mann-Kendall test; multitemporal inventory data; temporal trend analysis

Highlights: Untitled Document Contextual Mann-Kendall test detects significant trends in time-series of forest maps; Trends become more consistent as the areal unit size used for test input increases; Changes in different scales reflect different phenomena in forests; Significant trends were detected even after multiple testing correction.

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Since the 1990’s, forest resource maps and small area estimates have been produced by combining national forest inventory (NFI) field plot data, optical satellite images and numerical map data using a non-parametric k-nearest neighbour method. In Finland, thematic maps of forest variables have been produced by the means of multi-source NFI (MS-NFI) for eight to ten times depending on the geographical area, but the resulting time series have not been systematically utilized. The objective of this study was to explore the possibilities of the time series for monitoring the key ecosystem condition indicators for forests. To this end, a contextual Mann-Kendall (CMK) test was applied to detect trends in time-series of two decades of thematic maps. The usefulness of the observed trends may depend both on the scale of the phenomena themselves and the uncertainties involved in the maps. Thus, several spatial scales were tested: the MS-NFI maps at 16 × 16 m² pixel size and units of 240 × 240 m², 1200 × 1200 m² and 12 000 × 12 000 m² aggregated from the MS-NFI map data. The CMK test detected areas of significant increasing trends of mean volume on both study sites and at various unit sizes except for the original thematic map pixel size. For other variables such as the mean volume of tree species groups, the proportion of broadleaved tree species and the stand age, significant trends were mostly found only for the largest unit size, 12 000 × 12 000 m². The multiple testing corrections decreased the amount of significant p-values from the CMK test strongly. The study showed that significant trends can be detected enabling indicators of ecosystem services to be monitored from a time-series of satellite image-based thematic forest maps.

Katila, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Latokartanonkaari 9, FI-00790 Helsinki, Finland; https://orcid.org/0000-0001-6946-5736 E-mail: matti.katila@luke.fi
Rajala, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: tuomas.rajala@luke.fi
Kangas, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-8637-5668 E-mail: annika.kangas@luke.fi

article id 10276, category Research article

Adas Marčiulynas, Vaida Sirgedaitė-Šėžienė, Povilas Žemaitis, Āris Jansons, Virgilijus Baliuckas. (2020). Resistance of Scots pine half-sib families to Heterobasidion annosum in progeny field trials. Silva Fennica vol. 54 no. 4 article id 10276. https://doi.org/10.14214/sf.10276

Keywords: Pinus sylvestris; field trials; half-sib families; root rot pathogen; total phenolic compounds; tree susceptibility

Highlights: Large genetic variation was estimated in the resistance of Scots pine half-sib families to root rot in field trials; A strong relationship was observed between family resistance to root rot and phenolic compound concentration in the wood.

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Five Scots pine (Pinus sylvestris L.) progeny field trials, each established in different Lithuanian regions of provenance in 1983, were studied. Each progeny field trial consists of 140 half-sib families from seven populations (20 families from each population). The evaluation was carried out in 2012 and 2018 to assess the families resistance to Heterobasidion annosum (Fr.) Bref. An index of resistance in the infected plots was calculated. To verify the accuracy of the method, total phenolic compounds (TPC) was chosen as key parameter to compare with the plant resistance index. During the six years between the two assessments, the percentage of living Scots pine trees in the progeny field trials decreased up to 20 percentage points (range: 4 p.p. to 20 p.p.). In 2018 the area of H. annosum damaged plots (in percentage from total field trial area) varied from 17 to 27%. Tree mortality in the trial correlates with site soil fertility – more fertile soils were distinguished by higher tree percentage loss and vice versa. Using analysis from combined data of all progeny trials, the family variance component reached 13.3 ± 2.2% and family heritability was 0.81. Family heritability estimates for root rot resistance show possibilities of high breeding effectiveness. The correlations between the trials in family resistance estimates were negligible (ranging from 0 to 0.28). The significant high correlation coefficient was determined between the resistance index and TPC concentration (r = 0.77, p = 0.0003). This allows us to assume that plant resistance is directly linked on TPC synthesis. The results indicate that the chosen methods of chemical resistance for identification of root rot-resistant genotypes are applicable for the selection of Scots pine half-sib families in the field trials with higher resistance to pathogens.

Marčiulynas, Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1, LT-53101 Girionys, Kaunas District, Lithuania E-mail: adas.marciulynas@mi.lt
Sirgedaitė-Šėžienė, Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1, LT-53101 Girionys, Kaunas District, Lithuania E-mail: vaida.seziene@mi.lt
Žemaitis, Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1, LT-53101 Girionys, Kaunas District, Lithuania E-mail: povilas.zemaitis@mi.lt
Jansons, Latvian State Forest Research Institute “Silava”, Department of Forest Tree Breeding, Rigas St.t. 111, Salaspils LV-2169, Latvia E-mail: aris.jansons@silava.lv
Baliuckas, Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1, LT-53101 Girionys, Kaunas District, Lithuania E-mail: virgilijus.baliuckas@mi.lt

article id 10269, category Research article

Annika Kangas, Helena M. Henttonen, Timo P. Pitkänen, Sakari Sarkkola, Juha Heikkinen. (2020). Re-calibrating stem volume models – is there change in the tree trunk form from the 1970s to the 2010s in Finland? Silva Fennica vol. 54 no. 4 article id 10269. https://doi.org/10.14214/sf.10269

Keywords: TLS; OLS; regression; terrestrial laser scanning

Highlights: TLS data showed that trunk form has changed in Finland from the 1970s; Significant differences were observed for all tree species; The trees in TLS data are on average more slender than in the old data.

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The tree stem volume models of Norway spruce, Scots pine and silver and downy birch currently used in Finland are based on data collected during 1968–1972. These models include four different formulations of a volume model, with three different combinations of independent variables: 1) diameter at height of 1.3 m above ground (dbh), 2) dbh and tree height (h) and 3) dbh, h and upper diameter at height of 6 m (d6). In recent National Forest Inventories of Finland, a difference in the mean volume prediction between the models with and without the upper diameter as predictor has been observed. To analyze the causes of this difference, terrestrial laser scanning (TLS) was used to acquire a large dataset in Finland during 2017–2018. Field-measured predictors and volumes predicted using spline functions fitted to the TLS data were used to re-calibrate the current volume models. The trunk form is different in these two datasets. The form height is larger in the new data for all diameter classes, which indicates that the tree trunks are more slender than they used to be. One probable reason for this change is the increase in stand densities, which is at least partly due to changed forest management. In models with both dbh and h as predictors, the volume is smaller a given h class in the data new data than in the old data, and vice versa for the diameter classes. The differences between the old and new models were largest with pine and smallest with birch.

Kangas, Natural Resources Institute Finland (Luke), Yliopistokatu 6 B, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-8637-5668 E-mail: annika.kangas@luke.fi
Henttonen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: helena.henttonen@luke.fi
Pitkänen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0001-5389-8713 E-mail: timo.p.pitkanen@luke.fi
Sarkkola, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: sakari.sarkkola@luke.fi
Heikkinen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0003-3527-774X E-mail: juha.heikkinen@luke.fi

article id 10389, category Research article

Juho Matala, Harri Kilpeläinen, Henrik Heräjärvi, Tapio Wall, Erkki Verkasalo. (2020). Sawlog quality and tree dimensions of Scots pine 34 years after artificial moose browsing damage. Silva Fennica vol. 54 no. 3 article id 10389. https://doi.org/10.14214/sf.10389

Keywords: Pinus sylvestris; growth; timber quality; Alces alces; defect

Highlights: The first controlled, long-term, experimental study on the tree dimensions and sawlog quality after moose damage; The trees damaged at the seedling stage had a smaller diameter, height, and tree volume at the end of the experiment; The heavier the clipping treatment, the more likely the stem form deteriorated; Deteriorated stem form and vertical branches were the most typical defects.

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Moose (Alces alces L.) browsing causes severe damage in Scots pine (Pinus sylvestris L.) seedling stands. The effects of this damage on the quality of sawlogs were studied in a long-term controlled experiment. This article reports the stem size and external quality characteristics of Scots pine stems 34 years after artificial moose browsing damage. Damaging the trees by clipping the main stem at the seedling stage reduced the diameter, height, and tree volume of the trees at the end of the experiment. The tree growth reduction was dependent on the severity of clipping. The differences between the damaged and the control trees were more obvious in diameter than in height at the time of final felling. Stem form defects and vertical branches were the most typical externally detectable defects caused by clipping. Defects in the butt logs were detected in 71–89% of the damaged trees, depending on the clipping treatment severity. The stronger the clipping treatment, the more likely the stem form was defected and the more commonly were vertical branches and crooks detected in the stems. The results indicate that both tree dimensions and stem quality suffer from moose browsing. The findings of this controlled experiment more likely underestimate than overestimate the damage in comparison to real moose browsing. Further analyses are required to assess the effects of browsing damage on the internal quality of sawlogs and subsequent economic outcomes.

Matala, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6B, FI-80101 Joensuu, Finland E-mail: juho.matala@luke.fi
Kilpeläinen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6B, FI-80101 Joensuu, Finland E-mail: harri.kilpelainen@luke.fi
Heräjärvi, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6B, FI-80101 Joensuu, Finland E-mail: henrik.herajarvi@luke.fi
Wall, Natural Resources Institute Finland (Luke), Research infrastructure services, Yliopistokatu 6B, FI-80101 Joensuu, Finland E-mail: tapio.wall@luke.fi
Verkasalo, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6B, FI-80101 Joensuu, Finland E-mail: erkki.verkasalo@luke.fi

article id 10355, category Research article

Grzegorz Szewczyk, Raffaele Spinelli, Natascia Magagnotti, Paweł Tylek, Janusz M. Sowa, Piotr Rudy, Dominika Gaj-Gielarowiec. (2020). The mental workload of harvester operators working in steep terrain conditions. Silva Fennica vol. 54 no. 3 article id 10355. https://doi.org/10.14214/sf.10355

Keywords: logging; ergonomics; eye tracking; fatigue; gaze behaviour

Highlights: We analysed a harvester operator’s perception of his work environment as slope gradient increased; Increasingly difficult work conditions (steeper terrain) were reflected by increased eyeball activity; Fixation duration increased with slope gradient, while the duration of saccades was shorter; Variation of the eyeball movement cycles was also related to work difficulty caused by slope gradient.

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The use of modern multi-functional forestry machines has already been associated with central nervous system fatigue induced by high mental workload. As these machines are being used under increasingly difficult terrain conditions, further knowledge is required on the expected aggravation of operators’ mental workload, so that suitable work/rest schedules can be developed. Within such a context, the aim of this study was to gauge aggravations of mental workload derived from increasing slope gradient. Measurements of eye activity were obtained from a representative harvester operator working in corridors with the following mean inclinations: 9%, 23% and 47%. The duration, frequency and trajectory of eye movements were used to determine the harvester operator’s mental workload, on the assumption that worsening work conditions would be reflected by increased eyeball activity. The number of fixations during the performance of all tasks increased with the increasing slope gradient. Similarly, fixation duration increased with slope gradient. The mean duration of saccades when working on a 23% slope was 5% shorter compared to work under a 9% gradient. A further significant shortening of saccade duration (~22%) occurred when working on a 47% slope. The good match between eye activity cycles and work cycles, visible especially on steep slopes, indicates that mental workload is related to work conditions. Overall, operating a forest harvester on steep slopes results in a greatly increased mental workload and calls for suitable rest schedules.

Szewczyk, University of Agriculture in Krakow; al. 29 Listopada 46, 31-425 Kraków, Poland E-mail: rlszewcz@cyf-kr.edu.pl
Spinelli, National Research Council of Italy, Firenze, via Madonna del Piano, 10 50019 – Sesto Fiorentino, Italy E-mail: spinelli@ivalsa.cnr.it
Magagnotti, National Research Council of Italy, Firenze, via Madonna del Piano, 10 50019 – Sesto Fiorentino, Italy E-mail: natascia.magagnotti@ibe.cnr.it
Tylek, University of Agriculture in Krakow; al. 29 Listopada 46, 31-425 Kraków, Poland E-mail: rltylek@cyf-kr.edu.pl
Sowa, University of Agriculture in Krakow; al. 29 Listopada 46, 31-425 Kraków, Poland E-mail: janusz.sowa@urk.edu.pl
Rudy, State Forests, Biłgoraj Forest District, ul. Zamojska 96, 23-400 Biłgoraj, Poland E-mail: rudy.piotrek@o2.pl
Gaj-Gielarowiec, State Forests, Barycz Forest District, Barycz 69, 26-200 Końskie, Poland E-mail: dominika.gaj@gmail.com

article id 10273, category Research article

Lasse Aro, Anssi Ahtikoski, Jyrki Hytönen. (2020). Profitability of growing Scots pine on cutaway peatlands. Silva Fennica vol. 54 no. 3 article id 10273. https://doi.org/10.14214/sf.10273

Keywords: Pinus sylvestris; afforestation; bare land value; financial performance; peat cutaway area; stand-level optimization

Highlights: The potential wood production on cutaway peatlands can be high; Afforestation with seeding or planting was profitable at 3% rate of interest; In northern Finland, the afforestation method, ditch spacing and fertilization affected the bare land value.

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A major after-use option for former peat harvesting areas has been afforestation. The profitability of afforestation with Scots pine trees (Pinus sylvestris L.) was studied in two 31–32-year old experiments in southern and northern Finland. The stands were established by seeding and planting, and various fertilization treatments and drainage intensities were tested. The financial performance for each plot was assessed in three steps. First, the costs occurred during the measurement time were summed up according to their present value. Then, for the rest of the rotation (i.e., from the age of 31/32 onwards) the stand management was optimized in order to maximize the net present value (MaxNPV). Finally, bare land values (BLVs) were calculated by summing up the present value of costs and the MaxNPV and converting the sum of the series into infinity. The afforestation method did not affect the mean annual increment (MAI; 9.2–9.5 m³ ha^–1 a^–1) in the southern experiment. In the northern experiment the afforestation method, ditch spacing and fertilization had significant effects on the MAI of the stands. The average MAI of the planted pines was 8.9 m³ ha^–1 a^–1, and for seeded pines it was 7.5 m³ ha^–1 a^–1. The BLV at an interest rate of 3% was positive for all stands in both regions. In the northern region afforestation method, ditch spacing and fertilization also had a significant effect on the BLV. When the interest rate was 5%, almost two thirds of the stands had a negative BLV in both regions.

Aro, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Itäinen Pitkäkatu 4A, FI-20520 Turku, Finland E-mail: lasse.aro@luke.fi
Ahtikoski, Natural Resources Institute Finland (Luke), Natural resources, Paavo Havaksentie 3, FI-90570 Oulu, Finland https://orcid.org/0000-0003-1658-3813 E-mail: anssi.ahtikoski@luke.fi
Hytönen, Natural Resources Institute Finland (Luke), Natural resources, Teknologiakatu 7, FI-67100 Kokkola, Finland http://orcid.org/0000-0001-8475-3568 E-mail: jyrki.hytonen@luke.fi

article id 10259, category Research article

Jyrki Hytönen, Hannu Hökkä. (2020). Comparison of granulated and loose ash in fertilisation of Scots pine on peatland. Silva Fennica vol. 54 no. 2 article id 10259. https://doi.org/10.14214/sf.10259

Keywords: Pinus sylvestris; wood ash; nutrition; fertilisation; granulation; PK fertiliser

Highlights: Granulated ash and commercial PK fertilizer increased stand growth in similar way during 15-year study period; Loose ash gave stronger and faster response than granulated ash.

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The effects of wood ash fertilisation on tree nutrition and growth on forested peatlands has been studied using loose ash, but in practice, ash fertilisation is done almost exclusively with granulated ash. In this study, the effects of granulated ash and loose ash (both 5 Mg ha^–1) on the growth and nutrition of Scots pine (Pinus sylvestris L.) stands were compared between a nitrogen-poor and a nitrogen-rich site over 15 years. On the nitrogen-rich site, wood ash application was also compared with commercial PK fertilisation. On the nitrogen-rich site, mean stand volume growth increase over unfertilised control treatment during the 15 year study period using granulated ash and commercial PK fertiliser was of the same magnitude (on average, 2.2–2.3 m³ ha^–1 a^–1). However, when loose ash was used growth increase over control was higher (3.7 m³ ha^–1 a^–1). On the nitrogen-poor site, the mean growth increase gained by loose or granulated ash (1.4–1.5 m³ ha^–1 a^–1) over the unfertilised control treatment was not significant. Fertilisation with loose ash or PK increased foliar P, K and B concentrations already in the first or second growing season, following fertilisation on both sites. Granulated ash increased foliar P concentrations on the nitrogen-rich site less than loose ash. After an initial increase, foliar P, K and B concentrations decreased at the end of study period. On the nitrogen-poor site, foliar P concentrations were below the deficiency limit by the end of the study period.

Hytönen, Natural Resources Institute Finland, Natural Resources, Teknologiakatu 7, FI-67100 Kokkola, Finland https://orcid.org/0000-0001-8475-3568 E-mail: jyrki.hytonen@luke.fi
Hökkä, Natural Resources Institute Finland, Natural Resources, Paavo Havaksentie 3, FI-90570 Oulu, Finland E-mail: hannu.hokka@luke.fi

article id 10247, category Research article

Agnese Marcelli, Walter Mattioli, Nicola Puletti, Francesco Chianucci, Damiano Gianelle, Mirko Grotti, Gherardo Chirici, Giovanni D' Amico, Saverio Francini, Davide Travaglini, Lorenzo Fattorini, Piermaria Corona. (2020). Large-scale two-phase estimation of wood production by poplar plantations exploiting Sentinel-2 data as auxiliary information. Silva Fennica vol. 54 no. 2 article id 10247. https://doi.org/10.14214/sf.10247

Keywords: national forest inventories; Sentinel-2; design-based inference; first-phase tessellation stratified sampling; regression estimator; second-phase stratified sampling; simulation study

Highlights: A two-phase sampling for large-scale assessment of fast-growing forest crops is developed; Vegetation indices from Sentinel-2 are exploited in a linear regression estimator; The linear regression estimator turns out to be better than the estimator based on the sole sample information; The approach represents a reference for supporting outside-forest resource monitoring and assessment.

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Growing demand for wood products, combined with efforts to conserve natural forests, have supported a steady increase in the global extent of planted forests. Here, a two-phase sampling strategy for large-scale assessment of the total area and the total wood volume of fast-growing forest tree crops within agricultural land is presented. The first phase is performed using tessellation stratified sampling on high-resolution remotely sensed imagery and is sufficient for estimating the total area of plantations by means of a Monte Carlo integration estimator. The second phase is performed using stratified sampling of the plantations selected in the first phase and is aimed at estimating total wood volume by means of an approximation of the first-phase Horvitz-Thompson estimator. Vegetation indices from Sentinel-2 are exploited as freely available auxiliary information in a linear regression estimator to improve the design-based precision of the estimator based on the sole sample data. Estimators of the totals and of the design-based variances of total estimators are presented. A simulation study is developed in order to check the design-based performance of the two alternative estimators under several artificial distributions supposed for poplar plantations (random, clustered, spatially trended). An application in Northern Italy is also reported. The regression estimator turns out to be invariably better than that based on the sole sample information. Possible integrations of the proposed sampling scheme with conventional national forest inventories adopting tessellation stratified sampling in the first phase are discussed.

Marcelli, University of Tuscia, Department for Innovation in Biological, Agro-food and Forest systems, Viterbo, Italy; Fondazione Edmund Mach, Department of Sustainable Agro-Ecosystems and Bioresources, Research and Innovation Centre, San Michele all’Adige, Italy E-mail: agnese.marcelli@student.unisi.it
Mattioli, University of Tuscia, Department for Innovation in Biological, Agro-food and Forest systems, Viterbo, Italy; CREA, Research Centre for Forestry and Wood, Arezzo, Italy E-mail: walter.mattioli@crea.gov.it
Puletti, CREA, Research Centre for Forestry and Wood, Arezzo, Italy E-mail: nicola.puletti@crea.gov.it
Chianucci, CREA, Research Centre for Forestry and Wood, Arezzo, Italy E-mail: fchianucci@gmail.com
Gianelle, Fondazione Edmund Mach, Department of Sustainable Agro-Ecosystems and Bioresources, Research and Innovation Centre, San Michele all’Adige, Italy E-mail: damiano.gianelle@fmach.it
Grotti, CREA, Research Centre for Forestry and Wood, Arezzo, Italy; University of Roma La Sapienza, Department of Architecture and Design, Rome, Italy E-mail: mirkogrotti@gmail.com
Chirici, University of Firenze, Department of Agriculture, Food, Environment and Forestry, Florence, Italy E-mail: gherardo.chirici@unifi.it
D' Amico, University of Firenze, Department of Agriculture, Food, Environment and Forestry, Florence, Italy E-mail: giovanni.damico@unifi.it
Francini, University of Firenze, Department of Agriculture, Food, Environment and Forestry, Florence, Italy; University of Molise, Department of Agricultural, Environmental and Food Sciences, Campobasso, Italy E-mail: saverio.francini@gmail.com
Travaglini, University of Firenze, Department of Agriculture, Food, Environment and Forestry, Florence, Italy E-mail: davide.travaglini@unifi.it
Fattorini, University of Siena, Department of Economics and Statistics, Siena, Italy E-mail: lorenzo.fattorini@unisi.it
Corona, CREA, Research Centre for Forestry and Wood, Arezzo, Italy E-mail: piermaria.corona@crea.gov.it

article id 10220, category Research article

Arnis Gailis, Pauls Zeltiņš, Andis Purviņš, Juris Augustovs, Valts Vīndedzis, Inga Zariņa, Āris Jansons. (2020). Genetic parameters of growth and quality traits in open-pollinated silver birch progeny tests. Silva Fennica vol. 54 no. 2 article id 10220. https://doi.org/10.14214/sf.10220

Keywords: Betula pendula; tree breeding; genetic gain; genetic parameters

Highlights: Growth and stem quality traits were under strong genetic control; Weak genetic correlations between tree growth and stem quality were found; Strong age-age and type-B correlations suggest robust improvement over time and different environments; Simultaneous improvement of growth and stem quality might be applicable.

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Genetic parameters of growth and stem quality traits were estimated for open-pollinated silver birch Betula pendula Roth progenies in Latvia at the age of 10 and 14 years. Tree height and stem volume were found to be under strong genetic control at both inventories (narrow-sense heritabilities varied from 0.41 to 0.66). Mainly low heritabilities were found for stem defects, yet genetic control of branch diameter, stem straightness and overall stem quality varied from low to high depending on study site. High additive genetic coefficient of variation was found for stem volume (25.3–32.5%). Genetic correlations among growth traits were strong and positive (0.90–0.99). Mainly weak genetic correlations between growth and quality traits implied simultaneous improvement. Still, strong negative correlations between branch angle and stem straightness might result in enlarged knot size for straighter logs. The genetic age-age correlations were strong. Weak genotype by environment interaction and stability of best genotypes over different sites was indicated by strong genetic correlations between trials. Each growth or quality trait alone showed substantial improvement in terms of estimated genetic gain (up to 62% over trial mean for stem volume). Therefore, selection index combining both growth and stem quality may be developed.

Gailis, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: arnis.gailis@silava.lv
Zeltiņš, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia https://orcid.org/0000-0002-6286-5814 E-mail: pauls.zeltins@silava.lv
Purviņš, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: andis.purvins@silava.lv
Augustovs, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: juris.augustovs@silava.lv
Vīndedzis, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: valts.vindedzis@silava.lv
Zariņa, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: inga.zarina@silava.lv
Jansons, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: aris.jansons@silava.lv

article id 10215, category Research article

Korotimi Ouédraogo, Kangbéni Dimobe, Adjima Thiombiano. (2020). Allometric models for estimating aboveground biomass and carbon stock for Diospyros mespiliformis in West Africa. Silva Fennica vol. 54 no. 1 article id 10215. https://doi.org/10.14214/sf.10215

Keywords: Burkina Faso; biometric variables; African ebony; biomass estimation equations; carbon storages; jackalberry; Sudanian savanna

Highlights: Biomass estimation models developed for Diospyros mespiliformis; Models based on DBH alone predicted aboveground biomass with 97.11% accuracy; Published models had relative error between –72% and +98%; Models for branch and stem biomass were more accurate than those for leaf biomass.

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Accurate estimates of aboveground biomass (AGB) strongly depend on the suitability and precision of allometric models. Diospyros mespiliformis Hochst. ex A. DC. is a key component of most sub-Sahara agroforestry systems and, one of the most economically important trees in Africa. Despite its importance, very few scientific information exists regarding its biomass and carbon storage potential. In this study direct method was used to develop site-specific biomass models for D. mespiliformis tree components in Burkina Faso. Allometric models were developed for stem, branch and leaf biomass using data from 39 tree harvested in Sudanian savannas of Burkina Faso. Diameter at breast height (DBH), tree height, crown diameter (CD) and basal diameter (D₂₀) were regressed on biomass component using non-linear models with DBH alone, and DBH in combination with height and/or CD as predictor variables. Carbon content was estimated for each tree component using the ash method. Allometric models differed between the experimental sites, except for branch biomass models. Site-specific models developed in this study exhibited good model fit and performance, with explained variance of 81–98%. Using models developed from other areas would have underestimated or overestimated biomass by between –72% and +98%. Carbon content in aboveground components of D. mespiliformis in Tiogo, Boulon and Tapoa-Boopo was 55.40% ± 1.50, 55.52% ± 1.06 and 55.63% ± 1.00, respectively, and did not vary significantly (P-value = 0.909). Site-specific models developed in this study are useful tool for estimating carbon stocks and can be used to accurately estimate tree components biomass in vegetation growing under similar conditions.

Ouédraogo, University Joseph Ki-Zerbo, UFR/SVT, Laboratory of Plant Biology and Ecology, 03 B.P. 7021 Ouagadougou 03, Burkina Faso E-mail: okorotimi@yahoo.fr
Dimobe, University Joseph Ki-Zerbo, UFR/SVT, Laboratory of Plant Biology and Ecology, 03 B.P. 7021 Ouagadougou 03, Burkina Faso; University of Dédougou, Institut des Sciences de l’Environnement et du Développement Rural (ISEDR), BP 139 Dédougou, Burkina Faso; West African Science Service Center on Climate Change and Adapted Land Use, Competence Center, Avenue Muamar Ghadhafi, Ouagadougou, BP 9507, Burkina Faso https://orcid.org/0000-0001-5536-9700 E-mail: kangbenidimobe@gmail.com
Thiombiano, University Joseph Ki-Zerbo, UFR/SVT, Laboratory of Plant Biology and Ecology, 03 B.P. 7021 Ouagadougou 03, Burkina Faso E-mail: adjima_thiombiano@yahoo.fr

article id 10163, category Research article

Uttam Thangjam, Uttam K. Sahoo, Pentile Thong. (2020). Characterization of morphometric, reproductive and seedling traits of Parkia timoriana in northeast India. Silva Fennica vol. 54 no. 1 article id 10163. https://doi.org/10.14214/sf.10163

Keywords: seed source; heritability; genotype; tree bean; variations

Highlights: Among provenances, Pherema (P1) Serchip (P10) and Jiribam (P7) were associated with stress tolerant and better quality seedlings.; P1 gave the best result for seed traits including high germinability, P10 showed highest seedling vigour, while P7 corresponds to high-quality pod related traits; Variations in morphological, germinative and seedling growth characters of seeds across provenance further illustrate the importance of site selection for the production of better quality trees.

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We studied variations on different traits of Parkia timoriana (D.C.) Merr. in twelve provenances systematically from their source of origin to a controlled environment where representative seedlings were grown. Among the provenances, P1 gave the best result for seed traits including germination traits, P7 for pod traits and P10 for seedling vigour. Effects of seasonal distribution of rainfall and temperature on seed and pod traits were also determined by computing multiple regression analysis. The results displayed winter rainfall and summer temperature as the most important factor determining pod and seed traits. Latitude also significantly (P < 0.001) affected PWT (r = 0.52), SWP (r = 0.46) and SW (r = 0.50). A common garden study for germination and seedling growth indicated P1 and P10 provenance as the best among all. Seeds drawn from P10 gave the highest seedling vigour with an average growth rate of 0.61 cm/day from 90th to 180th day. Highest broad-sense heritability values (h²) were observed in germination traits, followed by seedling collar diameter. The lowest h² was observed for seedling height.

Thangjam, Department of Forestry, School of Earth Sciences & Natural Resource Management, Mizoram University, Aizawl-796004, Mizoram, India https://orcid.org/0000-0003-1263-5348 E-mail: thangjam1987@gmail.com
Sahoo, Department of Forestry, School of Earth Sciences & Natural Resource Management, Mizoram University, Aizawl-796004, Mizoram, India https://orcid.org/0000-0002-6524-1775 E-mail: uksahoo_2003@rediffmail.com
Thong, Department of Forestry, School of Earth Sciences & Natural Resource Management, Mizoram University, Aizawl-796004, Mizoram, India https://orcid.org/0000-0002-5358-181X E-mail: pentilethong@gmail.com

article id 10084, category Research article

Mihails Čugunovs, Eeva-Stiina Tuittila, Jari Kouki. (2020). Proximity to charred logs in burned forests likely affects decomposition processes in the soil. Silva Fennica vol. 54 no. 1 article id 10084. https://doi.org/10.14214/sf.10084

Keywords: coarse woody debris; forest fire; prescribed burning; cellulose decomposition; tea-bag method

Highlights: Standardised organic substrate decomposition was tentatively observed to be faster adjacent to non-charred downed logs than away from the logs or adjacent to charred logs; A spatial linkage was observed between non-charred logs and decomposition in the soil in burned boreal forests; Proximity to a charred log may provide a micro-environment where decomposition rates differ from the surrounding forest soil.

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We studied the spatial decomposition rates of standardised organic substrates in soils (burned boreal pine-dominated sub-xeric forests in eastern Finland), with respect to charred and non-charred coarse woody debris (CWD). Decomposition rates of rooibos plant litter inside teabags (C:N = 42.870 ± 1.841) and pressed-sheet Nordic hardwood pulp (consisting of mainly alpha-cellulose) were measured at 0.2 m distance from 20 charred (LC0.2) and 40 non-charred logs (LNC0.2). We also measured decomposition at 60 plots located 3–10 m away from downed logs (L3,10). The rooibos decomposition rate constant ‘k’ was 8.4% greater at the LNC0.2 logs than at the L3,10 or LC0.2 logs. Cellulose decomposed more completely in 1 micron mesh bags at LNC0.2 (44% of buried bags had leftover material) than at LC0.2 (76%) or L3,10 (70%). Decomposition of cellulose material was rapid but varied greatly between sampling plots. Our results indicate that decomposition of the standardised organic matter was more rapid close to CWD pieces than further away. However, only the plots located near non-charred logs (LNC0.2) exhibited high decomposition rates, with no corresponding increase observed at the charred logs (LC0.2). This suggests a possible noteworthy indirect effect of forest burning on soil organic matter (SOM) decomposition rates close to charred CWD after forest fires. We urge for more studies on this tentative observation as it may affect the estimates on how fires affect carbon cycling in forests.

Čugunovs, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: mihails.cugunovs@gmail.com
Tuittila, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0001-8861-3167 E-mail: eeva-stiina.tuittila@uef.fi
Kouki, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-2624-8592 E-mail: jari.kouki@uef.fi

article id 10051, category Research article

Anna-Kaisa Kosenius, Artti Juutinen, Liisa Tyrväinen. (2020). The role of state-owned commercial forests and firm features in nature-based tourism business performance. Silva Fennica vol. 54 no. 1 article id 10051. https://doi.org/10.14214/sf.10051

Keywords: business performance; entrepreneurial attitude; forest-based tourism business; forest management practices; landscape trading; recreational value trading

Highlights: State-owned commercial forests provide an important part of nature-based tourism enterprises’ service scope; Increase in turnover during five years vary depending on provided services; Entrepreneurial attitude associates with willingness to participate in a landscape and recreational value trading scheme; Increasing international demand for nature-based tourism promotes business possibilities, needs attention to forest environments and smooth co-operation between actors.

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Nature-based tourism (NBT) is a growing industry within regions rich in natural amenities worldwide. An important feature of NBT business is the dependence on the quality of surrounding environment. This paper addresses the role of the management of commercial forests owned by the state in Finnish Lapland. The paper explores the NBT entrepreneurs’ willingness to participate in a proposed new landscape and recreational value trading (LRVT) and elaborates the effect of entrepreneur and enterprise characteristics, such as entrepreneurial attitude, venture size, and a variety of services offered to customers, on the experienced and expected growth of NBT enterprise. The survey data on NBT enterprises were analyzed with ordered and binary logit models. The willingness of enterprises to participate in LRVT depended on the venture size, entrepreneurial attitude, and type of activities offered to customers. The results show that relatively young and small-sized enterprises have faced difficulties in developing their business. Entrepreneurial experience, risk-taking and intention to develop new business associate positively with expected increase in turnover.

Kosenius, University of Helsinki, Department of Economics and Management, P.O. Box 27, FI-00014 University of Helsinki, Finland https://orcid.org/0000-0002-1528-8145 E-mail: anna-kaisa.kosenius@helsinki.fi
Juutinen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Paavo Havaksentie 3, FI-90570 Oulu, Finland https://orcid.org/0000-0003-4300-5365 E-mail: artti.juutinen@luke.fi
Tyrväinen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0001-9941-8228 E-mail: liisa.tyrvainen@luke.fi

article id 10230, category Research article

Mohammed Henneb, Osvaldo Valeria, Nelson Thiffault, Nicole Fenton. (2019). Black spruce seedling growth response in controlled organic and organic-mineral substrates. Silva Fennica vol. 53 no. 4 article id 10230. https://doi.org/10.14214/sf.10230

Keywords: Picea mariana; paludification; seedling growth; seedling nutrition; semi-controlled experiment; substrate

Highlights: Seedling height and diameter were highest on clay and mesic substrates respectively; Foliar nutrients were relatively high in seedlings that were established on mesic substrates; We recommend the application of mechanical soil preparation techniques that promote the creation of organic-mesic substrates to support regeneration establishment.

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In the boreal forest of eastern Canada, a large proportion of black spruce (Picea mariana [Mill.] Britton, Sterns & Poggenb.) stands are affected by paludification. Edaphic conditions that are created by paludification processes, including an abundance of microsites with high moisture and low nutrient contents, hinder forest regeneration. Disturbance of paludified sites by mechanical soil preparation (MSP) reduces organic layer thickness, while generating a range of substrates for regeneration establishment. Yet, little information is available regarding the effects of these substrates on tree growth. Our objective was to determine the effect of organic, mineral and organo-mineral substrates that are created following MSP of a paludified site on the growth and root development of black spruce seedlings in a semi-controlled environment. We demonstrated that substrate exerted a significant effect on seedling growth and foliar concentrations of N, P and K. Increase in height and diameter were respectively greatest on clay (mineral) and mesic substrates. Substrate effects did not affect total biomass increases or final root biomass. Foliar nutrients (N, P, K) were relatively high in seedlings that were established on mesic substrates and relatively low for those established on clay substrates. To ensure successful seedling establishment, we recommend the application of MSP techniques that expose organic-mesic substrates on sites that are susceptible to paludification.

Henneb, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada http://orcid.org/0000-0003-4507-1219 E-mail: mohammed.henneb@uqat.ca
Valeria, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada http://orcid.org/0000-0002-9921-7474 E-mail: osvaldo.valeria@uqat.ca
Thiffault, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada; Natural Resources Canada, Canadian Wood Fibre Centre, 1055 rue du PEPS, P.O. Box 10380, Stn Sainte Foy, Quebec, QC G1V 4C7, Canada http://orcid.org/0000-0003-2017-6890 E-mail: nelson.thiffault@canada.ca
Fenton, Institut de recherche sur les forêts (IRF), Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada http://orcid.org/0000-0002-3782-2361 E-mail: nicole.fenton@uqat.ca

article id 10217, category Research article

Xingji Jin, Timo Pukkala, Fengri Li, Lihu Dong. (2019). Developing growth models for tree plantations using inadequate data – a case for Korean pine in Northeast China. Silva Fennica vol. 53 no. 4 article id 10217. https://doi.org/10.14214/sf.10217

Keywords: Pinus koraiensis; optimization-based modeling; quantile regression; self-thinning

Highlights: The permanent sample plots of Chinese plantation trees have not been designed for producing data for growth modeling; We used various methods to deal with the inadequacies of sample plot data; Optimization was used to fit diameter increment and survival models using data with varying measurement intervals and tree identification errors; Quantile regression was used to model self-thinning limit.

Abstract | Full text in HTML | Full text in PDF | Author Info

Korean pine (Pinus koraiensis Siebold & Zucc.) is economically the most important tree species in northeast China. Korean pine plantations are established and managed for the production of timber and seeds. Despite the importance of the species, few models have been developed for the comparison of alternative management schedules. Model development is affected by the fact that permanent sample plots and thinning experiments have not been designed and managed for modeling purposes. The permanent sample plots include few non-thinned plots, and weak trees are removed in thinning treatments, leading to low mortality rate. Moreover, the measurement interval is irregular. This study used optimization-based modeling approach in tree-level diameter increment and survival modeling to deal with the above problems. Models for self-thinning limit were developed to alleviate the problem of underestimated mortality arising from the features of the data. In addition, improved site index and individual-tree height models were developed. The model of Lundqvist and Korf was used as the site index model and the model proposed by Schumacher as the height model. Quantile regression was used to model the maximum stand basal area and maximum number of trees as a function of mean tree diameter and site index. Tree diameter, stand basal area, basal area in larger trees and site index were used as the predictors of diameter increment and tree survival. The models developed in this study constitute a model set that is suitable for simulation and optimization studies. The models produced simulation results that correspond to measured stand development.

Jin, Key Laboratory of Sustainable Forest Ecosystem Management - Ministry of Education, School of Forestry, Northeast Forestry University, Harbin 150040, Heilongjiang, People’s Republic of China http://orcid.org/0000-0003-2971-2709 E-mail: xingji_jin@163.com
Pukkala, Key Laboratory of Sustainable Forest Ecosystem Management - Ministry of Education, School of Forestry, Northeast Forestry University, Harbin 150040, Heilongjiang, People’s Republic of China; University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: timo.pukkala@uef.fi
Li, Key Laboratory of Sustainable Forest Ecosystem Management - Ministry of Education, School of Forestry, Northeast Forestry University, Harbin 150040, Heilongjiang, People’s Republic of China http://orcid.org/0000-0002-4058-769X E-mail: fengrili@126.com
Dong, Key Laboratory of Sustainable Forest Ecosystem Management - Ministry of Education, School of Forestry, Northeast Forestry University, Harbin 150040, Heilongjiang, People’s Republic of China http://orcid.org/0000-0002-3985-9475 E-mail: ldonglihu2006@163.com

article id 10209, category Research article

Claudie-Maude Canuel, Nelson Thiffault, Michael K. Hoepting, James C.G. Farrell. (2019). Legacy effects of precommercial thinning on the natural regeneration of next rotation balsam fir stands in eastern Canada. Silva Fennica vol. 53 no. 4 article id 10209. https://doi.org/10.14214/sf.10209

Keywords: silviculture; Abies balsamea; PCT; conifer; density management

Highlights: We investigated the potential legacy effects of precommercial thinning in next rotation, dense natural balsam fir stands; Precommercial thinning had few legacy effects on next rotation stands and should not impair their regeneration; Balsam fir dominated the regeneration layer. Other tree species were almost absent.

Abstract | Full text in HTML | Full text in PDF | Author Info

The Green River precommercial thinning (PCT) trial was established between 1959–1961 in New Brunswick (Canada) within natural balsam fir (Abies balsamea (L.) Mill.)-dominated stands. Three silviculture scenarios differing only by the increasing nominal spacings of PCT treatments (1.2 m, 1.8 m, 2.4 m) were compared to an unthinned control within randomized replicates that were clearcut harvested in 2008 and treated with herbicide in 2011. During the fourth post-harvest growing season, we assessed regeneration, competing vegetation and coarse woody debris (CWD; differentiated between large woody debris and slash) to assess the legacy effects of PCT on regeneration of next rotation stands. Our results confirmed that silviculture scenarios including PCT significantly increased conifer stocking in treated plots compared to control conditions, but only in the 1.8 m nominal spacing. Considering that treated and untreated stands were fully stocked, we conclude that PCT using the spacing gradient tested has no legacy effect on the regeneration of next rotation natural balsam fir stands. Given the known sensitivity of balsam fir to future climate conditions in this region, we suggest that future treatments should promote tree species diversity to support ecosystem resilience to climate change by favouring more warm-adapted species, such as some hardwoods.

Canuel, Faculté de foresterie, géographie et géomatique, Université Laval, Québec, QC G1V 0A6, Canada; Canadian Wood Fibre Centre, Natural Resources Canada, 1055 du P.E.P.S., P.O. Box 10380, Sainte-Foy Stn., Québec, QC G1V 4C7, Canada E-mail: claudie-maude.canuel.1@ulaval.ca
Thiffault, Canadian Wood Fibre Centre, Natural Resources Canada, 1055 du P.E.P.S., P.O. Box 10380, Sainte-Foy Stn., Québec, QC G1V 4C7, Canada http://orcid.org/0000-0003-2017-6890 E-mail: nelson.thiffault@canada.ca
Hoepting, Canadian Wood Fibre Centre, Natural Resources Canada, 1219 Queen St. E., Sault Ste. Marie, ON P6A 2E5, Canada E-mail: michael.hoepting@canada.ca
Farrell, Canadian Wood Fibre Centre, Natural Resources Canada, 1350 Regent Street, P.O. Box 4000, Fredericton, NB E3B 5P7, Canada E-mail: jamescg.farrell@canada.ca

article id 10183, category Research article

Tomi Karjalainen, Petteri Packalen, Janne Räty, Matti Maltamo. (2019). Predicting factual sawlog volumes in Scots pine dominated forests using airborne laser scanning data. Silva Fennica vol. 53 no. 4 article id 10183. https://doi.org/10.14214/sf.10183

Keywords: Pinus sylvestris; area based approach; k-NN; sawlog

Highlights: We predicted visually bucked factual sawlog volumes at the 30 × 30 m plot-level with several alternatives; The lowest root mean squared error value of approximately 21% was obtained with a linear mixed-effects model that employed factual sawlog volume as a response variable and airborne laser scanning metrics as predictors; The sawlog reduction model commonly used in Finland performed poorly.

Abstract | Full text in HTML | Full text in PDF | Author Info

The aim in the study was to compare alternatives for the prediction of factual sawlog volumes using airborne laser scanning (ALS) data in Scots pine (Pinus sylvestris L.) dominated forests in eastern Finland. Accurate estimates of factual sawlog volume are desirable to ease the planning of harvesting operations. The factual sawlog volume of pines was derived from visual bucking, i.e. a procedure where the defects were located on each stem during sample plot measurements. For other species, the theoretical sawlog volume was considered also as the factual sawlog volume due to data restrictions. We predicted factual sawlog volume with eight alternatives that were based on either linear mixed-effects models or k-nearest neighbour imputations. An existing sawlog reduction model, commonly used in Finland, was also tested individually and combined with a number of the alternatives, and site type information was also utilised. Model fitting and prediction was implemented at the 15 × 15 m level, but accuracy was assessed at the 30 × 30 m level. The relative root mean squared error (RMSE%) values for the factual sawlog volume predictions varied between 20.9% and 33.5%, and the best accuracy was obtained with a linear mixed-effects model. These results indicate that factual sawlog volumes in Scots pine dominated forests can be predicted with reasonable accuracy with ALS data.

Karjalainen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: tomikar@uef.fi
Packalen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: petteri.packalen@uef.fi
Räty, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: janne.raty@uef.fi
Maltamo, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: matti.maltamo@uef.fi

article id 10147, category Research article

Mika Aalto, Olli-Jussi Korpinen, Tapio Ranta. (2019). Feedstock availability and moisture content data processing for multi-year simulation of forest biomass supply in energy production. Silva Fennica vol. 53 no. 4 article id 10147. https://doi.org/10.14214/sf.10147

Keywords: bioenergy; simulation; forest resources; data analysis; geographic information system

Highlights: A method for allocating forest biomass availability for a multi-year simulation model was developed; The possibility to take the quality change of feedstock into account by moisture estimations was studied; A method to estimate weather data for moisture estimation equations with fewer parameters was presented.

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Simulation and modeling have become more common in forest biomass studies. Dynamic simulation has been used to study the supply chain of forest biomass with numerous different models. A robust predictive multi-year model requires biomass availability data, where annual variation is included spatially and temporally. This can be done by using data from enterprises, but in some cases relevant data is not accessible. Another option is to use forest inventory data to estimate biomass availability, but this data must be processed in the correct form to be utilized in the model. This study developed a method for preparing forest inventory data for a multi-year simulation supply model using the theoretical availability of feedstock. Methods for estimating quality changes during roadside storage are also presented, including a possible parameter estimation to decrease the amount of data needed. The methods were tested case by case using the inventory database “Biomass Atlas” and weather data from a weather station in Mikkeli, Finland. The data processing method for biomass allocation produced a reasonable quantity of stands and feedstock, having a realistic annual supply with variation for the demand point. The results of the study indicate that it is possible to estimate moisture content changes using weather data. The estimations decreased the accuracy of the model and, therefore, estimations should be kept minimal. The presented data preparation method can generate a supply of forest biomass for the simulation model, but the validity of the data must be ensured for correct model behavior.

Aalto, Lappeenranta-Lahti University of Technology LUT, School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland https://orcid.org/0000-0002-7768-1145 E-mail: mika.aalto@lut.fi
Korpinen, Lappeenranta-Lahti University of Technology LUT, School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland E-mail: olli-jussi.korpinen@lut.fi
Ranta, Lappeenranta-Lahti University of Technology LUT, School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland https://orcid.org/0000-0001-5464-5136 E-mail: tapio.ranta@lut.fi

article id 10010, category Research article

Panu Halme, Jenna Purhonen, Emma-Liina Marjakangas, Atte Komonen, Katja Juutilainen, Nerea Abrego. (2019). Dead wood profile of a semi-natural boreal forest – implications for sampling. Silva Fennica vol. 53 no. 4 article id 10010. https://doi.org/10.14214/sf.10010

Keywords: coarse woody debris; coniferous forest; forest structure; fine woody debris; forest disturbance dynamics; saproxylic

Highlights: We constructed a full dead wood profile of a semi-natural boreal forest; Abundance-diameter distributions were different among tree species; Extensive sampling is needed if focus on large dead wood and rare tree species.

Abstract | Full text in HTML | Full text in PDF | Author Info

Dead wood profile of a forest is a useful tool for describing forest characteristics and assessing forest disturbance history. Nevertheless, there are few studies on dead wood profiles, including both coarse and fine dead wood, and on the effect of sampling intensity on the dead wood estimates. In a semi-natural boreal forest, we measured every dead wood item over 2 cm in diameter from 80 study plots. From eight plots, we further recorded dead wood items below 2 cm in diameter. Based on these data we constructed the full dead wood profile, i.e. the overall number of dead wood items and their distribution among different tree species, volumes of different size and decay stage categories. We discovered that while the number of small dead wood items was immense, their number dropped drastically from the diameter below 1 cm to diameters 2–3 cm. Different tree species had notably different abundance-diameter distribution patterns: spruce dead wood comprised most strikingly the smallest diameter fractions, whereas aspen dead wood comprised a larger share of large-diameter items. Most of the dead wood volume constituted of large pieces (>10 cm in diameter), and 62% of volume was birch. The variation in the dead wood estimates was small for the numerically dominant tree species and smallest diameter categories, but high for the sub-dominant tree species and larger size categories. In conclusion, the more the focus is on rare tree species and large dead wood items, the more comprehensive should the sampling be.

Halme, Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland; School of Resource Wisdom, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: panu.halme@jyu.fi
Purhonen, Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: jenna.e.i.purhonen@jyu.fi
Marjakangas, Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway E-mail: emma-liina.marjakangas@ntnu.no
Komonen, Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland; School of Resource Wisdom, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: atte.komonen@jyu.fi
Juutilainen, Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: kjuutilainen@yahoo.com
Abrego, Department of Agricultural Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: nerea.abrego@helsinki.fi

article id 10187, category Research article

Timo Pukkala, Kjersti Holt Hanssen, Kjell Andreassen. (2019). Stem taper and bark functions for Norway spruce in Norway. Silva Fennica vol. 53 no. 3 article id 10187. https://doi.org/10.14214/sf.10187

Keywords: forest management; Picea abies; Kozak model; variable-exponent taper function

Highlights: New variable-exponent stem taper and bark functions were developed for Norway spruce; Both fixed and mixed-effects models were developed; Site index and tree age had statistically significant but small effects on stem taper.

Abstract | Full text in HTML | Full text in PDF | Author Info

Based on data from long-term experimental fields with Norway spruce (Picea abies (L.) H. Karst.), we developed new stem taper and bark functions for Norway. Data was collected from 477 trees in stands across Norway. Three candidate functions which have shown good performance in previous studies (Kozak 02, Kozak 97 and Bi) were fitted to the data as fixed-effects models. The function with the smallest Akaike Information Criterion (AIC) was then chosen for additional analyses, fitting 1) site index-dependent and 2) age-dependent versions of the model, and 3) fitting a mixed-effects model with tree-specific random parameters. Kozak 97 was found to be the function with the smallest AIC, but all three tested taper functions resulted in fairly similar predictions of stem taper. The site index-dependent function reduced AIC and residual standard error and showed that the effect of site index on stem taper is different in small and large trees. The predictions of the age-independent and age-dependent models were very close to each other. Adding tree-specific random parameters to the model clearly reduced AIC and residual variation. However, the results suggest that the mixed-effects model should be used only when it is possible to calibrate it for each tree, otherwise the fixed-effects Kozak 97 model should be used. A model for double bark thickness was also fitted as fixed-effects Kozak 97 model. The model behaved logically, predicting larger relative but smaller absolute bark thickness for small trees.

Pukkala, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-2853-9510 E-mail: timo.pukkala@uef.fi
Holt Hanssen, Norwegian Institute of Bioeconomy Research, P.O. Box 115, NO-1431 Ås, Norway https://orcid.org/0000-0002-1715-3092 E-mail: kjersti.hanssen@nibio.no
Andreassen, Norwegian Institute of Bioeconomy Research, P.O. Box 115, NO-1431 Ås, Norway https://orcid.org/0000-0003-4272-3744 E-mail: kjell.andreassen@nibio.no

article id 10075, category Research article

Matti Maltamo, Marius Hauglin, Erik Naesset, Terje Gobakken. (2019). Estimating stand level stem diameter distribution utilizing harvester data and airborne laser scanning. Silva Fennica vol. 53 no. 3 article id 10075. https://doi.org/10.14214/sf.10075

Keywords: LIDAR; cut-to length harvester; GPS; merchantable volume; tree list

Highlights: Tree level-positioned harvester data were successfully used as plot-level training data for k-nearest neighbor stem diameter distribution modelling applying airborne laser scanning information as predictor variables; Stand-level validation showed that merchantable volume of total tree stock could be estimated with RMSE value of about 9%; The fit of the stem diameter distribution assessed by a variant of Reynold’s error index showed values smaller than 0.2; The most accurate results were obtained for the training plot sizes of 200 m² and 400 m².

Abstract | Full text in HTML | Full text in PDF | Author Info

Accurately positioned single-tree data obtained from a cut-to-length harvester were used as training harvester plot data for k-nearest neighbor (k-nn) stem diameter distribution modelling applying airborne laser scanning (ALS) information as predictor variables. Part of the same harvester data were also used for stand-level validation where the validation units were stands including all the harvester plots on a systematic grid located within each individual stand. In the validation all harvester plots within a stand and also the neighboring stands located closer than 200 m were excluded from the training data when predicting for plots of a particular stand. We further compared different training harvester plot sizes, namely 200 m², 400 m², 900 m² and 1600 m². Due to this setup the number of considered stands and the areas within the stands varied between the different harvester plot sizes. Our data were from final fellings in Akershus County in Norway and consisted of altogether 47 stands dominated by Norway spruce. We also had ALS data from the area. We concentrated on estimating characteristics of Norway spruce but due to the k-nn approach, species-wise estimates and stand totals as a sum over species were considered as well. The results showed that in the most accurate cases stand-level merchantable total volume could be estimated with RMSE values smaller than 9% of the mean. This value can be considered as highly accurate. Also the fit of the stem diameter distribution assessed by a variant of Reynold’s error index showed values smaller than 0.2 which are superior to those found in the previous studies. The differences between harvester plot sizes were generally small, showing most accurate results for the training harvester plot sizes 200 m² and 400 m².

Maltamo, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu E-mail: matti.maltamo@uef.fi
Hauglin, Norwegian Institute of Bioeconomy Research, Division of Forest and Forest Resources, P.O. Box 115, 1431 Ås, Norway E-mail: marius.hauglin@nibio.no
Naesset, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, 1432 Ås, Norway E-mail: erik.naesset@nmbu.no
Gobakken, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O. Box 5003, 1432 Ås, Norway E-mail: terje.gobakken@nmbu.no

article id 10074, category Research article

Sebastian Kühle, Alfred Teischinger, Manfred Gronalt. (2019). Optimal location of laminated beech production plants within the solid hardwood supply network in Austria. Silva Fennica vol. 53 no. 3 article id 10074. https://doi.org/10.14214/sf.10074

Keywords: decision support system; facility location; laminated timber products; mixed integer linear programming; supply chain network design

Highlights: This paper provides data to the solid hardwood business and develops a mixed integer linear program model to design a laminated beech wood supply network; It covers the strategic decision where to locate a new production facility within the existing supply network with the lowest supply network cost; Sufficient sawn wood suppliers and potential facility locations are provided.

Abstract | Full text in HTML | Full text in PDF | Author Info

Due to changes in forest management in various European countries, hardwood forest areas and amounts will increase. Sustainable and individual utilization concepts have to be developed for the upcoming available resource. Studies conclude that there is low potential for hardwoods in the traditional appearance market thus the application areas have to be extended to new structural innovative products. This paper examines the extension to a future laminated beech wood supply network which would be a combination of already existing and new production facilities. For a better future use of hardwood raw materials it is necessary to consider the entire supply chain. This also better shows a total hardwood value chain. Therefore, this paper provides data to the solid hardwood business and develops a mixed integer linear programming to design a laminated beech wood supply network. The model is applied to Austria as the sample region. It covers the important strategic decisions where to locate a downstream facility within the existing production network with the lowest supply network cost. Fourteen scenarios are developed to examine various future network configurations. Results about optimal material flows and used sawmills as well as downstream production facilities are presented in form of material and financial performances. Two optimal laminated beech production locations are determined by the calculated scenarios results, and the impact of a new sawmill is analyzed which is focused on beech.

Kühle, BOKU - University of Natural Resources and Life Sciences, Vienna, Department of Material Science and Process Engineering, and Renewable Institute of Wood Technology Materials, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria E-mail: skuehle@boku.ac.at
Teischinger, BOKU - University of Natural Resources and Life Sciences, Vienna, Department of Material Science and Process Engineering, and Renewable Institute of Wood Technology Materials, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria E-mail: alfred.teischinger@boku.ac.at
Gronalt, BOKU - University of Natural Resources and Life Sciences, Vienna, Department of Economics and Social Sciences, Institute of Production and Logistics, Feistmantelstraße 4, 1180 Vienna, Austria E-mail: manfred.gronalt@boku.ac.at

article id 10161, category Research article

Jussi Manner, Anders Mörk, Martin Englund. (2019). Comparing forwarder boom-control systems based on an automatically recorded follow-up dataset. Silva Fennica vol. 53 no. 2 article id 10161. https://doi.org/10.14214/sf.10161

Keywords: automation; cut-to-length logging; haulage; crane work; extraction; boom-tip control

Highlights: Boom-tip control saves time compared to the conventional system; This study introduced a field-study design enabling establishment of causal relationships during ordinary forwarding operations; Although the study design requires some extra arrangements, it efficiently combines the representativeness of conventional follow-up datasets with establishment of causal relationships that traditionally have been possible only through observational time studies or standardized experiments.

Abstract | Full text in HTML | Full text in PDF | Author Info

Crane work is the most time-consuming work element in forwarding. Hence, assist systems like boom-tip control are of interest. The first commercially available boom-tip control for forwarders was introduced in 2013. In this study we analysed whether replacing conventional boom control (CBC) with John Deere’s version of boom-tip control (named Intelligent Boom Control, IBC), increases crane-work productivity. We used data automatically gathered from 10 final-felling stands, covering typical logging conditions for southern, central and northern Sweden. Two John Deere 1510E and two John Deere 1910G forwarders were operated by seven experienced operators during the follow-up study, covering 1238 loads in total. A split-plot design was applied to isolate effects of the boom-control system being used (CBC, IBC). We found that using IBC for loading work (crane work and driving included) saved 5.2% of productive machine time compared to using CBC (p ≤ 0.05). The corresponding saving when using IBC for unloading work was 7.9% (p ≤ 0.05). Depending on geophysical factors, this corresponds to approximately 4% savings in productive machine time for forwarding as a whole, including pure transport (with and without load). Moreover, the study introduced in cut-to-length context a novel field-study design to collect a large follow-up dataset in the course of ordinary forwarding operations. We found the study design to be a cost-efficient way to combine the representativeness of conventional follow-up datasets with the ability to establish causal relationships. Establishment of causal relationships has traditionally been possible only through observational time studies or standardized experiments.

Manner, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden http://orcid.org/0000-0002-4982-3855 E-mail: jussi.manner@skogforsk.se
Mörk, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: anders.mork@skogforsk.se
Englund, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: martin.englund@skogforsk.se

article id 10134, category Research article

Matti Sirén, Jari Ala-Ilomäki, Harri Lindeman, Jori Uusitalo, Kalle E.K. Kiilo, Aura Salmivaara, Ari Ryynänen. (2019). Soil disturbance by cut-to-length machinery on mid-grained soils. Silva Fennica vol. 53 no. 2 article id 10134. https://doi.org/10.14214/sf.10134

Keywords: rut formation; soil compaction; sandy soil; silty soil; harvesting damage

Highlights: The number of machine passes, volumetric water content in the mineral soil and the depth of the organic layer were the controlling factors for rut formation; The harvester rut depth was a good predictor of the forwarder rut formation; Changes in the penetration resistance were highest at depths of 20–40 cm.

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Factors affecting soil disturbance caused by harvester and forwarder were studied on mid-grained soils in Finland. Sample plots were harvested using a one-grip harvester. The harvester operator processed the trees outside the strip roads, and the remaining residues were removed to exclude the covering effect of residues. Thereafter, a loaded forwarder made up to 5 passes over the sample plots. The average rut depth after four machine passes was positively correlated to the volumetric water content at a depth of 0–10 cm in mineral soil, as well as the thickness of the organic layer and the harvester rut depth, and negatively correlated with penetration resistance at depths of both 0–20 cm and 5–40 cm. We present 5 models to predict forwarder rut depth. Four include the cumulative mass driven over a measurement point and combinations of penetration resistance, water content and the depth of organic layer. The fifth model includes harvester rut depth and the cumulative overpassed mass and provided the best fit. Changes in the penetration resistance (PR) were highest at depths of 20–40 cm. Increase in BD and VWC decreased PR, which increased with total overdriven mass. After four to five machine passes PR values started to stabilize.

Sirén, Natural Resources Institute Finland (Luke) c/o Aalto University, P.O. Box 15600, FI-00076 Aalto, Finland E-mail: matti.siren@luke.fi
Ala-Ilomäki, Natural Resources Institute Finland (Luke) c/o Aalto University, P.O. Box 15600, FI-00076 Aalto, Finland http://orcid.org/0000-0002-6671-7624 E-mail: jari.ala-ilomaki@luke.fi
Lindeman, Natural Resources Institute Finland (Luke), Korkeakoulunkatu 7, FI-33720 Tampere, Finland E-mail: harri.lindeman@luke.fi
Uusitalo, Natural Resources Institute Finland (Luke), Korkeakoulunkatu 7, FI-33720 Tampere, Finland http://orcid.org/0000-0003-3793-1215 E-mail: jori.uusitalo@luke.fi
Kiilo, Versowood, Teollisuuskatu 1, FI-11130 Riihimäki, Finland E-mail: kalle.kiilo@versowood.fi
Salmivaara, Natural Resources Institute Finland (Luke), P.O. Box 2, FI-00791 Helsinki, Finland E-mail: aura.salmivaara@luke.fi
Ryynänen, Natural Resources Institute Finland (Luke), Kaironiementie 15, FI-39700 Parkano, Finland E-mail: ari.ryynanen@luke.fi

article id 10088, category Research article

Antti-Jussi Lindroos, Kira Ryhti, Tomi Kaakkurivaara, Jori Uusitalo, Heljä-Sisko Helmisaari. (2019). Leaching of heavy metals and barium from forest roads reinforced with fly ash. Silva Fennica vol. 53 no. 2 article id 10088. https://doi.org/10.14214/sf.10088

Keywords: recycling; lysimeter; fly ash; forest road rehabilitation; environmental impact assessment; low-volume road

Highlights: Heavy metal concentrations were generally low in percolation and ditch water samples of ash roads, but elevated concentrations were found in some parts of ash roads; Risk for heavy metal leaching is negligible if road parts producing high concentrations are rare.

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The aim of this study was to determine the effect of leaching of heavy metals (Cr, As, Cd, Cu, Ni, Pb, Zn, Co, Mo) and earth-alkaline metal, barium (Ba), on the percolation and ditch water quality from the forest roads that contained ash in the road structures. Water quality was studied in the immediate vicinity below the ash layers as well as deeper in the road structure. Water quality was also determined in the drainage water in ditches that crossed the forest roads. A mixture of wood and peat based fly ash was used in the road structures. The treatments were: 1) no ash, 2) a 15 cm layer of ash/gravel mixture, 3) a 20 cm layer of ash/gravel mixture, 4) a 25 cm layer of ash, and 5) a 50 cm layer of ash. Large variation in the concentrations of Cr, As, Cu, Ni, Pb, Mo and Ba in the percolation water, even within the same treatment, caused difficulties to generalize the results. The concentrations of Cr, As, Ni, Pb, Mo and Ba in water samples were high in some treatment plot lysimeters containing ash compared to the control (no ash). On the other hand, many lysimeters had low and similar concentrations in water samples in the treatment plots containing ash compared to concentrations in the control plots. The ash in the roads did not affect the concentrations in the ditches. The leaching is uneven and seems to take place only from some parts of the ash layer. Risk for leaching is minimal if such parts are not widely spread.

Lindroos, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: antti.lindroos@luke.fi
Ryhti, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: kira.ryhti@helsinki.fi
Kaakkurivaara, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: tomi.kaakkurivaara@gmail.com
Uusitalo, Natural Resources Institute Finland (Luke), Korkeakoulunkatu 7, FI-33720 Tampere, Finland E-mail: jori.uusitalo@luke.fi
Helmisaari, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: helja-sisko.helmisaari@helsinki.fi

article id 10052, category Research article

Pentti Niemistö, Harri Kilpeläinen, Henrik Heräjärvi. (2019). Effect of pruning season and tool on knot occlusion and stem discolouration in Betula pendula – situation five years after pruning. Silva Fennica vol. 53 no. 1 article id 10052. https://doi.org/10.14214/sf.10052

Keywords: silver birch; pruning saw; discolouration; healing-over; secateurs; stick pruning

Highlights: The occlusion was the fastest in the case of small living branches of fast growing trees pruned in springtime; Occlusion was quicker after saw pruning than after secateurs pruning, due to shorter knot stubs; Branches that were pruned in living state occluded faster than the ones pruned as dead; Dead branches hit down with a stick occluded slowly.

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This paper investigates and models the effects of pruning season and tool on wound occlusion with varying tree and branch characteristics of silver birch (Betula pendula Roth) stems at the pruning height of 0−4 metres. Dates of eight secateurs prunings, three saw prunings and two sticks prunings as well as unpruned control were tested in permanent plots on four sites. Knot occlusion and discolouration in stemwood were measured from about 1600 studied knots of 112 sample trees felled five to six years after pruning in 2010. Knot occlusion rate was modelled according to pruning tool, date, tree growth, and branch characteristics. The occlusion was the fastest in trees pruned in spring or early summer, and the slowest in trees pruned in autumn. Stubs of living branches occluded faster than the dead ones with the same diameter. Saw pruning resulted in clearly better occlusion rates than secateurs pruning, caused by the shorter knot stubs after saw pruning. Hitting dead branches away with a stick resulted in the worst occlusion status. The colour defects spread more often upward from the knot than downward. Discolouration in stemwood was detected more frequently near to the pruned branches than the unpruned ones, and more widely near to the stubs of dead branches than the living ones. Most saw and secateurs pruned branches were completely occluded during the experiment, so these prunings were suitable for all branches under 20 mm in diameter, and for living branches even up to 30 mm in fast-growing trees.

Niemistö, Natural Resources Institute Finland (Luke), Natural resources, Kampusranta 9 C, FI-60320 Seinäjoki, Finland E-mail: pentti.niemisto@luke.fi
Kilpeläinen, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6 B, FI-80100 Joensuu, Finland E-mail: harri.kilpelainen@luke.fi
Heräjärvi, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6 B, FI-80100 Joensuu, Finland E-mail: henrik.herajarvi@luke.fi

article id 10050, category Research article

Jori Uusitalo, Jari Ala-Ilomäki, Harri Lindeman, Jenny Toivio, Matti Siren. (2019). Modelling soil moisture – soil strength relationship of fine-grained upland forest soils. Silva Fennica vol. 53 no. 1 article id 10050. https://doi.org/10.14214/sf.10050

Keywords: cone index; penetration resistance; shear strength; soil bulk density; VWC

Highlights: Penetration resistance (PR) is best predicted with moisture content (MC), bulk density and clay content; In fully saturated silty or clayey soils PR range from 600 to 800 kPa; The models can be linked with mobility models predicting rutting of forest machines.

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The strength of soil is known to be dependent on water content but the relationship is strongly affected by the type of soil. Accurate moisture content – soil strength models will provide forest managers with the improved ability to reduce soil disturbances and increase annual forest machine utilization rates. The aim of this study was to examine soil strength and how it is connected to the physical properties of fine-grained forest soils; and develop models that could be applied in practical forestry to make predictions on rutting induced by forest machines. Field studies were conducted on two separate forests in Southern Finland. The data consisted of parallel measurements of dry soil bulk density (BD), volumetric water content (VWC) and penetration resistance (PR). The model performance was logical, and the results were in harmony with earlier findings. The accuracy of the models created was tested with independent data. The models may be regarded rather trustworthy, since no significant bias was found. Mean absolute error of roughly 20% was found which may be regarded as acceptable taken into account the character of the penetrometer tool. The models can be linked with mobility models predicting either risks of rutting, compaction or rolling resistance.

Uusitalo, Natural Resources Institute Finland (Luke), Production systems, Korkeakoulunkatu 7, FI-33720 Tampere, Finland E-mail: jori.uusitalo@luke.fi
Ala-Ilomäki, Natural Resources Institute Finland (Luke), Production systems Maarintie 6, FI-02150 Espoo, Finland E-mail: jari.ala-ilomaki@luke.fi
Lindeman, Natural Resources Institute Finland (Luke), Production systems, Korkeakoulunkatu 7, FI-33720 Tampere, Finland E-mail: harri.lindeman@luke.fi
Toivio, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: toiviojenny@gmail.com
Siren, Natural Resources Institute Finland (Luke), Production systems Maarintie 6, FI-02150 Espoo, Finland E-mail: matti.siren@luke.fi

article id 9918, category Research article

Ari Nikula, Vesa Nivala, Juho Matala, Kari Heliövaara. (2019). Modelling the effect of habitat composition and roads on the occurrence and number of moose damage at multiple scales. Silva Fennica vol. 53 no. 1 article id 9918. https://doi.org/10.14214/sf.9918

Keywords: forestry; Alces alces; damage probability; forest damage; forest plantation; habitat selection; habitat modelling; zero-inflated negative binomial distribution

Highlights: The occurrence and number of moose damage were modelled with a zero-inflated count model; An admixture of mature forests within plantations increased the number of damage; Vicinity of inhabited areas and roads reduced damage; Plantations in landscapes with a large amount of pine-dominated thinning forests had less damage in Lapland; Damage risk assessment should include characteristics specific to each region.

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We modelled the effect of habitat composition and roads on the number and occurrence of moose (Alces alces L.) damage in Ostrobothnia and Lapland using a zero-inflated count model. Models were developed for 1 km², 25 km² and 100 km² landscapes consisting of equilateral rectangular grid cells. Count models predict the number of damage, i.e. the number of plantations and zero models the probability of a landscape being without damage for a given habitat composition. The number of moose damage in neighboring grid cells was a significant predictor in all models. The proportion of mature forest was the most frequent significant variable, and an increasing admixture of mature forests among plantations increased the number and occurrence of damage. The amount of all types of plantations was the second most common significant variable predicting increasing damage along with increasing amount of plantations. An increase in thinning forests as an admixture also increased damage in 1 km² landscapes in both areas, whereas an increase in pine-dominated thinning forests in Lapland reduced the number of damage in 25 km² landscapes. An increasing amount of inhabited areas in Ostrobothnia and the length of connecting roads in Lapland reduced the number of damage in 1 and 25 km² landscapes. Differences in model variables between areas suggest that models of moose damage risk should be adjusted according to characteristics that are specific to the study area.

Nikula, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, Ounasjoentie 6, FI-96200 Rovaniemi, Finland E-mail: ari.nikula@luke.fi
Nivala, Natural Resources Institute Finland (Luke), Bioeconomy and Environment, Ounasjoentie 6, FI-96200 Rovaniemi, Finland E-mail: vesa.nivala@luke.fi
Matala, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: juho.matala@luke.fi
Heliövaara, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: kari.heliovaara@helsinki.fi

article id 10036, category Research article

Karin Hjelm, Lars Rytter. (2018). The demand of hybrid aspen (Populus tremula × P. tremuloides) on site conditions for a successful establishment on forest land. Silva Fennica vol. 52 no. 5 article id 10036. https://doi.org/10.14214/sf.10036

Keywords: regeneration; site preparation; clone effects; poplars; soil acidity

Highlights: Low pH (below 3.5) reduced growth, but not survival, in a greenhouse study; Site preparation methods did not affect survival in field, but differences were found for growth; Mounding had generally the best effect on growth; Clonal differences were found that could be useful for improving establishment and growth.

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Hybrid aspen (Populus tremula L. × P. tremuloides Michx.) is a deciduous tree species suitable for producing large amounts of renewable biomass during short rotations. Its potential under North European conditions could be largely extended if not only agricultural land but also forest land was used for cultivation. Unfortunately, the knowledge of appropriate forest site conditions and effects of site preparation methods on hybrid aspen establishment is limited. In this paper, two studies that explore these questions are presented. In the first study, the sensitivity to acid soils was tested under greenhouse conditions in two type of soils: a) peat soil limed to certain pH levels (3.4–5.7) and b) collected forest soils where pH varied from 3.9 to 5.3. The lowest pH level resulted in reduced growth, elsewhere no significant differences were found. The second study was applied in the field and investigated the effect of four site preparation methods on survival and growth. The methods were: 1) control with no site preparation, 2) patch scarification, 3) mounding and 4) soil inversion. While no differences were found for survival, mounding was generally the method with the highest growth and patch scarification was least successful. The result was probably an effect of good soil aeration and less competition from vegetation after mounding. The field study also revealed clonal differences in growth performance, which stresses the importance of clone selection prior to planting. The results of these studies indicate that hybrid aspen is less sensitive to variation in pH and site preparation methods compared with other poplar species, as have been found in similar studies.

Hjelm, Skogforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden E-mail: karin.hjelm@skogforsk.se
Rytter, Skogforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden http://orcid.org/0000-0001-6183-4832 E-mail: lars.rytter@skogforsk.se

article id 10034, category Research article

Yan Ao, Peter M. Hirst, Guolei Li, Yahui Miao, Runzhe Zhang. (2018). Combined effects of provenance and slow-release fertilizer on nursery and field performance of yellowhorn seedlings. Silva Fennica vol. 52 no. 5 article id 10034. https://doi.org/10.14214/sf.10034

Keywords: nursery response; field performance; Xanthoceras sorbifolium; plant nutrition; short rotation plantation

Highlights: Combining slow-release fertilizer (SRF) and provenance in the nursery has large effects on most seedling characteristics in yellowhorn; Stem and root P contents in the nursery, and height at the end of the second growing season (T3) in the field were mainly affected by provenance; Higher rates of SRF tended to increase root N, stem and root P contents in the nursery, diameter, and biomass at T3; The combination of AQ provenance with 120–200 mg N seedling^–1 SRF yielding better nursery and field performance was recommended.

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Yellowhorn (Xanthoceras sorbifolium Bunge) has been widely planted for biodiesel production in China, but has frequently shown poor field performance. Container-grown yellowhorn seedlings originating from three Chinese provenances, Wengniute Qi (WQ), Alukeerqin Qi (AQ), and Shanxian (SX), were fertilized with slow-release fertilizer (SRF) at 40, 80, 120, 160 or 200 mg N seedling^–1. Tree growth, survival and nutrient content were measured after one year’s growth in a greenhouse followed by two years in a field site. Plants from AQ and SX tended to have higher stem and root P contents in the nursery. Higher rates of SRF increased root N, and stem and root P contents. After one year in the nursery, there were a number of interactions between provenance and SRF for plant growth responses and nutrient content in the nursery, however after two years of additional growth in the field, plants from the different provenances generally responded similarly to applied SRF in the nursery, with few interactions. Final plant height was approximately 10% lower in trees from provenance SX but was not affected by application of SRF. Conversely, final trunk diameter and stem and root biomass were unaffected by provenance but increased with higher rates of applied SRF. Our results indicate that application of SRF may be a useful tool to nutrient load yellowhorn in the nursery and facilitate transplanting performance in the field. Overall, optimal nursery and field performance of yellowhorn were observed in provenance AQ at 120–200 mg N seedling^–1 SRF. We suggest that growers consider a wider range of yellowhorn provenances and SRF rates (above 200 mg N seedling^–1) to yield even better growth response.

Ao, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing Forestry University, 35 East Qinghua Road, Haidian District, Beijing 100083, China E-mail: aoyan316@163.com
Hirst, Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA E-mail: hirst@purdue.edu
Li, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing Forestry University, 35 East Qinghua Road, Haidian District, Beijing 100083, China E-mail: glli226@163.com
Miao, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing Forestry University, 35 East Qinghua Road, Haidian District, Beijing 100083, China E-mail: 372902610@qq.com
Zhang, College of Forestry, Beijing Forestry University, 35 East Qinghua Road, Haidian District, Beijing 100083, China E-mail: 793755837@qq.com

article id 10001, category Research article

Karoliina Hämäläinen, Teemu Tahvanainen, Kaisa Junninen. (2018). Characteristics of boreal and hemiboreal herb-rich forests as habitats for polypore fungi. Silva Fennica vol. 52 no. 5 article id 10001. https://doi.org/10.14214/sf.10001

Keywords: biodiversity; species richness; coarse woody debris; threatened species; wood-decaying fungi

Highlights: Polypore species richness and diversity were affected positively by dead-wood diversity, and negatively by increasing latitude; Red-listed species responded only to the abundance of large-diameter dead wood; Main factor determining composition of polypore assemblages was host-tree species; High proportion of deciduous dead-wood in herb-rich forests provides complementary effect on polypore assemblages in boreal forest landscapes.

Abstract | Full text in HTML | Full text in PDF | Author Info

Herb-rich forests are often considered biodiversity hotspots in the boreal zone but their fungal assemblages, particularly those of wood-decaying fungi, remain poorly known. We studied herb-rich forests as habitats for polypores, a distinct group of wood-decaying fungi, and assessed the importance of tree- and stand-scale variables for polypore species richness, abundance, and diversity, including red-listed species. The data include 71 herb-rich forest stands in Finland and 4797 dead wood items, on which we made 2832 observations of 101 polypore species. Dead-wood diversity was the most important variable explaining polypore species richness and diversity, whereas increasing latitude had a negative effect. Red-listed species showed a positive response to the abundance of large-diameter dead wood, which, especially birch, supported also high general abundance of polypores. The composition of polypore assemblages reflected their host-tree species. The red-listed species did not show explicit patterns in the ordination space. Compared to old-growth spruce forests, herb-rich forests seem to host lower polypore species richness and less red-listed species. However, because of high proportion of deciduous trees in the dead wood profile, herb-rich forests have a clear complementary effect on polypore assemblages in boreal forest landscapes.

Hämäläinen, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: karoham@uef.fi
Tahvanainen, Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: teemu.tahvanainen@uef.fi
Junninen, Metsähallitus Parks & Wildlife Finland, c/o UEF/Borealis, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: kaisa.junninen@metsa.fi

article id 10000, category Research article

Hamed Yousefzadeh, Rasta Rajaei, Anna Jasińska, Łukasz Walas, Yann Fragnière, Gregor Kozlowski. (2018). Genetic diversity and differentiation of the riparian relict tree Pterocarya fraxinifolia (Juglandaceae) along altitudinal gradients in the Hyrcanian forest (Iran). Silva Fennica vol. 52 no. 5 article id 10000. https://doi.org/10.14214/sf.10000

Keywords: plant variation; Caucasian wingnut; population genetics; refugium; riparian forest; river system

Highlights: The Caucasian wingnut (Pterocarya fraxinifolia Spach) is an emblematic and relict riparian tree with limited distribution in Hyrcanian forest which investigating its genetic population structure and diversity along altitudinal gradients, and migration patterns are novel; We concluded that rivers are the main seed dispersal vector among P. fraxinifolia populations and there was no trend from upstream to downstream; The high level of gene flow and uniform genetic diversity along each river system suggest the “classical” metapopulation structure of the species.

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Riparian trees, especially relict trees, are attractive and important for research to understand both past and recent biogeographical and evolutionary processes. Our work is the first study to elucidate the genetic diversity and spatial genetic structure of the canopy-dominating riparian Pterocarya fraxinifolia (Juglandaceae) along two altitudinal gradients in different river systems of the Hyrcanian forest, which is one of the most important refugium of relict trees in Western Eurasia. Altitudinal gradients were chosen along two river systems at 100, 400 and 900 m a.s.l. Leaf samples were collected from 116 trees, and the genetic diversity was evaluated with eight SSR markers. Overall, 39 alleles were identified for all of the populations studied. The observed heterozygosity (Ho) varied from 0.79 to 0.87 (with a mean of 0.83). The results of the AMOVA analysis indicated that the variation within populations was 88%, whereas the variation among populations was 12% for all of the gradients. A structure analysis indicated that 93% of the trees were grouped in the same gradient. The genetic distance based on Fst confirmed the structure result and indicated a high rate of gene flow among the investigated populations. Based on high gene flow (low differentiation of the population along the same river) and the clearly distinct genetic structure of the investigated gradients, it can be concluded that rivers are the main seed dispersal vector among P. fraxinifolia populations. The genetic diversity of P. fraxinifolia did not show any trend from upstream to downstream. The high level of gene flow and uniform genetic diversity along each river suggest the “classical” metapopulation structure of the species.

Yousefzadeh, Department of Environmental Science, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Mazandaran, Iran E-mail: h.yousefzadeh@modares.ac.ir
Rajaei, Department of Forestry, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Mazandaran, Iran E-mail: r.rajaei@modares.ac.ir
Jasińska, Laboratory of Systematics and Geography, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, PL-62-035 Kornik, Poland E-mail: jasiak9@wp.pl
Walas, Laboratory of Systematics and Geography, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, PL-62-035 Kornik, Poland E-mail: lukaswalas@wp.pl
Fragnière, Department of Biology and Botanic Garden, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland E-mail: yann.fragniere@unifr.ch
Kozlowski, Department of Biology and Botanic Garden, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland; Natural History Museum Fribourg, Chemin du Musée 6, CH-1700 Fribourg, Switzerland E-mail: gregor.kozlowski@unifr.ch

article id 9985, category Research article

Antonín Martiník, Robert Knott, Jan Krejza, Jakub Černý. (2018). Biomass production of Betula pendula stands regenerated in the region of allochthonous Picea abies dieback. Silva Fennica vol. 52 no. 5 article id 9985. https://doi.org/10.14214/sf.9985

Keywords: silver birch; stem biomass; branch biomass; rotation period

Highlights: Biomass equations for individual components of above-ground wood biomass estimation are presented for stands at the age of 4, 8, 17 and 22 years; Peak of the mean annual increment was found at the age from 15 to 20 years and reached over 5.0 t ha^–1 y^–1 of dry biomass; The share of the stem to the total biomass increased with stand age.

Abstract | Full text in HTML | Full text in PDF | Author Info

The paper deals with production of above-ground biomass of silver birch (Betula pendula Roth) stands in the Czech Republic. One-year biomass dynamics was studied within chronosequence of birch stands at the age of 4–5, 8–9, 17–18 and 22–23 years. With the exception of the youngest stand, which was established by seeding, all experimental birch stands were regenerated naturally after the allochthonous spruce stands. Above-ground biomass (AB) was calculated from plot inventory data and biomass equations were parameterized from destructive sampling of biomass component of sampled trees. Results reveal that the peak of the mean annual increment (MAI_ABtotal) of birch stands can be expected at the age from 15 to 20 years. Additionally, the stand age, the value of basal area (BA) should be considered as a predictor of stand productivity. If the value of BA varied from 25 to 35 m² ha^–1, the MAI of the birch stands reached the range from 5.0 to 6.5 t of dry biomass per ha y^–1 at the age ranging between 15 and 25 years. The stem/branch proportion increased with stand age, the stem relative proportion ranging from 75 to 90% of total above-ground biomass. According to the results of this study, birch stand biomass production and utilization is one of the approaches in terms of forest recovery management in large disturbed areas. Although, no silvicultural treatments were occurred in all analysed stands, the pre-commercial thinning method could increase stand productivity and stability as well.

Martiník, Department of Silviculture, Faculty of Forestry and Wood Technology, Mendel University in Brno, 613 00 Brno, Czech Republic https://orcid.org/0000-0002-5906-8830 E-mail: martinik@mendelu.cz
Knott, Department of Silviculture, Faculty of Forestry and Wood Technology, Mendel University in Brno, 613 00 Brno, Czech Republic E-mail: robert.knott@mendelu.cz
Krejza, Global Change Research Institute CAS, v.v.i., Bělidla 4a, 603 00 Brno, Czech Republic E-mail: krejza.j@czechglobe.cz
Černý, The Forestry and Game Management Research Institute, Research Station at Opočno, Na Olivě 550, 517 73 Opočno, Czech Republic E-mail: cerny@vulhmop.cz

article id 7763, category Research article

Sergei Senko, Mikko Kurttila, Timo Karjalainen. (2018). Prospects for Nordic intensive forest management solutions in the Republic of Karelia. Silva Fennica vol. 52 no. 4 article id 7763. https://doi.org/10.14214/sf.7763

Keywords: forest management; thinning; forestry; Russia; SWOT

Highlights: SWOT (strengths, weaknesses, opportunities and threats) and multi-criteria decision support analysis were combined to examine the potential for Nordic intensive forest management solutions (NIFMS) in Karelia, Russia; NIFMS looks promising for Karelian forestry; Improving quality-and-value of timber and sustained yield are the highly prioritized strengths; Unprepared forestry regulations are the main threat that needs to be taken into account.

Abstract | Full text in HTML | Full text in PDF | Author Info

In this study, the prospects for future forest management in Republic of Karelia, Russia were analyzed. Forestry has an important role in the economy of Karelia. However, productivity and profitability in the forestry sector are extremely low, forest stand structure and quality are weak, the commercial forest land of coniferous species has declined and the wood processing industry struggles with a deficit of raw materials. The situation is typical to many forest regions in Russia with extensive forest management cited as one reason for the current situation. In contrast, the Nordic countries have significant experience in intensive and sustainable forest management and the results have been to a large extent positive. The transfer of Nordic intensive forest management solutions (NIFMS) could improve forestry in Karelia. SWOT analysis, combined with the multi-criteria decision support (MCDS) method was used to identify local operational environments and to assign priorities. Major threats included unprepared regulations, poor road infrastructure, insecure investments, low forestry productivity, forest degradation, high investment costs and a negative attitude to intensive forestry. The main opportunities are high forest resource potential in Karelia, favorable authority development programs, proven Nordic expertise, wood-based energy development and availability of new technology. Results also showed that the main weaknesses that might influence the NIFMS in Karelia are slow return on investments, low market demand for energy wood, high costs associated with young forest thinnings, high demand for skilled specialists and a lack of investment in research and development.

Senko, University of Eastern Finland (UEF), School of Forest Sciences, Yliopistokatu 7, FI-80111 Joensuu, Finland E-mail: sergei.senko@uef.fi
Kurttila, The Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: mikko.kurttila@luke.fi
Karjalainen, † Deceased E-mail: tjk@nn.fi

article id 10006, category Research article

Matti Maltamo, Tomi Karjalainen, Jaakko Repola, Jari Vauhkonen. (2018). Incorporating tree- and stand-level information on crown base height into multivariate forest management inventories based on airborne laser scanning. Silva Fennica vol. 52 no. 3 article id 10006. https://doi.org/10.14214/sf.10006

Keywords: forest inventory; LIDAR; alpha shape; crown height; nearest neighbor; mixed-effects model

Highlights: The most accurate tree-level alternative is to include crown base height (CBH) to nearest neighbour imputation; Also mixed-effects models can be applied to predict CBH using tree attributes and airborne laser scanning (ALS) metrics; CBH prediction can be included with an accuracy of 1–1.5 m to forest management inventory applications.

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This study examines the alternatives to include crown base height (CBH) predictions in operational forest inventories based on airborne laser scanning (ALS) data. We studied 265 field sample plots in a strongly pine-dominated area in northeastern Finland. The CBH prediction alternatives used area-based metrics of sparse ALS data to produce this attribute by means of: 1) Tree-level imputation based on the k-nearest neighbor (k-nn) method and full field-measured tree lists including CBH observations as reference data; 2) Tree-level mixed-effects model (LME) prediction based on tree diameter (DBH) and height and ALS metrics as predictors of the models; 3) Plot-level prediction based on analyzing the computational geometry and topology of the ALS point clouds; and 4) Plot-level regression analysis using average CBH observations of the plots for model fitting. The results showed that all of the methods predicted CBH with an accuracy of 1–1.5 m. The plot-level regression model was the most accurate alternative, although alternatives producing tree-level information may be more interesting for inventories aiming at forest management planning. For this purpose, k-nn approach is promising and it only requires that field measurements of CBH is added to the tree lists used as reference data. Alternatively, the LME-approach produced good results especially in the case of dominant trees.

Maltamo, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: matti.maltamo@uef.fi
Karjalainen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: tomimkarjalainen@gmail.com
Repola, Natural Resources Institute of Finland (Luke), Natural resources, Eteläranta 55, FI-96300 Rovaniemi, Finland E-mail: jaakko.repola@luke.fi
Vauhkonen, Natural Resources Institute of Finland (Luke), Bioeconomy and environment, Yliopistokatu 6, 80100 Joensuu, Finland E-mail: jari.vauhkonen@luke.fi

article id 9987, category Research article

Monika Dering, Katarzyna Sękiewicz, Grzegorz Iszkuło, Aleksandra Chojnacka, Dominik Tomaszewski, Emilia Pers-Kamczyc, Piotr Karolewski. (2018). Spatial genetic structure and clonal structure of Prunus serotina during invasive spread. Silva Fennica vol. 52 no. 3 article id 9987. https://doi.org/10.14214/sf.9987

Keywords: genetic structure; invasiveness; black cherry; colonization; clonal structure

Highlights: The spread of Prunus serotina in invaded forests is facilitated by high propagule pressure; The seed shadow overlap prevents strong spatial genetic structure; During colonization of isolated site, a strong spatial genetic structure is produced due to founder effect; Overall clonality in P. serotina was low but may efficiently support seedling bank thus contributing to species invasiveness.

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Prunus serotina Ehrh. (black cherry) is one of the most important invaders in the European forests, but existing studies have given limited insight into demo-genetic factors underpinning the process of species invasion. Fine-scale genetic structure (FSGS) may deliver important knowledge on genetics of invasion contributing to efficient management of the alien species. Using eight microsatellites we investigated FSGS, clonal structure and relatedness in four black cherry populations which represented different stages of the invasive spread into Scots pine forests. Three populations were in a continuous forest complex and represented the colonization (Z_1) and established stages (Z_2 and Z_3). To investigate how colonization ability of the species is modified by landscape features, we analyzed an isolated population at colonization stage located in limited forest patch located in an agricultural landscape (R). Populations from continuous forest showed low yet significant positive FSGS with Sp = 0.0068 in Z_1, 0.0054 in Z_2, and 0.0066 in Z_3, while in R spatial structure was the strongest (0.0145). Considerable relatedness noted in population R suggests a dominance of within-population mating and recruitments, low immigration rate and limited seed dispersal, all of which led to the observed strong FSGS. Also, we presume that a founder effect likely involved during colonization of isolated forest patch R led to strong FSGS. In contrary, the seed shadow overlap in the populations from continuous forest prevented strong FSGS and facilitated colonization. Despite of low level of clonality, we argue that it may efficiently support black cherry seedling bank contributing to species invasiveness.

Dering, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: mdering@man.poznan.pl
Sękiewicz, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: ksekiewicz@man.poznan.pl
Iszkuło, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland; Faculty of Biological Sciences, University of Zielona Góra, Prof. Z. Szafrana 1, 65-516 Zielona Góra, Poland E-mail: iszkulo@man.poznan.pl
Chojnacka, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: jagoda900@gmail.com
Tomaszewski, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: dominito@man.poznan.pl
Pers-Kamczyc, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: epk@man.poznan.pl
Karolewski, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: pkarolew@man.poznan.pl

article id 9980, category Research article

Eino Levkoev, Lauri Mehtätalo, Katri Luostarinen, Pertti Pulkkinen, Anatoly Zhigunov, Heli Peltola. (2018). Development of height growth and frost hardiness for one-year-old Norway spruce seedlings in greenhouse conditions in response to elevated temperature and atmospheric CO₂ concentration. Silva Fennica vol. 52 no. 3 article id 9980. https://doi.org/10.14214/sf.9980

Keywords: climate change; Picea abies; needles; tree growth; seedlings; cold acclimation

Highlights: Elevated temperature resulted in increased height growth, delayed onset and shortened duration of autumn frost hardiness development in Norway spruce seedlings; Elevated temperature increased variation between genotypes in height growth and frost hardiness development; Elevated atmospheric CO₂ concentration had no effect on the development of height or autumn frost hardiness in Norway spruce seedlings.

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The mean temperature during the potential growing season (April–September) may increase by 1 °C by 2030, and by 4 °C, or even more, by 2100, accompanied by an increase in atmospheric CO₂ concentrations of 536–807 ppm, compared to the current climate of 1981–2010, in which atmospheric CO₂ is at about 350 ppm. This may affect both the growth and frost hardiness of boreal trees. In this work, we studied the responses of height and autumn frost hardiness development in 22 half-sib genotypes of one-year-old Norway spruce (Picea abies (L.) Karst.) seedlings to elevated temperatures and atmospheric CO₂ concentration under greenhouse conditions. The three climate treatments used were: T+1 °C above ambient and ambient CO₂; T+4 °C above ambient and ambient CO₂; and T+4 °C above ambient and elevated CO₂ (700 ppm). The height growth rate and final height were both higher under T+4 °C compared to T+1 °C. Temperature increase also delayed the onset, and shortened the duration, of autumn frost hardiness development. Elevated CO₂ did not affect the development of height or frost hardiness, when compared to the results without CO₂ elevation under the same temperature treatment. Higher temperatures resulted in greater variation in height and frost hardiness development among genotypes. Three genotypes with different genetic backgrounds showed superior height growth, regardless of climate treatment; however, none showed a superior development of autumn frost hardiness. In future studies, clonal or full-sib genetic material should be used to study the details of autumn frost hardiness development among different genotypes.

Levkoev, University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: eino.levkoev@uef.fi
Mehtätalo, University of Eastern Finland, Faculty of Science and Forestry, School of Computing, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: lauri.mehtatalo@uef.fi
Luostarinen, University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: katri.luostarinen@uef.fi
Pulkkinen, Natural Resources Institute Finland (Luke), Production systems, Haapastensyrjä Breeding Station, FI-16200 Läyliäinen, Finland E-mail: pertti.pulkkinen@luke.fi
Zhigunov, Saint-Petersburg State Forest Technical University, Forestry Faculty, RU-194021, Institutskiy per. 5, Saint-Petersburg, Russia E-mail: a.zhigunov@bk.ru
Peltola, University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: heli.peltola@uef.fi

article id 9948, category Research article

Juha Heiskanen, Ville Hallikainen, Jori Uusitalo, Hannu Ilvesniemi. (2018). Co-variation relations of physical soil properties and site characteristics of Finnish upland forests. Silva Fennica vol. 52 no. 3 article id 9948. https://doi.org/10.14214/sf.9948

Keywords: site quality; vegetation; bulk density; trafficability; particle size; humus layer; water retention

Highlights: Atmospheric temperature sum is related to site index H100 as a covariate;Soil pH and water retention at field capacity (FC) are also closely related to H100;Fine fraction is related to water retention at FC, soil layer and site type;Fine fraction co-varies also with temperature sum, H100 and slope.

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Physical soil properties have a marked influence on the quality of forest sites and on the preconditions for forest growth and management. In this study, water retention characteristics (WRC) and related physical soil properties in addition to vegetation coverage and tree stand data were studied at upland forest sites in Finland. Fixed and mixed models between soil and site characteristics were formed to estimate physical and hydrologic soil characteristics and the site quality with indirect co-varying variables. In the present data, the site quality index (H100) shows a high coefficient of determination in respect to the temperature sum. It is also related to soil fine fraction content, topsoil pH and water retention at field capacity. The thickness of the humus layer is predictable from the pH and cover of xeric and mesic plant species. The soil fine fraction content (clay + silt) is closely related to water retention at field capacity, the soil layer and site type, and without WRC to the temperature sum and site index and type, as well as the slope angle. The soil bulk density is related to organic matter, depth (layer) or alternatively to organic matter, slope and field estimated textural class (fine, medium, coarse). Water retention characteristics were found to be best determinable by the fine fraction content, depth and bulk density. Water content and air-filled porosity at field capacity are closely related to the fine fraction. This study provides novel models for further investigations that aim at improved prediction models for forest growth, hydrology and trafficability.

Heiskanen, Natural Resources Institute Finland (Luke), Soil ecosystems, Neulaniementie 5, FI-70100 Kuopio, Finland E-mail: juha.heiskanen@luke.fi
Hallikainen, Natural Resources Institute Finland (Luke), Applied statistical methods, Eteläranta 55, FI-96300 Rovaniemi, Finland E-mail: ville.hallikainen@luke.fi
Uusitalo, Natural Resources Institute Finland (Luke), Forest technology and logistics, Korkeakoulunkatu 7, FI-33720 Tampere, Finland E-mail: jori.uusitalo@luke.fi
Ilvesniemi, Natural Resources Institute Finland (Luke), Biorefinery and bioproducts, Tietotie 2, FI-02150 Espoo, Finland E-mail: hannu.ilvesniemi@luke.fi

article id 9947, category Research article

Eric R. Labelle, Linus Huß. (2018). Creation of value through a harvester on-board bucking optimization system operated in a spruce stand. Silva Fennica vol. 52 no. 3 article id 9947. https://doi.org/10.14214/sf.9947

Keywords: buck-to-value; processing; single-grip-harvester; product recovery; harvesting productivity

Highlights: Use of harvester on-board computer bucking optimization remains highly under-utilized in German forestry; Revenue per tree and harvesting productivity were both statistically higher with automatic bucking as compared to quality bucking during a thinning operation in a spruce dominated stand.

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Tree bucking, defined as the process in which a stem is segmented into shorter logs of varying lengths, has a significant effect on the value adding potential of a forest enterprise. Because of its importance in terms of correct product and length combinations, improper bucking can lead to financial losses. In this study, two treatments (OFF: quality bucking performed by the operator while using hot keys and ON: automatic bucking using the optimized suggestions from the harvester on-board computer; OBC) were tested in a Norway spruce (Picea abies [L.] Karst.) dominated stand located in Germany. Both treatments had the aim to maximize the value of a stem. The research took place in an 80-year old spruce and beech stand under a regenerative cutting. Fully-mechanized harvesting was performed with an 8-wheel Ponsse Bear single-grip harvester equipped with a H8 harvesting head. Results indicated that the product recovery of the two treatments differed by 4% in undamaged trees (no broken tree-tops or stems) to the benefit of manual bucking. However, the revenue of trees subjected to optimized bucking were up to 4% higher (in average 3%) than those of the manual bucking once expressed on a per cubic meter basis. Moreover, the harvesting productivity of the ON treatment was at the maximum 17% higher compared to the OFF treatment. Based on the results from this case study, the use of an optimization software in Norway spruce dominated stands with the aim to maximize the value of single stems showed promising results.

Labelle, Assistant Professorship of Forest Operations, Department of Ecology and Ecosystem Management, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising, Germany E-mail: eric.labelle@tum.de
Huß, Assistant Professorship of Forest Operations, Department of Ecology and Ecosystem Management, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, D-85354 Freising, Germany E-mail: linus.huss@gmx.de

article id 9940, category Research article

Esteban Ceriani-Nakamurakare, Sergio Ramos, Carolina A. Robles, María V. Novas, María F. D´Jonsiles, Paola Gonzalez-Audino, Cecilia Carmarán. (2018). Metagenomic approach of associated fungi with Megaplatypus mutatus (Coleoptera: Platypodinae). Silva Fennica vol. 52 no. 3 article id 9940. https://doi.org/10.14214/sf.9940

Keywords: ambrosia; forest pest; metagenomic; fungi; Platypodinae; insect-fungus interactions

Highlights: There were no significant effects of host plant and location on fungal richness; Two fungal species, belonging to Fusarium and Candida genera, were present in all the studied associations; Results suggest that host plant identity would not be crucial to determine the composition of fungal communities associated to Megaplatypus mutatus.

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Megaplatypus mutatus is a major forest pest in Argentina and an emerging pest in Europe. In this study the multitrophic interactions between M. mutatus and associated fungi were assessed with a metagenomics approach (454-pyrosequencing). A total of 270 collection points from insect galleries from three locations in Argentina were pooled for pyrosequencing analyses. Two hosts, Populus deltoides and Casuarina cunninghamiana, were independently evaluated to characterize the fungal communities associated to M. mutatus; compare the culture-independent approach with previous culturing studies, in terms of data recovery related to the fungal community composition, and test the specificity of the fungal communities amongst locations and hosts. A Generalized Linear Mixed Model was performed to compare the fungal richness in each dataset, which showed no significant differences between taxa richness amongst locations. Principal Coordinates Analyses showed a separation between fungal communities within the same host, suggesting that host identity would not be crucial to determine the specificity in fungal communities. Candida insectalens and one Fusarium species, present in all hosts and locations, achieved 37.6% of the total relative frequency per taxa. These results complement the data from culturing methods previously reported, thus improving the accuracy and understanding of the fungal assemblages associated to M. mutatus.

Ceriani-Nakamurakare, Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Depto. Biodiversidad y Biología Experimental. Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires. Instituto de Micología y Botánica (INMIBO). Buenos Aires, (C1428EHA) Argentina E-mail: cerianinaka@gmail.com
Ramos, Instituto Nacional de Tecnología Agropecuaria. Estación Experimental Agropecuaria Concordia. Entre Ríos, (E3200) Argentina E-mail: ramos.sergio@inta.gob.ar
Robles, Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Depto. Biodiversidad y Biología Experimental. Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires. Instituto de Micología y Botánica (INMIBO). Buenos Aires, (C1428EHA) Argentina E-mail: carorobles@bg.fcen.uba.ar
Novas, Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Depto. Biodiversidad y Biología Experimental. Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires. Instituto de Micología y Botánica (INMIBO). Buenos Aires, (C1428EHA) Argentina E-mail: vicnovas@bg.fcen.uba.ar
D´Jonsiles, Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Depto. Biodiversidad y Biología Experimental. Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires. Instituto de Micología y Botánica (INMIBO). Buenos Aires, (C1428EHA) Argentina E-mail: lalijonsi@gmail.com
Gonzalez-Audino, Centro de Investigaciones de Plagas e Insecticidas (CITEFA-CONICET). Buenos Aires, (B1603ALO) Argentina E-mail: pgonzalezaudino@citedef.gob.ar
Carmarán, Centro de Investigaciones de Plagas e Insecticidas (CITEFA-CONICET). Buenos Aires, (B1603ALO) Argentina E-mail: carmaran@bg.fcen.uba.ar

article id 9905, category Research article

Mercedes M. Fernandez, Diana Bezos, Julio J. Diez. (2018). Fungi associated with necrotic galls of Dryocosmus kuriphilus (Hymenoptera: Cynipidae) in northern Spain. Silva Fennica vol. 52 no. 3 article id 9905. https://doi.org/10.14214/sf.9905

Keywords: Asian chestnut gall wasp; Castanea sativa; Fusarium spp.; Gnomoniopsis smithogilvyi; entomopathogens; fungal diversity.

Highlights: Presence of Dryocosmus kuriphilus in Northern Spain; The mycobiota associated to necrotic galls was studied for the first time; 7 fungal species were identified; The entomopathogenic fungi found could be use as potential biological control agents; Gnomomiopsis smithogilvyi, Fusarium oxysporum and F. avenaceum known by their toxicity against the insect, were found.

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The Asian chestnut gall wasp (ACGW), Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) is one of the most important pests in Castanea species worldwide. In 2012, it was found for the first time in Catalonia (Spain) and a year later, in the north of Spain (Cantabria). Today, it is present in 14 Spanish provinces. In search of biological control against the ACGW, several authors have previously found the relationship between the presence of some Fusarium Link species in necrotic galls and wasp mortality due to the production of different types of wall-degrading enzymes and entomopathogenic mycotoxins. The objective of this study was to investigate the mycobiota associated with necrotic galls to find interesting perspectives for biological control of the ACGW. For this purpose, in 2014, 119 necrotic galls of Castanea sativa Miller were plated to isolate and identify the associated fungi. The fungal isolates were identified by the morphology of the fruiting bodies and DNA analyses. From necrotic galls, 7 species of fungi were identified. Of these, we highlight three species of Fusarium Link as well as the presence of Gnomoniopsis smithogilvyi Shuttlew, Liew & Guest due to its toxic capacity. Further studies are required to verify the effectiveness of these fungal species as biocontrol agents against the ACGW.

Fernandez, Dpt. of Agroforestry Sciences, ETSIIAA, University of Valladolid, Av. Madrid 50, 34071 Palencia, Spain; Sustainable Forest Management Research Institute UVa-INIA, ETSIIAA, 34071 Palencia, Spain http://orcid.org/0000-0002-1646-5027 E-mail: mffernan@agro.uva.es
Bezos, Sustainable Forest Management Research Institute UVa-INIA, ETSIIAA, 34071 Palencia, Spain E-mail: dianabezos@yahoo.es
Diez, Sustainable Forest Management Research Institute UVa-INIA, ETSIIAA, 34071 Palencia, Spain; Dpt. of Plant Production and Forest Resources, University of Valladolid, Av. Madrid 50, 34071 Palencia, Spain E-mail: jdcasero@pvs.uva.es

article id 9938, category Research article

Jyrki Hytönen, Egbert Beuker, Anneli Viherä-Aarnio. (2018). Clonal variation in basic density, moisture content and heating value of wood, bark and branches in hybrid aspen. Silva Fennica vol. 52 no. 2 article id 9938. https://doi.org/10.14214/sf.9938

Keywords: moisture content; wood; bark; hybrid aspen; basic density; branches; clonal variation; heating value; ash content

Highlights: Hybrid aspen clones differed in their moisture content, ash content, basic density and heating value; Stem wood had lower ash content, basic density and effective heating value than stem bark; There was significant vertical variation in wood and bark along the stem in moisture content and basic density.

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Hybrid aspen (Populus tremula × P. tremuloides) is one of the fastest growing tree species in Finland. During the mid-1990s, a breeding programme was started with the aim of selecting clones that were superior in producing pulpwood. Hybrid aspen can also be grown as a short-rotation crop for bioenergy. To study clonal variation in wood and bark properties, seven clones were selected from a 12-year-old field trial located in southern Finland. From each clone, five trees were harvested and samples were taken from stem wood, stem bark and branches to determine basic density, effective heating value, moisture and ash content. Vertical within-tree variation in moisture content and basic density was also studied. The differences between clones were significant for almost all studied properties. For all studied properties there was a significant difference between wood and bark. Wood had lower ash content (0.5% vs. 3.9%), basic density (378 kg m^–3 vs. 450 kg m^–3) and effective heating value (18.26 MJ kg^–1 vs. 19.24 MJ kg^–1), but higher moisture content (55% vs. 49%) than bark. The values for branches were intermediate. These results suggest that the properties of hybrid aspen important for energy use could be improved by clonal selection. However, selecting clones based on fast growth only may be challenging since it may lead to a decrease in hybrid aspen wood density.

Hytönen, Natural Resources Institute Finland (Luke), Natural resources, Teknologiakatu 7, FI-67100 Kokkola, Finland E-mail: jyrki.hytonen@luke.fi
Beuker, Natural Resources Institute Finland (Luke), Production systems, Vipusenkuja 6, FI-57200 Savonlinna, Finland E-mail: egbert.beuker@luke.fi
Viherä-Aarnio, Natural Resources Institute Finland (Luke), Production systems, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: anneli.vihera-aarnio@luke.fi

article id 7699, category Research article

Dalytė Matulevičiūtė, Jurga Motiejunaite, Domas Uogintas, Ričardas Taraškevičius, Mindaugas Dagys, Valerijus Rašomavičius. (2018). Decline of a protected coastal pine forest under impact of a colony of great cormorants and the rate of vegetation change under ornithogenic influence. Silva Fennica vol. 52 no. 2 article id 7699. https://doi.org/10.14214/sf.7699

Keywords: coniferous forests; piscivorous birds; Baltic Sea; habitats

Highlights: We studied vegetation and its changes in a pine forest affected by a colony of great cormorants; Vegetation in the colony varied according to the period of bird influence and the stand elevation above sea level; Considerable vegetation changes occur in several years after bird colony establishment; Pine forest ecosystem cease to exist following a decade of bird activity.

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We investigated the impact of a colony of great cormorants on the vegetation of the old growth Pinus sylvestris L. forest on the Curonian Spit peninsula, Lithuania. We studied the characteristics and rates of plant cover changes under varying length and intensity of bird influence. Plant species numbers, as well as the coverage of plants with different ecological requirements, varied according to the period of bird influence, but the resulting vegetation also depended upon the stand elevation above sea level. In our study, the initial increase in plant species richness at the start of bird nesting was not obvious and was of a transient character, due to the weak invasion of non-forest species and the rapid decline of forest plants. The colony area showed obvious and rapid vegetation changes during the investigation period. According to the calculated colony expansion rates, after 6–7 years of impact from birds the tree layer decreased by about four fold; the shrub layer decreased by about two fold; the field layer decreased by about 15 fold; and the dwarf shrub and bottom layers disappeared. The coverage by oligotrophic species decreased by more than four fold, while the coverage by eutrophic species increased by more than 60 fold. After 9–10 years of ornithogenic impact, all the trees were dead, and the protected coniferous forest ecosystem, with its characteristic plant species, had ceased to exist as such.

Matulevičiūtė, Institute of Botany, Nature Research Centre, Žaliųjų ežerų Str. 49, LT-08406 Vilnius, Lithuania http://orcid.org/0000-0001-7550-1860 E-mail: dalyte.matuleviciute@botanika.lt
Motiejunaite, Institute of Botany, Nature Research Centre, Žaliųjų ežerų Str. 49, LT-08406 Vilnius, Lithuania http://orcid.org/0000-0002-6949-1990 E-mail: jurga.motiejunaite@botanika.lt
Uogintas, Institute of Botany, Nature Research Centre, Žaliųjų ežerų Str. 49, LT-08406 Vilnius, Lithuania http://orcid.org/0000-0002-3937-1218 E-mail: domas.uogintas@botanika.lt
Taraškevičius, Geology and Geography Institute, Nature Research Centre, Akademijos Str. 2, LT-08412 Vilnius, Lithuania http://orcid.org/0000-0002-5110-6142 E-mail: taraskevicius@geo.lt
Dagys, Institute of Ecology, Nature Research Centre, Akademijos Str. 2, LT-08412 Vilnius, Lithuania http://orcid.org/0000-0001-9342-3464 E-mail: dagys@ekoi.lt
Rašomavičius, Institute of Botany, Nature Research Centre, Žaliųjų ežerų Str. 49, LT-08406 Vilnius, Lithuania http://orcid.org/0000-0003-1314-4356 E-mail: valerijus.rasomavicius@botanika.lt

article id 9923, category Research article

Annika Kangas, Terje Gobakken, Stefano Puliti, Marius Hauglin, Erik Naesset. (2018). Value of airborne laser scanning and digital aerial photogrammetry data in forest decision making. Silva Fennica vol. 52 no. 1 article id 9923. https://doi.org/10.14214/sf.9923

Keywords: forest inventory; value of information; uncertainty; remote sensing; cost-plus-loss; data quality

Highlights: Airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) are nearly equally valuable for harvest scheduling decisions even though ALS data is more precise; Large underestimates of stand volume are most dangerous errors for forest owner because of missed cutting probabilities; Relative RMSE of stand volume and the mean volume in a test area explain 77% of the variation between the expected losses due to errors in the data in the published studies; Increasing the relative RMSE of volume by 1 unit, increased the losses in average by 4.4 € ha^–1.

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Airborne laser scanning (ALS) has been the main method for acquiring data for forest management planning in Finland and Norway in the last decade. Recently, digital aerial photogrammetry (DAP) has provided an interesting alternative, as the accuracy of stand-based estimates has been quite close to that of ALS while the costs are markedly smaller. Thus, it is important to know if the better accuracy of ALS is worth the higher costs for forest owners. In many recent studies, the value of forest inventory information in the harvest scheduling has been examined, for instance through cost-plus-loss analysis. Cost-plus-loss means that the quality of the data is accounted for in monetary terms through calculating the losses due to errors in the data in the forest management planning context. These costs are added to the inventory costs. In the current study, we compared the losses of ALS and DAP at plot level. According to the results, the data produced using DAP are as good as data produced using ALS from a decision making point of view, even though ALS is slightly more accurate. ALS is better than DAP only if the data will be used for more than 15 years before acquiring new data, and even then the difference is quite small. Thus, the increased errors in DAP do not significantly affect the results from a decision making point of view, and ALS and DAP data can be equally well recommended to the forest owners for management planning. The decision of which data to acquire, can thus be made based on the availability of the data on first hand and the costs of acquiring it on the second hand.

Kangas, Natural Resources Institute Finland (Luke), Bioeconomy and environment, P.O. Box 68, FI-80170 Joensuu, Finland E-mail: annika.kangas@luke.fi
Gobakken, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway E-mail: terje.gobakken@nmbu.no
Puliti, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway E-mail: stefano.puliti@nibio.no
Hauglin, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway E-mail: marius.hauglin@nmbu.no
Naesset, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway E-mail: erik.naesset@nmbu.no

article id 7803, category Research article

Lingbo Dong, Pete Bettinger, Huiyan Qin, Zhaogang Liu. (2018). Reflections on the number of independent solutions for forest spatial harvest scheduling problems: a case of simulated annealing. Silva Fennica vol. 52 no. 1 article id 7803. https://doi.org/10.14214/sf.7803

Keywords: simulated annealing; forest management planning; combinatorial optimization; neighborhood search; adjacency constraint

Highlights: No one particular neighborhood search technique of simulated annealing was found to be universally acceptable; The optimal number of independent solutions necessary for addressing the area restriction harvest scheduling model was described with a negative logarithmic function that was related with the problem size. However, optimal number of independent solutions necessary was not sensitive to the problem size for non-spatial and unit restriction harvest scheduling model problems, which should be somewhat above 250 independent runs; The types of adjacency constraints have moderate effects on the number of independent solutions, but these effects are not significant.

Abstract | Full text in HTML | Full text in PDF | Author Info

To assess the quality of results obtained from heuristics through statistical procedures, a number of independently generated solutions to the same problem are required, however the knowledge of how many solutions are necessary for this purpose using a specific heuristic is still not clear. Therefore, the overall aims of this paper are to quantitatively evaluate the effects of the number of independent solutions generated on the forest planning objectives and on the performance of different neighborhood search techniques of simulated annealing (SA) in three increasing difficult forest spatial harvest scheduling problems, namely non-spatial model, area restriction model (ARM) and unit restriction model (URM). The tested neighborhood search techniques included the standard version of SA using the conventional 1-opt moves, SA using the combined strategy that oscillates between the conventional 1-opt moves and the exchange version of 2-opt moves, and SA using the change version of 2-opt moves. The obtained results indicated that the number of independent solutions generated had clear effects on the conclusions of the performances of different neighborhood search techniques of SA, which indicated that no one particular neighborhood search technique of SA was universally acceptable. The optimal number of independent solutions generated for all alternative neighborhood search techniques of SA for ARM problems could be estimated using a negative logarithmic function based on the problem size, however the relationships were not sensitive (i.e., 0.13 < p < 0.78) to the problem size for non-spatial and URM harvest scheduling problems, which should be somewhat above 250 independent runs. The types of adjacency constraints did moderately affect the number of independent solutions necessary, but not significantly. Therefore, determining an optimal number of independent solutions generated is a necessary process prior to employing heuristics in forest management planning practices.

Dong, College of Forestry, Northeast Forestry University, Harbin 150040, China E-mail: farrell0503@126.com
Bettinger, Warnell School of Forestry and Natural Resources, University of Georgia, Athens 30602, GA, USA E-mail: pbettinger@warnell.uga.edu
Qin, College of Economic and Management, Northeast Forestry University, Harbin 150040, China E-mail: huiyanqin@hotmail.com
Liu, College of Forestry, Northeast Forestry University, Harbin 150040, China E-mail: lzg19700602@163.com

article id 7003, category Research article

Poje Anton, Raffaele Spinelli, Natascia Magagnotti, Matevz Mihelic. (2018). The effect of feedstock, knife wear and work station on the exposure to noise and vibrations in wood chipping operations. Silva Fennica vol. 52 no. 1 article id 7003. https://doi.org/10.14214/sf.7003

Keywords: biomass; fuelwood; ergonomics; safety

Highlights: Exposure to noise and vibration is higher when chipping branches rather than logs; Noise levels are higher in the separate cab, especially at some frequencies; Vibration is higher for the Z axis in the separate cab, for the X axis in the truck; Noise is higher when working with blunt knives, rather than new knives; Knife wear has no significant effect on exposure to whole-body vibration.

Abstract | Full text in HTML | Full text in PDF | Author Info

Industrial chipping is becoming increasingly popular, as the result of a growing demand for woody biomass. Industrial chippers are large, powerful machines that generate much noise and vibration. This study explored some factors that may affect exposure to noise and vibration, namely: feedstock type (branches vs. logs), work station characteristics (truck cab vs. separate cab) and knife wear (new knives vs. blunt knives). Exposure to noise was significantly affected by all three factors, and it was higher for branch feedstock, separate cabs and blunt knives. The higher exposure levels recorded for the separate cab were especially insidious, because they were below and above the hearing threshold and would elude immediate perception. Exposure to whole-body vibration (WBV) was significantly higher for branch feedstock and for the separate cab. Knife wear seemed to determine an increase in WBV, but this effect had no statistical significance and the result could not be taken as conclusive. Among the three factors studied, work station characteristics had the strongest effect. Further studies may extend the comparison to a wider range of options, as well as explore the use of exposure variation for machine diagnostics.

Anton, University of Ljubljana, Dept. of Forestry and Renewable Resources, Večna pot 83, 1000 Ljubljana, Slovenia E-mail: anton.poje@bf.uni-lj.si
Spinelli, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy; AFORA, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland, 4558 Australia http://orcid.org/0000-0001-9545-1004 E-mail: spinelli@ivalsa.cnr.it
Magagnotti, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy; AFORA, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland, 4558 Australia E-mail: magagnotti@ivalsa.cnr.it
Mihelic, University of Ljubljana, Dept. of Forestry and Renewable Resources, Večna pot 83, 1000 Ljubljana, Slovenia E-mail: matevz.mihelic@bf.uni-lj.si

article id 7759, category Research article

Jaana Luoranen, Sirkka Sutinen. (2017). Reduced height of short day induced bud scale complex may partly explain early bud burst in Norway spruce seedlings. Silva Fennica vol. 51 no. 5 article id 7759. https://doi.org/10.14214/sf.7759

Keywords: Picea abies; elongation; bud scale complex; primordia; shape

Highlights: Short day treatment used in tree seedling nurseries affects the structure of apical buds; Changes in bud structure may partly explain early bud burst and may be a reason for unburst buds of short day treated seedlings.

Abstract | Full text in HTML | Full text in PDF | Author Info

Short day (SD) treatment is used as a dormancy induction in forest tree seedling nurseries in the boreal forest zone. However, SD treatment has caused early bud burst in the following spring, which may expose the seedlings to spring frosts. Because the mechanisms affecting earlier bud burst in SD treated seedlings are not fully understood yet, here we have studied the effect of SD treatment on the structure of buds in Norway spruce [Picea abies (L.) Karst.] seedlings. Seedlings were exposed to SD treatments or natural (CTRL) light and photoperiod in July in a nursery in Central Finland. The experiments included two lots of seedlings over two summers and the analyses were done under a stereo microscope. SD treatment advanced initiation of bud scales and formation of needle primordia, and thus the formation period was shorter in CTRL seedlings. In mature buds, no differences in primordial shoots were found between the treatments, whereas notable differences were found in bud scales. The SD buds had fewer and shorter bud scales than the CTRL buds. This led to significantly shorter bud scale complex and, consequently, to shorter buds in SD than in CTRL seedlings. Buds and needles matured earlier in SD treated seedlings. In the following spring, the primordial shoots started to elongate in both treatments around mid-May, when the SD buds started to break down, whereas CTRL buds started to break down in late May. The fewer number and shorter height of protective bud scales may expose buds to harsh winter temperatures and early loss of scales may predispose the SD buds to spring frosts.

Luoranen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: jaana.luoranen@luke.fi
Sutinen, E-mail: sirusuti@gmail.com

article id 7723, category Research article

Mihails Čugunovs, Eeva-Stiina Tuittila, Ida Sara-Aho, Laura Pekkola, Jari Kouki. (2017). Recovery of boreal forest soil and tree stand characteristics a century after intensive slash-and-burn cultivation. Silva Fennica vol. 51 no. 5 article id 7723. https://doi.org/10.14214/sf.7723

Keywords: restoration; fire disturbance; historical land-use; rewildening

Highlights: Soil organic matter stocks have still not fully recovered after a century of stand succession and passive recovery after slash-and-burn period; Historical slash-and-burn stands feature higher live birch and standing dead wood volume than controls; If passive rewildening is used, Fennoscandian boreal forests need more than a century to regain naturalness.

Abstract | Full text in HTML | Full text in PDF | Author Info

Passive rewildening of forest ecosystems is commonly used for rehabilitating degraded habitats closer to their natural origin in addition to costly active restoration measures. However, it is not clear if passive processes are effective and how long the recovery of main ecosystem properties takes. We investigate the recovery of forest soil and tree stand characteristics a century after cessation of slash-and-burn cultivation, a major historical intensive disturbance regime that was applied widely in boreal zone of Finland until late 1800s. We systematically sampled soil and tree stand parameters within former slash-and-burn and nearby control areas. Humus layer thickness and soil organic matter (SOM) stocks were still lower in the historical slash-and-burn than in control areas. Slash-and-burn areas also had a larger volume of live birch trees and a higher standing dead wood volume than control areas. Accordingly, organic matter (humus layer thickness and SOM stocks) correlated negatively with birch standing live tree volume. Combined OM stock in humus and uppermost 10 cm mineral soil layer was positively correlated with lying dead wood volume. Overall, we observed clear recovery of several natural properties but we also found that a century after cessation of frequent anthropogenic burnings, clear legacies of disturbance in the above- and below-ground parts of boreal ecosystem were evident. Our results indicate that if only passive rewildening is applied as a restoration measure, the full recovery of boreal forest is slow and the effects of historical land-use may persist for over hundred years in soil and tree properties.

Čugunovs, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: mihails.cugunovs@uef.fi
Tuittila, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland http://orcid.org/0000-0001-8861-3167 E-mail: eeva-stiina.tuittila@uef.fi
Sara-Aho, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: ida.sara-aho@mhy.fi
Pekkola, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: laura.pekkola@gmail.com
Kouki, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland http://orcid.org/0000-0003-2624-8592 E-mail: jari.kouki@uef.fi

article id 7721, category Research article

Sakari Tuominen, Andras Balazs, Eija Honkavaara, Ilkka Pölönen, Heikki Saari, Teemu Hakala, Niko Viljanen. (2017). Hyperspectral UAV-imagery and photogrammetric canopy height model in estimating forest stand variables. Silva Fennica vol. 51 no. 5 article id 7721. https://doi.org/10.14214/sf.7721

Keywords: forest inventory; digital photogrammetry; aerial imagery; hyperspectral imaging; radiometric calibration; UAVs; stereo-photogrammetric canopy modelling

Highlights: Hyperspectral imagery and photogrammetric 3D point cloud based on RGB imagery were acquired under weather conditions changing from cloudy to sunny; Calibration of hyperspectral imagery was required for compensating the effect of varying weather conditions; The combination of hyperspectral imagery and photogrammetric point cloud data resulted in accurate forest estimates, especially for volumes per tree species.

Abstract | Full text in HTML | Full text in PDF | Author Info

Remote sensing using unmanned aerial vehicle (UAV) -borne sensors is currently a highly interesting approach for the estimation of forest characteristics. 3D remote sensing data from airborne laser scanning or digital stereo photogrammetry enable highly accurate estimation of forest variables related to the volume of growing stock and dimension of the trees, whereas recognition of tree species dominance and proportion of different tree species has been a major complication in remote sensing-based estimation of stand variables. In this study the use of UAV-borne hyperspectral imagery was examined in combination with a high-resolution photogrammetric canopy height model in estimating forest variables of 298 sample plots. Data were captured from eleven separate test sites under weather conditions varying from sunny to cloudy and partially cloudy. Both calibrated hyperspectral reflectance images and uncalibrated imagery were tested in combination with a canopy height model based on RGB camera imagery using the k-nearest neighbour estimation method. The results indicate that this data combination allows accurate estimation of stand volume, mean height and diameter: the best relative RMSE values for those variables were 22.7%, 7.4% and 14.7%, respectively. In estimating volume and dimension-related variables, the use of a calibrated image mosaic did not bring significant improvement in the results. In estimating the volumes of individual tree species, the use of calibrated hyperspectral imagery generally brought marked improvement in the estimation accuracy; the best relative RMSE values for the volumes for pine, spruce, larch and broadleaved trees were 34.5%, 57.2%, 45.7% and 42.0%, respectively.

Tuominen, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 2, FI-00791 Helsinki, Finland http://orcid.org/0000-0001-5429-3433 E-mail: sakari.tuominen@luke.fi
Balazs, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: andras.balazs@luke.fi
Honkavaara, Finnish Geospatial Research Institute, National Land Survey of Finland, Geodeetinrinne 2, FI-02430 Masala, Finland E-mail: eija.honkavaara@nls.fi
Pölönen, University of Jyväskylä, Faculty of Information Technology, P.O. Box 35, FI-40014 Jyväskylä, Finland E-mail: ilkka.polonen@jyu.fi
Saari, VTT Microelectronics, P.O. Box 1000, FI-02044 VTT, Finland E-mail: heikki.saari@vtt.fi
Hakala, Finnish Geospatial Research Institute, National Land Survey of Finland, Geodeetinrinne 2, FI-02430 Masala, Finland E-mail: teemu.hakala@nls.fi
Viljanen, Finnish Geospatial Research Institute, National Land Survey of Finland, Geodeetinrinne 2, FI-02430 Masala, Finland E-mail: niko.viljanen@nls.fi

article id 2018, category Research article

Sima Mohtashami, Lars Eliasson, Gunnar Jansson, Johan Sonesson. (2017). Influence of soil type, cartographic depth-to-water, road reinforcement and traffic intensity on rut formation in logging operations: a survey study in Sweden. Silva Fennica vol. 51 no. 5 article id 2018. https://doi.org/10.14214/sf.2018

Keywords: soil disturbance; forestry; forwarder; decision support tool

Highlights: Soil type and traffic intensity had significant effects on rut formation; Further studies are required to identify all factors affecting rut formation, especially on soils with medium bearing capacity; The cartographic depth-to-water index (DTW) alone did not predict rut formation, but used in combination with other information, e.g. soil type, could be an interesting tool for delineating soil areas that are potentially vulnerable to rut formation in logging operations.

Abstract | Full text in HTML | Full text in PDF | Author Info

Rut formation caused by logging operations has been recognised as a challenge for Swedish forestry. Frequent traffic with heavy machines on extraction roads, together with a warmer climate, is one of the factors that increases the risk of rut formation in forests. One possible way to control this impact of logging operations is to design and apply decision support tools that enable operators to take sensitive areas into account when planning extraction roads. In this study, 16 different logging sites in south-eastern Sweden were surveyed after clear-cut. Information was collected about extraction roads (i.e. traffic intensity, whether the roads had been reinforced with slash) and ruts. Digital maps such as cartographic depth-to-water (DTW) index and soil type were also examined for any connection to rut positions. Soil type and traffic intensity were found to be significant factors in rut formation, while DTW and slash reinforcement were not. However, the DTW map combined with other information, such as soil type, could contribute to decision support tools that improve planning of extraction roads.

Mohtashami, The forestry research institute of Sweden, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: sima.mohtashami@skogforsk.se
Eliasson, The forestry research institute of Sweden, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden http://orcid.org/0000-0002-2038-9864 E-mail: lars.eliasson@skogforsk.se
Jansson, The forestry research institute of Sweden, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden http://orcid.org/0000-0002-3018-9161 E-mail: gunnar.jansson@skogforsk.se
Sonesson, The forestry research institute of Sweden, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden http://orcid.org/0000-0002-2018-7496 E-mail: johan.sonesson@skogforsk.se

article id 1740, category Research article

Ram P. Sharma, Zdeněk Vacek, Stanislav Vacek. (2017). Modelling tree crown-to-bole diameter ratio for Norway spruce and European beech. Silva Fennica vol. 51 no. 5 article id 1740. https://doi.org/10.14214/sf.1740

Keywords: Picea abies; Fagus sylvatica; dominant height; exponential decay function; mixed effect model; spatially explicit competition index; species proportion; species mixture effect

Highlights: Modelled crown-to-bole diameter ratio (CDBDR) using tree and stand-level predictors, and sample plot random effects; Spatially explicit mixed-effects model described the largest part of CDBDR variation with no significant trend in the residuals; The CDBDR increased with increasing stand development stage and site quality, but decreased with decreasing proportion of the species of interest, and increasing competition.

Abstract | Full text in HTML | Full text in PDF | Author Info

Crown dimensions are correlated to growth of other parts of a tree and often used as predictors in growth models. The crown-to-bole diameter ratio (CDBDR), which is a ratio of maximum crown width to diameter at breast height (DBH), was modelled using data from permanent sample plots located on Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica L.) stands in different parts of the Czech Republic. Among various tree and stand-level measures evaluated, DBH, height to crown base (HCB), dominant height (HDOM), basal area of trees larger in diameter than a subject tree (BAL), basal area proportion of the species of interest (BAPOR), and Hegyi’s competition index (CI) were found to be significant predictors in the CDBDR model. Random effects were included using the mixed-effects modelling to describe sample plot-level variation. For each species, the mixed-effects model described a larger part of the variation of the CDBDR than nonlinear ordinary least squares model with no trend in the residuals. The spatially explicit mixed-effects model showed more attractive fit statistics [conditional R² ≈ 0.73 (spruce), 0.78 (beech)] than its spatially inexplicit counterpart [conditional R² ≈ 0.71 (spruce), 0.76 (beech)]. The model showed that CDBDR increased with increasing HDOM – a measure that combines the stand development stage and site quality – but decreased with increasing HCB and competition (increasing BAL and CI), and decreasing proportions of the species of interest (increasing BAPOR). For both species, the spatially explicit mixed-effects model should be a preferred choice for a precise prediction of the CDBDR. The CDBDR model will have various management implications such as determination of spacing, stand basal area, stocking, and planning of appropriate species mixture.

Sharma, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16521, Praha 6 – Suchdol, Czech Republic E-mail: sharmar@fld.czu.cz
Vacek, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16521, Praha 6 – Suchdol, Czech Republic E-mail: vacekz@fld.czu.cz
Vacek, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16521, Praha 6 – Suchdol, Czech Republic E-mail: vacekstanislav@fld.czu.cz

article id 7753, category Research article

Aarne Hovi, Pekka Raitio, Miina Rautiainen. (2017). A spectral analysis of 25 boreal tree species. Silva Fennica vol. 51 no. 4 article id 7753. https://doi.org/10.14214/sf.7753

Keywords: albedo; leaf; needle; reflectance; transmittance; integrating sphere; spectrometer

Highlights: An extensive spectral library containing leaf and needle reflectance and transmittance spectra was collected; The spectra openly available in SPECCHIO Spectral Information System; Effects of tree species, leaf/needle side, canopy position, and needle age on spectra were quantified; Seasonal variations were measured for four species; Spectra analysis highlights the importance of shortwave-infrared region in separating tree species.

Abstract | Full text in HTML | Full text in PDF | Author Info

Spectral libraries have a fundamental role in the development of interpretation methods for airborne and satellite-borne remote sensing data. This paper presents to-date the largest spectral measurement campaign of boreal tree species. Reflectance and transmittance spectra of over 600 leaf and needle samples from 25 species were measured in the Helsinki area (Finland) using integrating sphere systems attached to an ASD FieldSpec 4 spectroradiometer. Factors influencing the spectra and red edge inflection point (REIP) were quantified using one-way analysis of variance. Tree species differed most in the shortwave-infrared (1500–2500 nm) and least in the visible (400–700 nm) wavelength region. Species belonging to same genera showed similar spectral characteristics. Upper (adaxial) and lower (abaxial) leaf sides differed most in the visible region. Canopy position (sunlit/shaded) had a minor role in explaining spectral variation. For evergreen conifers, current and previous year needles differed in their spectra, current-year needles resembling those of broadleaved and deciduous conifers. Two broadleaved species were monitored throughout the growing season (May–October), and two conifers were measured twice during summer (June, September). Rapid changes were observed in the spectra in early spring and late autumn, whereas seasonal variations during summer months were relatively small for both broadleaved and coniferous species. Based on our results, shortwave-infrared seems promising in separating tree species, although it is to-date least studied. The spectral library reported here (Version 1.0) is publicly available through the SPECCHIO Spectral Information System.

Hovi, Aalto University, Department of Built Environment, P.O. Box 14100, FI-00076 Aalto, Finland E-mail: aarne.hovi@aalto.fi
Raitio, Aalto University, Department of Built Environment, P.O. Box 14100, FI-00076 Aalto, Finland E-mail: pekka.raitio@aalto.fi
Rautiainen, Aalto University, Department of Built Environment, P.O. Box 14100, FI-00076 Aalto, Finland; Aalto University, Department of Electronics and Nanoengineering, P.O. Box 15500, FI-00076 Aalto, Finland E-mail: miina.a.rautiainen@aalto.fi

article id 1760, category Research article

Marek Fajstavr, Kyriaki Giagli, Hanuš Vavrčík, Vladimír Gryc, Josef Urban. (2017). The effect of stem girdling on xylem and phloem formation in Scots pine. Silva Fennica vol. 51 no. 4 article id 1760. https://doi.org/10.14214/sf.1760

Keywords: Pinus sylvestris; radial increment; cambial activity; cell differentiation; phloemogenesis; xylogenesis

Highlights: Stem girdling ceased the cambial activity, below the girdled area, immediately after the removal of the bark strip; Pinus sylvestris survived for up to two years after stem girdling; The girdled trees formed phloem cells above the girdled area but failed to form latewood cells in the next growing season.

Abstract | Full text in HTML | Full text in PDF | Author Info

Scots pine (Pinus sylvestris L.) is a resilient, wide spread species. This paper reports on the xylem and phloem cell formation process, before and after, the species was put under artificial stress by stem girdling. Microcore method was applied to a healthy control group and a standing group of girdled trees within an 80-year-old pine forest for two consecutive growing seasons (2013 and 2014). The stem girdling was applied in the middle of the first growing season (July 2013). Cambial activity timings (onset and cessation of cell division), cell formation intensity, cell differentiation, and the dynamics of the annual radial increment in the stem were analyzed. Cambial activity was inhibited and eventually ceased below the stem girdling immediately after the removal of the strip. Therefore, no latewood tracheids were formed. However, above the stem girdling and in the control trees, cell formation and tissue differentiation continued until the end of the growing season, with the girdled trees moving at a less intensive pace but for a longer period of time. During the following growing season (2014), the cambial zone was reactivated only above the stem girdling, not below, and eventually the girdled trees died. In 2014, the onset of the cambial activity was delayed and the division rate of the cells was slower in the girdled trees. Furthermore, the girdled trees formed less phloem cells than the control trees.

Fajstavr, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic E-mail: fajstavr.marek@seznam.cz
Giagli, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic E-mail: kyriaki.giagli@mendelu.cz
Vavrčík, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic E-mail: vavrcik@mendelu.cz
Gryc, Department of Wood Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic E-mail: gryc@mendelu.cz
Urban, Department of Forest Botany, Dendrology and Geobiocenology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 3, 613 00 Brno, Czech Republic; Siberian Federal University, Svobodnyj Prospect 79, Krasnoyarsk, 660041 Krasnoyarsk, Russia E-mail: josef.urban@email.cz

article id 1691, category Research article

Enéas Ricardo Konzen, Raquel Peron, Márcio Akira Ito, Gilvano Ebling Brondani, Siu Mui Tsai. (2017). Molecular identification of bamboo genera and species based on RAPD-RFLP markers. Silva Fennica vol. 51 no. 4 article id 1691. https://doi.org/10.14214/sf.1691

Keywords: molecular markers; molecular screening; restriction enzymes; genetic divergence; Dendrocalamus; Bambusa

Highlights: We investigated the potential of RAPD-RFLP (Random Amplified Polymorphic DNA, Restriction Fragment Length Polymorphism) in detecting genetic relationships among bamboo genera and species; RFLP profiles resolved in acrylamide gels revealed high number of markers, which accurately differentiated species and genera, based on cophenetic correlation coefficients; We recommend RAPD-RFLP for analyses of genetic diversity and divergence among bamboo genera, species and varieties.

Abstract | Full text in HTML | Full text in PDF | Author Info

Bamboo species have a very significant ecological and economic impact. Determining morphological and genetic differences among bamboo genera and species are crucial to explore desirable traits for breeding purposes. Several advances have been made in the taxonomy of bamboos by using molecular fingerprinting tools and next generation sequencing technologies. Nevertheless, classical molecular markers such as RAPD (Random Amplified Polymorphic DNA), AFLP (Amplified Fragment Length Polymorphism) and ISSR (Inter Simple Sequence Repeats) also provide an accurate discrimination among genera and species. Moreover, the RAPD-RFLP (Random Amplified Polymorphic DNA, Restriction Fragment Length Polymorphism) method, in which amplification products from RAPD are digested with restriction enzymes, is a reliable, fast and cost-effective method for fingerprinting. RAPD-RFLP has been scarcely used in the literature and no report regarding bamboo taxonomy is available with this method. Here we explored the molecular (RAPD, RAPD-RFLP) variation among genera (Bambusa, Dendrocalamus, Guadua and Phyllostachys) and species of bamboo cultivated in Brazil. Both molecular markers allowed clear distinction among the genera studied. Moreover, high cophenetic correlation values in UPGMA clusters indicated their potential for discriminating bamboo species. The digestion of RAPD products (RFLP) resulted in high number of polymorphic bands and produced very characteristic profiles for each genus with three enzyme combinations (HindIII/HaeIII, HinfI/RsaI, and single digestion with MspI). We recommend RAPD-RFLP as a reproducible and informative method for screening differences among genera, species and varieties of bamboos. Providing a cost-effective and accurate method for species identification and characterization is straightforward for bamboo conservation, management and breeding.

Konzen, Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture (CENA), University of Sao Paulo (USP), Centenário Av., 303, Piracicaba, SP, P.O. Box 96, Brazil; Forest Sciences, Federal University of Lavras (UFLA), Lavras, MG, P.O. Box 3037, Brazil E-mail: erkonzen@gmail.com
Peron, Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture (CENA), University of Sao Paulo (USP), Centenário Av., 303, Piracicaba, SP, P.O. Box 96, Brazil E-mail: rperon@purdue.edu
Ito, Embrapa Western Agriculture, Brazilian Agricultural Research Corporation (EMBRAPA), BR 163 Rd., km 253, Dourados, MS, P.O. Box 449, Brazil E-mail: marcio.ito@embrapa.br
Brondani, Forest Sciences, Federal University of Lavras (UFLA), Lavras, MG, P.O. Box 3037, Brazil E-mail: gebrondani@gmail.com
Tsai, Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture (CENA), University of Sao Paulo (USP), Centenário Av., 303, Piracicaba, SP, P.O. Box 96, Brazil E-mail: tsai@cena.usp.br

article id 6986, category Research article

Mari Tilk, Tea Tullus, Katri Ots. (2017). Effects of environmental factors on the species richness, composition and community horizontal structure of vascular plants in Scots pine forests on fixed sand dunes. Silva Fennica vol. 51 no. 3 article id 6986. https://doi.org/10.14214/sf.6986

Keywords: biodiversity; inland dunes; microhabitats; soil conditions; vegetation–site relationships

Highlights: Factors affecting the species richness, composition and horizontal structure of vascular plants are related to dune topography, resulting in the differentiation of soils and therefore complexes of different microhabitats that are populated by various vascular plant species and causing vegetation zonation.

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Different environmental factors were studied to determine which factors influence the species richness, composition and structure of vascular plants in Pinus sylvestris L. forests in a fixed dune landscape in south-western Estonia. In addition to site topographic factors, different environmental parameters were investigated. Thirty-four vascular plant species were recorded in 232 quadrats. The most abundant species was Vaccinium vitis-idaea L., which was in 82.8% of quadrats, followed by Vaccinium myrtillus L. (74.1%), Melampyrum pratense L. (71.1%) and Deschampsia flexuosa (L.) Trin. (69.8%). The multiple response permutation procedure (MRPP) showed considerable differences in species composition at the bottoms of dunes compared with that on the slopes and at the tops of dunes. Indicator species analysis (ISA) determined species exhibited characteristics specific to zone: V. myrtillus had the highest indicator value at the bottoms of dunes; Calluna vulgaris L., at the tops. Soils were Haplic Podzols, and the presence of humus horizon depended on zone. Soil conditions on the dunes were variable and site specific, in general, soils at the bottoms of the dunes were more acidic and moist compared with those of the slopes and tops of the dunes, and the nutrient content decreased toward the dune tops. According to non-metric multidimensional scaling (NMDS) and linear mixed model analyses, species coverage, composition and richness were controlled by site-specific factors such as absolute height, location and aspect of the quadrat on the dune; soil nitrogen, potassium and phosphorus contents; soil pH and moisture; light conditions; and the thickness of the litter horizon.

Tilk, Department of Silviculture, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu, Estonia, 51014; Tallinn Botanic Garden, Kloostrimetsa Road 52, Tallinn, Estonia, 11913 E-mail: Mari.Tilk@botaanikaaed.ee
Tullus, Department of Silviculture, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu, Estonia, 51014 E-mail: Tea.Tullus@emu.ee
Ots, Department of Silviculture, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu, Estonia, 51014 E-mail: Katri.Ots@emu.ee

article id 2017, category Research article

Pentti Niemistö, Soili Kojola, Anssi Ahtikoski, Raija Laiho. (2017). From useless thickets to valuable resource? – Financial performance of downy birch management on drained peatlands. Silva Fennica vol. 51 no. 3 article id 2017. https://doi.org/10.14214/sf.2017

Keywords: forest management; Betula pubescens; thinning; energy wood; pulpwood; profitability; final cutting

Highlights: The most profitable management regimes for pulpwood and energy wood production in dense downy birch stands on drained peatlands include no thinnings, but final cutting at the stand age of 40–45 years as whole-tree harvesting, or as integrated harvesting of pulpwood and delimbed energy wood stems about 10 years later depending on applicable harvesting method; A competitive management regime is early precommercial thinning at 4 m dominant height to a density of 2500 stems per hectare and production of pulpwood with a rotation of 55–65 years. Equal profitability is achieved with or without traditional first thinning, which can thus be included for other reasons, for example to improve regeneration of spruce.

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Downy birch (Betula pubescens Ehrh.) stands on drained peatlands are often considered useless because they typically do not yield good-quality sawn timber. However, covering an area of ca. 0.5 million hectares and with total yields of up to 250 m³ ha^–1, downy birch stands on peatlands in Finland have a potential for pulpwood and/or energy wood production. We examined the financial performance of alternative management regimes (with or without thinnings, different thinning intensities, several rotation lengths) combined with alternative harvesting methods (pulpwood, energy wood, or integrated, energy wood being delimbed stems or whole trees). We used data from 19 experimental stands, monitored for 20–30 years. For harvesting removals we considered both actual thinning removals and final-cutting removals with alternative timings that were based on the monitoring data. We assessed the profitability as a combination of the net present value of the birch generation and the bare land value of future generations of Norway spruce (Picea abies (L.) Karst.). The most profitable management was growing without thinnings until whole-tree final cutting at the stand age of 40–45 years with an advanced multi-tree harvesting method. In contrast, the standard method in whole-tree final cutting resulted in the lowest profitability, and an integrated method with the energy wood as delimbed stems was the best of the standard methods. Thinnings were unprofitable especially when aiming to produce energy wood, whereas aiming for pulpwood, light precommercial thinning was competitive. Commercial thinning at the traditional “pulpwood stage” had little effect on profitability. The best stand age for final cutting was 40–65 years – earlier for very dense stands and whole-tree energy wood harvesting with advanced method, later for precommercially thinned stands and pulpwood harvesting.

Niemistö, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Kampusranta 9 C, 60320 Seinäjoki, Finland E-mail: pentti.niemisto@luke.fi
Kojola, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Latokartanonkaari 9, 00790 Helsinki, Finland E-mail: soili.kojola@luke.fi
Ahtikoski, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Paavo Havaksentie 3, 90014 University of Oulu, Finland E-mail: anssi.ahtikoski@luke.fi
Laiho, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Latokartanonkaari 9, 00790 Helsinki, Finland E-mail: raija.laiho@luke.fi

article id 1743, category Research article

Gintare Sabalinkiene, Darius Danusevicius, Michael Manton, Gediminas Brazaitis, Kastytis Simkevicius. (2017). Differentiation of European roe deer populations and ecotypes in Lithuania based on DNA markers, cranium and antler morphometry. Silva Fennica vol. 51 no. 3 article id 1743. https://doi.org/10.14214/sf.1743

Keywords: genetic structure; inbreeding; Capreolus capreolus; polymorphism; wild game management

Highlights: Lithuanian roe deer populations are genetically structured into southern and northern groups, most likely affected by a divergent gene flow and Lithuania’s largest rivers slowing down migration; Microsatellite and skull morphology based genetic differentiation between field and forest ecotypes are weak; Geographical location has a significant effect on antler morphometry traits and skull size of male roe deer, the latter increasing northwards.

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The objective of our study was to assess the genetic and morphological differentiation of European roe deer (Capreolus capreolus L.) in Lithuania based on DNA markers, skull and anther morphology. DNA was extracted from 79 culled individuals at 13 locations and genotyped at five nuclear microsatellite loci. Based on culling location, individuals were assigned to either a field (N = 43) or a forest ecotype (N = 36). Skull and antler morphometry was studied on 603 and 292 individuals, respectively. Results showed no significant genetic and skull morphology differentiation between the ecotypes. The forest ecotype tends to exhibit lower genetic diversity compared to the field ecotype, particularly for male individuals. The genetic differentiation of roe deer in Lithuania was significant based on the R_ST values, but not on the F_ST values. A STRUCTURE analyses revealed southern and northern genetic clusters, most likely affected by divergent gene flow. The country’s major rivers Nemunas and Neris are likely to increase differentiation between the clusters. ANOVA on skull morphology by gender and age indicated a significant effect of geographical location. Skull size (especially length) is greater in the northern part of the country. We also found significant effects of age, ecotype and geographical location on most of the roe deer male antler morphometric traits.

Sabalinkiene, Institute of Forest Biology and Silviculture, Faculty of Forest Sciences and Ecology, Aleksandras Stulginskis University, Studentu street 11, Akademija, Kaunas district, Lithuania E-mail: gintare.sabalinkiene@asu.lt
Danusevicius, Institute of Forest Biology and Silviculture, Faculty of Forest Sciences and Ecology, Aleksandras Stulginskis University, Studentu street 11, Akademija, Kaunas district, Lithuania E-mail: darius.danusevicius@asu.lt
Manton, Institute of Forest Biology and Silviculture, Faculty of Forest Sciences and Ecology, Aleksandras Stulginskis University, Studentu street 11, Akademija, Kaunas district, Lithuania E-mail: michael.manton@asu.lt
Brazaitis, Institute of Forest Biology and Silviculture, Faculty of Forest Sciences and Ecology, Aleksandras Stulginskis University, Studentu street 11, Akademija, Kaunas district, Lithuania E-mail: gediminas.brazaitis@asu.lt
Simkevicius, Institute of Forest Biology and Silviculture, Faculty of Forest Sciences and Ecology, Aleksandras Stulginskis University, Studentu street 11, Akademija, Kaunas district, Lithuania E-mail: kastytis.simkevicius@asu.lt

article id 1734, category Research article

Jyrki Hytönen, Paula Jylhä, Keith Little. (2017). Positive effects of wood ash fertilization and weed control on the growth of Scots pine on former peat-based agricultural land – a 21-year study. Silva Fennica vol. 51 no. 3 article id 1734. https://doi.org/10.14214/sf.1734

Keywords: Pinus sylvestris; fertilization; vegetation management; shading; agricultural soil; overgrowth; potassium deficiency; production potential

Highlights: Weed control decreased and fertilization increased vegetation height and shading of seedlings; Weed control decreased mortality, but fertilization had no effect; Despite improved foliar K concentration though ash fertilization, all trees in the trial had severe K deficiency after 21 years; Weed control increased growth by 20 m³ ha^–1 and fertilization by 35 m³ ha^–1 in 21 years.

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The impacts of weed control, ash fertilization and their interaction were tested for the afforestation of former agricultural peat-based soil with Scots pine (Pinus sylvestris L.) in northern Finland in a factorial arrangement of four treatments. Weed control with herbicides was carried out in July 1 and 2 years from planting, and wood ash (5 Mg ha^–1) was applied in the spring of the 2nd year. Various vegetation, tree growth and nutrient assessments were made over the 21-year study period. Weed control decreased the weed cover by 36–56 percentage points, vegetation height by 4–26 cm and thus shading of seedlings by vegetation for at least 4 years after planting. For the same period, ash fertilization increased vegetation height by 6–15 cm and shading of seedlings. Weed control reduced seedling mortality by 27 percentage points in 21 years, but ash fertilization had no significant effect. Ash fertilization increased foliar potassium and boron concentrations, but its effect declined, and severe K-deficiency was recorded 21 years after planting. Up to the 9th year, weed control had a greater influence on growth than fertilization. Later the significance of fertilization increased due to an aggravated K-deficiency. Stand volume at year 21 for the untreated control plots was 8 m³ ha^–1. Weed control and fertilization increased stand volume by 20 and 35 m³ ha^–1, with a combined effect of 55 m³ ha^–1. The effects of weed control and fertilization were additive and no significant interactions were found. Due to severe K-deficiencies, re-fertilization of all treatments would be necessary for the continued survival and growth of Scots pine.

Hytönen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Teknologiakatu 7, FI-67100 Kokkola, Finland http://orcid.org/0000-0001-8475-3568 E-mail: jyrki.hytonen@luke.fi
Jylhä, Natural Resources Institute Finland (Luke), Green technology, Teknologiakatu 7, FI-67100 Kokkola, Finland E-mail: paula.jylha@luke.fi
Little, Nelson Mandela Metropolitan University, George Campus, Western Cape, South Africa E-mail: keith.little@nmmu.ac.za

article id 1666, category Research article

Mareike Wieczorek, Alexei Kolmogorov, Stefan Kruse, Inga Jacobsen, Ingmar Nitze, Anatoly N. Nikolaev, Ingo Heinrich, Luidmila A. Pestryakova, Ulrike Herzschuh. (2017). Disturbance-effects on treeline larch-stands in the lower Kolyma River area (NE Siberia). Silva Fennica vol. 51 no. 3 article id 1666. https://doi.org/10.14214/sf.1666

Keywords: stand structure; fire; treeline; Larix cajanderi; Siberia

Highlights: Disturbances are an important shaping factor of larch stands at lower Kolyma; Youngest larch stands have the highest population densities and highest growth rates; Saplings grow clustered, irrespective of the underlying disturbance regime; Mixed climate-disturbance signals make it difficult to infer future treeline processes.

Abstract | Full text in HTML | Full text in PDF | Author Info

Tree stands in the boreal treeline ecotone are, in addition to climate change, impacted by disturbances such as fire, water-related disturbances and logging. We aim to understand how these disturbances affect growth, age structure, and spatial patterns of larch stands in the north-eastern Siberian treeline ecotone (lower Kolyma River region), an insufficiently researched region. Stand structure of Larix cajanderi Mayr was studied at seven sites impacted by disturbances. Maximum tree age ranged from 44 to 300 years. Young to medium-aged stands had, independent of disturbance type, the highest stand densities with over 4000 larch trees per ha. These sites also had the highest growth rates for tree height and stem diameter. Overall lowest stand densities were found in a polygonal field at the northern end of the study area, with larches growing in distinct “tree islands”. At all sites, saplings are significantly clustered. Differences in fire severity led to contrasting stand structures with respect to tree, recruit, and overall stand densities. While a low severity fire resulted in low-density stands with high proportions of small and young larches, high severity fires resulted in high-density stands with high proportions of big trees. At water-disturbed sites, stand structure varied between waterlogged and drained sites and latitude. These mixed effects of climate and disturbance make it difficult to predict future stand characteristics and the treeline position.

Wieczorek, Periglacial Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany; Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, Germany E-mail: mareike.wieczorek@awi.de
Kolmogorov, Institute of Natural Sciences, North-Eastern Federal University of Yakutsk, 677000 Yakutsk, Russia E-mail: kilatroooon@gmail.com
Kruse, Periglacial Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany; Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, Germany E-mail: Stefan.Kruse@awi.de
Jacobsen, Periglacial Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany; Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, Germany E-mail: Inga.Jacobsen@awi.de
Nitze, Periglacial Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany; Institute of Geography, University of Potsdam, 14476 Potsdam, Germany E-mail: Ingmar.Nitze@awi.de
Nikolaev, Institute of Natural Sciences, North-Eastern Federal University of Yakutsk, 677000 Yakutsk, Russia; Melnikov Permafrost Institute of the Siberian Branch of RAS, 677000 Yakutsk, Russia E-mail: yktnan@rambler.ru
Heinrich, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany E-mail: heinrich@gfz-potsdam.de
Pestryakova, Institute of Natural Sciences, North-Eastern Federal University of Yakutsk, 677000 Yakutsk, Russia E-mail: lapest@mail.ru
Herzschuh, Periglacial Research Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 14473 Potsdam, Germany; Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, Germany E-mail: Ulrike.Herzschuh@awi.de

article id 5643, category Research article

Katarzyna A. Jadwiszczak, Stanisław Kłosowski, Iwona Zalewska, Agata Banaszek, Agnieszka Chrzanowska. (2017). Genetic diversity and sexual reproduction in relict populations of Betula nana. Silva Fennica vol. 51 no. 2 article id 5643. https://doi.org/10.14214/sf.5643

Keywords: flowering; AFLP; dwarf birch; meiotic recombination; seed germination

Highlights: Genetic diversity parameters and meiotic recombination frequencies in the relict populations were comparable to those from widespread localities; Contribution of seeds without ovule was very high; Fully developed seeds germinated better in central populations; Significant differences of groundwater parameters were observed between relict and central populations.

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In the present study, the impact of geographical isolation and habitat conditions on genetic diversity and sexual reproduction was tested in four relict populations of dwarf birch Betula nana L. in Poland and Belarus. Amplified fragment length polymorphism (AFLP) method revealed that the endangered central European stands were not genetically extirpated compared with the widespread localities from Finland and Russia, which can result from infrequent outcrossing events in long-living clonal populations. However, genetic clustering methods indicated significant differentiation of the Polish populations because of their small sizes and long-term geographical isolation. Considerable numbers of empty seeds were observed in both relict and central locations, although fully developed seeds germinated better in widespread populations. Analysis of groundwater chemical parameters indicated that two relict populations were significantly different from the remaining samples with respect to pH, electrical conductivity and concentrations of phosphorus ions, which can also influence the efficiency of sexual reproduction. In the light of results obtained it seems that endangered B. nana localities are relatively stable.

Jadwiszczak, Institute of Biology, University of Białystok, Ciołkowskiego 1J, 15-245 Białystok, Poland http://orcid.org/0000-0002-9345-8891 E-mail: jadwiszczak2010@gmail.com
Kłosowski, Department of Environment Protection and Modelling, The Jan Kochanowski University, Świętokrzyska 15, 25-406 Kielce, Poland E-mail: stanislaw.klosowski@ujk.kielce.pl
Zalewska, Faculty of Pharmacy, Medical University of Białystok, Mickiewicza 2a, 15-222 Białystok, Poland E-mail: iwonazalewska1988@gmail.com
Banaszek, Institute of Biology, University of Białystok, Ciołkowskiego 1J, 15-245 Białystok, Poland E-mail: banaszek@uwb.edu.pl
Chrzanowska, Institute of Biology, University of Białystok, Ciołkowskiego 1J, 15-245 Białystok, Poland E-mail: maga.chrzanowska@gmail.com

article id 1693, category Research article

Olalla Díaz-Yáñez, Blas Mola-Yudego, José Ramón González-Olabarria. (2017). What variables make a forest stand vulnerable to browsing damage occurrence? Silva Fennica vol. 51 no. 2 article id 1693. https://doi.org/10.14214/sf.1693

Keywords: moose; forest damage; cervid; machine learning; risk modelling; ungulates

Highlights: Stands more vulnerable to browsing damage are young with lower densities and dominated by birch, pine or mixed species; Stand size could play a role on forest susceptibility to browsing occurrence.

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Ungulate browsing results in important damages on the forests, affecting their structure, composition and development. In the present paper, we examine the occurrence of browsing damage in Norwegian forests, using data provided by the National Forest Inventory along several consecutive measurements (entailing the period 1995–2014). A portfolio of variables describing the stand, site and silvicultural treatments are analyzed using classification trees to retrieve combinations related to browsing damage. Our results indicate that the most vulnerable forest stands are young with densities below 1400 trees ha^–1 and dominated by birch, pine or mixed species. In addition, stand diversity and previous treatments (e.g. thinnings) increase the damage occurrence and other variables, like stand size, could play a role on forest susceptibility to browsing occurrence although the latter is based on weaker evidence. The methods and results of our study can be applied to implement management measures aiming at reducing the browsing damages of forests.

Díaz-Yáñez, School of Forest Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland http://orcid.org/0000-0003-3829-5759 E-mail: olalla.diaz@gmail.com
Mola-Yudego, Norwegian Institute of Bioenergy Research, P.O. Box, 115, 1431 Ås, Norway; School of Forest Sciences, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland http://orcid.org/0000-0003-0286-0170 E-mail: blas.mola@uef.fi
González-Olabarria, Forest Sciences Centre of Catalonia (CTFC-CEMFOR), Ctra. de St. Llorenç de Morunys, km 2, 25280 Solsona, Spain http://orcid.org/0000-0002-5040-712X E-mail: jr.gonzalez@ctfc.es

article id 1678, category Research article

Juan F. Jimenez, Pedro Sánchez-Gómez, Jose Luis Cánovas, Isabell Hensen, Miloud Aouissat. (2017). Influence of natural habitat fragmentation on the genetic structure of Canarian populations of Juniperus turbinata. Silva Fennica vol. 51 no. 2 article id 1678. https://doi.org/10.14214/sf.1678

Keywords: genetic diversity; AFLP markers; Canarian juniper; oceanic islands

Highlights: Canarian populations of Juniperus turbinata exhibited levels of genetic diversity similar to those of mainland populations; Despite the historical geologic events occurred in Canary Islands, and the documented decrease of populations since the arrival of settlers, no genetic differentiation between islands has been observed; As it has been observed for other Macaronesian endemics, J. turbinata long dispersal ability seems to be the main force driving the genetic structure of populations.

Abstract | Full text in HTML | Full text in PDF | Author Info

Oceanic archipelagos provide an important platform from which to evaluate the effects of isolation and fragmentation on the genetic structure of species. As a result of oceanic isolation, such species usually show lower levels of genetic diversity and higher genetic differentiation than their mainland congeners. However, this is not necessarily the case for long distance dispersal species, whose genetic structure is not strictly defined by population isolation. We assessed the level and distribution of genetic diversity among Canarian populations of Juniperus turbinata in order to evaluate the influence of population isolation on its genetic structure. Using Amplified Fragment Length Polymorphism markers, we analyzed molecular diversity among 175 individuals from five populations occurring across the Canary Island and three Moroccan populations. Principal Coordinate Analysis, neighbor joining clustering, AMOVA and Bayesian-based analysis were applied to examine population structure. Despite the documented habitat loss and decline in Canarian populations, Amplified Fragment Length Polymorphism markers revealed levels of intra-population genetic diversity that were similar to those from mainland populations, and low levels of genetic differentiation. Bayesian analysis of population structure showed three main clusters, one comprising El Hierro population and a few individuals from several islands, a second cluster that grouped the remaining Canarian populations together, and a third cluster grouping Moroccan populations. Our results suggest that the main force driving the genetic structure of Canarian populations of J. turbinata is its capacity for long distance dispersal.

Jimenez, Departamento de Biología Vegetal (Botánica), Universidad de Murcia, Campus de Espinardo s/n, E-30100 Murcia, Spain E-mail: fjimenez@um.es
Sánchez-Gómez, Departamento de Biología Vegetal (Botánica), Universidad de Murcia, Campus de Espinardo s/n, E-30100 Murcia, Spain http://orcid.org/0000-0001-6754-1512 E-mail: psgomez@um.es
Cánovas, Departamento de Biología Vegetal (Botánica), Universidad de Murcia, Campus de Espinardo s/n, E-30100 Murcia, Spain E-mail: joseluis.canovas@um.es
Hensen, Institut für Biologie, Martin-Luther Universitat, 06099 Halle, Germany E-mail: isabell.hensen@botanik.uni-halle.de
Aouissat, Centre Universitaire Salhi Ahmed Naama, BP 66, Naâma, Algérie E-mail: aouissatm@yahoo.fr

article id 1607, category Research article

Yanlin Fu, Juan A. Oliet, Guolei Li, Jiaxi Wang. (2017). Effect of controlled release fertilizer type and rate on mineral nutrients, non-structural carbohydrates, and field performance of Chinese pine container-grown seedlings. Silva Fennica vol. 51 no. 2 article id 1607. https://doi.org/10.14214/sf.1607

Keywords: growth; nursery fertilization; Pinus tabulaeformis; nutrient loading; outplanting performance

Highlights: We demonstrated that Chinese pine container-grown seedling nutrient status and non-structural carbohydrate content were sufficient over a wide range of fertilization rates; Fertilization at 80 mg N seedling^–1 was optimal for seedling responses in the nursery and field; Nursery fertilization using controlled release fertilizer (CRF) with a single coating layer yielded better seedling nursery performance than CRF with multiple coatings.

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Although controlled release fertilizer (CRF) with single and multiple-layer coatings are extensively used in tree seedlings, studies that compare the impact of CRF type and application rate on seedling growth, nutrient storage, and, most importantly, outplanting performance, are lacking. In the current study, container-grown Pinus tabulaeformis Carr. (Chinese pine) seedlings were fertilized with commercial CRF with either one or multiple coating layers with equivalent formulation and longevity, at six rates ranging from 40 to 240 mg N seedling^–1. Seedlings were sampled for dry mass, non-structural carbohydrate (NSC) content, and mineral nutrient status at the end of the growing season in the nursery, and subsequently outplanted for one season. Compared to Chinese pine seedlings fertilized with single-layer CRF treatments, seedlings treated with multiple-layer CRF had higher starch concentrations but reduced dry mass and N, P, K concentrations in the nursery, and reduced diameter growth in the field. Fertilization rates of 80 and 120 mg N seedling^–1 generally yielded maximal plant dry mass and mineral nutrient content. Field survival peaked at 80 mg N seedling^–1. Seedling growth, soluble sugar content, and starch concentration in the nursery and survival in the field consistently decreased at rates of 200 and 240 mg N seedling^–1. In our study, optimal nursery and field performance of P. tabulaeformis were observed using single layer CRF at 80 mg N seedling^–1 (3.3 g CRF l^–1 media).

Fu, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing Forestry University; Beijing Laboratory of Urban and Rural Ecological Environment; 35 East Qinghua Road, Haidian District, Beijing 100083, China E-mail: bjfu_fu@163.com
Oliet, Department of Natural Systems and Resources, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain E-mail: juan.oliet@upm.es
Li, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing Forestry University; Beijing Laboratory of Urban and Rural Ecological Environment; 35 East Qinghua Road, Haidian District, Beijing 100083, China E-mail: glli226@163.com
Wang, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing Forestry University; Beijing Laboratory of Urban and Rural Ecological Environment; 35 East Qinghua Road, Haidian District, Beijing 100083, China E-mail: wjx198979@163.com

article id 1599, category Research article

Andrew McEwan, Michal Brink, Raffaele Spinelli. (2017). Factors affecting the productivity and work quality of chain flail delimbing and debarking. Silva Fennica vol. 51 no. 2 article id 1599. https://doi.org/10.14214/sf.1599

Keywords: modeling; plantation; coppice; efficiency; pulpwood; processing

Highlights: Machine productivity averaged 59 m³ ub SMH^–1, with a 19% incidence of delay time; Productivity increased 70% if tree volume increased from 0.1 to 0.4 m³ ub; Debarking quality was good for 58% of the trees, medium for 29% and poor for 13%; The more trees in a bunch and the higher BWBS, the lower debarking quality.

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Chain flail delimbing and debarking may improve value recovery from small tree harvests, without renouncing the benefits of multi-tree processing. The technology is mature and capable of excellent performance, which has been documented in many benchmark studies. This paper offers new insights into the relationship between the performance of chain flail delimbing and debarking and such factors as tree volume, load volume, tree form and bark-wood bond strength (BWBS). The study was conducted in Chile, during the commercial harvesting of a Eucalyptus globulus Labill. plantation. In an observational study, researchers collected production data from over 780 work cycles, and work quality data from over 1000 individual trees. The analysis of these data shows that productivity is affected primarily by load volume. Work quality is affected by BWBS and by the number of trees in a load. Work quality degrades with increasing BWBS and tree number, since more trees tend to shield each other. Tree form has no effect on either productivity or work quality. Regression and probability functions are provided, and can be used for predictive purposes when trying to optimize current operations or to prospect the introduction of chain flail technology to new work environments.

McEwan, Postgraduate Forest Programme, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag X20 Hatfield, Pretoria, 0028, South Africa E-mail: Andrew.McEwan@nmmu.ac.za
Brink, Postgraduate Forest Programme, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag X20 Hatfield, Pretoria, 0028, South Africa E-mail: michal@cmo.co.za
Spinelli, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (FI), Italy http://orcid.org/0000-0001-9545-1004 E-mail: spinelli@ivalsa.cnr.it

article id 1618, category Research article

Miguel Genin, Mohamed Alifriqui, Abdessamad Fakhech, Mohamed Hafidi, Lahcen Ouahmane, Didier Genin. (2017). Back to forests in pre-Saharan Morocco? When prickly pear cultivation and traditional agropastoralism reduction promote argan tree regeneration. Silva Fennica vol. 51 no. 1B article id 1618. https://doi.org/10.14214/sf.1618

Keywords: arid zones; Argania spinosa; agroforestry parklands; desertification; facilitation factors; land use changes; Opuntia ficus-indica

Highlights: There was a significant positive relationship between the age of implanted prickly pear orchards and natural argan tree regeneration; This relationship is mainly associated with interconnected changes in traditional land uses and the activation of facilitation factors such as an enhancement of the soil’s organic matter and nurse plant phenomena; This example constitutes a remarkable alternative model for thinking about agricultural development while combating desertification.

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In the southwestern pre-Saharan arid zone of Morocco, the endemic argan forest (Argania spinosa) had been almost completely destroyed in the 1960s due to intensive coal mining and mixed cereal-livestock farming. These activities turned out to be unviable and a massive rural exodus occurred in the 1970s. Local populations started to develop maintenance-free prickly pear (Opuntia ficus-indica) cultivation at large scale in order to keep their land ownership rights, while reducing their traditional agropastoral activity. We conducted a survey in order to characterize the relationships between the age of prickly pear orchards and argan tree regeneration. We also explored facilitating factors, such as soil organic matter and mycorrhiza. Results showed a high positive correlation (r² = 0.75, p < 0.001) between the age of prickly pear orchards and argan tree resprouts, but with differences depending on a continentality gradient. The soil organic matter content also showed highly significant differences (p < 0.001) depending on the age of the prickly pear plantation, while spora density did not show such differences. The recent high economic value attributed to prickly pear fruits, and to both argan and prickly pear seed oil, has given farmers the opportunity to develop a lucrative agricultural activity, while promoting the recovery of native vegetation. This situation constitutes a remarkable example of speculative agricultural development in a very harsh environment, in phase with ecological priorities for combating desertification. It could represent an alternative to the externally-generated projects sustained by high levels of public funding, with ecological, economic and social impacts which are sometimes questionable.

Genin, Institut de Recherche pour le Développement (IRD) & Aix-Marseille Université, Laboratoire Population, Environnement, Développement, UMR151 AMU-IRD, Marseille, France E-mail: miguel.genin@gmail.com
Alifriqui, Cadi Ayyad University (UCAM), Laboratoire d’Ecologie et Environnement (CNRST, URAC 32), Faculté des Sciences Semlalia, Marrakech, Morocco E-mail: alifriqui@gmail.com
Fakhech, Cadi Ayyad University (UCAM), Laboratoire d’Ecologie et Environnement (CNRST, URAC 32), Faculté des Sciences Semlalia, Marrakech, Morocco E-mail: abdessamad.fakhech@edu.uca.ac.ma
Hafidi, Cadi Ayyad University (UCAM), Laboratoire d’Ecologie et Environnement (CNRST, URAC 32), Faculté des Sciences Semlalia, Marrakech, Morocco E-mail: hafidi.ucam@gmail.com
Ouahmane, Cadi Ayyad University (UCAM), Laboratoire d’Ecologie et Environnement (CNRST, URAC 32), Faculté des Sciences Semlalia, Marrakech, Morocco E-mail: l.ouahmane@gmail.com
Genin, Institut de Recherche pour le Développement (IRD) & Aix-Marseille Université, Laboratoire Population, Environnement, Développement, UMR151 AMU-IRD, Marseille, France E-mail: didier.genin@univ-amu.fr

article id 1553, category Research article

Miguel Angel Salinas-Melgoza, Margaret Skutsch, Jon C. Lovett, Armonia Borrego. (2017). Carbon emissions from dryland shifting cultivation: a case study of Mexican tropical dry forest. Silva Fennica vol. 51 no. 1B article id 1553. https://doi.org/10.14214/sf.1553

Keywords: carbon stocks; slash-and-burn; swidden cultivation; REDD ; land sparing; Borlaug hypothesis

Highlights: Under REDD+, shifting cultivation should be considered degradation rather than deforestation; Carbon stocks in old fallows (>20 years) are higher than those in old growth forests which have never been used for shifting cultivation; Extending length of fallows increases rates of carbon emissions; Shortened fallow cycles result in higher carbon stocks and lower emissions at the landscape level; Cycle lengths could be optimized for carbon sequestration in a land sharing approach.

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The article considers the relation of shifting cultivation to deforestation and degradation, and hence its impacts in terms of carbon emissions and sequestration potential. There is a need to understand these relationships better in the context of international policy on Reduced Emissions from Deforestation and Forest Degradation (REDD+). The article reviews the way in which shifting cultivation has been incorporated in global and national estimations of carbon emissions, and assembles the available information on shifting cultivation in Tropical Dry Forests (TDF) in Mexico, where it is widely practiced. It then takes the case of two villages, Tonaya and El Temazcal, which lie within the basin of the River Ayuquila in Jalisco, Mexico. Field data for the typical carbon stocks and fluxes associated with shifting cultivation are compared with stocks and fluxes associated with more intensive agricultural production in the same dry tropical forest area to highlight the carbon sequestration dynamics associated with the shortening and potential lengthening of the fallow cycles. The biomass density in the shifting cultivation system observed can reach levels similar to that of old growth forests, with old fallows (>20 years) having higher carbon stocks than old growth forests. Per Mg of maize produced, the biomass-related emissions from shifting cultivation in the traditional 12 year cycle are about three times those from permanent cultivation. We did not, however, take into account the additional emissions from inputs that result from the use of fertilizers and pesticides in the case of permanent agriculture. Shortening of the fallow cycle, which is occurring in the study area as a result of government subsidies, results in higher remaining stocks of carbon and lower emissions at the landscape level.

Salinas-Melgoza, University of Twente, Drienerlolaan 5, 7522 NB Enschede, the Netherlands http://orcid.org/0000-0003-3209-1659 E-mail: ma.masm@gmail.com
Skutsch, Universidad Nacional Autónoma de México (CIGA-UNAM), Antigua Carretera a Pátzcuaro No. 8701, Col. Ex-Hacienda de San José de la Huerta, Campus Morelia, C.P. 58190, Michoacán, Mexico http://orcid.org/0000-0001-6120-4945 E-mail: mskutsch@ciga.unam.mx
Lovett, University of Leeds, Leeds, LS2 9JT, UK E-mail: j.lovett@leeds.ac.uk
Borrego, CONACYT-Centro de Investigaciones en Geografía Ambiental, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex-Hacienda de San José de la Huerta, Campus Morelia, C.P. 58190, Michoacán, México E-mail: aborrego@ciga.unam.mx

article id 1718, category Research article

Mihails Čugunovs, Eeva-Stiina Tuittila, Lauri Mehtätalo, Laura Pekkola, Ida Sara-Aho, Jari Kouki. (2017). Variability and patterns in forest soil and vegetation characteristics after prescribed burning in clear-cuts and restoration burnings. Silva Fennica vol. 51 no. 1 article id 1718. https://doi.org/10.14214/sf.1718

Keywords: disturbance; restoration; sampling; spatial variability; prescribed fire; SOM stocks

Highlights: Soil parameter variability is similar across sites of different disturbance type; Variability of understory vegetation biomass and cover is higher and more different between sites than soil variability; Sites studied here reflect well the assumed disturbance-type gradient based on PCA; Sampling six forest sites per treatment should provide good statistical power to capture the differences in soil organic matter stocks.

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Forest ecological restoration by burning is widely applied to promote natural, early-successional sites and increase landscape biodiversity. Burning is also used as a forest management practice to facilitate forest regeneration after clearcutting. Besides the desired goals, restoration burnings also affect soil biogeochemistry, particularly soil organic matter (SOM) and related soil carbon stocks but the long-term effects are poorly understood. However, in order to study these effects, a reliable estimate of spatial variability is first needed for effective sampling. Here we investigate spatial variability of SOM and vegetation features 13 years after burnings and in combination with variable harvest levels. We sampled four experimental sites representing distinct management and restoration treatments with an undisturbed control. While variability of vegetation cover and biomass was generally higher in disturbed sites, soil parameter variability was not different between the four sites. The joint ecological patterns of soil and vegetation parameters across the whole sample continuum support well the prior assumptions on the characteristic disturbance conditions within each of the study sites. We designed and employed statistical simulations as a means to plan prospective sampling. Sampling six forest sites for each treatment type with 30 independent soil cores per site would provide enough statistical power to adequately capture the impacts of burning on SOM based on the data we obtained here and statistical simulations. In conclusion, we argue that an informed design-based approach to documenting the ecosystem effects of forest burnings is worth applying both through obtaining new data and meta-analysing the existing.

Čugunovs, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: mihails.cugunovs@uef.fi
Tuittila, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland http://orcid.org/0000-0001-8861-3167 E-mail: eeva-stiina.tuittila@uef.fi
Mehtätalo, University of Eastern Finland, School of Computing, Science Park, Länsikatu 15, P.O. Box 111, 80101 Joensuu, Finland http://orcid.org/0000-0002-8128-0598 E-mail: lauri.mehtatalo@uef.fi
Pekkola, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: laura.pekkola@gmail.com
Sara-Aho, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: ida.sara-aho@mhy.fi
Kouki, University of Eastern Finland, School of Forest Sciences, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland http://orcid.org/0000-0003-2624-8592 E-mail: jari.kouki@uef.fi

article id 1705, category Research article

Sulmaz Janfaza, Hamed Yousefzadeh, Seyed Mohammad Hosseini Nasr, Roberto Botta, Asad Asadi Abkenar, Daniela Torello Marinoni. (2017). Genetic diversity of Castanea sativa an endangered species in the Hyrcanian forest. Silva Fennica vol. 51 no. 1 article id 1705. https://doi.org/10.14214/sf.1705

Keywords: population structure; microsatellite markers; sweet chestnut

Highlights: This is the first report of genetic diversity of the few remaining populations of C. sativa in the southern limits of its distribution in Eurasia; Low genetic diversity and high genetic differentiation among small isolated populations of C. sativa with low geographical distance represent serious genetic erosion indicators in the Hyrcanian forest, even hinting at an ongoing extinction vortex.

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Castanea sativa Mill. is one of the most endangered tree species in Iran where it is represented by small fragmented populations in the north of the country. 18 simple sequence repeat (SSR) loci (10 nuclear and 8 chloroplastic) were used to evaluate the genetic diversity and population structure of C. sativa from the Hyrcanian forest. For nuclear SSR, the number of alleles detected per locus ranged from 1 to 5 and observed heterozygosity (H_O) was between 0.125 and 1.000. Analysis of molecular variance (AMOVA) indicated a high level of variation within populations (84%) and low levels between populations (16%). Based on structure analysis, the four studied populations were divided into two main clusters that have genetic distance F_st = 0.3. The Shafaroud population was separated in the first cluster, Siyahmazgi, Qalehroudkhan and Veysroud were placed in the second cluster. The UPGMA analysis confirmed the results of Structure analysis, separating the Shafaroud population from the others. The 8 chloroplast SSR loci used to screen the populations showed no polymorphism. In General, low nuclear genetic diversity, no polymorphism in cpDNA and considerable genetic differentiation among populations in short geographical distance represent a serious genetic erosion threat for C. sativa in the Hyrcanian forest, even hinting at an ongoing extinction vortex. Therefore, due to significant decline in genetic diversity, it is essential to introduce constraints protection upon the areas of distribution of all four populations of this species in Iran.

Janfaza, Department of Forestry, Sari University of Agriculture Sciences and Natural Resources, Km 9 Darya Road, P.O. Box 578, Mazandaran, Iran E-mail: aristocratka_b@yahoo.com
Yousefzadeh, Department of Environment, Faculty of Natural Resources and Marine Science ,Tarbiat Modares University, Noor, Mazandaran, Iran E-mail: h.yousefzadeh@modares.ac.ir
Hosseini Nasr, Department of Forestry, Sari University of Agriculture Sciences and Natural Resources, Km 9 Darya Road, P.O. Box 578, Mazandaran, Iran E-mail: s.hosseini@sanru.ac.ir
Botta, Dipartimento di Scienze Agrarie Forestali e Alimentari, DISAFA, Università di Torino, Via Verdi 8, 10124 Torino, Italy E-mail: roberto.botta@unito.it
Asadi Abkenar, Agricultural Research, Education and Extension Organization (AREEO) of IRAN, Agricultural Biotechnology Research Institute of Iran (RBRII), Branch of North Region, Guilan, Rasht, Iran E-mail: asadiabkenarasad@gmail.com
Marinoni, Dipartimento di Scienze Agrarie Forestali e Alimentari, DISAFA, Università di Torino, Via Verdi 8, 10124 Torino, Italy E-mail: daniela.marinoni@unito.it

article id 1704, category Research article

Inger Sundheim Fløistad, Toril Drabløs Eldhuset. (2017). Effect of photoperiod and fertilization on shoot and fine root growth in Picea abies seedlings. Silva Fennica vol. 51 no. 1 article id 1704. https://doi.org/10.14214/sf.1704

Keywords: Norway spruce; nitrogen; nutrients; potassium; root collar diameter; root scanning; short day treatment

Highlights: Effects of photoperiod and fertilization treatment on Norway spruce seedling growth were examined; Short day treatment and ordinary K:N ratio in the fertilization proved the best combination for achieving seedlings with suitable root and shoot properties for field establishment; Increased K:N ratio in the fertilization did not reduce shoot height growth.

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Picea abies seedlings were given three different fertilization treatments in the nutrient solution by varying the potassium:nitrogen (K:N) ratios (2.5, 3.0 or 3.9 g g^–1). All fertilization treatments were combined with short-day (SD) treatment or no such treatment (control). Above- and belowground growth responses in the seedlings were analyzed. The SD treatment resulted in significantly reduced shoot height, compared to untreated control, irrespective of K:N ratio. No combination of photoperiod treatment or fertilization treatment affected the root collar diameter. In the current year root fraction with diameter < 0.5 mm, the highest K:N ratio led to significantly increased root length in control plants. In each 0.1 mm root diameter class up to 0.5 mm, the highest K:N ratio significantly stimulated root growth in control plants, while the effect was less evident for SD plants. SD treatment stimulated length growth in some fine root diameter classes. We conclude that SD treatment is a good and sufficient measure to reduce height growth without compromising fine root growth of P. abies seedlings. Fertilization treatment did not significantly improve aboveground growth in SD treated seedlings, and only limited effects on root growth was seen on control plants.

Fløistad, Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, NO-1431 Ås, Norway E-mail: inger.floistad@nibio.no
Eldhuset, Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, NO-1431 Ås, Norway E-mail: toril.eldhuset@nibio.no

article id 1694, category Research article

Katri Luostarinen, Katja Hakkarainen, Henri Kaksonen. (2017). Wood anatomy of seed and basal bud originated downy birches (Betula pubescens Ehrh.) grown at four different sites. Silva Fennica vol. 51 no. 1 article id 1694. https://doi.org/10.14214/sf.1694

Keywords: fibre; xylem; parenchyma; ray; vessel; sprout; wood structure

Highlights: Young xylem of sprouts did not clearly show more mature characteristics than that of seedlings; Marked differences in xylem structure could be observed between growing sites.

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In trees, xylem must fulfil three important tasks: conducting water to leaves, storing nutrients and water, and supporting the trunk. The origin of the trunk, i.e., seed or basal bud that forms sprouts, and the growth site may affect xylem anatomy, differences of which can affect successful growth of trees. Both seedlings and sprouts of downy birch (Betula pubescens Ehrh.) from four different growth sites with two different soil media, peat and mineral soil, were studied. The diameter of fibres and vessels and the thickness of the double fibre wall were measured, and the number of vessels, rays and axial parenchyma cells was counted. The fibre wall:lumen ratio, vessel percentage area and vessel size:number ratio were calculated. Xylem from sprouts showed only occasionally more mature characteristics than that of seedlings. The number of rays was similar at all four sites, but differences were observed in all other studied characteristics between sites, particularly if soil type was different. The vessel size and number correlated with the number of axial parenchyma cells in juvenile wood, which emphasises the importance of their connections with storage cells particularly at this stage of growth. Good water conductivity was connected with weaker wood, particularly in maturing wood.

Luostarinen, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: katri.luostarinen@uef.fi
Hakkarainen, Natural Resources Institute of Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: katjahak@gmail.com
Kaksonen, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: hkaksone@gmail.com

article id 1684, category Research article

Anna Kowalska, Jan Marek Matuszkiewicz, Jerzy Solon, Anna Kozłowska. (2017). Indicators of ancient forests in nutrient-deficient pine habitats. Silva Fennica vol. 51 no. 1 article id 1684. https://doi.org/10.14214/sf.1684

Keywords: forest continuity; central Poland; life-history traits; mixed oak-pine forests; phi coefficient; pine forests

Highlights: Distinct groups of species with a preference for ancient pine and mixed oak-pine forests can be determined; The ancient forest indicator composition in pine habitats differs remarkably from ancient forest indicators in deciduous forests; Dispersal-related traits significantly distinguish ancient forest indicators from other species found in nutrient-poor forest habitats.

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Pine forests are common in many European regions. Nonetheless, there are only a few studies on regeneration of plant species populations in nutrient-deficient pine habitats. Ancient temperate forests are perceived to be particularly important objects of environmental conservation, due to their ability to sustain a considerable number of rare and vulnerable species. In this paper, we present indicator species of ancient pine and mixed oak-pine forests, together with their trait profiles. Phytosociological relevés were collected from mature stands in the Masuria and Kurpie regions of central Poland. Forest persistence was determined on the basis of historical maps, with the data set divided into three categories. The indicator value of species was evaluated using Tichý and Chytrý’s phi coefficient. Functional response traits of indicator species were identified. Distinct groups of species with a preference for ancient forests can be determined. The dispersal-related traits significantly distinguish ancient forest indicators from other species found in nutrient-poor forest habitats. Since the low potential for long-distance dispersal hinders the establishment of new plant populations in isolated stands, we stress the need to avoid ancient forest clearance and fragmentation of woodland; afforestation should be located in the vicinity of ancient stands. Moreover, as recent forests have turned out to support several rare plant species, to maintain phytodiversity on a landscape level a mixture of ancient and recent forests, both managed and strictly protected, is needed.

Kowalska, Institute of Geography and Spatial Organization, Polish Academy of Science, Twarda 51/55, 00-818 Warsaw, Poland E-mail: aniak@twarda.pan.pl
Matuszkiewicz, Institute of Geography and Spatial Organization, Polish Academy of Science, Twarda 51/55, 00-818 Warsaw, Poland E-mail: jan.mat@twarda.pan.pl
Solon, Institute of Geography and Spatial Organization, Polish Academy of Science, Twarda 51/55, 00-818 Warsaw, Poland E-mail: j.solon@twarda.pan.pl
Kozłowska, Institute of Geography and Spatial Organization, Polish Academy of Science, Twarda 51/55, 00-818 Warsaw, Poland E-mail: a.kozl@twarda.pan.pl

article id 1689, category Research article

Juha Laitila, Eeva Lehtonen, Tapio Ranta, Perttu Anttila, Saija Rasi, Antti Asikainen. (2016). Procurement costs of cereal straw and forest chips for biorefining in South-East Finland. Silva Fennica vol. 50 no. 5 article id 1689. https://doi.org/10.14214/sf.1689

Keywords: supply chains; stumps; young stands; logging residues; delimbed stems; agrobiomass

Highlights: Procurement cost at the plant was 59 € dry tonne ^–1 when the annual procurement volume of biomass was 100 000 tonnes. Of that amount, the proportion of logging residues was 58.4%, stumps 24.3% and delimbed stems 17.3%; Cereal straw represents an important source of biomass in Kouvola but the cost competiveness is poor compared the procurement costs of forest chips due to high baling and transporting costs.

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In Finland the increasing use of biofuel in transport presupposes a search for new raw material sources for biorefining. The aim of this study was, at the regional level, to compare the procurement costs of logging residues, stumps, delimbed stems and cereal straw for biorefining. The accumulation and procurement costs of forest chips and cereal straw were estimated within a 100-kilometre transporting distance via existing road network from an end-use-facility located in Kouvola in South-East Finland. The analyses were performed as simulated treatments in thinnings of young stands, cereal fields and regeneration fellings using existing productivity and cost functions and yield calculations based on crop statistics, the forest industry stand data and the sample plots data of the National Forest Inventory of Finland. Accumulation of raw material assortments and costs of production stages were defined per dry tonnes. Subsidies and raw material prices were excluded from consideration in the study. The results indicate that recovering logging residues requires lower costs than utilization of stumps, delimbed stems or cereal straw. Cereal straw represents an important source of biomass in Kouvola but the cost competiveness is poor compared the procurement costs of forest chips. When the annual procurement volume of biomass was 50 000 dry tonnes the cost at the plant was 49 € dry tonne ^–1 and biomass was comprised totally of logging residues. Procurement cost grew to 59 € dry tonne ^–1 when the annual procurement volume of biomass was doubled to 100 000 dry tonnes. Of that amount, the proportion of logging residues was 58.4%, stumps 24.3% and delimbed stems 17.3%. First cereal straw dry tonnes were delivered to end-use-facility, when procurement cost grew to 60 € dry tonne ^–1 and annual procurement volume of biomass was 110 000 dry tonnes.

Laitila, Natural Resources Institute Finland (Luke), Bio-based Business and Industry, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: juha.laitila@luke.fi
Lehtonen, Natural Resources Institute Finland (Luke), Green Technology, Halolantie 31A, FI-71750 Maaninka, Finland E-mail: eeva.lehtonen@luke.fi
Ranta, Lappeenranta University of Technology, LUT School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland E-mail: tapio.ranta@luke.fi
Anttila, Natural Resources Institute Finland (Luke), Bio-based Business and Industry, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: perttu.anttila@luke.fi
Rasi, Natural Resources Institute Finland (Luke), Bio-based Business and Industry, Survontie 9A, FI-40500 Jyväskylä E-mail: saija.rasi@luke.fi
Asikainen, Natural Resources Institute Finland (Luke), Bio-based Business and Industry, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: antti.asikainen@luke.fi

article id 1680, category Research article

Liisa Kulmala, Indre Žliobaitė, Eero Nikinmaa, Pekka Nöjd, Pasi Kolari, Kourosh Kabiri Koupaei, Jaakko Hollmén, Harri Mäkinen. (2016). Environmental control of growth variation in a boreal Scots pine stand – a data-driven approach. Silva Fennica vol. 50 no. 5 article id 1680. https://doi.org/10.14214/sf.1680

Keywords: height growth; diameter growth; Gross primary production; turgor pressure; predictive modelling; Least Angle Regression

Highlights: High water potential and carbon gain during bud forming favoured height growth; High water potential during the elongation period favoured height growth; A spring with high carbon gain favoured diameter growth; The obtained regression models had generally low generalization performance.

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Despite the numerous studies on year-to-year variation of tree growth, the physiological mechanisms controlling annual variation in growth are still not understood in detail. We studied the applicability of data-driven approach i.e. different regression models in analysing high-dimensional data set including continuous and comprehensive measurements over meteorology, ecosystem-scale water and carbon fluxes and the annual variation in the growth of app. 50-year-old Scots pine stand in southern Finland. Even though our dataset covered only 16 years, it is the most extensive collection of interactions between a Scots pine ecosystem and atmosphere. The analysis revealed that height growth was favoured by high water potential of the tree and carbon gain during the bud forming period and high water potential during the elongation period. Diameter growth seemed to be favoured by a winter with high precipitation and deep snow cover and a spring with high carbon gain. The obtained models had low generalization performance and they would require more evaluation and iterative validation to achieve credibility perhaps as a mixture of data-driven and first principle modeling approaches.

Kulmala, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: liisa.kulmala@helsinki.fi
Žliobaitė, Aalto University, Department of Computer Science and Helsinki Institute for Information Technology, P.O. Box 11000, FI-00076 Aalto, Finland; University of Helsinki, Department of Geosciences and Geography, P.O. Box 64, FI-00014 University of Helsinki, Finland E-mail: zliobaite@gmail.com
Nikinmaa, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: eero.nikinmaa@helsinki.fi
Nöjd, Natural Resources Institute Finland (Luke), Bio-based business and industry, Tietotie 2, FI-02150 Espoo, Finland E-mail: pekka.nojd@luke.fi
Kolari, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland; University of Helsinki, Department of Physics, P.O. Box 64, FI-00014 University of Helsinki, Finland E-mail: pasi.kolari@helsinki.fi
Kabiri Koupaei, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: kourosh.kabiri@helsinki.fi
Hollmén, Aalto University, Department of Computer Science and Helsinki Institute for Information Technology, P.O. Box 11000, FI-00076 Aalto, Finland; University of Helsinki, Department of Geosciences and Geography, P.O. Box 64, FI-00014 University of Helsinki, Finland E-mail: jaakko.hollmen@aalto.fi
Mäkinen, Natural Resources Institute Finland (Luke), Bio-based business and industry, Tietotie 2, FI-02150 Espoo, Finland E-mail: harri.makinen@luke.fi

article id 1615, category Research article

Minna Blomqvist, Päivi Lyytikäinen-Saarenmaa, Tuula Kantola, Maiju Kosunen, Mervi Talvitie, Markus Holopainen. (2016). Impacts of natural enemies and stand characteristics on cocoon mortality of the pine sawfly Diprion pini in a Fennoscandian boreal forest. Silva Fennica vol. 50 no. 5 article id 1615. https://doi.org/10.14214/sf.1615

Keywords: needle loss; Diprionidae; population dynamics; forest floor vegetation; parasitism; predation

Highlights: Annual cocoon mortality caused by natural enemies varied between 66% and 80% during the six-year study period, most of it caused by the family Ichneumonidae; Basal area, and coverage of lichen (Lichenes) and lingonberry (Vaccinium vitis-idaea L.) best explained cocoon parasitism and predation; Combination of suitable stand characteristics, abiotic environmental factors, and incomplete control by natural enemies enabled pest species to extend its gradation phase.

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We investigated the impact of natural enemies on the cocoon mortality of the common pine sawfly (Diprion pini L.) during a six-year period in eastern Finland. The enemies were classified into parasitoids (insect families Chalcidoidea, Ichneumonidae, and Tachinidae), and predators (birds, small mammals, and insect families Elateridae and Carabidae). The appearance of D. pini was estimated as the intensity of annual defoliation. The impact of stand characteristics on the performance of parasitoids and predators was also investigated. Influence of the natural enemy complex on cocoon mortality of D. pini was nearly stable, but defoliation intensity slowly declined towards the end of the study period. Annual cocoon mortality by natural enemies varied between 66% and 80%. Our results verified that the most significant mortality factors were ichneumonid parasitoids and small mammals. Random Forest classification indicated that stand characteristics, such as basal area, and coverage of lichen (Lichenes) and lingonberry (Vaccinium vitis-idaea L.) affected the performance of parasites and predators. We suggest that a combination of optimal stand characteristics, abiotic environmental factors and mild to moderate control by natural enemies acted as drivers, which drove the pine sawfly population to extended gradation. For future forest health management, detailed information on abiotic and biotic regulating factors, along with long-term monitoring campaigns for conifer sawflies are needed to adapt Fennoscandian forests to altered climatic and silvicultural conditions.

Blomqvist, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland http://orcid.org/0000-0003-2328-8839 E-mail: minna.blomqvist@helsinki.fi
Lyytikäinen-Saarenmaa, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland E-mail: paivi.lyytikainen-saarenmaa@helsinki.fi
Kantola, Knowledge Engineering Laboratory, Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA E-mail: tuula.kantola@helsinki.fi
Kosunen, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland E-mail: maiju.kosunen@helsinki.fi
Talvitie, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland E-mail: mervi.talvitie@dnainternet.net
Holopainen, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland E-mail: markus.holopainen@helsinki.fi

article id 1687, category Research article

Hannu Hökkä, Jori Uusitalo, Harri Lindeman, Jari Ala-Ilomäki. (2016). Performance of weather parameters in predicting growing season water table depth variations on drained forested peatlands – a case study from southern Finland. Silva Fennica vol. 50 no. 4 article id 1687. https://doi.org/10.14214/sf.1687

Keywords: peatland; precipitation; bearing capacity; evapotranspiration; mixed linear model; water table depth

Highlights: Four-week precipitation and evapotranspiration explain much of drained peatland water table depth variation during a growing season.

Abstract | Full text in HTML | Full text in PDF | Author Info

The amount of water in peat soil is one factor affecting its bearing capacity, which is a crucial aspect in planning peatland timber harvesting operations. We studied the influence of weather variables on the variation of drained peatland growing season water conditions, here the ground water table depth (WTD). WTD was manually monitored four times in 2014 and three times in 2015 in 10–30 sample plots located in four drained peatland forests in south-western Finland. For each peatland, precipitation and evapotranspiration were calculated from the records of the nearest Finnish Meteorological Institute field stations covering periods from one day to four weeks preceding the WTD monitoring date. A mixed linear model was constructed to investigate the impact of the weather parameters on WTD. Precipitation of the previous four–week period was the most important explanatory variable. The four-week evapotranspiration amount was interacting with the Julian day showing a greater effect in late summer. Other variables influencing WTD were stand volume within the three-metre radius sample plot and distance from nearest ditch. Our results show the potential of weather parameters, specifically that of the previous four-week precipitation and evapotranspiration, for predicting drained peatland water table depth variation and subsequently, the possibility to develop a more general empirical model to assist planning of harvesting operations on drained peatlands.

Hökkä, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Paavo Havaksen tie 3, FI-90014 Oulun yliopisto, Finland E-mail: hannu.hokka@luke.fi
Uusitalo, Natural Resources Institute Finland (Luke), Green Technology, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: jori.uusitalo@luke.fi
Lindeman, Natural Resources Institute Finland (Luke), Green Technology, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: harri.lindeman@luke.fi
Ala-Ilomäki, Natural Resources Institute Finland (Luke), Green Technology, Jokiniemenkuja 1, FI-01370 Vantaa, Finland E-mail: jari.ala-ilomaki@luke.fi

article id 1622, category Research article

Lingbo Dong, Pete Bettinger, Zhaogang Liu, Huiyan Qin, Yinghui Zhao. (2016). Evaluating the neighborhood, hybrid and reversion search techniques of a simulated annealing algorithm in solving forest spatial harvest scheduling problems. Silva Fennica vol. 50 no. 4 article id 1622. https://doi.org/10.14214/sf.1622

Keywords: spatial harvest scheduling; metaheuristics; combinatorial optimization; neighborhood search; reversion search

Highlights: The performances of neighborhood, hybrid and reversion search strategies of simulated annealing were evaluated when implemented with a forest spatial harvest scheduling problem; The performances of alternative search strategies of simulated annealing were all systematic and clear better than the conventional strategy; The reversion techniques were significant superior to the other search strategies in solving forest spatial harvest scheduling problems.

Abstract | Full text in HTML | Full text in PDF | Author Info

Heuristic techniques have been increasingly used to address the complex forest planning problems over the last few decades. However, heuristics only can provide acceptable solutions to difficult problems, rather than guarantee that the optimal solution will be located. The strategies of neighborhood, hybrid and reversion search processes have been proved to be effective in improving the quality of heuristic results, as suggested recently in the literature. The overall aims of this paper were therefore to systematically evaluate the performances of these enhanced techniques when implemented with a simulated annealing algorithm. Five enhanced techniques were developed using different strategies for generating candidate solutions. These were then compared to the conventional search strategy that employed 1-opt moves (Strategy 1) alone. The five search strategies are classified into three categories: i) neighborhood search techniques that only used the change version of 2-opt moves (Strategy 2); ii) self-hybrid search techniques that oscillate between 1-opt moves and the change version of 2-opt moves (Strategy 3), or the exchange version of 2-opt moves (Strategy 4); iii) reversion search techniques that utilize 1-opt moves and the change version of 2-opt moves (Strategy 5) or the exchange version of 2-opt moves (Strategy 6). We found that the performances of all the enhanced search techniques of simulated annealing were systematic and often clear better than conventional search strategy, however the required computational time was significantly increased. For a minimization planning problem, Strategy 6 produced the lowest mean objective function values, which were less than 1% of the means developed using conventional search strategy. Although Strategy 6 performed very well, the other search strategies should not be neglected because they also have the potential to produce high-quality solutions.

Dong, Department of Forest Management, College of Forestry, Northeast Forestry University, Harbin 150040, China E-mail: farrell0503@126.com
Bettinger, Warnell School of Forestry and Natural Resources, University of Georgia, Athens 30602, GA, USA E-mail: pbettinger@warnell.uga.edu
Liu, Department of Forest Management, College of Forestry, Northeast Forestry University, Harbin 150040, China E-mail: lzg19700602@163.com
Qin, Department of Forestry Economic, College of Economic & Management, Northeast Forestry University, Harbin 150040, China E-mail: huiyanqin@hotmail.com
Zhao, Department of Forest Management, College of Forestry, Northeast Forestry University, Harbin 150040, China E-mail: zyinghui0925@126.com

article id 1611, category Research article

Ilpo Ervasti. (2016). Wood fiber contents of different materials in the paper industry material chain expressed in roundwood equivalents (RWEs). Silva Fennica vol. 50 no. 4 article id 1611. https://doi.org/10.14214/sf.1611

Keywords: pulpwood; paper production; raw materials; roundwood equivalent (RWE); wood pulp; recycled fiber; recovered paper; material recycling

Highlights: The paper industry material recycling chain consists of different material streams; Consumed paper products form a huge fiber source for industry. However, a reliable measuring system should be developed to quantify these fiber volumes; Converting factors are introduced to quantify the wood fiber contents of different paper industry-related materials of the chain, namely, wood pulp, paper and recovered paper; By using these conversion factors it is possible to convert for example global recovered paper utilization volumes into wood fiber volumes expressed in roundwood equivalents (RWEs).

Abstract | Full text in HTML | Full text in PDF | Author Info

At present, there are no means for reliably comparing the wood fiber contents of different material streams within the paper industry material chain with each other. The aim of this article is to introduce conversion factors that make it possible to quantify the volume of wood expressed in roundwood equivalent (RWE) values for different paper industry-related materials in the material chain. These conversion factors apply to wood pulp, paper, and recovered paper. European data are used in quantifying the paper industry material streams and calculating the RWE conversion factors. The introduced conversion factors can be used to estimate RWE volumes at a global scale. With assumption that paper recycling did not occur and that paper production volume remained unchanged, an additional volume of 666 million m³ RWEs would be required globally per annum to produce 167 million tons of virgin wood pulp to replace 222 million tons of recovered paper utilized by the paper industry in 2010. This volume is approximately the same as 1.6 times the total removal of wood in Europe (EU27), or the total annual removal of wood in the USA, Canada, and Brazil combined.

Ervasti, Aalto University, Industrial Engineering and Management, Maarintie 8, 02150 Espoo, Finland E-mail: ilervasti@gmail.com

article id 1564, category Research article

Stanislav Vacek, Zdeněk Vacek, Lukáš Bílek, Jaroslav Simon, Jiří Remeš, Iva Hůnová, Jan Král, Tereza Putalová, Miroslav Mikeska. (2016). Structure, regeneration and growth of Scots pine (Pinus sylvestris L.) stands with respect to changing climate and environmental pollution. Silva Fennica vol. 50 no. 4 article id 1564. https://doi.org/10.14214/sf.1564

Keywords: Pinus sylvestris; natural regeneration; climate; stand development; production; air-pollution

Highlights: Pine forest stands showed positive development of stand structural characteristics related to their diversity, number of regeneration individuals and growth characteristics; Tree-ring width was positively correlated with precipitation, while it was negatively correlated with temperature in growing seasons; Mean NO_x concentrations showed positive effect on radial growth of pine; Serious defoliation was caused by SO₂ concentrations and N deposition in combination with extreme climate events.

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Changes in the structure and development of managed Scots pine (Pinus sylvestris L.) stands with respect to changing environmental conditions were set for the period 1979–2015. The study was conducted in conditions of natural pinewoods and pine-oak sites on five permanent research plots (0.25 ha) in Eastern Bohemia, Czech Republic (CR). Studied forest stands showed positive development of stand structural characteristics related to their diversity, number of regeneration individuals and growth characteristics. The standing volume of regularly distributed tree layer in 2015 was in the range of 320–434 m³ ha^–1, which indicates an increase by 5.9–20.0% over 10 years. Correlation between pine radial increment and the amount of precipitation was generally the strongest one. Positive statistically significant correlation between diameter increment and temperature was demonstrated only for the average March temperature of the current year. Within the CR, study site can be characterised as a medium polluted area both for sulphur and nitrogen, despite this SO₂concentrations and N deposition in combination with extreme climate events caused severe defoliation in pine stands. Conversely, radial growth was positively significantly correlated with mean NO_x concentrations. Drought mainly in combination with even medium environmental pollution can further worsen the health status of pine stands in lowland areas of Central Europe. Thus, formulation of silvicultural techniques able to mitigate the impact of these stress factors is needed.

Vacek, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: vacekstanislav@fld.czu.cz
Vacek, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: vacekz@fld.czu.cz
Bílek, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: bilek@fld.czu.cz
Simon, Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, 613 00 Brno, Czech Republic E-mail: jaroslav.simon@mendelu.cz
Remeš, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: remesj@email.cz
Hůnová, Czech Hydrometeorological Institute, Na Šabatce 17 143 06 Prague, Czech Republic E-mail: hunova@chmi.cz
Král, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: kraljan@fld.czu.cz
Putalová, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: putalova@fld.czu.cz
Mikeska, University of Hradec Králové, Faculty of Science, Rokitanského 62, 500 03 Hradec Králové, Czech Republic E-mail: Mikeska.Miroslav@uhul.cz

article id 1565, category Research article

Teija Ruuhola, Ari Nikula, Nivala Vesa, Seppo Nevalainen, Juho Matala. (2016). Effects of bedrock and surficial deposit composition on moose damage in young forest stands in Finnish Lapland. Silva Fennica vol. 50 no. 3 article id 1565. https://doi.org/10.14214/sf.1565

Keywords: Pinus sylvestris; plantation; Alces alces; soil; damage risk; topography; geochemistry

Highlights: The effect of bedrock and soil on moose damage in forest plantations were examined; Moose damage were concentrated in nutrient rich bedrock areas; Bedrock of damaged stands contained a higher proportion of mafic and alkaline rocks; Pine-dominated stands on fine grained fertile forest sites had the highest damage risk.

Abstract | Full text in HTML | Full text in PDF | Author Info

There is evidence that moose are attracted to fertile growth habitats apparently due to better quality and larger quantities of food. The nutrients in mineral soils originate from the weathering of bedrock and the composition of parental bedrock affects the fertility of produced mineral soil, thus affecting also the import of nutrients into the whole food web. We surveyed the connection between moose damage in forest plantations and the composition of bedrock and surficial deposits in Finnish Lapland. We used a database of compensated moose damage in private forests in years 1997−2010. Undamaged stands in National Forest Inventories (NFI) from years 1986–2008 served as a control data and moose-damaged NFI-stands as a reference data. Bedrock and surficial depositions and the location of studied stands in relation to ancient shorelines were explored by using the digital databases of the Geological Survey of Finland. Moose-damaged stands were concentrated in southwestern and east Lapland in the areas of the Peräpohja Schist Belt and Lapland’s Greenstone Belt that are both composed of nutrient-rich rocks. The bedrock of damaged stands contained a higher proportion of mafic and alkaline rocks than did the control stands. Moose-damaged stands were pine-dominated and grew in more fertile forest sites than did control stands. Part of pine stands probably located in soils formerly occupied by spruce, which may increase the stands’ vulnerability to biotic threats. Especially, there were relatively more moose damage in pine plantations regenerated on fine-grained mineral soils derived from nutrient rich rocks than in less fertile soils.

Ruuhola, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Yliopistokatu 6, FI-80101 Joensuu, Finland; University of Eastern Finland, Faculty of Science and Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: teija.ruuhola@uef.fi
Nikula, Natural Resources Institute Finland (Luke), Economics and Society, Eteläranta 55, FI-96300 Rovaniemi, Finland E-mail: ari.nikula@luke.fi
Vesa, Natural Resources Institute Finland (Luke), Economics and Society, Eteläranta 55, FI-96300 Rovaniemi, Finland E-mail: vesa.nivala@luke.fi
Nevalainen, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Yliopistokatu 6, FI-80101 Joensuu, Finland E-mail: seppo.nevalainen@luke.fi
Matala, Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, Yliopistokatu 6, FI-80101 Joensuu, Finland E-mail: juho.matala@luke.fi

article id 1562, category Research article

Mats Erik Berlin, Torgny Persson, Gunnar Jansson, Matti Haapanen, Seppo Ruotsalainen, Lars Bärring, Bengt Andersson Gull. (2016). Scots pine transfer effect models for growth and survival in Sweden and Finland. Silva Fennica vol. 50 no. 3 article id 1562. https://doi.org/10.14214/sf.1562

Keywords: Pinus sylvestris; adaptation; tree breeding; reaction patterns; forest regeneration material

Highlights: Scots pine transfer effect models for growth and survival, valid in both Sweden and Finland have been developed; The models use high-resolution gridded climate data and can predict performance in future climatic conditions; The models perform well both for unimproved and genetically improved material and can be used to develop deployment recommendations of contemporary forest regeneration material in Sweden and Finland.

Abstract | Full text in HTML | Full text in PDF | Author Info

In this study, we developed models of transfer effects for growth and survival of Scots pine (Pinus sylvestris L.) in Sweden and Finland using a general linear mixed-model approach. For model development, we used 378 provenance and progeny trials with a total of 276 unimproved genetic entries (provenances and stand seed check-lots) distributed over a wide variety of climatic conditions in both countries. In addition, we used 119 progeny trials with 3921 selected genetic entries (open- and control pollinated plus-tree families) for testing model performance. As explanatory variables, both climatic indices derived from high-resolution gridded climate datasets and geographical variables were used. For transfer, latitude (photoperiod) and, for describing the site, temperature sum were found to be main drivers for both survival and growth. In addition, interaction terms (between transfer in latitude and site altitude for survival, and transfer in latitude and temperature sum for growth) entail changed reaction patterns of the models depending on climatic conditions of the growing site. The new models behave in a way that corresponds well to previous studies and recommendations for both countries. The model performance was tested using selected plus-trees from open and control pollinated progeny tests. Results imply that the models are valid for both countries and perform well also for genetically improved material. These models are the first step in developing common deployment recommendations for genetically improved forest regeneration material in both Sweden and Finland.

Berlin, Uppsala Science Park, SE-75183 Uppsala, Sweden E-mail: mats.berlin@skogforsk.se
Persson, Skogforsk, Box 3, SE-91821 Sävar, Sweden E-mail: torgny.persson@skogforsk.se
Jansson, Uppsala Science Park, SE-75183 Uppsala, Sweden E-mail: gunnar.jansson@skogforsk.se
Haapanen, Natural Resources Institute Finland (Luke), Green Technology, Box 18, FI-01301 Vantaa, Finland E-mail: matti.haapanen@luke.fi
Ruotsalainen, Natural Resources Institute Finland (Luke), Green Technology, Finlandiantie 18, FI-58450 Punkaharju, Finland E-mail: seppo.ruotsalainen@luke.fi
Bärring, Rossby Centre, Swedish Meteorological and Hydrological Institute, Folkborgsvägen 17, SE-60176 Norrköping, Sweden E-mail: lars.barring@smhi.se
Andersson Gull, Skogforsk, Box 3, SE-91821 Sävar, Sweden E-mail: bengt.andersson@skogforsk.se

article id 1560, category Research article

Marina Gurskaya, Pavel Moiseev, Martin Wilmking. (2016). Does slope exposure affect frost ring formation in Picea obovata growing at treeline in the Southern Urals? Silva Fennica vol. 50 no. 3 article id 1560. https://doi.org/10.14214/sf.1560

Keywords: tree line; topography; frost injury; Siberian spruce

Highlights: Frost ring formation was ubiquitous from continuous forest cover to treeline, but, surprisingly, was not affected by slope exposure; Late frosts in spring were the main cause for frost ring formation; While mainly young trees (< 30 years) recorded frost events, at the climatically harshest site (highest elevation, northeastern exposure), frost events were recorded also in trees older than 70 years.

Abstract | Full text in HTML | Full text in PDF | Author Info

Topographic complexity in mountainous ecosystems strongly influences plant growth and as such also wood formation. This wood formation can possibly be used to understand topographic variation of the main climatic drivers, e.g. by modulating frost events. Here we test the influence of different slope exposures on the spatio-temporal distribution of frost rings in Siberian spruce (Picea obovata Ledeb.) in the Southern Urals, Russia. We sampled on two opposite slopes, northeast (NE) and southwest (SW), on three elevation levels from the highest single trees to closed canopy forest and analysed frost ring occurrence and their seasonal timing. Frost ring formation at all exposure-elevation combinations was common and mainly concentrated in the early part of the growing season. The age until trees record frost rings was equally similar (until about 35 years) on both slopes and different elevational levels with the exception of the climatically harshest site, the highest elevation on the NE slope. While we could not deduce a direct, easily identifiable climatic driver for the formation of frost rings, our analysis shows high potential to disentangle the complex interplay between climate, site condition and tree growth in mountainous ecosystems.

Gurskaya, Institute of Plant and Animal Ecology (IPAE), Ural Branch of Russian Academy of Sciences , 8 Marta St. 202, 620144 Ekaterinburg, Russia E-mail: mgurskaya@yandex.ru
Moiseev, Institute of Plant and Animal Ecology (IPAE), Ural Branch of Russian Academy of Sciences , 8 Marta St. 202, 620144 Ekaterinburg, Russia E-mail: moiseev@ipae.uran.ru
Wilmking, Institute of Botany and Landscape Ecology, Soldmanstrasse 15, Ernst-Moritz-Arndt-University Greifswald, 17487 Greifswald, Germany E-mail: wilmking@uni-greifswald.de

article id 1461, category Research article

Ludmila Novitskaya, Nadezhda Nikolaeva, Natalia Galibina, Tatiana Tarelkina, Ludmila Semenova. (2016). The greatest density of parenchyma inclusions in Karelian birch wood occurs at confluences of phloem flows. Silva Fennica vol. 50 no. 3 article id 1461. https://doi.org/10.14214/sf.1461

Keywords: Betula pendula; patterned wood; parenchyma; branch attachments; forks; sucrose content

Highlights: Dark-colored inclusions creating the figured pattern in Karelian birch wood consist of storage parenchyma cells; Their greatest density is formed above branch attachments and below forks; In these zones, the sucrose content is elevated since photoassimilate flows of the trunk and branches merge into one pathway; A high level of sucrose enhances the differentiation of parenchyma cells.

Abstract | Full text in HTML | Full text in PDF | Author Info

The specific pattern of the wood of Karelian birch (Betula pendula Roth var. carelica (Merckl.) Hämet-Ahti), is created mainly by dark-coloured inclusions of parenchyma tissue. Our study revealed that the greatest density of parenchyma inclusions in Karelian birch wood is observed above branch attachments to the trunk and below forks. In the place of branch attachment, phloem flows of photoassimilates (sucrose) from the branch and along the trunk merge into one pathway, causing a rise in sucrose content in tissues there. In the area below the fork, sucrose flows from two (or more) trunk axes are combined. Many studies have demonstrated that elevated sucrose level is associated with the differentiation of parenchyma. We believe that where large phloem fluxes merge a high level of sucrose promotes mass differentiation of parenchyma cells instead of fibers and vessels. As a result, the density of the figured pattern in the wood increases. The obtained data have a practical value and can be used in developing recommendations for Karelian birch cultivation.

Novitskaya, Forest Research Institute, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya str. 11, 185910, Petrozavodsk, Russia E-mail: ludnovits@rambler.ru
Nikolaeva, Forest Research Institute, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya str. 11, 185910, Petrozavodsk, Russia E-mail: kar-birch@mail.ru
Galibina, Forest Research Institute, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya str. 11, 185910, Petrozavodsk, Russia E-mail: galibina@krc.karelia.ru
Tarelkina, Forest Research Institute, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya str. 11, 185910, Petrozavodsk, Russia E-mail: karelina.t.v@gmail.com
Semenova, Forest Research Institute, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya str. 11, 185910, Petrozavodsk, Russia E-mail: mi7enova@gmail.com

article id 1441, category Research article

Dorota Zawadzka, Stanisław Drozdowski, Grzegorz Zawadzki, Jerzy Zawadzki. (2016). The availability of cavity trees along an age gradient in fresh pine forests. Silva Fennica vol. 50 no. 3 article id 1441. https://doi.org/10.14214/sf.1441

Keywords: Pinus sylvestris; forest management; Poland; Augustów Forest; cavity-nesting birds; woodpeckers

Highlights: The density of cavity trees in pine-dominated, managed forests varied in relation to stand age and was highest in stands older than 130 years of age; Cavities excavated by woodpeckers dominated among all cavities; The number of trees with cavities appears insufficient to ensure the effective protection of bird diversity in managed stands of Augustów Forest.

Abstract | Full text in HTML | Full text in PDF | Author Info

Given their importance as a resource for many forest organisms, tree cavities were inventoried in the managed pine forests of north-east Poland, in relation to the: 70–100, 101–130 and >130 year age-classes within the clear-cutting system. The densities at which cavities were present was found to depend on forest age, given that stands 70–100 years old were characterised by an average density of 0.62 trees ha^–1, while forests older than 130 years reported 3.28 trees ha^–1. Stands aged 70–100 years differed from those aged 130+ in having just 0.27 trees ha^–1 of cavity trees, as compared with 2.91 trees ha^–1. The total volume of cavity trees in stands up to 100 years old was 0.37 m³ha^–1on average, as compared with 5.42 m³ha^–1 in stands over 130 years old. The cavities created by woodpeckers constituted 76% of all of those found, and included 53% excavated by great spotted woodpeckers (Dendrocopos major L.) and 23% by black woodpeckers (Dryocopus martius L.) The proportion of cavities excavated by D. major was highest in the youngest age class of stands. There, cavities made by D. martius constituted only 8% of the total, as compared with 31% in the oldest stands. The abundance of cavity trees thus differed along an age gradient, though in any event the availability of cavity trees appears to be too limited to provide for the needs of hole-nesting birds. Forest managers must thus take more account than hitherto of the need to protect cavity trees.

Zawadzka, Institute of Forest Science, University of Łódź, Branch in Tomaszów Mazowiecki, Konstytucji 3 Maja 65/67, 97-200 Tomaszów Mazowiecki, Poland E-mail: dorota_zaw@wp.pl
Drozdowski, Department of Silviculture, Warsaw University of Life Sciences - SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland E-mail: stanislaw_drozdowski@sggw.pl
Zawadzki, Eagle Conservation Committee, Okółek 14, 16-506 Giby, Poland E-mail: grzesiekgfz@op.pl
Zawadzki, Eagle Conservation Committee, Okółek 14, 16-506 Giby, Poland E-mail: jerzy_zaw@wp.pl

article id 1521, category Research article

Kalle Karttunen, Juha Laitila, Tapio Ranta. (2016). First-thinning harvesting alternatives for industrial or energy purposes based on regional Scots pine stand simulations in Finland. Silva Fennica vol. 50 no. 2 article id 1521. https://doi.org/10.14214/sf.1521

Keywords: harvesting; energy wood; stand simulation; stumpage price; small-diameter wood

Highlights: Small-diameter delimbed wood from Scots pine stands delivered directly for energy use was the most cost-efficient option in terms of the total supply-chain cost in comparison with corresponding industrial use or a whole-tree supply chain for energy use; Forest-management and harvesting decisions influenced the removal of forest biomass and stumpage price as well as the total supply-chain costs for forest biomass; The greatest cost-reduction potential (10.0%, 4.00 € m^–3) was achieved for the delimbed energy wood’s supply chain in the regional case of South Savo in eastern Finland.

Abstract | Full text in HTML | Full text in PDF | Author Info

Combining research into forest management stand conditions and wood supply chain processes has been missing from earlier forestry studies. There is a clear need to develop more cost-efficient small-diameter wood production, harvesting and transportation methods from first thinning, which could be used for either industrial or energy wood purposes. This study considers the total cost for small-diameter wood originating from young Scots pine (Pinus sylvestris L.) dominated stands. Pine pulpwood is the most harvested and most used roundwood assortment, use of which is expected to rise following new pulp-mill investments in Finland. In addition, utilisation of small-diameter trees directly for energy purposes has been increasing steadily in recent years. The aim of the study was to determine the cost-reduction potential of alternative forest management options and supply chains for small diameter-wood in the regional case of South Savo in eastern Finland. The total costs of three distinct scenarios were studied on the basis of forest management, first-thinning harvesting methods, and transportation: 1) industrial wood, 2) delimbed energy wood, and 3) whole trees for energy purposes. The cost-reduction potential for energy-wood supply chains from first thinning was compared to the industrial supply chain. Small-diameter delimbed wood delivered straight for energy purposes was found to be the most cost-efficient as far as the total cost of the supply chain is concerned. More cost-efficient small-diameter wood processes can be found by linking forest stand simulations with supply chain analysis.

Karttunen, Lappeenranta University of Technology, LUT School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland E-mail: kalle.karttunen@lut.fi
Laitila, Natural Resources Institute Finland (Luke), Bio-based business and industry, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: juha.laitila@luke.fi
Ranta, Lappeenranta University of Technology, LUT School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland E-mail: tapio.ranta@lut.fi

article id 1495, category Research article

Per-Ola Olsson, Tuula Kantola, Päivi Lyytikäinen-Saarenmaa, Anna Maria Jönsson, Lars Eklundh. (2016). Development of a method for monitoring of insect induced forest defoliation – limitation of MODIS data in Fennoscandian forest landscapes. Silva Fennica vol. 50 no. 2 article id 1495. https://doi.org/10.14214/sf.1495

Keywords: remote sensing; insect defoliation detection; coarse-resolution; EVI2; z-score; Sentinel-2

Highlights: We developed and tested a method to monitor insect induced defoliation in forests based on coarse-resolution satellite data (MODIS); MODIS data may fail to detect defoliation in fragmented landscapes, especially if defoliation history is long. More homogenous forests results in higher detection accuracies; The method may be applied to future coarse and medium-resolution satellite data with high temporal resolution.

Abstract | Full text in HTML | Full text in PDF | Author Info

We investigated if coarse-resolution satellite data from the MODIS sensor can be used for regional monitoring of insect disturbances in Fennoscandia. A damage detection method based on z-scores of seasonal maximums of the 2-band Enhanced Vegetation Index (EVI2) was developed. Time-series smoothing was applied and Receiver Operating Characteristics graphs were used for optimisation. The method was developed in fragmented and heavily managed forests in eastern Finland dominated by Scots pine (Pinus sylvestris L.) (pinaceae) and with defoliation of European pine sawfly (Neodiprion sertifer Geoffr.) (Hymenoptera: Diprionidae) and common pine sawfly (Diprion pini L.) (Hymenoptera: Diprionidae). The method was also applied to subalpine mountain birch (Betula pubescens ssp. Czerepanovii N.I. Orlova) forests in northern Sweden, infested by autumnal moth (Epirrita autumnata Borkhausen) and winter moth (Operophtera brumata L.). In Finland, detection accuracies were fairly low with 50% of the damaged stands detected, and a misclassification of healthy stands of 22%. In areas with long outbreak histories the method resulted in extensive misclassification. In northern Sweden accuracies were higher, with 75% of the damage detected and a misclassification of healthy samples of 19%. Our results indicate that MODIS data may fail to detect damage in fragmented forests, particularly when the damage history is long. Therefore, regional studies based on these data may underestimate defoliation. However, the method yielded accurate results in homogeneous forest ecosystems and when long-enough periods without damage could be identified. Furthermore, the method is likely to be useful for insect disturbance detection using future medium-resolution data, e.g. from Sentinel‑2.

Olsson, Lund University, Department of Physical Geography and Ecosystem Science, Sölvegatan 12, S-223 62 Lund, Sweden E-mail: per-ola.olsson@nateko.lu.se
Kantola, Texas A & M University, Knowledge Engineering Laboratory, Department of Entomology, College Station, TX, USA E-mail: tuula.kantola@helsinki.fi
Lyytikäinen-Saarenmaa, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: paivi.lyytikainen-saarenmaa@helsinki.fi
Jönsson, Lund University, Department of Physical Geography and Ecosystem Science, Sölvegatan 12, S-223 62 Lund, Sweden E-mail: anna_maria.jonsson@nateko.lu.se
Eklundh, Lund University, Department of Physical Geography and Ecosystem Science, Sölvegatan 12, S-223 62 Lund, Sweden E-mail: lars.eklundh@nateko.lu.se

article id 1475, category Research article

Jiaxi Wang, Haiqun Yu, Guolei Li, Feng Zhang. (2016). Growth and nutrient dynamics of transplanted Quercus variabilis seedlings as influenced by pre-hardening and fall fertilization. Silva Fennica vol. 50 no. 2 article id 1475. https://doi.org/10.14214/sf.1475

Keywords: nutrient loading; nutrient storage; nursery transplanting; seedling quality

Highlights: High pre-hardening fertilization favored seedling growth and nutrient storage at the rapid growth and hardening phases following transplantation. Overall, high fall fertilization was beneficial only at the hardening phase; The combination of 100 mg N seedling^–1 during pre-hardening with 36 mg N seedling^–1 during hardening was recommended for satisfactory transplanting performance for Quercus variabilis.

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Stored nutrient reserves are closely correlated with survival and growth of transplanted seedlings. Previous studies have proven that combining pre-hardening fertilization (PF) with fall fertilization (FF) built seedling nutrient reserves more effectively; however, their effect on transplanting performance is poorly documented. We investigated the independent and interacting effects of 2 levels of PF and 4 levels of FF on seedling growth, nutrient acquisition and accumulation during different growth phases 1 year after transplanting of Quercus variabilis Blume in a nursery. High PF benefited nutrient reserves and subsequent transplanted seedling growth and tissue nutrient storage at the end of the rapid growth and hardening phases. Fall fertilization with 36 mg N increased stem dry mass and tissue nutrient content at the end of the hardening phase. At the conclusion of establishment, PF and FF showed a significant interaction for N and K uptake from soil. At the end of the rapid growth and hardening phases, high PF consistently increased nutrient uptake. Enhanced N and K uptake occurred following application of 36 mg N of FF at the end of the hardening phase. Distinct roles for PF and FF on 3 phases of transplanted seedlings demonstrated the necessity to evaluate fertilization in terms of nutrient reserves and subsequent transplanting performance in consecutive phases. Combining 100 mg N seedling^–1 during pre-hardening with 36 mg N seedling^–1 during fall yielded ideal transplanting performance for Quercus variabilis seedlings.

Wang, Key Laboratory for Silviculture and Conservation, Ministry of Education; Beijing Laboratory of Urban and Rural Ecological Environment, Beijing Forestry University, 35 East Qinghua Road, Haidian District, Beijing 100083, China E-mail: wjx198979@163.com
Yu, Beijing Forestry Carbon Administration, room 201, No.1 Xiao Huang Zhuang Bei Jie, Dongcheng District, Beijing 100013, China E-mail: yuhq@bfdic.com
Li, Key Laboratory for Silviculture and Conservation, Ministry of Education; Beijing Laboratory of Urban and Rural Ecological Environment, Beijing Forestry University, 35 East Qinghua Road, Haidian District, Beijing 100083, China E-mail: glli226@163.com
Zhang, Beijing Forestry Carbon Administration, room 201, No.1 Xiao Huang Zhuang Bei Jie, Dongcheng District, Beijing 100013, China E-mail: zhangf@bfdic.com

article id 1448, category Research article

Andrew McEwan, Natascia Magagnotti, Raffaele Spinelli. (2016). The effects of number of stems per stool on cutting productivity in coppiced Eucalyptus plantations. Silva Fennica vol. 50 no. 2 article id 1448. https://doi.org/10.14214/sf.1448

Keywords: modeling; logging; short rotation forestry; efficiency; operator effect

Highlights: Double- and single stem coppice stools were harvested mechanically; Stem size had the strongest impact on productivity; An experienced operator performed equally well with both stool treatments; Cost was ~10% higher with double stems for the less experienced operator; Operator experience may play a major role when cutting coppice stands.

Abstract | Full text in HTML | Full text in PDF | Author Info

A time study was conducted to determine whether stem crowding had any impact on harvester productivity in Eucalyptus grandis stands. This represents an important element when trying to balance the advantages and disadvantages of coppice management in fast growing plantations designated for mechanized harvesting (i.e. machine felling, delimbing, debarking and cross-cutting). The study material consisted of 446 coppice stems, half of which grew as single stems per stool and half as double stems per stool as a result of different coppice reduction strategies. The dataset was balanced and randomized, with both subsets replicating exactly the same stem size distribution and the single and double stems alternating randomly. Harvester productivity ranged between 6 and 50 m³ under bark per productive machine hour, following the variation of tree diameter from 10 to 40 cm at breast height (1.37 m according to South African standards). Regression analysis indicated that both tree size and stem crowding (e.g. one or two stems per stool) had a significant effect on harvester productivity, which increased with stem size and decreased with stem crowding. However, operator experience may overcome the effect of stem crowding, which was not significant when the harvester was manned by a highly experienced operator. In any case, the effect of stem size was much greater than that of stem crowding, which resulted in a cost difference of less than 10%. However, this figure excludes the possible effects of stem crowding on volume recovery and stem development, which should be addressed in the future.

McEwan, Nelson Mandela Metropolitan University – George Campus, Saasveld, 6529, George, South Africa E-mail: Andrew.McEwan@nmmu.ac.za
Magagnotti, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (FI), Italy E-mail: magagnotti@ivalsa.cnr.it
Spinelli, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (FI), Italy E-mail: spinelli@ivalsa.cnr.it

article id 1414, category Research article

Rami Saad, Jörgen Wallerman, Johan Holmgren, Tomas Lämås. (2016). Local pivotal method sampling design combined with micro stands utilizing airborne laser scanning data in a long term forest management planning setting. Silva Fennica vol. 50 no. 2 article id 1414. https://doi.org/10.14214/sf.1414

Keywords: LIDAR; forest management planning; local pivotal method (LPM); segmentation; most similar neighbor (MSN) imputation; suboptimal loss; Heureka; decision support system

Highlights: Most similar neighbor imputation was used to estimate forest variables using airborne laser scanning data as auxiliary data; For selecting field reference plots the local pivotal method (LPM) was compared to systematic sampling design; The LPM sampling design combined with a micro stand approach showed potential for improvement and has the potential to be a competitive method when considering cost efficiency.

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A new sampling design, the local pivotal method (LPM), was combined with the micro stand approach and compared with the traditional systematic sampling design for estimation of forest stand variables. The LPM uses the distance between units in an auxiliary space – in this case airborne laser scanning (ALS) data – to obtain a well-spread sample. Two sets of reference plots were acquired by the two sampling designs and used for imputing data to evaluation plots. The first set of reference plots, acquired by LPM, made up four imputation alternatives (varying number of reference plots) and the second set of reference plots, acquired by systematic sampling design, made up two alternatives (varying plot radius). The forest variables in these alternatives were estimated using the nonparametric method of most similar neighbor imputation, with the ALS data used as auxiliary data. The relative root mean square error (RelRMSE), stem diameter distribution error index and suboptimal loss were calculated for each alternative, but the results showed that neither sampling design, i.e. LPM vs. systematic, offered clear advantages over the other. It is likely that the obtained results were a consequence of the small evaluation dataset used in the study (n = 30). Nevertheless, the LPM sampling design combined with the micro stand approach showed potential for improvement and might be a competitive method when considering the cost efficiency.

Saad, Swedish University of Agricultural Sciences (SLU), Department of Forest Resource Management, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: rami.saad@slu.se
Wallerman, Swedish University of Agricultural Sciences (SLU), Department of Forest Resource Management, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: jorgen.wallerman@slu.se
Holmgren, Swedish University of Agricultural Sciences (SLU), Department of Forest Resource Management, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: johan.holmgren@slu.se
Lämås, Swedish University of Agricultural Sciences (SLU), Department of Forest Resource Management, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: tomas.lamas@slu.se

article id 1410, category Research article

Seppo Nevalainen, Juho Matala, Kari T. Korhonen, Antti Ihalainen, Ari Nikula. (2016). Moose damage in National Forest Inventories (1986–2008) in Finland. Silva Fennica vol. 50 no. 2 article id 1410. https://doi.org/10.14214/sf.1410

Keywords: Populus tremula; Pinus sylvestris; regeneration; soil preparation; thinning; Betula spp.; Keywords Alces alces; seedling stands; tree species mixture

Highlights: Almost 100 000 stands were studied; The proportion of damage doubled during the study period; Tree species mixture had a clear effect on the damage frequency; The damage was more common in mineral soils than in peatlands, in artificially than in naturally regenerated stands and in stands that needed thinning or clearing or in which soil preparation was used.

Abstract | Full text in HTML | Full text in PDF | Author Info

The occurrence of moose damage was studied using data from three National Forest Inventories (NFIs) accomplished between 1986 and 2008 in Finland. The combined data included a total of 97 390 young stands. The proportion of moose damage increased from 3.6% to 8.6% between the 8th NFI (1986–1994) and the 10th NFI (2004–2008). The majority (75%) of the damage occurred in Scots pine-dominated stands. The proportion of damage was higher in aspen-dominated stands than in stands dominated by any other tree species. The tree species mixture also had a clear effect on the occurrence of damage. Pure Scots pine stands had less damage than mixed Scots pine stands, and moose damage decreased linearly with the increasing proportion of Scots pine. Stands on mineral soil had more frequent moose damage than stands on peatlands. The fertility class of the site had no straightforward effect on the damage frequency. Artificially regenerated stands had more damage than naturally regenerated stands. Accomplished soil preparation measures and the need for thinning or clearing operations increased moose damage. High proportions of moose damage in young stands were found around the country. In the 10th NFI, the largest concentration of damage was found in southwestern Finland. Our study shows the temporal and spatial changes in the occurrence of moose damage and pinpoints some important silvicultural factors affecting the relative risk of young stands over a large geographical area.

Nevalainen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: seppo.nevalainen@luke.fi
Matala, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: juho.matala@luke.fi
Korhonen, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: kari.t.korhonen@luke.fi
Ihalainen, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: antti.ihalainen@luke.fi
Nikula, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: ari.nikula@luke.fi

article id 1442, category Research article

Silva Šēnhofa, Mārtiņš Zeps, Roberts Matisons, Jānis Smilga, Dagnija Lazdiņa, Āris Jansons. (2015). Effect of climatic factors on tree-ring width of Populus hybrids in Latvia. Silva Fennica vol. 50 no. 1 article id 1442. https://doi.org/10.14214/sf.1442

Keywords: dendroclimatology; hybrid aspen; hybrid poplar; fast-growing hybrids; weather conditions

Highlights: Hybrid poplar and hybrid aspen were sensitive to temperature in summer and dormant periods, but none of the tested factors were strictly limiting; Hybrid poplar was sensitive to a higher number of climatic factors than hybrid aspen; Temperature showed a negative correlation with tree-ring width.

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Fast-growing hybrids of Populus L. have an increasing importance as a source of renewable energy and as industrial wood. Nevertheless, the long-term sensitivity of Populus hybrids to weather conditions and hence to possible climatic hazards in Northern Europe have been insufficiently studied, likely due to the limited age of the trees (short rotation). In this study, the climatic sensitivity of ca. 65-year-old hybrid poplars (Populus balsamifera L. × P. laurifolia Ledeb.), growing at two sites in the western part of Latvia, and ca. 55-year-old hybrid aspens (Populus tremuloides Michx. × P. tremula L.), growing in the eastern part of Latvia, have been studied using classical dendrochronological techniques. The high-frequency variation of tree-ring width (TRW) of hybrid poplar from both sites was similar, but it differed from hybrid aspen due to the diverse parental species and geographic location of the stands. Nevertheless, some common tendencies in TRW were observed for both hybrids. Climatic factors influencing TRW were generally similar for both hybrids, but their composition differed. The strength of climate-TRW relationships was similar, but the hybrid poplar was affected by a higher number of climatic factors. Hybrid poplar was sensitive to factors related to water deficit in late summer in the previous and current years. Hybrid aspen was sensitive to conditions in the year of formation of tree-ring. Both hybrids also displayed a reaction to temperature during the dormant period. The observed climate-growth relationships suggest that increasing temperatures might burden the radial growth of the studied hybrids of Populus.

Šēnhofa, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: silva.senhofa@gmail.com
Zeps, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: martins.zeps@silava.lv
Matisons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
Smilga, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: janis.smilga@silava.lv
Lazdiņa, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: dagnija.lazdina@silava.lv
Jansons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv

article id 1428, category Research article

Gernot Erber, Franz Holzleitner, Maximilian Kastner, Karl Stampfer. (2015). Effect of multi-tree handling and tree-size on harvester performance in small-diameter hardwood thinnings. Silva Fennica vol. 50 no. 1 article id 1428. https://doi.org/10.14214/sf.1428

Keywords: productivity; thinning; energy wood; motor-manual; accumulating harvester head; delimbing

Highlights: Harvesting with the accumulating energy wood head EF28 was studied under small tree dimension (8 dm³) in hardwood thinnings; Reasonable productivity was achieved; Maximum achieved cutting diameter in hornbeam stand was 23 cm and 15% lower than in softwood stands; Head has potential under such conditions.

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Early thinnings are laborious and costly. Thus forest companies are searching for cost and time efficient ways to carry out this task. The study’s purpose was to determine the productivity of the EF28 accumulating energy wood harvesting head in harvesting small-diameter hornbeam (Carpinus betulus L.) undergrowth trees and evaluate the effect of its multi-tree handling (MTH) capacity on time consumption. The harvester was a wheeled, three-axle Komatsu 911. A time study of 7.1 hours on 19 plots, with a total area of 0.76 ha was conducted. On average, the harvested tree volume was 8 dm³ and the stand density was 2666 trees/ha. The productivity was modelled with MTH conduction, mean diameter at breast height and the number of trees handled per cycle as independent variables. On average, MTH took 27% longer per cycle, increased extracted volume per cycle by 33% and consequently increased productivity with 5.0%. In 71.9% of the cycles more than one tree was handled and if so, dimensions were smaller than in single-tree handling (5.8 cm vs. 12.0 cm). Maximum felling diameter of 23 cm was about 15% smaller than in softwood (according to the manufacturer’s specifications) and the driver didn’t exploit the EF28’s theoretical potential in terms of trees handled per cycle. It can be concluded that the head could significantly improve productivity in small-diameter wood procurement.

Erber, Addresses University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, Institute of Forest Engineering, Peter-Jordan Straße 82/3, A-1190 Vienna, Austria E-mail: gernot.erber@boku.ac.at
Holzleitner, Addresses University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, Institute of Forest Engineering, Peter-Jordan Straße 82/3, A-1190 Vienna, Austria E-mail: franz.holzleitner@boku.ac.at
Kastner, Addresses University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, Institute of Forest Engineering, Peter-Jordan Straße 82/3, A-1190 Vienna, Austria E-mail: maximilian.kastner@boku.ac.at
Stampfer, Addresses University of Natural Resources and Life Sciences Vienna, Department of Forest and Soil Sciences, Institute of Forest Engineering, Peter-Jordan Straße 82/3, A-1190 Vienna, Austria E-mail: karl.stampfer@boku.ac.at

article id 1384, category Research article

Staffan Berg, Erik Valinger, Torgny Lind, Tommi Suominen, Diana Tuomasjukka. (2015). Comparison of co-existing forestry and reindeer husbandry value chains in northern Sweden. Silva Fennica vol. 50 no. 1 article id 1384. https://doi.org/10.14214/sf.1384

Keywords: carbon sequestration; agroforestry; global warming potential; gross value added; employment; ToSIA

Highlights: Forestry adapted to reindeer husbandry results in: potential economic improvement of reindeer husbandry, potential reduced cuttings in forestry and reduced wood flow to industry, reduced gross value added for forest industry and increased carbon storage in standing forest.

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Forestry in Malå, northern Sweden, coexists with other land uses. Reindeer husbandry is in the area for centuries and requires large areas of grazing land. Competing land uses may threaten the Malå Sami village. The aim of the study was to evaluate increased consideration in forest management towards 1) reindeer husbandry, 2) nature and 3) a combination of the two. These scenarios were compared with forest management as it was in 2009. Results indicate that all three scenarios lead to a decrease in annual harvesting volumes of 0.2 to 0.4 million m³. Forest industry dominated the economic viability in the area. Forest management adapted to the needs of reindeer husbandry resulted in less potential for yearly harvest, employment and profits from forest industry. On the other hand, it led to an increase in growing stock and consequently the potential for carbon sequestration over time. Indeed the increased sequestration would compensate for all fossil emissions of carbon from the Forest Wood Chain (FWC). The nature scenario had minor effects on economic result and on the emissions of fossil carbon. The combined scenario gave a reduced economic performance for the FWC. A scenario based on forest management accommodating the needs of reindeer husbandry gave the best economic result for the reindeer chain, due to high survival rate of the reindeer. However the economic importance of reindeer husbandry in the region was small compared to the FWC. Results from scenario analysis could serve as a platform for mutual understanding between stakeholders.

Berg, Swedish University of Agricultural Sciences (SLU), Department of Forest Ecology and Management, Skogsmarksgränd, SE-90 183 Umeå, Sweden E-mail: staffan.berg@efi.int
Valinger, Swedish University of Agricultural Sciences (SLU), Department of Forest Ecology and Management, Skogsmarksgränd, SE-90 183 Umeå, Sweden E-mail: erik.valinger@slu.se
Lind, Swedish University of Agricultural Sciences (SLU), Department of Forest Resource Management, Skogsmarksgränd, SE-90 183 Umeå, Sweden E-mail: torgny.lind@slu.se
Suominen, European Forest Institute, Sustainability and Climate Change Research Programme, Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: tommi.suominen@efi.int
Tuomasjukka, European Forest Institute, Sustainability and Climate Change Research Programme, Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: diana.tuomasjukka@efi.int

article id 1348, category Research article

Sakari Tuominen, Andras Balazs, Heikki Saari, Ilkka Pölönen, Janne Sarkeala, Risto Viitala. (2015). Unmanned aerial system imagery and photogrammetric canopy height data in area-based estimation of forest variables. Silva Fennica vol. 49 no. 5 article id 1348. https://doi.org/10.14214/sf.1348

Keywords: forest inventory; aerial imagery; unmanned aerial system; UAV; photogrammetric surface model; canopy height model

Highlights: Orthoimage mosaic and 3D canopy height model were derived from UAV-borne colour-infrared digital camera imagery and ALS-based terrain model; Features extracted from orthomosaic and canopy height data were used for estimating forest variables; The accuracy of forest estimates was similar to that of the combination of ALS and digital aerial imagery.

Abstract | Full text in HTML | Full text in PDF | Author Info

In this paper we examine the feasibility of data from unmanned aerial vehicle (UAV)-borne aerial imagery in stand-level forest inventory. As airborne sensor platforms, UAVs offer advantages cost and flexibility over traditional manned aircraft in forest remote sensing applications in small areas, but they lack range and endurance in larger areas. On the other hand, advances in the processing of digital stereo photography make it possible to produce three-dimensional (3D) forest canopy data on the basis of images acquired using simple lightweight digital camera sensors. In this study, an aerial image orthomosaic and 3D photogrammetric canopy height data were derived from the images acquired by a UAV-borne camera sensor. Laser-based digital terrain model was applied for estimating ground elevation. Features extracted from orthoimages and 3D canopy height data were used to estimate forest variables of sample plots. K-nearest neighbor method was used in the estimation, and a genetic algorithm was applied for selecting an appropriate set of features for the estimation task. Among the selected features, 3D canopy features were given the greatest weight in the estimation supplemented by textural image features. Spectral aerial photograph features were given very low weight in the selected feature set. The accuracy of the forest estimates based on a combination of photogrammetric 3D data and orthoimagery from UAV-borne aerial imaging was at a similar level to those based on airborne laser scanning data and aerial imagery acquired using purpose-built aerial camera from the same study area.

Tuominen, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: sakari.tuominen@luke.fi
Balazs, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: andras.balazs@luke.fi
Saari, VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Finland E-mail: Heikki.Saari@vtt.fi
Pölönen, University of Jyväskylä, Department of Mathematical Information Technology, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: ilkka.polonen@jyu.fi
Sarkeala, Mosaicmill Oy, Kultarikontie 1, FI-01300 Vantaa, Finland E-mail: janne.sarkeala@mosaicmill.com
Viitala, Häme University of Applied Sciences (HAMK), P.O. Box 230, FI-13101 Hämeenlinna, Finland E-mail: Risto.Viitala@hamk.fi

article id 1340, category Research article

Mostafa Farhadi, Mulualem Tigabu, Per Christer Odén. (2015). Near Infrared Spectroscopy as non-destructive method for sorting viable, petrified and empty seeds of Larix sibirica. Silva Fennica vol. 49 no. 5 article id 1340. https://doi.org/10.14214/sf.1340

Keywords: larch; NIRS; OPLS; precision sowing; seed sorting; seed quality

Highlights: Near Infrared spectroscopy discriminates filled-viable, empty and petrified seeds of Larix sibirica with 98%, 82% and 87% accuracy, respectively based on spectral differences attributed to moisture and storage reserves; The classification accuracy reached 100% when sorting seeds into viable and non-viable class; The results demonstrate that NIR spectroscopy has great potential as non-destructive sorting technique to upgrade seed lot quality.

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Larix sibirica Ledeb. is one of the promising timber species for planting in the boreal ecosystem; but poor seed lot quality is the major hurdle for production of sufficient quantity of planting stocks. Here, we evaluated the potential of Near Infrared (NIR) Spectroscopy for sorting viable and non-viable seeds, as the conventional sorting technique is inefficient. NIR reflectance spectra were collected from single seeds, and discriminant models were developed with Orthogonal Projections to Latent Structure – Discriminant Analysis (OPLS-DA). The computed model predicted the class membership of filled-viable, empty and petrified seeds in the test set with 98%, 82% and 87% accuracy, respectively. When two-class OPLS-DA model was fitted to discriminate viable and non-viable (empty and petrified seeds combined), the predicted class membership of test set samples was 100% for both classes. The origins of spectral differences between non-viable (petrified and empty) and viable seeds were attributed to differences in seed moisture content and storage reserves. In conclusion, the result provides evidence that NIR spectroscopy is a powerful non-destructive method for sorting non-viable seeds of Larix sibirica; thus efforts should be made to develop on-line sorting system for large-scale seed handling.

Farhadi, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: mostafa.farhadi@slu.se
Tigabu, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: mulualem.tigabu@slu.se
Odén, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: per.oden@slu.se

article id 1328, category Research article

Nelly N. Selochnik, Nataliya V. Pashenova, Evgeny Sidorov, Michael J. Wingfield, Riikka Linnakoski. (2015). Ophiostomatoid fungi and their roles in Quercus robur die-back in Tellermann forest, Russia. Silva Fennica vol. 49 no. 5 article id 1328. https://doi.org/10.14214/sf.1328

Keywords: Ophiostomatales; Ophiostoma; oak die-back; pathogenicity

Highlights: Dominant ophiostomatoid fungi associated with Q. robur in the post-outbreak region of oak die-back were investigated; Ophiostoma quercus was the most commonly encountered fungus; This is the first report of O. grandicarpum from Russia; The results of preliminary pathogenicity experiments demonstrate that fungi investigated in this study are unlikely to play causal role in oak die-back

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Several eastern European countries have reported outbreaks of oak die-back during the 1980’s. Species of Ophiostoma Syd. were isolated from diseased trees and have been suggested to be the possible causal agents of the die-back, but this view have generally not been accepted. In order to monitor the post-outbreak region of oak die-back and to consider the possible role of Ophiostoma spp. in the syndrome, research has been conducted in the Tellerman forest, Voronezh region, Russia between 2005 and 2011. Our study resulted in the isolation of ophiostomatoid fungi from Quercus robur L. trees displaying external signs of desiccation. Fungi were identified based on morphological characteristics and DNA sequence comparisons. Three species of Ophiostoma were identified including O. grandicarpum (Kowalski & Butin) Rulamort, a species closely related to O. abietinum Marm. & Butin, O. fusiforme Aghayeva & M.J. Wingf. and O. lunatum Aghayeva & M.J. Wingf. representing a poorly understood species complex, and most commonly O. quercus (Georgev.) Nannf. Pathogenicity of these fungi was tested using artificial inoculations on Q. robur trees. The fungi were shown to be non-pathogenic and unlikely to play any role in oak die-back. These fungi are most likely only components in a complex of abiotic, biotic and anthropogenic factors that have contributed to a die-back of Quercus spp. in Russia.

Selochnik, Forest Science Institute of RAS, Uspenskoe 143030, Moscow Region, Russia E-mail: lenelse@yandex.ru
Pashenova, V.N. Sukachev Institute of Forest SB RAS, Krasnoyarsk 660036, Russia E-mail: pasnat@ksc.krasn.ru
Sidorov, Department of Forest Protection and Game Management, St. Petersburg State Forest Technical University, St. Petersburg 194021, Russia E-mail: sidorov_evgeny@mail.ru
Wingfield, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, 0002 Pretoria, South Africa E-mail: mike.wingfield@up.ac.za
Linnakoski, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, 0002 Pretoria, South Africa; Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland http://orcid.org/0000-0002-3294-8088 E-mail: riikka.linnakoski@helsinki.fi

article id 1310, category Research article

Deliang Lu, Jiaojun Zhu, Yirong Sun, Lile Hu, Guangqi Zhang. (2015). Gap closure process by lateral extension growth of canopy trees and its effect on woody species regeneration in a temperate secondary forest, Northeast China. Silva Fennica vol. 49 no. 5 article id 1310. https://doi.org/10.14214/sf.1310

Keywords: canopy closure; recruitment; canopy opening; opening size; crown expansion; duration; hemispherical photograph

Highlights: Gap closure process by lateral extension growth can be described by quadratic functions; Large gaps (514–621 m²) had higher closure rates but lower closure percentages compared with middle (174–321 m²) and small gaps (68–125 m²); Gaps promoted woody species regeneration in early stage; Large and middle gaps would provide opportunities for filling regeneration, but regeneration in small gaps may eventually fail.

Abstract | Full text in HTML | Full text in PDF | Author Info

Gap formation and its effects on regeneration have been reported as being important in forest development, but seldom studies concentrated on the gap closure process by lateral extension growth of canopy trees surrounding gaps. We monitored the closure process of 12 artificial gaps for 7 years with three size classes: small (from 68 m²to 125 m²), middle (from 174 m² to 321 m²), and large (from 514 m² to 621 m²); and investigated the regeneration twice in a temperate secondary forest, Northeast China. The closure process can be described through quadratic functions, which showed the closure rates slowed down with gap ages. Large gaps had a higher closure rate (39 m² a^–1) than middle gaps (25 m² a^–1) and small gaps (11 m² a^–1). According to the quadratic equations, the lateral growth could last 11, 13 and 16 years for small, middle and large gaps with a remaining size of 12, 69 and 223 m², respectively. As expected, regeneration exhibited the highest seedling density and volume in large gaps. There was no significant difference in regeneration density between middle gaps, small gaps and forest understory in the final investigation; but the volume of regenerated woody species increased significantly from small gaps to large gaps compared with forest understory. These results may provide references on the choice of appropriate gap sizes to promote the regeneration in temperate secondary forests.

Lu, State Key Laboratory of Forest and Soil Ecology, Qingyuan Forest CERN, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; University of Chinese Academy of Sciences, Beijing 100049, China E-mail: delianglu14@hotmail.com
Zhu, State Key Laboratory of Forest and Soil Ecology, Qingyuan Forest CERN, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China E-mail: jiaojunzhu@iae.ac.cn
Sun, State Key Laboratory of Forest and Soil Ecology, Qingyuan Forest CERN, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China E-mail: yirongsun@iae.ac.cn
Hu, Chinese Research Academy of Environmental Sciences, Beijing 100012, China E-mail: lilehu@gmail.com
Zhang, State Key Laboratory of Forest and Soil Ecology, Qingyuan Forest CERN, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; University of Chinese Academy of Sciences, Beijing 100049, China E-mail: zgq04713@163.com

article id 1391, category Research article

Roberts Matisons, Jānis Jansons, Juris Katrevičs, Āris Jansons. (2015). Relation of tree-ring width and earlywood vessel size of alien Quercus rubra L. with climatic factors in Latvia. Silva Fennica vol. 49 no. 4 article id 1391. https://doi.org/10.14214/sf.1391

Keywords: dendroclimatology; climate-growth relationships; introduced species; earlywood vessel lumen area; wood anatomy; shifting sensitivity

Highlights: Climate-growth relationships of red oak from three sites in Latvia were studied; Tree-ring width was mainly affected by temperature and precipitation in late summer; Vessel size was correlated with temperature parameters in autumn–spring; Sets of climatic factors significant for growth of red oak differed between sites; Changes in climate-growth relationships occurred during 20th century.

Abstract | Full text in HTML | Full text in PDF | Author Info

The effect of climatic factors on wood anatomy of the alien red oak (Quercus rubra L.) growing in three experimental plantations in Latvia was assessed by classical dendrochronological techniques. Two tree-ring proxies – tree-ring width (TRW) and mean area of earlywood vessel lumen (VLA) – were studied on 33 trees. Annual variation of TRW amongst trees was similar (mean r = 0.46), but there was more individuality in VLA (mean r = 0.26); nevertheless, chronologies of both proxies had rather synchronous variation amongst the sites. Annual variation of TRW was affected by factors related to water deficit in late summer, as suggested by the negative effect of temperature and positive effect of precipitation that have intensified during the 20th century, likely due to warming. Although weather conditions during the dormant period did not directly affect TRW, temperature during the autumn-spring period has been the main climatic determinant of VLA likely via influence on overwintering and hence vigour of tree. This suggests that conductive properties of wood and hence the susceptibility to water deficit have been affected by weather conditions before the formation of tree rings. During the 20th century, sensitivity of VLA has shifted from temperature in winter to temperature in autumn likely due to climate change. Still, the positive effect of these factors suggests that warming of climate would increase VLA and hence the risk of embolism and xylem disfunction. Therefore, the importance of availability of water for growth of red oak in Latvia is increasing.

Matisons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
Jansons, Latvian Forest Competence Centre, Dzērbenes str. 27, Riga, Latvia, LV 1006 E-mail: janis.jansons@silava.lv
Katrevičs, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: juris.katrevics@silava.lv
Jansons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv

article id 1326, category Research article

Joanna Bachmatiuk, Jordi Garcia-Gonzalo, Jose Guilherme Borges. (2015). Analysis of the performance of different implementations of a heuristic method to optimize forest harvest scheduling. Silva Fennica vol. 49 no. 4 article id 1326. https://doi.org/10.14214/sf.1326

Keywords: harvest scheduling; simulated annealing; heuristic; cooling schedule; initial temperature

Highlights: The number of treatment schedules available for each stand has an impact on the optimal configuration of opt-moves (i.e. number stands where the treatment schedule is changed in an iteration); Considering a large number of treatment schedules per stand, the one-opt move implementation is preferred, yet when considering a low number of decision choices the two-opt moves option performs better.

Abstract | Full text in HTML | Full text in PDF | Author Info

Finding an optimal solution of forest management scheduling problems with even flow constraints while addressing spatial concerns is not an easy task. Solving these combinatorial problems exactly with mixed-integer programming (MIP) methods may be infeasible or else involve excessive computational costs. This has prompted the use of heuristics. In this paper we analyze the performance of different implementations of the Simulated Annealing (SA) heuristic algorithm for solving three typical harvest scheduling problems. Typically SA consists of searching a better solution by changing one decision choice in each iteration. In forest planning this means that one treatment schedule in a single stand is changed in each iteration (i.e. one-opt move). We present a comparison of the performance of the typical implementation of SA with the new implementation where up to three decision choices are changed simultaneously in each iteration (i.e. treatment schedules are changed in more than one stand). This may allow avoiding local optimal. In addition, the impact of SA - parameters (i.e. cooling schedule and initial temperature) are tested. We compare our heuristic results with a MIP formulation. The study case is tested in a real forest with 1000 stands and a total of 213116 decision choices. The study shows that when the combinatorial problem is very large, changing simultaneously the treatment schedule in more than one stand does not improve the performance of SA. Contrarily, if we reduce the size of the problem (i.e. reduce considerably the number of alternatives per stand) the two-opt moves approach performs better.

Bachmatiuk, Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Lisboa, Portugal E-mail: jbachmatiuk@isa.ulisboa.pt
Garcia-Gonzalo, Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Lisboa, Portugal E-mail: jordigarcia@isa.ulisboa.pt
Borges, Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Lisboa, Portugal E-mail: joseborges@isa.ulisboa.pt

article id 1283, category Research article

Ivana Bjedov, Dragica Obratov–Petković, Danijela Mišić, Branislav Šiler, Jelena M Aleksic. (2015). Genetic patterns in range-edge populations of Vaccinium species from the central Balkans: implications on conservation prospects and sustainable usage. Silva Fennica vol. 49 no. 4 article id 1283. https://doi.org/10.14214/sf.1283

Keywords: marginal populations; genetic structure; Vaccinium sp.; the Balkans; RAPD markers; genetic profiles; interspecific hybridization

Highlights: We studied fragmentary distributed range-edge populations of Vaccinium myrtillus, Vaccinium uliginosum and Vaccinium vitis-idaea from the Balkans using RAPDs; Low genetic diversities and high genetic differentiation were found in all species; The prevalence of clonal individuals was not observed; Past interspecific hybridization among V. vitis-idaea and the other two species was detected; Guidelines for conservation and sustainable usage were provided.

Abstract | Full text in HTML | Full text in PDF | Author Info

Vaccinium myrtillus L., Vaccinium uliginosum L. and Vaccinium vitis-idaea L. are perennial, cold-adapted clonal shrubs distributed throughout Europe, northern Asia and North America. Due to their usage in food (berries) and pharmaceutical industry (berries and leaves), their natural populations are exposed to anthropogenic and other impacts that affect their genetic make-up. We analyzed 14 fragmentary distributed and small-sized peripheral populations of these species from the Balkans, which represents the southeastern-European marginal area of their wide European distributions, using RAPD molecular markers. The contemporary genetic patterns in all three species within the Balkans were generally similar, and in comparison to previous reports on populations of these species found in northward Europe, where they have a more continuous distribution, the levels of genetic diversity were more or less halved, genetic differentiation was several times higher, gene flow exceptionally low, and the expected prevalence of clonal individuals was lacking. The population dynamics of all three species within the Balkans was complex and distinct, and was characterized by a past admixture of individuals from discrete populations of the same species and interspecific hybridisation not only between V. myrtillus and V. vitis-idaea but also between V. uliginosum and V. vitis-idaea, the latter not being reported to date. Conservation measures suitable for preservation of presumably genetically distinct portions of the Balkans’ gene pools of studied species have been suggested, while the utility of interspecific hybrids in breeding programs and/ or in food/pharmaceutical industry is yet to be assessed.

Bjedov, University of Belgrade, Faculty of Forestry, Kneza Višeslava 1, 11000 Belgrade, Serbia E-mail: ivana.bjedov@sfb.bg.ac.rs
Obratov–Petković, University of Belgrade, Faculty of Forestry, Kneza Višeslava 1, 11000 Belgrade, Serbia E-mail: dragica.obratov-petkovic@sfb.bg.ac.rs
Mišić, University of Belgrade, Institute for Biological Research “Siniša Stanković”, Boulevard Despota Stefana 142, 11000 Belgrade, Serbia E-mail: dmisic@ibiss.bg.ac.rs
Šiler, University of Belgrade, Institute for Biological Research “Siniša Stanković”, Boulevard Despota Stefana 142, 11000 Belgrade, Serbia E-mail: branislav.siler@ibiss.bg.ac.rs
Aleksic, University of Belgrade, Institute of Molecular Genetics and Genetic Engineering, Vojvode Stepe 444a, P.O. Box 23, 11010 Belgrade, Serbia E-mail: aleksic_jelena@yahoo.com.au

article id 1265, category Research article

Eva Ring, Lars Högbom, Hans-Örjan Nohrstedt, Staffan Jacobson. (2015). Soil and soil-water chemistry below different amounts of logging residues at two harvested forest sites in Sweden. Silva Fennica vol. 49 no. 4 article id 1265. https://doi.org/10.14214/sf.1265

Keywords: clearcutting; final felling; bio fuel; conifer; fuel-adapted felling; nutrient; soil solution

Highlights: Soil-water chemistry, ground vegetation cover and water flux were affected by the amounts of logging residues stored on the ground after harvest; A strong response on soil-water chemistry was recorded at only one of the two sites; At the site showing a weak response, less residue remained after seven years in the treatments giving the most pronounced effects.

Abstract | Full text in HTML | Full text in PDF | Author Info

Logging residues (LR), i.e. tops, branches, and needles, are increasingly being harvested for energy production in Fennoscandia. These residues are temporarily piled on site awaiting transport. This study was undertaken to investigate effects on the soil and soil-water chemistry below different amounts of LR at two recently harvested coniferous sites in Sweden. Seven treatments were included and the studied amounts of LR ranged from no LR left on the ground to four times the estimated LR amount of the harvested stands. Two treatments included eight times the estimated LR amount of the harvested stands but here the LR were removed after 7 or 20 weeks. Soil-water samples were collected during the first six or seven growing seasons. Effects of treatment were detected in the soil water for 11 chemical variables at the northern site, and for the NO₃^- and Cl^- concentrations at the southern site. The strongest response was generally found in the treatment with four times the estimated LR amount, for which the highest concentrations were recorded in most cases. In the first three seasons, the water flux through the LR decreased with an increasing amount of residue. Effects on the exchangeable store of Ca²⁺ in the mor layer and the upper 20 cm of the mineral soil was detected at both sites. At the northern site, the weight of the remaining LR, ground vegetation and all other material above the mor layer in the treatments with two and four times the estimated LR amount was roughly twice the corresponding weights at the southern site seven years after treatment. Although strong effects on the soil-solution chemistry were detected at one of the study sites, in the treatments corresponding to two and four times the estimated logging residue amount, the effect on the leaching from an entire regeneration area is likely to be relatively small given the percentage of the area hosting these logging residue amounts (ca. 20% after stem-only harvesting and 9% after fuel-adapted felling).

Ring, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: eva.ring@skogforsk.se
Högbom, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: lars.hogbom@skogforsk.se
Nohrstedt, Swedish University of Agricultural Sciences, Department of Soil and Environment, P.O. Box 7014, SE-750 07 Uppsala, Sweden E-mail: hans-orjan.nohrstedt@slu.se
Jacobson, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: staffan.jacobson@skogforsk.se

article id 1243, category Research article

Curt Almqvist, Gunnar Jansson. (2015). Effects of pruning and stand density on cone and pollen production in an experimental Pinus sylvestris seed orchard. Silva Fennica vol. 49 no. 4 article id 1243. https://doi.org/10.14214/sf.1243

Keywords: spacing; seed orchard management; crown management; seed production

Highlights: Pollen production of Pinus sylvestris began at the same age for all studied stand density and pruning height combinations but increased more rapidly at higher densities; Treatments with dense spacing increased seed production earlier; Many combinations of stand density and target height gave comparable levels of seed production, yielding a wide range of viable management options.

Abstract | Full text in HTML | Full text in PDF | Author Info

Seed orchards are the link between tree breeding and reforestation. This paper presents data on cone, seed and pollen production and seed quality gathered over 21 years in a Pinus sylvestris (L.) experimental seed orchard containing plots with 14 different combinations of stand density and targeted pruning height. The treatments’ stand densities ranged from 267 to 4000 stems ha^-1, and the target graft heights ranged from 2 to 6 meters. Pollen production began at the same orchard age for all studied combinations of stand density and target height but the level of pollen production per hectare increased more rapidly in treatments with higher stand densities. In treatments with dense spacing, cone and seed production initially increased more rapidly than in treatments with wider spacing, thereby providing an earlier return on investment and a shorter seed production lag time. However, the levels of cone and seed production in such treatments over the entire study period were not appreciably different to those achieved in treatments with wider spacing and higher target height. The treatments did not differ substantially with respect to seed quality. These results show that comparable levels of seed production can be obtained with different combinations of stand density and target height, giving seed orchard owners and managers a wide range of viable management options.

Almqvist, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: curt.almqvist@skogforsk.se
Jansson, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: gunnar.jansson@skogforsk.se

article id 1236, category Research article

Monika Litkowiec, Beata P. Plitta-Michalak, Andrzej Lewandowski, Grzegorz Iszkuło. (2015). Homogenous genetic structure in populations of Taxus baccata with varied proportions of male and female individuals. Silva Fennica vol. 49 no. 4 article id 1236. https://doi.org/10.14214/sf.1236

Keywords: genetic diversity; dioecy; English yew; Poland; sex ratio; nSSR markers

Highlights: Polish populations of Taxus baccata showed a high level of genetic diversity within populations and moderate genetic differentiation between them after nSSR marker testing; No significant differences in the genetic variation between T. baccata male and female individuals were observed, and microsatellite loci neutrality was verified; Determining the sex ratio in T. baccata populations is not essential to develop a clear understanding of genetic differentiation and diversity within and between populations of this species.

Abstract | Full text in HTML | Full text in PDF | Author Info

English yew (Taxus baccata L.) is a strictly outcrossing and dioecious species whose populations are small and isolated. It is known that sex ratios may vary in natural populations due to local environmental conditions or stochastic events. However, unbalanced sex ratios may have negative impacts on genetic diversity through enhanced genetic drift and inbreeding. The present study represents one of the first attempts to compare the genetic variation at microsatellite loci within and between populations with different gender proportions. Our results indicated that there were no significant correlations between sex ratio and the extent of genetic variation in different populations. All populations exhibited high levels of genetic diversity. Additionally, the genetic structure was characterized separately in male and female individuals. Statistical analyses of the set estimators describing the genetic structure of male and female individuals of T. baccata revealed no significant differences between the two groups. Molecular analysis verified that microsatellite nuclear loci neutrality developed for T. baccata, as there were no significant differences in the genetic variation between males and females and no evidence for any outlier loci using coalescent and hierarchical Bayesian simulations. The results demonstrate that ignoring biased sex ratios in T. baccata populations had no effect on the assessment of genetic differentiation and genetic diversity within and between populations of this species. These results are discussed with regards to the practical application of molecular markers in conservation programs.

Litkowiec, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: mlit@man.poznan.pl
Plitta-Michalak, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: beata-plitta@wp.pl
Lewandowski, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: alew@man.poznan.pl
Iszkuło, Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland & University of Zielona Góra, Faculty of Biological Sciences, Prof. Z. Szafrana 1, 65-516 Zielona Góra, Poland E-mail: iszkulo@man.poznan.pl

article id 1337, category Research article

Leszek Bujoczek, Małgorzata Bujoczek, Jan Banaś, Stanisław Zięba. (2015). Spruce regeneration on woody microsites in a subalpine forest in the western Carpathians. Silva Fennica vol. 49 no. 3 article id 1337. https://doi.org/10.14214/sf.1337

Keywords: Picea abies; coarse woody debris; stumps; decomposition; regression model; fallen deadwood

Highlights: The occurrence probability of Picea abies seedlings on fallen deadwood was found to increase with diameter and decay stage of deadwood and with the volume of living trees, and to decrease with the density of living trees, sapling density, and land slope. It was also higher on stumps with greater diameter and in plots with higher sapling density, but decreased with increasing stump height.

Abstract | Full text in HTML | Full text in PDF | Author Info

The density of Picea abies [L.] Karst. regeneration on different microsites, the quantity and quality of woody microsites, and seedling occurrence probability on stumps and fallen deadwood were studied in a subalpine forest that has been under protection for approximately 30–40 years (Gorce Mountains in the western Carpathians). Thirty percent of seedlings and 29% of saplings grew on stumps and fallen deadwood, while the remaining regeneration occurred on soil surface and mounds created by uprooted trees. The occurrence probability of Picea seedlings on fallen deadwood increased with deadwood diameter and decay stage and with the volume of living trees, and decreased with increased density of living trees, sapling density, and land slope. Furthermore, seedlings were more likely to grow on stumps with a greater diameter and in plots with higher sapling density, but less likely to grow on higher stumps. Stumps and fallen deadwood covered about 4% of the forest floor, but the material that is most important for promoting regeneration (strongly decomposed logs and those of a diameter exceeding 30 cm) took up only about 22 m² ha^-1. We have concluded that in a subalpine forest that has been protected for 30–40 years regeneration processes take place mostly on soil surface and stumps. The role of fallen deadwood increases over time as a greater number of suitable logs (in terms of size and decay stage) become available.

Bujoczek, University of Agriculture in Krakow, E-mail: lbujoczek@gmail.com
Bujoczek, University of Agriculture in Krakow, E-mail: bujoczek.m@gmail.com
Banaś, University of Agriculture in Krakow, E-mail: rlbanas@cyf-kr.edu.pl
Zięba, University of Agriculture in Krakow, E-mail: rlzieba@cyf-kr.edu.pl

article id 1267, category Research article

Caroline Mary Adrianne Franklin, Karen A Harper, Liam Kyte Murphy. (2015). Structural dynamics at boreal forest edges created by a spruce budworm outbreak. Silva Fennica vol. 49 no. 3 article id 1267. https://doi.org/10.14214/sf.1267

Keywords: edge influence; balsam fir; insect disturbance; structure; forest influence

Highlights: Insect outbreak edges were 10 m wide with different canopy cover, stem density and tree structural diversity than adjacent ecosystems; Although edge influence on forest structure was weak, forest influence was stronger and extended further, creating an edge zone skewed towards the disturbed area; After thirty years, high-contrast and structurally-diverse transition zones persist on the landscape.

Abstract | Full text in HTML | Full text in PDF | Author Info

Natural disturbances such as insect outbreaks create boundaries that influence vegetation patterns and ecological processes. To better understand the effects of natural edge creation on relatively intact forests and adjacent disturbed areas, we investigated forest structure on both sides of 30 year-old forest edges created by a spruce budworm (Choristoneura fumiferana Clemens) outbreak in the boreal forest of Cape Breton Highlands National Park, Canada. Our objectives were: 1) to determine edge influence (compared to interior forest) and forest influence (compared to disturbed areas) on vegetation structure, and 2) to gain insight into the structural development of the edges. Canopy cover, tree density, radial growth and deadwood were sampled in 5 m x 20 m plots along 120 m transects across six edges. Randomization tests were used to estimate the magnitude and distance of edge and forest influence. Narrow transition zones approximately 10 m wide characterized the spruce budworm-induced edges. Edge influence did not extend into the forest; however, forest influence on structure was detected up to 40 m from the edge into the disturbed area. We found evidence of the insect outbreak in the form of reduced radial growth during the disturbance across the entire disturbed area-forest gradient, which indicates that spruce budworm activity may not have ceased directly at the edge. Tree mortality caused by the insect outbreak resulted in snags, many of which have transformed into logs since the outbreak collapsed. Spruce budworm outbreak-induced forest edges are narrow but dynamic boundaries separating two distinct vegetation communities in the boreal landscape.

Franklin, Department of Renewable Resources, University of Alberta, 751 General Services Building, Edmonton, Alberta, T6G 2H1, Canada E-mail: cfrankli@ualberta.ca
Harper, School for Resource and Environmental Studies, Dalhousie University, Suite 5010, 6100 University Ave., Halifax, Nova Scotia, B3H 3J5, Canada E-mail: Karen.Harper@dal.ca
Murphy, Department of Environmental Science, Saint Mary’s University, 923 Robie St., Halifax, Nova Scotia, B3H 3C3, Canada E-mail: liamkmurphy@gmail.com

article id 1262, category Research article

Āris Jansons, Roberts Matisons, Māra Zadiņa, Linards Sisenis, Jānis Jansons. (2015). The effect of climatic factors on height increment of Scots pine in sites differing by continentality in Latvia. Silva Fennica vol. 49 no. 3 article id 1262. https://doi.org/10.14214/sf.1262

Keywords: Pinus sylvestris; dendroecology; height growth reconstruction; meteorological conditions; Baltic region; increment variation

Highlights: Height increment-climate relationships of Scots pine were assessed using dendrochronological techniques; Annual height increment was significantly affected by climatic factors; In western Latvia, temperature in preceding summer mainly affected height increment; In eastern Latvia height increment was affected by previous autumn temperature; During the 20th century, the effect of climatic factors has altered likely dues to climate change.

Abstract | Full text in HTML | Full text in PDF | Author Info

Height growth of trees is a crucial parameter that influences the composition and productivity of forest stands and quality of timber; however, the relationships between annual height increment (HI) and climatic factors have been poorly studied. In this study, the effect of monthly mean temperature and precipitation sums on the HI of Scots pine in two sites in Latvia have been determined using dendrochronological techniques. Correlation and response function analyses were conducted for entire chronologies of HI and for 50-year intervals within them. Climatic factors significantly affected the HI of Scots pine; however, not only did the suite of significant factors differ between the sites, but the influence of these factors changed during the 20th century. In the site in western Latvia where climate is milder, temperature in the preceding summer was the main climatic determinant of HI. The effect of temperature in the dormant period and spring was significant during the first part of the 20th century, while the effect of temperature in the previous September and November has become significant since the second half of the 20th century. In the site in eastern Latvia where summers are hotter, HI has been affected by both temperature and water deficit related factors in the summer. However, since the later part of the 20th century, the effect of temperature in the previous October has intensified and become the main climatic determinant of HI.

Jansons, LSFRI “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv
Matisons, LSFRI “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
Zadiņa, LSFRI “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 E-mail: mara.zadina@silava.lv
Sisenis, LUA Forestry Faculty, Akadēmijas str. 11, Jelgava, Latvia E-mail: linards.sisenis@llu.lv
Jansons, Forest Competence Centre, Dzērbenes str. 27, Riga, Latvia, LV1006 E-mail: janis.jansons@silava.lv

article id 1226, category Research article

Santiago Pereira, Antonio Prieto, Rafael Calama, Luis Diaz-Balteiro. (2015). Optimal management in Pinus pinea L. stands combining silvicultural schedules for timber and cone production. Silva Fennica vol. 49 no. 3 article id 1226. https://doi.org/10.14214/sf.1226

Keywords: forest management; goal programming; non-timber forest product

Highlights: Three management scenarios are proposed to integrate timber and pine nuts; Different silvicultural regimes for each output are addressed jointly; Goal programming is used in order to solve forest management models; In the mixed scenario, the area allocated to pine nuts should be notably greater.

Abstract | Full text in HTML | Full text in PDF | Author Info

This work aimed to tackle a timber harvest scheduling problem by simultaneously integrating into the analysis two forestry products derived from the same species: the timber and the pine nut. For this purpose, three management scenarios were proposed: two in which each of the productions is maximised separately, and a third mixed where, in each management unit, the product to which the silvicultural effort should be devoted is decided. After defining a set of objectives, and optimising the rotation length, a multi-criteria model based on goal programming was considered since no feasible solutions have been obtained when employing linear programming. The results in our case study show how the feasible solutions reached can be more attractive for the manager. Specifically, the area to be devoted to timber and cone/pine-nut production was computed in a scenario where the optimal silviculture (oriented towards timber or pine nuts) in each stand was selected, and it was concluded that the area allocated to pine nuts should be notably greater. This situation is the opposite of the current management.

Pereira, Technical University of Madrid, ETS Ingenieros de Montes, Ciudad Universitaria s/n, 28040 Madrid, Spain E-mail: spereirasaez@gmail.com
Prieto, Technical University of Madrid, ETS Ingenieros de Montes, Ciudad Universitaria s/n, 28040 Madrid, Spain E-mail: antonio.prieto@upm.es
Calama, Dpto. Selvicultura y Gestión Forestal, INIA-CIFOR, Ctra. A Coruña km 7.5, 28040 Madrid, Spain E-mail: rcalama@inia.es
Diaz-Balteiro, Technical University of Madrid, ETS Ingenieros de Montes, Ciudad Universitaria s/n, 28040 Madrid, Spain E-mail: luis.diaz.balteiro@upm.es

article id 1056, category Research article

Katri Himanen, Markku Nygren. (2015). Seed soak-sorting prior to sowing affects the size and quality of 1.5-year-old containerized Picea abies seedlings. Silva Fennica vol. 49 no. 3 article id 1056. https://doi.org/10.14214/sf.1056

Keywords: Norway spruce; seed treatment; seed radiography; seedling emergence; seedling morphology

Highlights: After soak-sorting all sunken seeds (bottom fraction) were full and viable, whereas floating seeds contained larvae-filled and immature seed; Seedlings originating from the bottom fraction were greater in height and diameter than control seedlings or those originating from the floating seeds; The proportion of saleable seedlings was four percentage points higher in the bottom fraction than in the other seedlings.

Abstract | Full text in HTML | Full text in PDF | Author Info

We studied the effect of soak-sorting Norway spruce (Picea abies (L.) H. Karst.) seeds on emergence, development and quality of container seedlings in two commercial seed lots. The seeds, separated by soaking into bottom and surface fractions, were sown in June, and the seedlings were grown during two growing seasons under typical Finnish nursery conditions. The first summer seedlings were grown in a greenhouse and outdoors for the second, full growing season. All sunken seeds were full and viable according to radiography, whereas the floating seeds contained 2% and 13% larvae-filled and 8% and 11% anatomically immature seeds, depending on the seed lot. Seedlings grown from the bottom fraction seed emerged 2.5–3.5 days earlier than seedlings of storage dry (i.e. control) seed. Height, diameter, and shoot and root dry mass of the seedlings were affected by soaking after both the first and second growing seasons. The largest seedlings originated from the bottom fraction. The proportion of saleable seedlings was four percentage points higher in the bottom fraction than in the other seedlings. The effects of soaking found in this study are more notable than as previously reported for Norway spruce seedlings. This suggests that soaking and soak-sorting may be most useful when the growing conditions are stressful, i.e. when seeds are sown in summer rather than 1-year-old seedling crops sown in spring under the climate conditions typical of Finland.

Himanen, Natural Resources Institute Finland (Luke), Green technology, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: katri.himanen@luke.fi
Nygren, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: markku.nygren@luke.fi

article id 1279, category Research article

Andreas Kreutz, Tuomas Aakala, Russell Grenfell, Timo Kuuluvainen. (2015). Spatial tree community structure in three stands across a forest succession gradient in northern boreal Fennoscandia. Silva Fennica vol. 49 no. 2 article id 1279. https://doi.org/10.14214/sf.1279

Keywords: Picea abies; age structure; spatial structure; natural forest; Betula spp.; point pattern analysis; northern boreal; community composition

Highlights: We studied the tree community spatial structure in three 1.2-ha plots representing naturally developed northern boreal forests of varying ages; Spatial structure showed little differences between the mid-successional, late-successional and old-growth stands; The occurrence of Picea abies relative to Betula spp. indicated a mosaic-like spatial assembly; Mosaics are likely maintained by species-specific replacement, not reciprocal replacement as thought earlier.

Abstract | Full text in HTML | Full text in PDF | Author Info

Development of species composition during succession is well studied in natural boreal forests, but empirical assessments of how within-stand spatial structure develops in late-successional stages are few. Here, we quantified spatial patterns in three unmanaged stands consisting of Picea abies (L.) Karst. and Betula pubescens Ehrh. and Betula pendula Roth (hereafter Betula spp.) in northern boreal Fennoscandia. We conducted a comprehensive analysis of small-scale spatial point patterns in three fully mapped 1.2-ha sample plots, representing different forest developmental stages: mid-successional, late-successional and old-growth forest. We used several variants of Ripley’s K-function to analyze the spatial point patterns along the successional gradient. Univariate analyses showed that mature trees of both species were either randomly distributed or clumped. P. abies saplings were clumped, and Betula spp. saplings occurred in a random or clumped manner. In the bivariate analyses, saplings were more likely to be found in the surroundings of mature trees of the same species, but occurred independent of the individuals of other tree species. Mature trees showed interspecific repulsion. Only modest differences occurred in the univariate patterns between the three successional stages, but in the bivariate analyses the most evident patterns, i.e. intraspecific attraction and interspecific repulsion, were stronger in the older successional stages. Overall, the studied stands appear structured as species-specific mosaics. These mosaics, along with mixed species composition, seem to be maintained by species self-replacement, which contrasts with findings from earlier studies.

Kreutz, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: andreas.kreutz@wald-rpl.de
Aakala, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland http://orcid.org/0000-0003-0160-6410 E-mail: tuomas.aakala@helsinki.fi
Grenfell, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: russell.grenfell@gmail.com
Kuuluvainen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: timo.kuuluvainen@helsinki.fi

article id 1274, category Research article

Juho Hautsalo, Paul Mathieu, Sakina Elshibli, Pekka Vakkari, Juha Raisio, Pertti Pulkkinen. (2015). Variation in height and survival among northern populations of pedunculate oak (Quercus robur L.): results of a 13-year field study. Silva Fennica vol. 49 no. 2 article id 1274. https://doi.org/10.14214/sf.1274

Keywords: adaptation; growth; pedunculate oak; northern stands

Highlights: A height-sum function allowed us to compare the combined growth and survival of northernmost stands of pedunculate oak; Individuals from Turku-Katariinanlaakso performed the best, although other families performed more consistently across trials, which should be considered in future conservation and breeding. Surprisingly, trees planted in a trial location beyond the natural northern limit of pedunculate oak showed the best performance.

Abstract | Full text in HTML | Full text in PDF | Author Info

We analysed the adaptive potential of pedunculate oak (Quercus robur L.) in terms of variation in height and survival in five field trials located in southern and central Finland. The trials were established with Finnish native material from six different seed origins. Thirteen years after planting, the number of living trees was counted and measured for height. Analysis of height and survival revealed a significant effect of origin, i.e., a genetic basis to individual tree performance. Two origins from the Turku region (Ruissalo and Katariinanlaakso) performed the best while trees originating from Parainen (Lenholmen) performed the worst. In order to study the effects due to tree origin, a comparison of families (half-sibling trees, i.e. those sharing the same ‘mother’ tree) was made by combining height and survival through a height-sum equation (i.e., the product of mean survival and height of each family in each trial) and used to calculate family- and origin-level ecovalences. Ecovalence is a metric for performance consistency, and indicates how much each variable contributes to the total variation; the higher the value, the lower the consistency of trees across the trials based on their origin or family. Analysis of consistency showed similar results to growth and survival, with Turku families performing the best and families from Parainen performing the worst. Families in the Katariinanlaakso stand (Turku) generally had more stable ecovalence values and more dispersed height-sums, while Ruissalo (Turku) families had higher mean height-sum but higher variability in ecovalence values. These results suggest that seed origins (i.e., genotypes) can be optimized in terms of their suitability for commercial or ecological forest management.

Hautsalo, Natural Resources Institute Finland (Luke), Green technology, Antinniementie 1, FI-41330 Vihtavuori, Finland E-mail: juho.hautsalo@luke.fi
Mathieu, Agrocampus Ouest, 35000 Rennes, France E-mail: pm@nn.fr
Elshibli, University of Helsinki, Helsinki, Finland E-mail: se@nn.fi
Vakkari, Natural Resources Institute Finland (Luke), Vantaa, Finland E-mail: pekka.vakkari@luke.fi
Raisio, City of Helsinki, Helsinki, Finland E-mail: jr@nn.fi
Pulkkinen, Natural Resources Institute Finland (Luke), Vantaa, Finland E-mail: pertti.pulkkinen@luke.fi

article id 1232, category Research article

Pete Bettinger, Mehmet Demirci, Kevin Boston. (2015). Search reversion within s-metaheuristics: impacts illustrated with a forest planning problem. Silva Fennica vol. 49 no. 2 article id 1232. https://doi.org/10.14214/sf.1232

Keywords: forest planning; heuristics; threshold accepting; tabu search; spatial harvest scheduling; adjacency constraints; mixed integer goal programming

Highlights: The interruption of the sequence of events used to explore a solution space and develop a forest plan, and the re-initiation of the search process from a high-quality, known starting point (reversion) seems necessary for some s-metaheuristics; When using a s-metaheuristic, higher quality forest plans may be developed when the reversion interval is around six iterations of the model.

Abstract | Full text in HTML | Full text in PDF | Author Info

The use of a reversion technique during the search process of s-metaheuristics has received little attention with respect to forest management and planning problems. Reversion involves the interruption of the sequence of events that are used to explore the solution space and the re-initiation of the search process from a high-quality, known starting point. We explored four reversion rates when applied to three different types of s-metaheuristics that have previously shown promise for the forest planning problem explored, threshold accepting, tabu search, and the raindrop method. For two of the s-metaheuristics, we also explored three types of decision choices, a change to the harvest timing of a single management unit (1-opt move), the swapping of two management unit’s harvest timing (2-opt moves), and the swapping of three management unit’s harvest timing (3-opt moves). One hundred independent forest plans were developed for each of the metaheuristic / reversion rate combinations, all beginning with randomly-generated feasible starting solutions. We found that (a) reversion does improve the quality of the solutions generated, and (b) the rate of reversion is an important factor that can affect solution quality.

Bettinger, School of Forestry and Natural Resources, 180 E. Green Street, University of Georgia, Athens, Georgia, USA 30602 E-mail: pbettinger@warnell.uga.edu
Demirci, General Directorate of Forestry, Ministry of Forest and Water Affairs, Republic of Turkey E-mail: mehmetdemirci@yahoo.com
Boston, Department of Forest Engineering, Resources and Management, College of Forestry, Oregon State University, USA E-mail: Kevin.Boston@oregonstate.edu

article id 1300, category Research article

Jaana Luoranen, Risto Rikala. (2015). Post-planting effects of early-season short-day treatment and summer planting on Norway spruce seedlings. Silva Fennica vol. 49 no. 1 article id 1300. https://doi.org/10.14214/sf.1300

Keywords: Picea abies; height growth; survival; bud burst; short-day treatment; summer planting

Highlights: Summer planting and short-day treatment advanced the bud burst and increased the height of Norway spruce seedlings after planting, compared to autumn and spring planted or untreated seedlings.

Abstract | Full text in HTML | Full text in PDF | Author Info

Effects of short-day (SD) treatment on bud burst, growth and survival of Norway spruce (Picea abies [L.] Karst.) container seedlings after summer planting were studied in an experiment established in Suonenjoki, Central Finland. One-year-old seedlings were SD-treated for three weeks starting on 18 June, 24 June and 8 July 2004 and then planted on 22 July, 5 August, 6 September 2004 and, as a normal spring planting, on 10 May, 2005. Untreated control seedlings were also planted on these dates. Second flush on the planting year and bud burst the following spring was monitored in planted seedlings, whereas seedling height and survival were determined at the end of growing seasons 2004–2006. We observed a non-significant risk of a second flush if seedlings were SD-treated on 18 June. Also, SD-treated seedlings planted in July or August showed advanced bud burst and increased height the following growing season without significant effects on survival, compared to autumn and spring planted seedlings. Planting in July or early August was associated with a significant increase in the incidence of multiple leaders in later years. Based on our results, to begin a three-week SD treatment in late June or early July and then plant seedlings in late July or early August could be a good practice.

Luoranen, Natural Resources Institute Finland (Luke), Natural resources and bioproduction, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: jaana.luoranen@luke.fi
Rikala, The Finnish Forest Research Institute, Suonenjoki Unit, Suonenjoki, Finland E-mail: rikala@dnainternet.fi

article id 1260, category Research article

Jyrki Hytönen, Anna Saarsalmi. (2015). Biomass production of coppiced grey alder and the effect of fertilization. Silva Fennica vol. 49 no. 1 article id 1260. https://doi.org/10.14214/sf.1260

Keywords: biomass production; coppicing; grey alder; fertilisation

Highlights: Fertilisation (wood ash, N, PK) did not affect grey alder biomass production; Leafless above-ground biomass of 17–20 year old stands was 52–57 Mg ha^–1; MAI increased with increase of rotation length to the end of the follow-up period of 17–20 years; Coppicing increased stand density manifold.

Abstract | Full text in HTML | Full text in PDF | Author Info

We studied biomass production of two naturally originated grey alder (Alnus incana (L.) Moench) stands having a mixture of birch and willow located in central Finland. One of the stands was growing on a peatland site (Muhos) and the other on a mineral soil site (Juuka). The stands were clear-cut and fertilization experiments were laid out with several treatments. At Muhos, the treatments included nitrogen fertilisation with different amounts of wood ash and an unfertilized control. At Juuka, the treatments included nitrogen fertilisation either with ash or with PK, and ash and PK treatments alone and an unfertilized control. The sprouts at Muhos were grown for 17 years and at Juuka for 20 years. At Juuka the stand was clear-cut second time at the age of 20 years and grown for 8 years. The stands were measured several times and foliar samples were taken twice during the study period. Clear-cutting increased stem number manifold. The stand density of new coppiced forests after the clear-cutting decreased from 67 000–89 000 stems ha^–1 at the age of 3–6 years to 10 000–12 000 stems ha^–1 at the age of 17–20 years. On neither site fertilization affected biomass production of alders during the study period. Leafless above-ground biomass was 52–57 Mg ha^–1 after 17–20 years. Mean annual leafless above-ground biomass production (MAI) increased with increase of rotation time. At the age of 17–20 years the MAI was 2.8–3.0 Mg ha a^–1. At Muhos, ash increased foliar P and Ca concentrations, but decreased those of Mn.

Hytönen, Natural Resources Institute Finland, Silmäjärventie 2, FI-69100 Kannus, Finland E-mail: jyrki.hytonen@luke.fi
Saarsalmi, Natural Resources Institute Finland, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: anna.saarsalmi@luke.fi

article id 1220, category Research article

Elisabeth Düthorn, Lea Schneider, Oliver Konter, Philipp Schön, Mauri Timonen, Jan Esper. (2015). On the hidden significance of differing micro-sites on tree-ring based climate reconstructions. Silva Fennica vol. 49 no. 1 article id 1220. https://doi.org/10.14214/sf.1220

Keywords: Pinus sylvestris; climate change; Picea abies; Finland; temperature reconstruction; RCS detrending

Highlights: Pines and spruces show growth level differences in wet and dry micro-sites with higher growth rates in the dry sites; Spruces show a robust climate-growth relationship with June-July temperatures; Application of collective detrending methods can bias long-term trends in climate reconstructions, if relict and recent samples originate from different micro-sites.

Abstract | Full text in HTML | Full text in PDF | Author Info

Tree-ring chronologies are commonly extended back in time by combining samples from living trees with relict material preserved in man-made structures or natural archives (e.g. lakes). Although spatially close, these natural archives and living-tree-sites often comprise different micro-climates. Inhomogeneous growth conditions among these habitats, which may yield offsets in growth-rates, require caution in data processing. Here we assess species-specific growth dynamics in two micro-habitats and their potential effects on long chronologies by combining tree-ring data from different living-tree-sites with an “artificial” subfossil dataset. Well replicated (n > 80) Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) chronologies from northern Fennoscandia, sampled directly at the lakeshore (wet) and several meters beyond the lakeshore (dry) reveal high coherence of the variance between micro-sites (r_spruce = 0.59, r_pine = 0.68). Significant differences of the Regional Curves (RC) indicate faster growth of both species at the drier site though. Growth differences are more pronounced between the spruce micro-sites. The combination of recent dry and wet spruce data with artificial relict data results in two long chronologies covering the last 800 years with substantially different trends, although they consist of the same relict material and the micro-site chronologies correlate significantly over the past two centuries. The combination of spruce samples from dry inland micro-sites with subfossil samples originating from the wet lake shore can result in an underestimation of past temperatures prior to the 19th century. Such effects, hidden in the composition of long chronologies (living trees + subfossil samples) can bias long-term trends in climate reconstructions.

Düthorn, Department of Geography, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany E-mail: duethorn@uni-mainz.de
Schneider, Department of Geography, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany E-mail: l.schneider@geo.uni-mainz.de
Konter, Department of Geography, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany E-mail: O.Konter@geo.uni-mainz.de
Schön, Department of Geography, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany E-mail: philipp.schoen@gmx.de
Timonen, Natural Resources Institute Finland (Luke), Natural resources and bioproduction, FI-96301 Rovaniemi, Finland E-mail: mauri.timonen@metla.fi
Esper, Department of Geography, Johannes Gutenberg University, Becherweg 21, 55099 Mainz, Germany E-mail: J.Esper@geo.uni-mainz.de

article id 1219, category Research article

Thomas P. Sullivan, Druscilla S. Sullivan. (2014). Diversifying clearcuts with green-tree retention and woody debris structures: conservation of mammals across forest ecological zones. Silva Fennica vol. 48 no. 5 article id 1219. https://doi.org/10.14214/sf.1219

Keywords: clearcutting; green-tree retention; small mammals; coniferous forests; ecological zones; Myodes gapperi; population dynamics; red-backed voles; woody debris structures

Highlights: Species diversity of small mammals increased with structural complexity left on clearcut sites; Productivity of red-backed vole populations was higher in sites with green-tree retention (GTR) and windrows of woody debris; GTR and windrows may provide additive effect for providing habitat to conserve mammals on clearcuts.

Abstract | Full text in HTML | Full text in PDF | Author Info

We tested the hypotheses (H) that on newly clearcut-harvested sites, (H1) abundance and species diversity of the forest-floor small mammal community, and (H2) abundance, reproduction, and recruitment of red-backed voles (Myodes gapperi Vigors), would increase with higher levels of structural retention via green-tree retention (GTR) and woody debris (dispersed and constructed into windrows). Study areas were located in three forest ecological zones in southern British Columbia, Canada. For H1, mean total abundance did generally increase with the gradient of retained habitat structure. Mean species richness and diversity were similar among treatment sites but did show an increasing gradient with structural compexity. For H2, mean abundance, reproduction, and recruitment of M. gapperi were higher in GTR and windrow sites than those without retained structures. There was a positive relationship between mean abundance of M. gapperi and total volume of woody debris across treatments. This study is the first investigation of the responses of forest-floor small mammals to an increasing gradient of retained habitat structure via GTR and woody debris on clearcuts. Our assessment of a combination of these two interventions suggested a potentially strong additive effect that could be cautiously extrapolated across three forest ecological zones. With the advent of low levels of GTR on clearcuts, woody debris structures should help provide some habitat to conserve forest mammals on harvest openings.

Sullivan, Department of Forest and Conservation Sciences, Faculty of Forestry, University of BC, 2424 Main Mall, Vancouver, BC, Canada V6T 1Z4 E-mail: tom.sullivan@ubc.ca
Sullivan, Applied Mammal Research Institute, 11010 Mitchell Avenue, Summerland, BC, Canada V0H 1Z8 E-mail: dru.sullivan@appliedmammal.com

article id 1192, category Research article

Hannu Hökkä, Hanna Mäkelä. (2015). Post-harvest height growth of Norway spruce seedlings in northern Finland peatland forest canopy gaps and comparison to partial and complete canopy removals and plantations. Silva Fennica vol. 48 no. 5 article id 1192. https://doi.org/10.14214/sf.1192

Keywords: Picea abies; height growth; peatlands; growth models; advance growth; canopy gap

Highlights: Norway spruce seedlings’ height growth recovered within four years after the cutting of canopy gaps; Growth was linearly related to tree height, being highest for tallest seedlings; Seedlings in the 20 m diameter gap and in the central and northern parts in the 15 m diameter gap showed the best growth; In gaps early height growth was 60% of that in peatland spruce plantations but 2–3 times higher than in uneven-aged cut forests.

Abstract | Full text in HTML | Full text in PDF | Author Info

Recent studies have shown the establishment of Norway spruce (Picea abies (L.) Karst.) to be successful in small canopy gaps cut in drained spruce mire stands in northern Finland. The aim of this study was to quantify seedling height growth in gaps and compare it to that observed in other canopy cuttings and plantations. We sampled spruce crop seedlings (maximum density ca. 3000 ha^–1) in the spring of 2013 in a field experiment in which canopy gaps of 10, 15 and 20 m in diameter had been cut in winter 2004. The total seedling height in 2013 and the length of annual shoots over the past five years (2012–2008) were recorded in the survey. Seedling height varied from 20 cm to 2.7 m, with an average of 65 cm. The average annual height growth was 7.1 cm. A mixed linear model analysis was carried out to investigate seedling height growth variation. Seedling height was linearly and positively related to growth. Height growth started to increase in the fifth growing season after cutting. Seedling height growth in the 20 m gap was slightly better than in the smaller ones. In the 15 m gap, both the centrally located seedlings and those located at the northern edge grew best. In the 20 m gap, southerly located seedlings grew more slowly than seedlings in all other locations. The average seedling height growth in this study was about 60% of that in peatland plantations, but comparable to that in mineral soil gaps, and 2–3 times higher than in uneven-age cut stands.

Hökkä, Finnish Forest Research Institute, Rovaniemi Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland E-mail: hannu.hokka@metla.fi
Mäkelä, Lapland University of Applied Sciences, Jokiväylä 11 C, FI-96300 Rovaniemi, Finland E-mail: hanna.makela@edu.ramk.fi

article id 1124, category Research article

Āris Jansons, Mārtiņš Zeps, Juris Rieksts-Riekstiņš, Roberts Matisons, Oskars Krišāns. (2014). Height increment of hybrid aspen Populus tremuloides x P. tremula as a function of weather conditions in central part of Latvia. Silva Fennica vol. 48 no. 5 article id 1124. https://doi.org/10.14214/sf.1124

Keywords: height growth; energy wood; tree growth; temperature; intra-annual dynamics; plantation silviculture

Highlights: Intra-annual height growth of hybrid aspen was monitored; Clones with early leaf flushing dates showed faster height growth; Height growth was generally controlled by temperature; Fast-growing hybrids were more robust to weather conditions than slow-growing ones; Potential evapotranspiration (moisture regime) negatively affected height growth of clones with delayed phenology.

Abstract | Full text in HTML | Full text in PDF | Author Info

Height growth of young hybrid aspen (Populus tremula L. × P. tremuloides Michx.) was studied in relation to weather conditions. Height of clones with different leaf flushing phenology (early, intermediate and late) was monitored during the growing periods of 2010 and 2011 in a plantation established on former agricultural land. Mean daily height increment (HI) was calculated. Multiple linear regression was used to determine which weather factors (variables) had significant effect on HI. Mean seasonal height growth (mean seasonal HI) between clones (groups) was compared by ANOVA. In both years, HI was significantly higher for clones with early and intermediate leaf flushing compared to clones with late leaf flushing. The effect of weather factors also differed between clones according to their leaf flushing phenology; it was the weakest for HI of clones with early leaf flushing compared to clones with intermediate and late leaf flushing. Mean temperature was the main factor, which positively affected HI of all clones, suggesting that warmer climate might be beneficial for height growth of young hybrid aspen in Latvia. Nevertheless, significant negative relationship between HI and potential evapotranspiration (PET) was observed for clones with delayed leaf flushing, suggesting negative effect of increasing variability of precipitation on growth. Thus, the differences in height growth intensity might be related to growth sensitivity to weather conditions. On the other hand, such differences in height growth between clones might be caused by competition (i.e. with herbs), as trees with early leaf flushing might conquer more resources and become more robust against the environmental fluctuation.

Jansons, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv
Zeps, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 E-mail: martins.zeps@silava.lv
Rieksts-Riekstiņš, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 E-mail: Juris.Riekstins@silava.lv
Matisons, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
Krišāns, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 E-mail: oskars.krisans@silava.lv

article id 1211, category Research article

Xiao Chen, Deborah Page-Dumroese, Ruiheng Lv, Weiwei Wang, Guolei Li, Yong Liu. (2014). Interaction of initial litter quality and thinning intensity on litter decomposition rate, nitrogen accumulation and release in a pine plantation. Silva Fennica vol. 48 no. 4 article id 1211. https://doi.org/10.14214/sf.1211

Keywords: litter quality; litter decomposition; nitrogen cycling; thinning intensity; Pinus tabulaeformis

Highlights: Litter quality and thinning showed an interaction on one year litter decomposition rates, N accumulation, and net N release; N accumulated until the underlying critical acid-unhydrolyzable residue to nitrogen ratio (approximately 57–69) was met; Increased N concentration in litter and thinning intensity induced rapid litter decomposition and N cycling in coniferous plantation with a slow decomposition rate.

Abstract | Full text in HTML | Full text in PDF | Author Info

Thinning alters litter quality and microclimate under forests. Both of these two changes after thinning induce alterations of litter decomposition rates and nutrient cycling. However, a possible interaction between these two changes remains unclear. We placed two types of litter (LN, low N concentration litter; HN, high N concentration litter) in a Chinese pine (Pinus tabulaeformis Carrière) plantation under four thinning treatments to test the impacts of litter quality, thinning or their combination on decomposition rate and N cycling. In our study, N was accumulated to approach an underlying critical acid-unhydrolyzable residue to nitrogen ratio (approximately 57–69) in litter. Moreover, an interaction between litter quality and thinning on decomposition rates, N accumulation and net release did exist. On one hand, one year decomposition rate of LN was elevated after thinning while that of HN remained the same or even lower (under light thinning); N accumulation of LN declined with light thinning and was restored with the increase of thinning intensity whereas that of HN did not decline with thinning and increased under heavy thinning; Net N release from LN was only found in light and heavy thinning while that from HN was found in all treatments, moreover net N release from LN and HN were both elevated under heavy thinning. On the other hand, HN decomposed faster, accumulated less and released more N than LN did under all treatments. Generally, high N concentration in litter and high-intensity thinning can lead to rapid litter decomposition and N cycling in coniferous plantations.

Chen, Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing, 100083, China E-mail: chenxiao_0123@126.com
Page-Dumroese, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 1221 South Main Street, Moscow, ID 83843, USA E-mail: ddumroese@fs.fed.us
Lv, College of Plant Science and Technology, Tarim University, Alar Xinjiang, 843300, China E-mail: lvrh514723@126.com
Wang, Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing, 100083, China E-mail: fuyuerdejia@126.com
Li, Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing, 100083, China E-mail: glli226@163.com
Liu, Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing, 100083, China E-mail: lyong@bjfu.edu.cn

article id 1207, category Research article

Olli-Pekka Tikkanen, Irina A. Chernyakova. (2014). Past human population history affects current forest landscape structure of Vodlozero National Park, Northwest Russia. Silva Fennica vol. 48 no. 4 article id 1207. https://doi.org/10.14214/sf.1207

Keywords: boreal forests; forest fires; recovery; forest structure; landscape change

Highlights: In large scale (0–20 km), the proportion of spruce in forest stands was positively affected by distance from old villages. This relationship was non-linear with a threshold distance of 15 km; In small scale (0–5 km), old villages affected tree species composition and age structure of forests. Effect on age structure was the strongest on stands growing on mineral soils.

Abstract | Full text in HTML | Full text in PDF | Author Info

The information about location and size of past human settlements can give new insights into the analysis of landscape structures. Vodlozero National Park (NP) is one the largest strictly protected areas in Northwestern Europe. We mapped the location of historic villages, which were abandoned in 1958, and studied the effect of past human activity in the forest landscape in two different scales using forest survey data. We assessed the possible change in age, volume and tree species composition from the edge of open fields up to the distance of 5 km from villages. We made a larger landscape analysis using a grid of forest stands covering the whole northern part of the NP. The past human activity was clearly visible in the present forest landscape. Distance from villages affected age, volume and tree species composition of the forest stands. This effect was the strongest within the first two kilometers from the villages. At the level of whole northern NP, the proportion of spruce markedly increased after approximately 15 km from the nearest old village. The changes in the forests surrounding the villages were most likely the result of the intensive use of wood for different commodities needed in households and farming, in addition to short rotation slash and burn agriculture. If the occurrence of forest fires was more frequent closer to villages than in more remote areas, it can well explain the observed pattern in the abundance of spruce in the larger landscape that is less tolerant to fire than pine.

Tikkanen, Department of Biology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland (Current: School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland) & Interdisciplinary Research and Educational Center of Cross-border Communication CARELICA, Institute of History, Political and Social Sciences, Petrozavodsk State University, 33 Lenin Prospectus, 185910 Petrozavodsk, Republic of Karelia, Russia E-mail: Olli-Pekka.Tikkanen@uef.fi
Chernyakova, Interdisciplinary Research and Educational Center of Cross-border Communication CARELICA, Institute of History, Political and Social Sciences, Petrozavodsk State University, 33 Lenin Prospectus, 185910 Petrozavodsk, Republic of Karelia, Russia E-mail: irina.chernyakova@onego.ru

article id 1119, category Research article

Beata Woziwoda, Agnieszka Parzych, Dominik Kopeć. (2014). Species diversity, biomass accumulation and carbon sequestration in the understorey of post-agricultural Scots pine forests. Silva Fennica vol. 48 no. 4 article id 1119. https://doi.org/10.14214/sf.1119

Keywords: biodiversity; Pinus sylvestris plantation; overstorey-understorey interaction; biotic homogenization; Leucobryo-Pinetum community

Highlights: Understorey plant species diversity significantly increases with the age of a Scots pine stand; Biomass of mosses decreases by a quarter, while biomass of herbs increases several times; Total understorey’s carbon stock increases over three times. The highest amount of carbon is accumulated in understorey species like Vaccinium myrtillus and Dicranum polysetum; The growing proportion of vascular plants in the understorey biomass results in an increase in the understorey C/N ratio.

Abstract | Full text in HTML | Full text in PDF | Author Info

The purpose of this study was to examine how the age of a stand of post-agricultural Scots pine forests affects the species composition, biomass and the carbon stock of the forest understorey. The community structure and species composition were studied in 75 plots (100 m² in size), the amount of biomass, organic carbon and total nitrogen were analysed in 75 subplots (1/16 m² in size). The plots were located in 21 plantations with the stand age of 41–60, 61–80 and over 80-years. Results show that the understorey species diversity increased with the increasing age of Scots pine stands, and the structure and species composition of secondary forests (although managed for timber production) became similar to the fresh pine forest of the European temperate region (Leucobryo-Pinetum community). Despite the increasing species diversity, however, only six understorey vascular and moss species played an important role in the biomass accumulation and C sequestration. Due to the differences in the dominant species composition, the total amount of understorey biomass significantly differed among the forest stands. The mean moss biomass ranged from 3046 kg ha^–1 in 41–60-year-old stands, trough 2686 kg ha^–1 in 61–80-year-old stands to 2273 kg ha^–1 in over 80-year-old stands, and the mean understorey vascular plant biomass amounted to 2 kg ha^–1, 1924 kg ha^–1 and 3508 kg ha^–1, respectively. The concentration of organic C varied considerably between species; it was the highest in Vaccinium myrtillus (50.6%) and in Dicranum polysetum (49.5%). The total mass of C was nearly 800 kg ha^–1 in the youngest forests, in the subsequent age series it was two times higher and 3.5 times higher in the oldest ones. Differences in the species composition and in the C/N ratio in different species (generally higher for vascular plants and lower for mosses) were expressed in an increase in the understorey C/N ratio, which was 39.5, 46.6 and 48.6, respectively.

Woziwoda, Department of Geobotany and Plant Ecology, Faculty of Biology and Environmental Protection, University of Lodz, Banacha 12/16, 90-237 Lodz, Poland E-mail: woziwoda@biol.uni.lodz.pl
Parzych, Environmental Chemistry Research Unit, Institute of Biology and Environmental Protection, Pomeranian University in Słupsk, Arciszewskiego 22b, 76-200 Słupsk, Poland E-mail: parzycha1@op.pl
Kopeć, Department of Geobotany and Plant Ecology, Faculty of Biology and Environmental Protection, University of Lodz, Banacha 12/16, 90-237 Lodz, Poland E-mail: domin@biol.uni.lodz.pl

article id 1107, category Research article

Arvo Tullus, Arne Sellin, Priit Kupper, Reimo Lutter, Linnar Pärn, Anna K. Jasinska, Meeli Alber, Maarja Kukk, Tea Tullus, Hardi Tullus, Krista Lõhmus, Anu Sõber. (2014). Increasing air humidity – a climate trend predicted for northern latitudes – alters the chemical composition of stemwood in silver birch and hybrid aspen. Silva Fennica vol. 48 no. 4 article id 1107. https://doi.org/10.14214/sf.1107

Keywords: climate change; Betula; Populus; macronutrients; atmospheric humidity; wood characteristics; structural carbohydrates

Highlights: Hybrid aspen and silver birch trees grew more slowly under increased air humidity conditions and had higher concentrations of N and P and a lower K to N ratio in stemwood; Minor species-specific changes were detected in stemwood concentrations of cellulose and hemicellulose; Density, calorific value and concentrations of lignin and ash in stemwood were not affected by elevated humidity.

Abstract | Full text in HTML | Full text in PDF | Author Info

We studied the physicochemical properties of stemwood in saplings of silver birch (Betula pendula Roth) and hybrid aspen (Populus tremula L. × P. tremuloides Michx.), grown for four years under artificially elevated relative air humidity (on average by 7%) in field conditions, using the Free Air Humidity Manipulation (FAHM) research facility in Estonia. Altogether 91 sample trees from three experimental plots with manipulated air humidity and from three control plots were cut in the dormant season and sampled for the analysis of cellulose, hemicellulose, acid detergent lignin, macronutrients (N, P, K), ash content, density, and calorific value of wood. The analysed trees grew significantly more slowly under elevated humidity conditions, with a more pronounced effect on aspens. Significantly higher concentrations of N and P were observed in the stemwood of both aspens and birches grown under elevated humidity. This could be the result of a change in the content of living parenchyma cells and/or enhanced retranslocation of nutrients into wood parenchyma. Additionally, humidification resulted in a significantly higher concentration of cellulose and a lower concentration of hemicellulose in aspen stemwood, and in significantly lower concentrations of cellulose and K in birch stemwood. Elevated humidity did not affect lignin concentration, ash content, basic density and calorific value of stemwood. Results from the FAHM experiment suggest that the increasing air humidity accompanying global warming at northern latitudes will affect the growth and functioning of deciduous trees and forests, with obvious consequences also for forest management and industry.

Tullus, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: arvo.tullus@ut.ee
Sellin, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: arne.sellin@ut.ee
Kupper, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: priit.kupper@ut.ee
Lutter, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51014, Estonia E-mail: reimo.lutter@emu.ee
Pärn, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51014, Estonia E-mail: linnar.parn@emu.ee
Jasinska, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia & Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: jasiak9@wp.pl
Alber, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: meeli.alber@ut.ee
Kukk, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: maarja.kukk@ut.ee
Tullus, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51014, Estonia E-mail: tea.tullus@emu.ee
Tullus, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51014, Estonia E-mail: hardi.tullus@emu.ee
Lõhmus, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: krista.lohmus@ut.ee
Sõber, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: anu.sober@ut.ee

article id 1153, category Research article

Anu Akujärvi, Ville Hallikainen, Mikko Hyppönen, Eero Mattila, Kari Mikkola, Pasi Rautio. (2014). Effects of reindeer grazing and forestry on ground lichens in Finnish Lapland. Silva Fennica vol. 48 no. 3 article id 1153. https://doi.org/10.14214/sf.1153

Keywords: forest management; timber harvesting; reindeer herding; pastures; lichen cover; lichen biomass

Highlights: Both reindeer grazing and forestry affect the cover and biomass of reindeer lichens; Reindeer grazing has bigger impact than forestry; The lichen cover was about five-fold and the biomass about fifteen-fold in the ungrazed (fenced) sites than in the grazed ones; The decrease of not only the biomass, but also the cover of lichens, is alarming.

Abstract | Full text in HTML | Full text in PDF | Author Info

Reindeer husbandry and forestry are practiced in the same areas in northern Fennoscandia. Reindeer pastures have largely deteriorated. We aimed to quantify the separate and combined effects of reindeer grazing and forestry on the amount of ground lichens. To do this, we mapped and inventoried all larger enclosures (49) in Finnish Lapland where forest management practices were similar in both sides of the fence. The average time since fencing was 43 years. We recorded the cover and estimated dry biomass of ground lichens, as well as parameters describing forest stand characteristics. The effect of reindeer grazing on both the cover and estimated dry biomass of lichens was clear: in the ungrazed (fenced) sites, the lichen cover (35.8%) was on average 5.3-fold and the dry biomass (1929 kg ha^–1) 14.8-fold compared with the corresponding estimates in the grazed sites (6.8% and 130 kg ha^–1). The effect of forestry on lichens was smaller. In the grazed stands the cover and biomass of lichens were higher in the mature stands compared to the younger stand development classes, whereas in the ungrazed stands there were no significant differences between the development classes. Both reindeer grazing and forestry affect the cover and biomass of ground lichens. The influence of reindeer grazing is, however, much heavier than that of forestry. The decrease of not only the biomass, but also the lichen cover, is alarming. The decrease of lichen cover may hinder the recovery of reindeer pastures, which in the long run endangers the sustainability of reindeer husbandry.

Akujärvi, Finnish Environment Institute, Helsinki, Finland E-mail: anu.akujarvi@ymparisto.fi
Hallikainen, Finnish Forest Research Institute, Northern Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: ville.hallikainen@metla.fi
Hyppönen, Finnish Forest Research Institute, Northern Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: mikko.hypponen@metla.fi
Mattila, Finnish Forest Research Institute, Northern Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: eero.mattila@metla.fi
Mikkola, Finnish Forest Research Institute, Northern Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: kari.mikkola@metla.fi
Rautio, Finnish Forest Research Institute, Northern Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: pasi.rautio@metla.fi

article id 1120, category Research article

Ilari Lehtonen, Petri Hoppula, Pentti Pirinen, Hilppa Gregow. (2014). Modelling crown snow loads in Finland: a comparison of two methods. Silva Fennica vol. 48 no. 3 article id 1120. https://doi.org/10.14214/sf.1120

Keywords: climate; forests; snow damage; rime; dry snow; wet snow; frozen snow

Highlights: A new method to model crown snow loads is presented and compared with a previously published simpler method; The heaviest crown snow loads in Finland are found to typically occur in the eastern parts of the country; The relative importance of different snow load types varies between different regions of Finland.

Abstract | Full text in HTML | Full text in PDF | Author Info

The spatial occurrence of heavy crown snow loads in Finland between 1961 and 2010 is studied by using for the first time a model that classifies the snow load into four different types: rime, dry snow, wet snow and frozen snow. In producing this climatology, we used meteorological observations made at 29 locations across Finland. The model performance is evaluated against classified daily images of canopy snow cover and with the help of two short case studies. The results are further compared to those achieved with a simpler method used in previous studies. The heaviest crown snow loads are found to occur typically in eastern Finland. The new method reveals that this holds not only for the total snow loads but also for the different snow load types, although there are certain differences in their geographical occurrence. The greatest benefit achieved with the new method is the inclusion of rime accretion. The forests most prone to heavy riming are those located on tree-covered hills in northern Finland, but as the terrain elevation affects riming efficiency greatly, these small-scale variations in the snow load amounts could not be described in this study in great detail. Moreover, the results are more inaccurate in northern Finland where variations in the terrain elevation are greater than elsewhere. Otherwise, the largest uncertainties in this study are related to wind speed measurements and possibly partly because of that, we were not able to detect any significant trends in the crown snow-load amounts over the study period.

Lehtonen, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland E-mail: ilari.lehtonen@fmi.fi
Hoppula, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland E-mail: petri.hoppula@fmi.fi
Pirinen, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland E-mail: pentti.pirinen@fmi.fi
Gregow, Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland E-mail: hilppa.gregow@fmi.fi

article id 1064, category Research article

Back Tomas Ersson, Urban Bergsten, Ola Lindroos. (2014). Reloading mechanized tree planting devices faster using a seedling tray carousel. Silva Fennica vol. 48 no. 2 article id 1064. https://doi.org/10.14214/sf.1064

Keywords: productivity; cost analysis; seedling feed; silviculture; time study; tree planting machine; containerized seedling

Highlights: Seedling reloading onto the Bracke Planter crane-mounted planting device was twice as fast with the MagMat tray-wise-loaded carousel as today’s seedling-wise-loaded carousel; Tray-wise reloading combined with deplugging seedlings from suitable cultivation trays has the potential to be an efficient and robust way to feed seedlings on any type of tree planting machine.

Abstract | Full text in HTML | Full text in PDF | Author Info

On Nordic clearcuts, today’s tree planting machines produce high-quality but costly regenerations. Much of this high cost is attributable to the planting machines’ low productivity. One promising way of raising productivity is to lessen the time spent manually reloading seedlings onto the carousels of crane-mounted planting devices. Using MagMat, a carousel test-rig designed by engineering students, we studied how much faster tray-wise seedling reloading is on the Bracke Planter compared to reloading with today’s seedling-wise-loaded carousel. The MagMat test-rig held eight Hiko cultivation trays from which seedlings were deplugged individually and dropped into the planting tube. The time study confirmed that seedling reloading was on average twice as fast with MagMat compared to today’s seedling carousel, thereby increasing assumed planting machine productivity by 8–9% depending on the planting device used. MagMat’s cost-efficiency was analysed to be particularly reliant on its added investment cost, mechanical availability and how quickly trays can be switched automatically. Nevertheless, MagMat’s field performance illustrated the overall potential of tray-wise loading compared to piecewise seedling loading for increasing the productivity of crane-mounted planting devices. Also, deplugging proved to be a reliable method of extracting seedlings from the rigid, copper-painted Hiko cultivation trays even when performed at the excavator’s boom-tip during mounding work. We conclude that, rather than piecewise seedling loading, tray-wise loading combined with deplugging seedlings from suitable cultivation trays is a reliable and much more time-efficient method to feed seedlings on probably any type of tree planting machine.

Ersson, Department of Forest Biomaterials and Technology, SLU, SE-90183 Umeå, Sweden E-mail: back.tomas.ersson@slu.se
Bergsten, Department of Forest Biomaterials and Technology, SLU, SE-90183 Umeå, Sweden E-mail: urban.bergsten@slu.se
Lindroos, Department of Forest Biomaterials and Technology, SLU, SE-90183 Umeå, Sweden E-mail: ola.lindroos@slu.se

article id 1019, category Research article

Michael Henke, Stephan Huckemann, Winfried Kurth, Branislav Sloboda. (2014). Reconstructing leaf growth based on non-destructive digitizing and low-parametric shape evolution for plant modelling over a growth cycle. Silva Fennica vol. 48 no. 2 article id 1019. https://doi.org/10.14214/sf.1019

Keywords: growth modelling; non-destructive data acquisition; automated data extraction; image processing tool; leaf shape modelling; reusable modules; Populus x canadensis

Highlights: A complete pipeline for plant organ modelling (at the example of poplar leaves) is presented, from non-destructive data acquisition, over automated data extraction, to growth and shape modelling; Leaf contour models are compared; Resulting “organ” modules are ready for use in FSPMs.

Abstract | Full text in HTML | Full text in PDF | Author Info

A simple and efficient photometric methodology is presented, covering all steps from field data acquisition to binarization and allowing for leaf contour modelling. This method comprises the modelling of area and size (correlated and modelled with a Chapman-Richards growth function, using final length as one parameter), and four shape descriptors, from which the entire contour can be reconstructed rather well using a specific spline methodology. As an improvement of this contour modelling method, a set of parameterized polynomials was used. To model the temporal kinetics of the shape, geodesics in shape spaces were employed. Finally it is shown how this methodology is integrated into the 3D modelling platform GroIMP.

Henke, Department Ecoinformatics, Biometrics & Forest Growth, University of Göttingen, 37077 Göttingen, Germany E-mail: mhenke@uni-goettingen.de
Huckemann, Institute of Mathematical Stochastics, University of Göttingen, 37077 Göttingen, Germany E-mail: huckeman@math.uni-goettingen.de
Kurth, Department Ecoinformatics, Biometrics & Forest Growth, University of Göttingen, 37077 Göttingen, Germany E-mail: wk@informatik.uni-goettingen.de
Sloboda, Department Ecoinformatics, Biometrics & Forest Growth, University of Göttingen, 37077 Göttingen, Germany E-mail: bslobod@web.de

article id 1013, category Research article

Nils Fahlvik, Björn Elfving, Peder Wikström. (2014). Evaluation of growth functions used in the Swedish Forest Planning System Heureka. Silva Fennica vol. 48 no. 2 article id 1013. https://doi.org/10.14214/sf.1013

Keywords: basal area; simulation; validation; volume; empirical

Highlights: Growth models based on historical growth data gave reliable growth predictions up to the century shift; Detailed single tree growth models had lower precision for estimation of total growth than one single stand-based model; The prediction error was in average about 15% and did not increase with extended prediction period.

Abstract | Full text in HTML | Full text in PDF | Author Info

The performance of growth models implemented in the Swedish Forest Planning System Heureka was evaluated. Four basal area growth models were evaluated by comparing their predictions to data from five-year growth records for 1711 permanent sample plots of the National Forest Inventory (NFI-data). Also, two alternative implementations of Heureka, including a combined stand- and tree-level basal area growth model and a single tree-level model, respectively, were evaluated using data from 57 blocks in a thinning experiment (GG-data) involving Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst) in which the trees were monitored for 30 years after the first thinning. The predicted volume growth was also compared to observed values. Growth models based on data from 1970’s and 1980’s overestimated growth in the NFI test plots from the early 2000’s by about 3%. Stand-level models had larger precision than tree-level models. Basal area growth was underestimated in dense NFI-plots and overestimated in non-thinned GG-plots, illustrating an un-solved modelling problem. Basal area growth was overestimated by 2–5% also in the GG-plots over the whole observation period. Volume growth was however accurately predicted for pine and underestimated by 2% for spruce. The relative prediction error did not increase with increasing length of prediction period. Thinning response models calibrated with GG-data worked well in the total application and produced growth levels for different thinning alternatives in line with observations.

Fahlvik, Department of Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: nils.fahlvik@slu.se
Elfving, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden E-mail: bjorn.elfving@slu.se
Wikström, Peder Wikström Skogsanalys AB, c/o Peder Wikström, Huldrans väg 1, SE-907 52 Umeå, Sweden E-mail: peder.wikstrom@slu.se

article id 983, category Research article

Sakari Tuominen, Juho Pitkänen, Andras Balazs, Kari T. Korhonen, Pekka Hyvönen, Eero Muinonen. (2014). NFI plots as complementary reference data in forest inventory based on airborne laser scanning and aerial photography in Finland. Silva Fennica vol. 48 no. 2 article id 983. https://doi.org/10.14214/sf.983

Keywords: airborne laser scanning; National Forest Inventory; aerial imagery; plot sampling

Highlights: Using NFI plots in forest management inventories could provide a way for rationalising forest inventory data acquisition; NFI plots were used as additional reference data in laser scanning and aerial image based forest inventory; NFI plots improved the estimates of some forest variables; There are differences between the two inventory types that cause difficulties in combining the data.

Abstract | Full text in HTML | Full text in PDF | Author Info

In Finland, there are currently two, parallel sample-plot-based forest inventory systems, which differ in their methodologies, sampling designs, and objectives. One is the National Forest Inventory (NFI), aimed at unbiased inventory results at national and regional level. The other is the Forest Centre’s management-oriented forest inventory based on interpretation of airborne laser scanning and aerial images, with the aim of locally accurate stand-level forest estimates. The National Forest Inventory utilises relascope sample plots with systematic cluster sampling. This inventory method is optimised for accuracy of regional volume estimates. In contrast, the management-oriented forest inventory utilises circular sample plots with an allocation system covering certain pre-defined forest classes in the inventory area. This method is optimised to produce reference data for interpretation of the remote-sensing materials in use. In this study, we tested the feasibility of the National Forest Inventory sample plots in provision of additional reference data for the management-oriented inventory. Various combinations of NFI plots and management inventory plots were tested in the interpretation of the laser and aerial-image data. Adding NFI plots in the reference data generally improved the accuracy of the volume estimates by tree species but not the estimates of total volume or stand mean height and diameter. The difference between the plot types in the NFI and management inventories causes difficulties in combination of the two datasets.

Tuominen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: sakari.tuominen@metla.fi
Pitkänen, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: juho.pitkanen@metla.fi
Balazs, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: andras.balazs@metla.fi
Korhonen, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: kari.t.korhonen@metla.fi
Hyvönen, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: pekka.hyvonen@metla.fi
Muinonen, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: eero.muinonen@metla.fi

article id 989, category Research article

Anna Saarsalmi, Pekka Tamminen, Mikko Kukkola. (2014). Effects of long-term fertilisation on soil properties in Scots pine and Norway spruce stands. Silva Fennica vol. 48 no. 1 article id 989. https://doi.org/10.14214/sf.989

Keywords: boreal forest; nitrogen; Pinus sylvestris L.; phosphorus; liming; forest soils; Picea abies (L.) Karst.

Highlights: N fertilisation increased the amount of carbon in the organic layer; N fertilisation decreased the C/N ratio in the surface soil; N addition increased the amount of most nutrients in the organic layer; N fertilisation tended to lower pH, although only slightly.

Abstract | Full text in HTML | Full text in PDF | Author Info

The response of surface soil after 45- to 52-years to repeated nitrogen and phosphorus fertilisation was studied. This study included 30 factorial experiments established in young (5- to 30-year-old) stands using plots of 900 m², on average, and by randomising treatments within each experiment. Total amount of N added varied from 534 to 1908 kg ha^–1 and that of P from 69 to 193 kg ha^–1, repeated at every second N fertilisation. Liming was performed twice; in total, 6000 kg ha^–1 of dolomite was applied. Nitrogen fertilisation increased the mass of the organic layer and the amount of carbon and consequently the amounts of most of the elements in the organic layer. In both the organic layer and the 0–10 cm layer of mineral soil, nitrogen fertilisation decreased the C/N ratio and tended to lower pH, although only slightly. Phosphorus fertilisation increased the amounts of P and Ca. Liming increased the total amounts of most elements in the organic layer, except for C and N. We were able to derive models to describe how changes in the chemical properties of the surface soil depended on doses of elements and on site and stand properties.

Saarsalmi, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: anna.saarsalmi@metla.fi
Tamminen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: pekka.tamminen@metla.fi
Kukkola, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mikko.kukkola@metla.fi

article id 984, category Research article

Christian Rottensteiner, Petros Tsioras, Heinz Neumayer, Karl Stampfer. (2013). Vibration and noise assessment of tractor-trailer and truck-mounted chippers. Silva Fennica vol. 47 no. 5 article id 984. https://doi.org/10.14214/sf.984

Keywords: chippers; noise; whole-body vibration; exposure limit values

Highlights: Truck-mounted chippers were associated with higher vibration values, while tractor-trailer chippers had higher noise level; Chipping hardwood produced higher vibration magnitudes than softwood; Vibration and noise values in most cases did not exceed the exposure limit values set by the European Union.

Abstract | Full text in HTML | Full text in PDF | Author Info

During chipping, machine operators are exposed to whole-body vibration and noise bearing a risk to health. Vibration on the operator’s seat and noise inside the chipper cab was measured and analyzed. The factorial design considered two setup variants (tractor-trailer and truck-mounted) of two chipper models from different manufacturers during chipping of softwood and hardwood tree species. Furthermore, exposure to noise was measured during chipping of hardwood. Vibration and noise during chipping, driving between wood piles, and operational delays were measured separately. The results associated truck-mounted chippers with higher vibration values and tractor-trailer chippers with higher noise levels. The highest vibration levels were recorded while driving on the forest road from one log pile to another and the second highest during chipping. On the contrary, the lowest vibration levels were measured during operational delays with the chipper in idling condition. Chipping hardwood produced higher vibration magnitudes than softwood. Exposure to noise was significantly higher during chipping compared to driving and operational delays. Vibration and noise data were combined with time studies data, for the calculation of eight-hour energy equivalent total values, both for vibration and noise. In all cases, the exposure limit values set by the European Union were not exceeded, with the exception of truck-mounted chippers, which are likely to exceed the exposure action value for vibration.

Rottensteiner, University of Natural Resources and Life Sciences Vienna, Institute of Forest Engineering, Peter Jordan Straße 82, 1190 Wien, Austria E-mail: christian.rottensteiner@boku.ac.at
Tsioras, Aristotle University, P.O. Box 227, GR-541 24 Thessaloniki, Greece E-mail: ptsioras@for.auth.gr
Neumayer, Specialist in Occupational Medicine, Wörndlestraße 10, 6020 Innsbruck, Austria E-mail: heinz.neumayer@die-arbeitsmedizin.at
Stampfer, University of Natural Resources and Life Sciences Vienna, Institute of Forest Engineering, Peter Jordan Straße 82, 1190 Wien, Austria E-mail: karl.stampfer@boku.ac.at

article id 937, category Research article

Rene Zamora-Cristales, Kevin Boston, John Sessions, Glen Murphy. (2013). Stochastic simulation and optimization of mobile chipping economics in processing and transport of forest biomass from residues. Silva Fennica vol. 47 no. 5 article id 937. https://doi.org/10.14214/sf.937

Keywords: forest planning; simulation; optimization; economics; decision analysis; forest biomass; renewable energy

Highlights: A stochastic simulation model is proposed to analyze forest biomass operations; The cost of chipper and truck waiting times was estimated in forest biomass recovery operations; The economic effect of truck-machine interactions under uncertainty was analyzed; Road characteristics and processing location have an economic impact in truck and chipper waiting times

Abstract | Full text in HTML | Full text in PDF | Author Info

We analyzed the economics of mobile chipping and transport of biomass from forest residues for energy purposes under uncertainty. A discrete-event simulation model was developed and utilized to quantify the impacts of controllable and environmental variables on productivity in order to determine the most cost effective transportation options under steep terrain conditions. Truck-chipper interactions were analyzed to show their effect on truck and chipper standing time. A costing model was developed to account for operating and standing time cost (for the chipper and trucks). The model used information from time studies of each activity in the productive cycle and spatial-temporal information obtained from geographic information system (GIS) devices, and tracking analysis of machine and truck movements. The model was validated in field operations, and proved to be accurate in providing the expected productivity. A cost distribution was elaborated to support operational decisions of forest managers, landowners and risk-averse contractors. Different scenarios were developed to illustrate the economic effects due to changes in road characteristics such as in-highway transport distance, in-forest internal road distance and pile to trailer chipper traveling distances.

Zamora-Cristales, Department of Forest Engineering, Resources, and Management, College of Forestry, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA E-mail: rene.zamora@oregonstate.edu
Boston, Department of Forest Engineering, Resources, and Management, College of Forestry, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA E-mail: kevin.boston@oregonstate.edu
Sessions, Department of Forest Engineering, Resources, and Management, College of Forestry, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA E-mail: john.sessions@oregonstate.edu
Murphy, Waiariki Institute of Technology, Rotorua, New Zealand E-mail: glen.murphy@waiariki.ac.nz

article id 1046, category Research article

Eva-Maria Nordström, Hampus Holmström, Karin Öhman. (2013). Evaluating continuous cover forestry based on the forest owner’s objectives by combining scenario analysis and multiple criteria decision analysis. Silva Fennica vol. 47 no. 4 article id 1046. https://doi.org/10.14214/sf.1046

Keywords: forest planning; decision making; sustainable forest management; uneven-aged forestry

Highlights: Scenario analysis and multiple criteria decision analysis were combined to evaluate alternative forest management strategies for Linköping municipality, Sweden; Continuous cover forestry (CCF) promoted ecological and social objectives better than even-aged forestry but was worse for economic objectives; Ecological and social objectives were important to the municipality and thus, in summary, CCF seemed to be a suitable strategy.

Abstract | Full text in HTML | Full text in PDF | Author Info

Forests are increasingly managed both to provide a sustainable yield of timber and for supplying a range of ecosystem services in line with the concept of sustainable forest management. Several incommensurable interests must then be considered, and it is necessary to strike a balance between different objectives. In evaluation of trade-offs to be made, both objective factors and subjective values need to be taken into account. In recent years, continuous cover forestry (CCF) has been put forward as an alternative to even-aged forestry. The aim of this study was to use scenario analysis in combination with multi criteria decision analysis (MCDA) to evaluate whether CCF is a suitable strategy based on the decision makers’ objectives and preferences for sustainable forest management in a specific landscape. This approach was applied to a planning case on the forest estate of the Linköping municipality in southwestern Sweden. The scenario analyses provided insights into relevant quantitative factors, while the MCDA evaluation helped in clarifying the objectives of the forest management and in assessing the relative importance of various objectives. The scenario analyses showed that in this case CCF is a good management strategy in ecological and social terms but yields worse economic outcomes than conventional even-aged forestry. In the Linköping case, there was a relatively strong emphasis on ecological and social aspects and thus, in summary, CCF seemed to be the most suitable option.

Nordström, Swedish University of Agricultural Sciences, Department of Forest Resource Management, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: eva-maria.nordstrom@slu.se
Holmström, Swedish University of Agricultural Sciences, Department of Forest Resource Management, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: hampus.holmstrom@slu.se
Öhman, Swedish University of Agricultural Sciences, Department of Forest Resource Management, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: karin.ohman@slu.se

article id 1043, category Research article

Jorge Martín-García, Luc Barbaro, Julio Javier Diez, Hervé Jactel. (2013). Contribution of poplar plantations to bird conservation in riparian landscapes. Silva Fennica vol. 47 no. 4 article id 1043. https://doi.org/10.14214/sf.1043

Keywords: management; Populus x euramericana; clone I-214; hybrid; native

Highlights: Poplar plantations should not be used as surrogate habitat for native riparian forests with the aim of preserving bird species diversity; Native riparian forests should be preserved or restored as far as possible; Bird communities occurring in poplar plantations can still accommodate rich communities of forest bird species, providing that suitable management is applied at local and landscape levels.

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In Mediterranean areas, riparian zones are particularly important for maintaining biodiversity. Nevertheless, the native vegetation in these zones has been modified or lost at an alarming rate during the last decades. The main objective of this study was to investigate the influence of poplar plantations on bird diversity in riparian zones, in order to estimate the ecological implications of a substantial expansion of poplar plantations. Breeding birds were sampled by the point-count method in twenty-four poplar plantations of I-214 clone, according to a factorial design combining stand age and understory management. Furthermore, the three native riparian forests remaining in the study area were also surveyed. Explanatory variables included (1) dendrometric, (2) understory and (3) landscape variables within six different radii of circular buffers. The species richness and abundance index were higher in riparian forests than in poplar plantations. Landscape variables (percentage of poplar plantations in the surrounding landscape) strongly influenced bird diversity in poplar plantations. Furthermore, at the local scale, understory cover was also a key factor in shaping bird assemblages. This suggests that poplar plantations should not be used as surrogates for native forests. Nevertheless, poplar plantations can still accommodate rich communities of forest bird species, providing that suitable management is applied at local and landscape levels.

Martín-García, Sustainable Forest Management Research Institute, University of Valladolid – INIA, Avenida Madrid, 57, 34004 Palencia, Spain E-mail: jorgemg@pvs.uva.es
Barbaro, NRA, UMR 1202 BIOGECO, 69 Route d’Arcachon, F-33612 Cestas cedex, France E-mail: luc@pierroton.inra.fr
Diez, Sustainable Forest Management Research Institute, University of Valladolid – INIA, Avenida Madrid, 57, 34004 Palencia, Spain E-mail: jdcasero@pvs.uva.es
Jactel, NRA, UMR 1202 BIOGECO, 69 Route d’Arcachon, F-33612 Cestas cedex, France; Université de Bordeaux, UMR 1202, Bordeaux, F-33000 France E-mail: herve.jactel@pierroton.inra.fr

article id 1030, category Research article

Jussi Manner, Tomas Nordfjell, Ola Lindroos. (2013). Effects of the number of assortments and log concentration on time consumption for forwarding. Silva Fennica vol. 47 no. 4 article id 1030. https://doi.org/10.14214/sf.1030

Keywords: productivity; time study; forest haulage; forwarders; cut-to-length logging; log extraction; terrain transport

Highlights: We analysed the effects of total and forwarded log concentrations (m³ (100 m)^–1) and the number of loaded assortments on forwarding; The combination of the number of loaded assortments and their abundance (i.e. forwarded log concentration) affected time consumption most; This knowledge enables improved efficiency by optimizing number and assortment proportions in the various loads required to forward a stand.

Abstract | Full text in HTML | Full text in PDF | Author Info

Forwarding has been carried out for 50 years, but much is still unknown about this work. Its complexity comes from both stand features and essential decision-making. Forwarding time consumption is influenced by e.g. log concentrations and number of assortments. Traditionally, focus has been on the total log concentration (TLC), referring to all logs at the harvesting site. However, we focused on forwarded log concentration (FLC), the load-specific log concentration which depends on the assortment distribution at harvesting site and the load-specific number of assortments. To evaluate the effects of TLC, number of assortments in a load and FLC on the loading and unloading times, a standardized field experiment was carried out. Pile and load sizes were constant, while TLC and FLC were manipulated by varying the pile distribution on the test path. For all work elements, the time consumption per m³ was significantly affected by the number of assortments that were loaded, but only the “driving while loading” work element was also significantly influenced by TLC. However, when untangling the intercorrelation between tested factors, it was found that the time consumption for driving while loading significantly decreased as a function of FLC and was unaffected by the number of assortments in a load. That FLC influences the forwarding time consumption highlights the need to study the effects of combining various assortment proportions in a load. Such knowledge will enable analysis of the most efficient number and assortment proportions to combine in the various loads required to forward a given stand.

Manner, Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, SE-901 83 Umeå, Sweden E-mail: jussi.manner@slu.se
Nordfjell, Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, SE-901 83 Umeå, Sweden E-mail: tomas.nordfjell@slu.se
Lindroos, Swedish University of Agricultural Sciences, Department of Forest Biomaterial and Technology, SE-901 83 Umeå, Sweden E-mail: ola.lindroos@slu.se

article id 1009, category Research article

Inger Sundheim Fløistad, Aksel Granhus. (2013). Timing and duration of short-day treatment influence morphology and second bud flush in Picea abies seedlings. Silva Fennica vol. 47 no. 3 article id 1009. https://doi.org/10.14214/sf.1009

Keywords: Norway spruce; photoperiod; autumn bud break; root collar diameter; second bud break; sturdyness

Highlights: The duration of short-day treatment, calculated as number of days, influenced the root collar diameter growth more than the timing of the treatment; If short-day treatment starts early in summer, a longer duration of the treatment is recommended to avoid second bud flush.

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A slower reaction of diameter growth cessation compared to that of height growth in response to short day (SD) treatment is well documented in Picea abies (L.) Karst. seedlings, suggesting that the height/diameter ratio of seedlings could be controlled through appropriate timing and/or duration of SD treatment is forest nurseries. Here, we applied specific combinations of timing (starting date 20 and 27 June, 4 or 11 July) and duration (7, 10, 14 or 17 days) of SD treatment to assess the possibility of obtaining more sturdy seedlings. We observed a rapid and uniform height growth cessation following SD treatment compared with the delayed cessation of diameter growth. Height growth responded significantly only to starting date of SD treatment, resulting in taller seedlings for later starting dates. Diameter growth responded to the duration of SD treatment, with significantly less diameter growth in seedlings exposed to 14 or 17 days of SD treatment than in seedlings exposed to 7 or 10 days of SD treatment. Also starting date influenced diameter growth, resulting in significantly more diameter growth with the earliest starting date compared with the two latest starting dates of the SD treatment. A second bud flush occurred only in seedlings exposed to SD treatment starting on 20 or 27 of June and only following 7-14 days of duration. This implies a need of longer duration if the SD treatment starts early. This will be at the expense of sustained diameter growth, thus compromising the objective of obtaining more sturdy seedlings.

Fløistad, Norwegian Institute for Agricultural and Environmental Research, Høgskolevn 7, N-1430 Ås, Norway & Norwegian Forest and Landscape Institute, P.O. Box 115, N-1431 Ås, Norway E-mail: isf@skogoglandskap.no
Granhus, Norwegian Forest and Landscape Institute, P.O. Box 115, N-1431 Ås, Norway E-mail: aksel.granhus@skogoglandskap.no

article id 972, category Research article

Outi H. Manninen, Rainer Peltola. (2013). Effects of picking methods on the berry production of bilberry (Vaccinium myrtillus), lingonberry (V. vitis-idaea) and crowberry (Empetrum nigrum ssp. hermaphroditum) in Northern Finland. Silva Fennica vol. 47 no. 3 article id 972. https://doi.org/10.14214/sf.972

Keywords: berry yields; commercial picking; wild forest berries

Highlights: Berry production of bilberry, lingonberry and crowberry was studied after picking the berries by plastic hand rake, long-handed metal rake, and powerful picking by long-handed metal rake; Berry production was not affected by the damage caused by any of the picking method; Current commercial picking methods do not endanger the berry production of the berry species at least in short-term.

Abstract | Full text in HTML | Full text in PDF | Author Info

The effect of commercial wild berry picking on berry yields is under a strong public debate in Finland. Especially high concern has been arisen over damages caused by metal rakes used in commercial picking to subsequent berry production. We studied the berry production of bilberry (Vaccinium myrtillus L.), lingonberry (V. vitis-idaea L.) and crowberry (E. nigrum ssp. hermaphroditum (Hagerup) Böcher) after picking the berries by 1) plastic hand rake, 2) long-handed metal rake and 3) powerful picking by long-handed metal rake, in northern Finland during 2010–2012. In the powerful long-handed metal rake treatment the aboveground vegetation was raked twice to the moss layer after berry picking. Biomass, which was removed from the vegetation by rakes was collected and used as a measure of the damage. We assumed that picking by plastic hand rake would result in lowest, long-handed metal rake intermediate and powerful picking by long-handed metal rake highest biomass loss from vegetation. The amount of biomass loss should in turn be reversely reflected into berry production. However, only the powerful picking by long-handed metal rake removed higher amount of biomass than other picking methods in bilberry and lingonberry. In crowberry, the amount of biomass removed by rakes increased from treatment to treatment. Contrary to our assumption, berry production of bilberry, lingonberry and crowberry was not affected by the damage caused by any of the picking method. We conclude that long-handed metal rake used in commercial picking is comparable to hand rake in terms of berry production.

Manninen, Agrifood Research Finland MTT, Eteläranta 55, FI-96300 Rovaniemi, Finland E-mail: outi.h.manninen@mtt.fi
Peltola, Agrifood Research Finland MTT, Eteläranta 55, FI-96300 Rovaniemi, Finland E-mail: rainer.peltola@mtt.fi

article id 970, category Research article

Zhen-Yu Du, Qing-Hua Wang, Shang-Jun Xing, Fang-Chun Liu, Bing-Yao Ma, Hai-Lin Ma, De-Xi Liu. (2013). Fine root distribution, characteristics and rhizosphere soil properties in a mixed stand of Robinia pseudoacacia and Fraxinus velutina in a saline soil. Silva Fennica vol. 47 no. 3 article id 970. https://doi.org/10.14214/sf.970

Keywords: mixed forest; fine root; black locust; velvet ash; rhizhosphere soil

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The spatial distribution and characteristics of fine roots (< 2 mm in diameter), and rhizosphere soil properties were studied in a mixed planted forest of black locust (Robinia pseudoacacia L.) and velvet ash (Fraxinus velutina Torr.) 27 years after planting in a coastal saline soil of the Yellow River delta, China. The results of fine root analysis showed that the fine roots of both black locust and velvet ash were mainly distributed in the soil layer at 0–20 cm depth and 50–150 cm from trees. The fine root distribution of both species suggests a strategy of avoiding salinity rather than salt –tolerance. The horizontal spread distance of fine roots of velvet ash was evidently longer than that of black locust. The fine root biomass, specific root length, specific root area, specific root volume and root activity were significantly higher for velvet ash in comparison with black locust. The results of soil analysis showed that rhizosphere soil pH of black locust and velvet ash were significantly lower compared with non-rhizosphere soil. The available N content in rhizosphere soil of black locust was higher than that of velvet ash. However, the contents of soluble salt, organic matter, available P and available K in rhizosphere soil of velvet ash were higher than those of black locust. The above results indicated that the differences between black locust and velvet ash in fine root distribution, characteristics and rhizosphere soil properties were the major reasons for that velvet ash showed stronger acclimation responses than black locust to the coastal saline soil.

Du, Shandong Academy of Forestry, 42 Wenhua East Road, Jinan 250014, P. R. China E-mail: zydu@qq.com
Wang, Shandong Academy of Forestry, Jinan, P. R. China E-mail: wqh0228@163.com
Xing, Shandong Academy of Forestry, Jinan, P. R. China E-mail: xingsj-126@126.com
Liu, Shandong Academy of Forestry, Jinan, P. R. China E-mail: fchliu@126.com
Ma, Shandong Academy of Forestry, Jinan, P. R. China E-mail: mby777@163.com
Ma, Shandong Academy of Forestry, Jinan, P. R. China E-mail: mahlin@163.com
Liu, Shandong Academy of Forestry, Jinan, P. R. China E-mail: llyldx@163.com

article id 964, category Research article

Liisa Huttunen, Matthew P. Ayres, Pekka Niemelä, Susanne Heiska, Riitta Tegelberg, Matti Rousi, Seppo Kellomäki. (2013). Interactive effects of defoliation and climate change on compensatory growth of silver birch seedlings. Silva Fennica vol. 47 no. 3 article id 964. https://doi.org/10.14214/sf.964

Keywords: root; shoot ratio; biomass; Betula pendula; elevated CO2; elevated temperature; folivory

Highlights: The main components affecting growth compensation in silver birch seedlings are the timing and severity of foliage damage; The ability to compensate growth is also dependent upon the limits of temperature and nutrient availability; The responses of birches imply that folivory does not necessarily lead to reduced net productivity under changing climate

Abstract | Full text in HTML | Full text in PDF | Author Info

Atmospheric warming increases the abundance of insect herbivores and intensifies the risk of defoliation, especially in high latitude forests. At the same time, the effects of increasing temperature and CO₂ on plant responses to foliage damage are poorly understood. We examined if previous-year defoliation, varying between 0 and 75% of total leaf area, and different combinations of elevated temperature, CO₂ and nutrient availability alter the growth of two-year old silver birch (Betula pendula Roth) seedlings. We measured the greatest height growth in seedlings that were fertilized and defoliated twice at the level of 50% of total leaf area, and subjected to elevated temperature with ambient CO₂. The lowest growth was recorded in unfertilized seedlings that were defoliated twice at the level of 25% of total leaf area, and grew under ambient temperature with ambient CO₂. The total biomass increased in all seedlings that were fertilized or grew under elevated temperature. The root: shoot ratios were low in defoliated seedlings, or seedlings subjected to fertilization or temperature elevation. Our conclusion is that ability of birches to compensate height growth is highly dependent upon the magnitude and frequency of defoliation on the limits of temperature and nutrient availability. These responses imply that folivory does not necessarily lead to reduced net productivity of trees under changing climate.

Huttunen, Section of Ecology, Department of Biology, University of Turku, FI-20014 Turku, Finland E-mail: liisa.huttunen@utu.fi
Ayres, Biological Sciences, Dartmouth College, Hanover, NH 03755, USA E-mail: matt.ayres@dartmouth.edu
Niemelä, Section of Biodiversity and Environmental Science, Department of Biology, University of Turku, FI-20014 Turku, Finland E-mail: pekka.niemela@utu.fi
Heiska, The Finnish Forest Research Institute, Punkaharju Unit, Finlandiantie 18, FI-58450 Punkaharju, Finland E-mail: susanne.heiska@metla.fi
Tegelberg, Digitarium - Digitization Centre of the Finnish Museum of Natural History and the University of Eastern Finland, Joensuu Science Park, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: riitta.tegelberg@helsinki.fi
Rousi, The Finnish Forest Research Institute, Vantaa Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: matti.rousi@metla.fi
Kellomäki, Faculty of Science and Forestry, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: seppo.kellomaki@uef.fi

article id 956, category Research article

Michał Zasada. (2013). Evaluation of the double normal distribution for tree diameter distribution modeling. Silva Fennica vol. 47 no. 2 article id 956. https://doi.org/10.14214/sf.956

Keywords: diameter distribution; simulated annealing; goodness-of-fit; Weibull distribution; maximum likelihood method; method of moments

Abstract | Full text in HTML | Full text in PDF | Author Info

The double normal distribution consists of two normal distributions truncated at their means and then combined in such a way, that points of truncation now become the overall distribution mode. So far, parameters of the double normal distribution have been estimated exclusively using the method of moments. This study evaluates the maximum likelihood method for the estimation of the double normal distribution parameters in Scots pine stands in Poland, and compares it to the results of the method of moments and the two-parameter Weibull distribution fitted using the maximum likelihood method and the method of moments. Presented results show that it is not recommended to use the maximum likelihood method of parameter fitting with Nelder-Mead and quasi-Newton optimization algorithms for the double normal distribution for small samples. However, it can be used for large samples, giving the fit comparable to the two-parameter Weibull distribution and providing parameters having sound practical and biological meaning. In the case of smaller samples for the double normal distribution it is recommended to apply the maximum likelihood method with the alternative simulated annealing optimization algorithm, use the method of moments or substitute the described distribution with more the flexible and robust Weibull distribution. For the smaller samples, the method of moments was superior to the maximum likelihood method.

Zasada, Warsaw University of Life Sciences, Faculty of Forestry, Laboratory of Dendrometry and Forest Productivity, Nowoursynowska 159, 02-776 Warsaw, Poland E-mail: michal.zasada@wl.sggw.pl

article id 954, category Research article

Anna-Maria Eriksson, Jörgen Olsson, Bengt Gunnar Jonsson, Sara Toivanen, Mattias Edman. (2013). Effects of restoration fire on dead wood heterogeneity and availability in three Pinus sylvestris forests in Sweden. Silva Fennica vol. 47 no. 2 article id 954. https://doi.org/10.14214/sf.954

Keywords: Scots pine; CWD; prescribed burning; decay stage; charred wood

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Restoration fires are increasingly used as a conservation tool in Sweden to recreate forests with characteristics of previous forests that were periodically disturbed by fires and promote fire-dependent species. Restoration fires can result in large inputs of fresh dead wood, but there are risks of losing some of the existing, pre-fire dead wood. To assess these counteracting effects we studied the heterogeneity and availability of dead wood before and after three restoration fires in boreal Scots pine forests. Specifically, we studied volumes of stumps, high stumps, snags and logs. The fires decreased the total volume of pre-fire dead wood (23-41%) and consumed logs in late decay stages (26-54%) to a higher extent than logs in earlier stages. The input of new fresh dead wood after the fires exceeded losses of pre-fire dead wood and resulted in a net increase of dead wood in all three sites. The added dead wood consisted of fresh snags killed by the fires. Fire also affected log characteristics: reducing their vegetation coverage (60-98%), decreasing their ground contact (4-50%) and increasing their surface area of charred wood (>50%). Such changes have important consequences for the micro environmental conditions inside logs, but have been rarely studied in relation to restoration fires. Our results show that restoration fire causes changes in dead wood availability and characteristics of logs. The results imply that ideally stands with low abundance of rare and heavily decayed wood substrates should be burned to optimize dead wood values. Alternatively, management practices should include protection of these substrates during restoration fires.

Eriksson, Department of Natural Sciences, Mid Sweden University, SE-851 70, Sundsvall, Sweden E-mail: anna-maria.eriksson@miun.se
Olsson, Department of Ecology and Environmental Science, Umeå University, SE-901 87, Umeå, Sweden E-mail: jorgen.m.olsson@slu.se
Jonsson, Department of Natural Sciences, Mid Sweden University, SE-851 70, Sundsvall, Sweden E-mail: bengt-gunnar.jonsson@miun.se
Toivanen, Department of Natural Sciences, Mid Sweden University, SE-851 70, Sundsvall, Sweden E-mail: sara.toivanen@lansstyrelsen.se
Edman, Department of Natural Sciences, Mid Sweden University, SE-851 70, Sundsvall, Sweden E-mail: mattias.edman@miun.se

article id 930, category Research article

Raffaele Spinelli, Eugenio Cavallo, Lars Eliasson, Alessio Facello. (2013). Comparing the efficiency of drum and disc chippers. Silva Fennica vol. 47 no. 2 article id 930. https://doi.org/10.14214/sf.930

Keywords: productivity; biomass; wood; energy; fuel

Abstract | Full text in HTML | Full text in PDF | Author Info

The study compared the effect of chipper type on productivity, power demand, fuel consumption and product quality. Tests were conducted on two commercial chipper models, a disc and a drum chipper. Both chippers had the same diameter capacity, were applied to the same tractor and fed with the same feedstock types. Fifteen replications were conducted per machine and for each of four different feedstock types, reaching a total of 120 tests. The disc chipper had a higher energy efficiency and used 19% less fuel per unit product, possibly due to its simpler design, integrating comminuting and discharge system in one synergic device. In contrast, the drum chipper was 8% more productive, since it cut with the same energy all along the length of its knives. The drum chipper produced smaller chips, with a higher incidence of fines. Feedstock type had a strong effect on productivity, energy efficiency and product quality. The effect of feedstock type was mainly related to piece size, and may be stronger than the effect of chipper type. Further studies should determine the effect of blade wear on the relative performance of the two chipper types.

Spinelli, CNR IVALSA, Via Madonna del Piano 10, Sesto Fiorentino (FI), Italy E-mail: spinelli@ivalsa.cnr.it
Cavallo, CNR IVALSA, Via Madonna del Piano 10, Sesto Fiorentino (FI), Italy E-mail: e.cavallo@imamoter.cnr.it
Eliasson, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: lars.eliasson@skogforsk.se
Facello, CNR IVALSA, Via Madonna del Piano 10, Sesto Fiorentino (FI), Italy E-mail: a.facello@ima.to.cnr.it

article id 904, category Research article

Raul Fernandez-Lacruz, Fulvio Di Fulvio, Dan Bergström. (2013). Productivity and profitability of harvesting power line corridors for bioenergy. Silva Fennica vol. 47 no. 1 article id 904. https://doi.org/10.14214/sf.904

Keywords: accumulating felling head; clearing; maintenance; motor-manual; power grid; wood fuel

Abstract | Full text in HTML | Full text in PDF | Author Info

Trees growing under the wires and around the pylons carrying power lines (PL) represent a significant threat to the power supply because they can cause power outages and damage. The vegetation in these PL corridors is cleared motor-manually on a regular basis, which represents about 50% of the PL maintenance costs. In Sweden, PL corridors account for 140 000 ha of productive forest land, with an estimated bioenergy potential of 3 TWh/year. The aim of this study was to measure the productivity of a harvester (with an accumulating felling head) and a forwarder, performing PL corridor clearing (with the collection of whole trees for energy use) and to calculate how the cost and economic profitability is dependent on tree height, biomass removal, harvested area, forwarding distance and wood fuel price. The study also compared the economic profitability of the mechanized harvesting system with motor-manual clearing. Experimental units were inventoried along a PL corridor in central Sweden and a time study of one harvester and one forwarder (with a single operator per machine), working in those units, was carried out. The results showed that if the tree height was greater than about 6 m, the mechanized harvesting system became a more cost-efficient alternative, when compared to motor-manual clearing, but it was also found that mechanized clearing is not always the most cost-effective option. Nevertheless, mechanization of PL clearing has a huge potential for expansion, requiring further research in the combined management of the PL corridors and side areas.

Fernandez-Lacruz, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden E-mail: raul.fernandez@slu.se
Di Fulvio, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden E-mail: fulvio.di.fulvio@slu.se
Bergström, Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden E-mail: dan.bergstrom@slu.se

article id 899, category Research article

Franz Holzleitner, Christian Kanzian, Norbert Höller. (2013). Monitoring the chipping and transportation of wood fuels with a fleet management system. Silva Fennica vol. 47 no. 1 article id 899. https://doi.org/10.14214/sf.899

Keywords: forest fuel; supply chain; monitoring; logistic; fleet management; wood chips

Abstract | Full text in HTML | Full text in PDF | Author Info

Controlling and organizing the complex forest-to-consumer supply chain of wood fuels is a challenging task, especially for the chipping and transport processes. Truck mounted chippers and transport trailer-trucks must be scheduled to minimize delay to be profitable. Job management within the supply chain, including machine activity based controlling, offers a new way to increase efficiency and productivity. However, detailed data are required to detect and analyze potential gaps and improve forest fuel supply. Generally, data regarding the wood fuel supply chain process are obtained from extensive time studies that are based on a specific process step. Although time studies can detect details during the production of forest fuels, they only describe certain time frames. Long-term data that are recorded during the entire year could encompass seasonal and short term effects. This study aims to monitor the forest fuel supply processes (semi-automated), specifically regarding time and fuel consumption. Large data sets were automatically and efficiently gathered with little effort by drivers and operators. Data were recorded with fleet management equipment for more than 14 months. Vehicle data, including GPS data, were logged at an interval of one minute. Data management was conducted in a pre-configured database that contained pre-defined reports and were run by the Institute of Forest Engineering, Vienna. Work step assignments were implemented with Structured Query Language (SQL)-routines by using the raw machine activities data and GPS. The chipping and transport activities of more than 240 loads were analyzed by focusing on fuel consumption, time needed and traffic. The average distance between chipping sites and plants was approximately 54 kilometers. Fuel consumption from transport reached 50 l/100 km. The chipping unit reached a productivity of 12.8 odt/PSH15 and had a fuel consumption of 58 liters per operating hour.

Holzleitner, Institute of Forest Engineering, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences, Peter Jordanstrasse 82/3, 1190 Vienna, Austria E-mail: franz.holzleitner@boku.ac.at
Kanzian, Institute of Forest Engineering, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences, Peter Jordanstrasse 82/3, 1190 Vienna, Austria E-mail: christian.kanzian@boku.ac.at
Höller, Institute of Forest Engineering, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences, Peter Jordanstrasse 82/3, 1190 Vienna, Austria E-mail: norbert.hoeller@boku.ac.at

article id 924, category Research article

Minna Pulkkinen. (2012). On non-circularity of tree stem cross-sections: effect of diameter selection on cross-section area estimation, Bitterlich sampling and stem volume estimation in Scots pine. Silva Fennica vol. 46 no. 5B article id 924. https://doi.org/10.14214/sf.924

Keywords: basal area; Scots pine; stem volume; forest mensuration; cross-section; non-circularity; Bitterlich sampling

Abstract | View details | Full text in PDF | Author Info

In the common methods of forest mensuration, including stem volume models and Bitterlich sampling, stem cross-sections are assumed to be circular. In nature this assumption is never exactly fulfilled. Errors due to non-circularity have been presumed to be small and unimportant but studied little: theoretical and empirical studies exist on cross-section area estimation, but errors in stem volume estimation have not been investigated at all, and errors in Bitterlich sampling are theoretically known only for stand basal area estimation. In the theoretical part of this study, we developed methods for quantifying the systematic and sampling errors that 22 common ways of selecting diameter within non-circular cross-sections induce (i) in area estimates by the circle area formula, (ii) in stand total estimates by Bitterlich sampling, and (iii) in stem volume estimates by a volume equation, by a cubic-spline-interpolated stem curve, and by a generalised volume estimator. In the empirical part, based on the digital images of 709 discs taken at 6–10 heights in 81 Scots pine stems from different parts of Finland, we investigated the variation in cross-section shape, and demonstrated the magnitude of the errors presented in the theoretical part. We found that non-circularity causes systematic overestimation of area and volume, and inflicts potentially systematic error on stand total estimates by Bitterlich sampling. In our data these effects were small, but the finding is not generalisable due the skewed size distribution and poor geographical representativeness of the data. We recommend using diameter derived from girth for both tree and stand level estimation, as it involves no sampling error and produces clearly the most stable systematic errors.

Pulkkinen, E-mail: minna.pulkkinen@iki.fi

article id 921, category Research article

Katri Luostarinen. (2012). Tracheid wall thickness and lumen diameter in different axial and radial locations in cultivated Larix sibirica trunks. Silva Fennica vol. 46 no. 5 article id 921. https://doi.org/10.14214/sf.921

Keywords: wood; earlywood; latewood; fibre; Siberian larch; xylem

Abstract | View details | Full text in PDF | Author Info

In Larix trunks the properties of wood differ clearly radially, but the axial differences are smaller as well as being less studied. Wood anatomy is in particular poorly studied, even though all other wood properties derive from cell and tissue structure. The aim of this study was to chart variation in tracheid size (double wall thickness (2CWT), diameter of lumen (RD)) within fast grown cultivated Siberian larch (Larix sibirica Ledeb.) trunks. The differences in 2CWT and RD were clear between earlywood (EW) and latewood (LW), 2CWT increasing clearly less in EW than in LW towards the bark, while RD stayed quite stable in LW but in EW increased markedly towards the bark. The difference in 2CWT between EW and LW increased towards the upper trunk. In conclusion, the radial variation in RD and 2CWT was different between the butt and other studied heights. As the difference in 2CWT between EW and LW was smaller at the butt than the upper portion of the trunk, the wood was the most homogenous at the butt.

Luostarinen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: katri.luostarinen@uef.fi

article id 920, category Research article

Hannu Hökkä, Jaakko Repola, Mikko Moilanen, Markku Saarinen. (2012). Seedling establishment on small cutting areas with or without site preparation in a drained spruce mire – a case study in northern Finland. Silva Fennica vol. 46 no. 5 article id 920. https://doi.org/10.14214/sf.920

Keywords: Picea abies; site preparation; canopy gaps; natural regeneration; drained peatlands; seedling establishment; clear-cut

Abstract | View details | Full text in PDF | Author Info

A large proportion of drained spruce mire stands is currently approaching regeneration maturity in Finland. We studied the effect of cutting – small canopy openings (78, 177, and 314 m²) and small clear-cuts (0.25–0.37 ha) – with or without site preparation (scalping) on the establishment of natural Norway spruce seedlings in one experimental drained spruce mire stand in northern Finland. The cuttings were made in winter 2004–2005 and site preparation with scalping in early June 2005. The experimental design was composed of four blocks with altogether four clear-cuts and 33 canopy openings. The seedling establishment was surveyed annually (2006, 2008–2010) from five circular sample plots (one 10 m² and four 5 m² plots in size) located within the canopy openings and from 18 circular 5 m² sample plots systematically located in the scalped and untreated halves of the clear-cuts. Site preparation was found unnecessary, because it resulted in a clearly lower number of seedlings in the openings. A slight negative effect was also found in the clear-cuts. In the two years following the cuttings, the number of seedlings increased quickly in the canopy openings, but more gradually in the clear-cut areas. In 2010, on average 15 500 new seedlings were observed in the canopy openings and 6700 in the clear-cut areas, of which 5050 and 1200, respectively, were >0.1 m tall spruces. The proportion of birch increased in the last two years, being ca. 22% in the openings and 45% in the clear-cuts in 2010. The spatial distribution of seedlings was more uneven in the clear-cuts than in the openings, with 41% and 20% of survey plots empty, respectively.

Hökkä, Finnish Forest Research Institute, Rovaniemi Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: hannu.hokka@metla.fi
Repola, Finnish Forest Research Institute, Rovaniemi Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: jaakko.repola@metla.fi
Moilanen, Finnish Forest Research Institute, Oulu Unit, P.O. Box 413, FI-90014 University of Oulu, Finland E-mail: mikko.moilanen@metla.fi
Saarinen, Finnish Forest Research Institute, Parkano Unit, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: markku.saarinen@metla.fi

article id 916, category Research article

M. Carmen San José, Lourdes Romero, Laura V. Janeiro. (2012). Effect of indole-3-butyric acid on root formation in Alnus glutinosa microcuttings. Silva Fennica vol. 46 no. 5 article id 916. https://doi.org/10.14214/sf.916

Keywords: alder; mature trees; histology; rooting

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A study of the in vitro rooting process in mature alder (Alnus glutinosa (L.) Gaertn.) shoots is described. Microcuttings from shoots cultured in vitro were transferred to a half-strength Woody Plant Medium containing 0 or 0.1 mg l^–1 indole-3-butyric acid (IBA) for 0 to 7 days. The presence of IBA in the medium increased the rooting percentage, number of roots, percentage of lateral roots, and length of the shoots. Histological studies were carried out with shoots treated with 0 or 0.1 mg l^–1 IBA for 7 days. According to these criteria, treatment with IBA for 2–3 days proved to be the most successful. In both treatments, substancial reactivation of cell division was observed at the base of the shoots after 1 day. Some cambial zone and adjacent phloem cells became dense cytoplasm, having nuclei with prominent nucleoli. The first cell divisions were also observed at this time. In the treatment with IBA (0.1 mg l^–1 for 7 days), meristemoids became individualized, consisting of densely staining cells, by day 3. Identifiable conical shaped root primordia with several cell layers were visible after 4–5 days. Roots with an organized tissue system emerged from the stem after 6 days in the IBA-treated shoots. Meristemoid formation was delayed until the fourth day and root emergence until the eight day in the control treatment (no IBA).

San José, Instituto de Investigaciones Agrobiológicas de Galicia, CSIC, Avda de Vigo s/n, Apartado 122, 15780 Santiago de Compostela, Spain E-mail: sanjose@iiag.csic.es
Romero, CIFP Politécnico de Santiago, Santiago de Compostela, Spain E-mail: lr@nn.es
Janeiro, INLUDES, Diputación Provincial de Lugo, Lugo, Spain E-mail: lauravj68@hotmail.com

article id 909, category Research article

Veikko Hiltunen, Mikko Kurttila, Jouni Pykäläinen. (2012). Strengthening top-level guidance in geographically hierarchical large scale forest planning: experiences from the Finnish state forests. Silva Fennica vol. 46 no. 4 article id 909. https://doi.org/10.14214/sf.909

Keywords: efficiency; acceptability; hierarchical planning; strategic forest planning

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Different planning approaches conclude to different results. The top-down approach allocates resources efficiently from the top-level perspective, while the bottom-up approach provides optimal results for the lower levels. Integrated approach that combines the elements of these two basic approaches provides compromise solutions for decision makers. The aim of this study was to examine potential efficiency improvements in hierarchically structured large scale forest management through increased top-level guidance. The resulting effects on the acceptability of the plans on the lower level were also studied. Large scale planning typically considers forests owned by states, companies and municipalities. In the case study of the Finnish state forests, alternative country level solutions were generated by combining regional forest plans in different ways. The results showed that the currently applied bottom-up approach, which produces regionally optimal management strategies, did not result in the most efficient use of resources on the country level. However, the new country level solutions did not produce huge improvements in the country level objective values compared to the results of the current approach. Furthermore, if country level efficiency improvements were emphasized more, together with wide approval by regional stakeholders and local residents, new kind of interaction and participation between the planning levels and also between the regions would be needed.

Hiltunen, Metsähallitus, Viestitie 2, FI-87700 Kajaani, Finland E-mail: veikko.hiltunen@metsa.fi
Kurttila, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: mikko.kurttila@metla.fi
Pykäläinen, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jouni.pykalainen@metla.fi

article id 908, category Research article

Sattar Ezzati, Akbar Najafi, M. A. Rab, Eric K. Zenner. (2012). Recovery of soil bulk density, porosity and rutting from ground skidding over a 20-year period after timber harvesting in Iran. Silva Fennica vol. 46 no. 4 article id 908. https://doi.org/10.14214/sf.908

Keywords: soil disturbance; timber harvesting; soil conservation; skid trail slope; mountainous forest

Abstract | View details | Full text in PDF | Author Info

Ground-based skidding can have detrimental effects on soil properties trough soil profile disturbance and compaction that can persist for decades. We investigated the recovery of physical properties of disturbed brown soils on four abandoned downhill skid trails in a deciduous mountain forest in northern Iran. The most recent skidding operations had taken place 1–5 yrs, 6–10 yrs, 11–15 yrs, and 16–20 yrs ago, providing a 20-year chronosequence with four 5-year recovery periods. For each recovery period, mean values for soil bulk density (BD), total porosity (TP), macroporosity (MP), soil moisture content (SM), and rut depth (RD) were assessed for three levels of traffic intensity (Primary (PS), Secondary (SS) and Tertiary (TS) skid trails) and two levels of slope gradients (Gentle (G) and Steep (S)) and compared to those in undisturbed (control) areas. Over the 20-year recovery period, PS trails on gentle slopes exhibited mean values that were 35–42% (BD), 3–7% (SM), and 13–19 cm (RD) greater and 18–24% (TP) and 19–28% (MP) lower compared to undisturbed areas; on steep PS trails, values were 40–46% (BD), 2–13% (SM), and 13–21 cm (RD) greater and 23–27% (TP) and 28–35% (MP) lower, respectively. While RD and SM recovered, 20 years was not long enough for the other physical soil properties, particularly on steep slopes. To minimize soil disturbance, skidding should be confined to areas with gentle slopes and alternative harvesting methods such as cable yarding should be used where slope gradients exceed 20%.

Ezzati, Department of Forestry and Forest Engineering, Tarbiat Modares University, P.O. Box 64414-356, Iran E-mail: se@nn.ir
Najafi, Department of Forestry and Forest Engineering, Tarbiat Modares University, P. Box 64414-356, Iran E-mail: a.najafi@modares.ac.ir
Rab, Soil Physics Future Farming Systems Research Division, Department of Primary Industries, Victoria, Australia E-mail: mr@nn.ir
Zenner, Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA, USA E-mail: eric.zenner@psu.edu

article id 907, category Research article

Chunyu Zhang, Yazhou Zhao, Xiuhai Zhao, Klaus von Gadow. (2012). Species-habitat associations in a northern temperate forest in China. Silva Fennica vol. 46 no. 4 article id 907. https://doi.org/10.14214/sf.907

Keywords: species richness; spatial autocorrelation; dispersal limitations; indicator species; topographic differentiation

Abstract | View details | Full text in PDF | Author Info

This contribution identifies species-habitat associations in a temperate forest in north-eastern China, based on the assumption that habitats are spatially autocorrelated and species are spatially aggregated due to limited seed dispersal. The empirical observations were obtained in a large permanent experimental area covering 660 x 320 m. The experimental area was subdivided into four habitat types using multivariate regression tree (MRT) analysis. According to an indicator species analysis, 38 of the 47 studied species were found to be significant indicators of the MRT habitat types. The relationships between species richness and topographic variables were found to be scale-dependent, while the great majority of the species shows distinct habitat-dependence. There are 188 potential species-habitat associations, and 114 of these were significantly positive or negative based on habitat randomization. We identified 139 significant associations using a species randomization. A habitat is not a closed system it may be both, either a sink or a source. Therefore, additional to the randomization, the Poisson Cluster Model (PCM) was applied. PCM considers the spatial autocorrelation of species and habitats, and thus appears to be more realistic than the traditional randomization processes. It identified only 37 associations that were significant. In conclusion, the deviation from the random process, i.e. the high degree of species spatial mingling may be explained by persistent immigration across habitats.

Zhang, Key Laboratory for Forest Resources & Ecosystem Processes of Beijing, Beijing Forestry University, Beijing 100083, China E-mail: zcy_0520@163.com
Zhao, Department of Landscape Architecture, School of Architecture, Tsinghua University, Beijing 100084, China E-mail: yz@nn.cn
Zhao, Key Laboratory for Forest Resources & Ecosystem Processes of Beijing, Beijing Forestry University, Beijing 100083, China E-mail: xz@nn.cn
von Gadow, Faculty of Forestry and Forest Ecology, Georg-August-University Göttingen, Büsgenweg 5, D-37077 Göttingen, Germany E-mail: KGadow@gwdg.de

article id 906, category Research article

Eivind Meen, Anders Nielsen, Mikael Ohlson. (2012). Forest stand modelling as a tool to predict performance of the understory herb Cornus suecica. Silva Fennica vol. 46 no. 4 article id 906. https://doi.org/10.14214/sf.906

Keywords: canopy layer; field layer; stand structure dynamics; forest simulator; composite models; Akaike’s information criterion

Abstract | View details | Full text in PDF | Author Info

Forest simulation models have been widely used to predict future stand structure. Generally these models do not include the understory vegetation and its response on stand structure change or other environmental factors. Previous simulation studies have shown that stand structure related variables, e.g. basal area, can explain diversity of the forest floor vegetation in boreal forests. We hypothesise that such variables also can be used to explain the performance of understory species and we conceptualise how plant ecology and forest modelling can be combined to predict the performance of understory plants in Norwegian boreal forests. We predict the performance of an understory plant species (Cornus suecica) over time using simulated values of forest variables as input to models expressing the relationship between forest environment variables and plant performance variables (viz. plant height, plant dry weight, number of flowers, number of branches and number of leaves). We also present relationships between plant performance and explanatory variables commonly used in basic ecological research, variables that currently not are readily compatible with forest simulators (e.g. soil chemical variables).We found basal area of canopy trees being the most important explanatory variable explaining C. suecica performance. The performance variable dry weight was predicted by one single model whereas the other performance variables were best predicted by model averaging. Forest simulations for 150 years showed values of plant performance of C. suecica to be reduced during forest succession.

Meen, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: eivind.meen@umb.no
Nielsen, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: an@nn.no
Ohlson, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O. Box 5003, NO-1432 Ås, Norway E-mail: mo@nn.no

article id 51, category Research article

Sanna Hautamäki, Antti Mutanen, Jari Viitanen. (2012). Substitution in the Finnish forest industry’s roundwood procurement. Silva Fennica vol. 46 no. 3 article id 51. https://doi.org/10.14214/sf.51

Keywords: roundwood procurement; imports; substitution; translog cost function

Abstract | View details | Full text in PDF | Author Info

In this study, the interaction and substitution between domestic and imported roundwood in the Finnish forest industry’s wood procurement is analysed by timber assortments. The results from the translog cost function approach and quarterly data of the total wood procurement and its components during the euro regime indicate that, to a certain extent, the Finnish forest industry has had the possibility of substituting imported roundwood volumes between countries in the Baltic Sea region. Contrary to earlier studies, also in the case of Russian birch pulpwood, the most important imported timber assortment, the results suggest that Russian birch pulpwood has rather substituted for than complemented the domestic supply in Finland. The increase in roundwood export duties in Russia has had a statistically significant effect on the trade in birch pulpwood and spruce sawlogs. Moreover, the results confirm the earlier findings of a rigid demand for roundwood in Finnish roundwood markets.

Hautamäki, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: sh@nn.fi
Mutanen, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: antti.mutanen@metla.fi
Viitanen, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jv@nn.fi

article id 49, category Research article

Kalle Karttunen, Kari Väätäinen, Antti Asikainen, Tapio Ranta. (2012). The operational efficiency of waterway transport of forest chips on Finland’s Lake Saimaa. Silva Fennica vol. 46 no. 3 article id 49. https://doi.org/10.14214/sf.49

Keywords: barges; discrete-event simulation; forest fuels; logistics; supply chains; tugboats

Abstract | View details | Full text in PDF | Author Info

New and cost-efficient methods for use in supply chains for energy wood should be found, to reach the targets of the renewable energy utilisation set by the European Union. The long-distance waterway transportation of forest fuels should be thoroughly investigated, especially in areas where the transport distance is long and waterways could provide a feasible method of conveying forest fuel. In comparison to transport of forest chips by truck, barge-based waterway transport shows a competitive advantage due to the larger loads and higher bulk density of chips it allows. The cost-efficiency of waterway transportation operations related to forest chips in Finland’s Lake Saimaa region was studied using practical demonstrations and discrete-event simulation. The varying demand for fuel wood in three separate bio-power plants on the Saimaa lakeside (near the cities of Varkaus, Mikkeli, and Savonlinna) was addressed in several barge transportation scenarios. Finally, the economy of barge transportation was compared to the economy of truck transportation as a function of transportation distance and in terms of the annual performance of the transportation methods examined. The waterway supply chain of forest chips was cost-competitive to road transport by truck after 100–150 km. According to the simulation study, the most economical waterway transport options were based on fixed barge system and shift-independent harbor logistics where loading and unloading of barges were carried-out with a wheeled loader and a belt conveyor. Total supply chain costs including the best waterway logistics from road side storage to power plant ranged from 10.75 euros to 11.64 euros/MWh in distances of 100–150 km by waterways. The energy-density of forest chips in the barge load was found to be, on average, 25% higher than that in truck hauling, because of the better compaction of chips. Waterway transport is a viable option for long-distance transportation of forest chips in Eastern Finland.

Karttunen, Lappeenranta University of Technology, LUT Savo Sustainable Technologies, Mikkeli, Finland E-mail: kalle.karttunen@lut.fi
Väätäinen, The Finnish Forest Research Institute, Joensuu, Finland E-mail: kari.vaatainen@metla.fi
Asikainen, The Finnish Forest Research Institute, Joensuu, Finland E-mail: antti.asikainen@metla.fi
Ranta, Lappeenranta University of Technology, LUT Savo Sustainable Technologies, Mikkeli, Finland E-mail: tapio.ranta@lut.fi

article id 48, category Research article

Jyrki Hytönen, Lasse Aro. (2012). Biomass and nutrition of naturally regenerated and coppiced birch on cutaway peatland during 37 years. Silva Fennica vol. 46 no. 3 article id 48. https://doi.org/10.14214/sf.48

Keywords: Betula; biomass production; coppicing; fertilization; PK fertilizers; wood ash

Abstract | View details | Full text in PDF | Author Info

Biomass production and nutrient use of birch thickets with a mixture of willow on a cut away peatland in southern Finland over a period of 37 years was studied. Dense, naturally regenerated 16-year-old birch stands were cut down, fertilized with either wood ash (P 108 and K 339 kg ha^–1) or PK fertilizer (P 50 and K 95 kg ha^–1) or left unfertilized. The biomass production of the coppiced stands and one uncut stand was monitored for a period of 21 years. Soil nutrient and foliar nutrient concentrations were analyzed several times during the study period. Ash fertilization supplied more nutrients than PK fertilization and increased the soil nutrient amounts more. The foliar phosphorus concentration of birch on control plots indicated a severe phosphorus deficiency which was removed by PK and ash fertilization. Fertilization did not increase nutrient concentrations of the stem (wood + bark) nor the amount of nutrients bound in the biomass. Two energy wood rotations (16+21 years) produced 124–158 Mg ha^–1 of leafless, above-ground biomass altogether corresponding to 61–78 Mg ha^–1 of carbon. The highest biomass yield was achieved with a rotation of 37 years in the uncut stand (211 Mg ha^–1). Corresponding values for mean annual increment (MAI) were 3.4–4.3 Mg ha^–1 and 5.7 Mg ha^–1. This study shows that the length of the rotation for birch in energy wood production should be longer than 21 years. PK and ash fertilization increased the biomass of coppiced 21-year-old birch by 23 Mg ha^–1 and 33 Mg ha^–1, respectively.

Hytönen, Finnish Forest Research Institute, Kannus, Finland E-mail: jyrki.hytonen@metla.fi
Aro, Finnish Forest Research Institute, Kannus, Finland E-mail: lasse.aro@metla.fi

article id 46, category Research article

Matti Rousi, Boy J.H.M. Possen, Risto Hagqvist, Barb R. Thomas. (2012). From the Arctic Circle to the Canadian prairies – a case study of silver birch acclimation capacity. Silva Fennica vol. 46 no. 3 article id 46. https://doi.org/10.14214/sf.46

Keywords: acclimation; Betula papyrifera; Betula pendula; birch adaptability; critical night length; provenance transfers

Abstract | View details | Full text in PDF | Author Info

Earlier provenance research has indicated poor success even in short distance transfers (> 2–3° latitude) of silver birch (Betula pendula Roth) southward from their origin. These results may indicate poor adaptability of silver birch to a warming climate. Some of the scenarios for a warming climate in Finland suggest effective heat sums are likely to double in the north and increase 1.5 fold in the south for the period of 2070–2099. Consequently, the outlook for silver birch appears bleak. To study the acclimation of birch to this projected change we established a provenance trial in northeastern Alberta, Canada, at the temperature area currently predicted for Central Finland (lat. 64–66°N) at the turn of this century (1400 dd). Our 10-year experiment showed that all the Finnish provenances (origins 61–67°N) have acclimated well to the warmer growth conditions experienced in Alberta at 54°N. These results suggest that silver birch has the potential to acclimate to thermal conditions predicted for Finland at the end of the 21st century. Our results also indicate that silver birch has the potential as a plantation species in Canada, where the Finnish birch grew faster in the boreal forest region of Canada than local paper birch (Betula papyrifera Marsh.) provenances.

Rousi, The Finnish Forest Research Institute, Finland E-mail: matti.rousi@metla.fi
Possen, The Finnish Forest Research Institute, Finland E-mail: bjhmp@nn.fi
Hagqvist, The Finnish Forest Research Institute, Finland E-mail: rh@nn.fi
Thomas, University of Alberta, Dept of Renewable Resources, Edmonton & Alberta-Pacific Forest Industries Inc., Boyle, Alberta, Canada E-mail: brt@nn.ca

article id 45, category Research article

Guolei Li, Yong Liu, Yan Zhu, Qing Mei Li, R. Karsten Dumroese. (2012). Effect of fall-applied nitrogen on growth, nitrogen storage and frost hardiness of bareroot Larix olgensis seedlings. Silva Fennica vol. 46 no. 3 article id 45. https://doi.org/10.14214/sf.45

Keywords: deciduous trees; fall fertilization; frost hardiness; Olga Bay larch

Abstract | View details | Full text in PDF | Author Info

Nursery response of evergreen trees to fall fertilization has been studied widely, but little attention has been given to deciduous trees. Bareroot Olga Bay larch (Larix olgensis Henry) seedlings were fertilized in the nursery with urea at four rates (0, 30, 60, 90 kg N ha^–1), with half of each rate applied on two dates (September 16 and October 1, 2009). The seedlings were excavated for evaluation on October 15. In the unfertilized (control) treatment, root and shoot dry mass increased by 100% and 57% respectively, while N concentration in the roots and shoots increased by 43% and 40% during the 30 day period. This indicated that substantial biomass growth during this period did not lead to internal nutrient dilution. Root dry mass increased when fall fertilization rates were ≥ 60 kg N ha^–1. Fall fertilization increased N concentrations in root tissue by 48–73%. Compared with the control, shoot tissues of fall fertilized seedlings had slightly higher N concentration and content and significantly higher frost hardiness.

Li, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing 100083, China E-mail: gl@nn.cn
Liu, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing 100083, China E-mail: lyong@bjfu.edu.cn
Zhu, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing 100083, China E-mail: yz@nn.cn
Li, Research Institute of Forestry, Chinese Academy of Forestry; Key Laboratory of Forest Silviculture of State Forestry Administration, Beijing 100091, China E-mail: qml@nn.cn
Dumroese, US Department of Agriculture, Forest Service, Rocky Mountain Research Station, Moscow, ID, USA E-mail: rkd@nn.us

article id 43, category Research article

Anni Markkanen, Panu Halme. (2012). Polypore communities in broadleaved boreal forests. Silva Fennica vol. 46 no. 3 article id 43. https://doi.org/10.14214/sf.43

Keywords: birch; deciduous; slash and burn; species-area relationship; wood-inhabiting fungi

Abstract | View details | Full text in PDF | Author Info

The cover and extent of boreal broadleaved forests have been decreasing due to modern forest management practices and fire suppression. As decomposers of woody material, polypores are ecologically important ecosystem engineers. The ecology and conservation biology of polypores have been studied intensively in boreal coniferous forests. However, only a few studies have focused on the species living on broadleaved trees. To increase knowledge on this species group we conducted polypore surveys in 27 broadleaved forests and 303 forest compartments (539 ha) on the southern boreal zone in Finland and measured dead wood and forest characteristics. We detected altogether 98 polypore species, of which 13 are red-listed in Finland. 60% of the recorded species are primarily associated with broadleaved trees. The number of species in a local community present in a broadleaved forest covered approximately 50 species, of which 30–40 were primarily associated with broadleaved trees. The size of the inventoried area explained 67% of the variation in the species richness, but unlike in previous studies conducted in coniferous forests, dead wood variables as well as forest structure had very limited power in explaining polypore species richness on forest stand level. The compartments occupied by red listed Protomerulius caryae had an especially high volume of living birch, but otherwise the occurrences of red-listed species could not be predicted based on the forest structure.

Markkanen, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: anni.e.markkanen@gmail.com
Halme, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: ph@nn.fi

article id 441, category Research article

Ane Zubizarreta-Gerendiain, Petri Pellikka, Jordi Garcia-Gonzalo, Veli-Pekka Ikonen, Heli Peltola. (2012). Factors affecting wind and snow damage of individual trees in a small management unit in Finland: assessment based on inventoried damage and mechanistic modelling. Silva Fennica vol. 46 no. 2 article id 441. https://doi.org/10.14214/sf.441

Keywords: Pinus sylvestris; Picea abies; Betula spp.; critical wind speed; snow loading; damage risk

Abstract | View details | Full text in PDF | Author Info

In this work, we assessed the factors affecting wind and snow damage of individual trees in a small management unit in western Finland. This was done based on inventoried damage and observed wind speeds and snow loading in storms Pyry and Janika in 2001 and Mielikki in 2002 together with mechanistic model. First, we studied which factors explain the observed damage in individual trees. Secondly, we studied how well the mechanistic model (HWIND) could predict the wind speed needed to uproot individual trees at the margins of permanent upwind edges. We found that Pyry storm caused 70% and Janika and Mielikki 18 and 12% of observed damage. In Janika storm, all trees uprooted. In other storms, both uprooting and stem breakage occurred. Scots pine suffered the most damage. Recently thinned stands on the upwind edges of open areas suffered the most damage. But, damage occurred also on soils with relatively shallow anchorage. HWIND predicted correctly damage for 69% of all uprooted trees. No-uprooting was correctly predicted for 45 and 19% of standing trees (all Scots pines), which were measured within and at the immediate upwind edge of same stands. HWIND model needs further validation at the permanent edges and/or on soils with shallow rooting to improve its prediction accuracy in such conditions.

Zubizarreta-Gerendiain, Technical University of Lisbon, School of Agriculture, Forest Research Centre, Lisbon, Portugal E-mail: azg@nn.po
Pellikka, University of Helsinki, Dept. of Geosciences and Geography, Helsinki, Finland E-mail: pp@nn.fi
Garcia-Gonzalo, Technical University of Lisbon, School of Agriculture, Forest Research Centre, Lisbon, Portugal E-mail: jgg@nn.po
Ikonen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: vpi@nn.fi
Peltola, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: heli.peltola@uef.fi

article id 58, category Research article

Ilona Suuriniemi, Jukka Matero, Harri Hänninen, Jussi Uusivuori. (2012). Factors affecting enlargement of family forest holdings. Silva Fennica vol. 46 no. 2 article id 58. https://doi.org/10.14214/sf.58

Keywords: economies of scale; structural change; forest ownership; non-industrial private forest owners; land policy; parcelization; consolidation

Abstract | View details | Full text in PDF | Author Info

This study contributes to the research of enlargement – a counterforce of parcelization – of forest holdings. To help planning policy measures aiming at increased average size of forest holdings, we study the characteristics of family forest owners who acquired additional forestland area during the years 2004–2008. Increases of forestland area due to purchases on the open market, purchases from parents or other relatives, inheritance or gift are studied. Survey data, containing information of 6318 forest owners, are analyzed with logistic regression analysis in order to establish a relationship between the probability of increasing the forestland area and the characteristics of landowners. The results indicate that young male owners, who appreciate economic values of the ownership and are active users of their forest estates, most often expand their forest property. This can be considered as an encouraging result from the point of view of the political objective to boost forest management activity through enlarging family forest holdings.

Suuriniemi, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: is@nn.fi
Matero, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: jukka.matero@uef.fi
Hänninen, Finnish Forest Research Institute, Vantaa Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: hh@nn.fi
Uusivuori, Finnish Forest Research Institute, Vantaa Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ju@nn.fi

article id 57, category Research article

Corrado Costa, Paolo Menesatti, Raffaele Spinelli. (2012). Performance modelling in forest operations through partial least square regression. Silva Fennica vol. 46 no. 2 article id 57. https://doi.org/10.14214/sf.57

Keywords: chipping; productivity; harvesting; skidding

Abstract | View details | Full text in PDF | Author Info

Partial Least Square (PLS) regression is a recent soft-modelling technique that generalizes and combines features from principal component analysis (PCA) and multiple regression. It is particularly useful when predicting one or more dependent variables from a large set of independent variables, often collinear. The authors compared the potential of PLS regression and ordinary linear regression for accurate modelling of forest work, with special reference to wood chipping, wood extraction and the continuous harvesting of short rotation coppice. Compared to linear regression, PLS regression allowed producing models that better fit the original data. What is more, it allowed handling collinear variables, facilitating the extraction of sound models from large amounts of field data obtained from commercial forest operations. On the other hand, PLS regression analysis is not as easy to conduct, and produces models that are less user-friendly. By producing alternative models, PLS regression may provide additional – and not alternative – ways of reading the data. Ideally, a comprehensive data analysis could include both ordinary and PLS regression and proceed from their results in order to get a better understanding of the phenomenon under examination. Furthermore, the computational complexity of PLS regression may stimulate interdisciplinary team-building, to the greater benefit of scientific research within the field of forest operations.

Costa, CRA ING, Monterotondo Scalo (Roma), Italy E-mail: cc@nn.it
Menesatti, CRA ING, Monterotondo Scalo (Roma), Italy E-mail: pm@nn.it
Spinelli, CNR IVALSA, Sesto Fiorentino (FI), Italy E-mail: spinelli@ivalsa.cnr.it

article id 56, category Research article

Johan Holmgren, Andreas Barth, Henrik Larsson, Håkan Olsson. (2012). Prediction of stem attributes by combining airborne laser scanning and measurements from harvesters. Silva Fennica vol. 46 no. 2 article id 56. https://doi.org/10.14214/sf.56

Keywords: ALS data; pre-harvest inventory; tree detection

Abstract | View details | Full text in PDF | Author Info

In this study, a new method was validated for the first time that predicts stem attributes for a forest area without any manual measurements of tree stems by combining harvester measurements and Airborne Laser Scanning (ALS) data. A new algorithm for automatic segmentation of tree crowns from ALS data based on tree crown models was developed. The test site was located in boreal forest (64°06’N, 19°10’E) dominated by Norway spruce (Picea abies) and Scots Pine (Pinus sylvestris).The trees were harvested on field plots, and each harvested tree was linked to the nearest tree crown segment derived from ALS data. In this way, a reference database was created with both stem data from the harvester and ALS derived features for linked tree crowns. To estimate stem attributes for a tree crown segment in parts of the forest where trees not yet have been harvested, tree stems are imputed from the most similar crown segment in the reference database according to features extracted from ALS data. The imputation of harvester data was validated on a sub-stand-level, i.e. 2–4 aggregated 10 m radius plots, and the obtained RMSE of stem volume, mean tree height, mean stem diameter, and stem density (stems per ha) estimates were 11%, 8%, 12%, and 19%, respectively. The imputation of stem data collected by harvesters could in the future be used for bucking simulations of not yet harvested forest stands in order to predict wood assortments.

Holmgren, Swedish University of Agricultural Sciences, Forest Resource Management, Umeå, Sweden E-mail: johan.holmgren@slu.se
Barth, The Forestry Research Institute of Sweden, Uppsala, Sweden E-mail: ab@nn.se
Larsson, Swedish University of Agricultural Sciences, Forest Resource Management, Umeå, Sweden E-mail: hl@nn.se
Olsson, Swedish University of Agricultural Sciences, Forest Resource Management, Umeå, Sweden E-mail: ho@nn.se

article id 54, category Research article

Urban Nilsson, Björn Elfving, Kjell Karlsson. (2012). Productivity of Norway spruce compared to Scots pine in the interior of northern Sweden. Silva Fennica vol. 46 no. 2 article id 54. https://doi.org/10.14214/sf.54

Keywords: Pinus sylvestris; current annual increment; mean annual increment; Picea abies; site index; yield

Abstract | View details | Full text in PDF | Author Info

Productivity of Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.) was studied in 12 paired plots in the interior of northern Sweden. Stands were established between 1928 and 1959; yield plots were established between 1974 and 1983 during pre-commercial thinning of the stands. Gross stem-wood production was significantly higher for Scots pine than for Norway spruce, stem-wood production by Norway spruce being 29.4% that of Scots pine. The site index for Norway spruce was lower than for Scots pine at all sites except one; the average difference in site index was 4.8 m. The simulated maximum mean annual increment (MAI_max) during the rotation was 19% higher than the MAI_max estimated with the site index for Scots pine, whereas simulated MAI_max and MAI_max estimated from the site index was about the same for Norway spruce. The simulations also indicated that MAI peaked about 50 years later for Norway spruce than for Scots pine. More small trees were included in the diameter distribution of Norway spruce than of Scots pine resulting in a lower stem-wood volume for Norway spruce when stands with the same dominant height were compared. This study shows that the difference in growth and rotation length between Scots pine and Norway spruce has implications when choosing which species to grow in the interior of northern Sweden.

Nilsson, Swedish University of Agricultural Sciences (SLU), Southern Swedish Forest Research Centre, Alnarp, Sweden E-mail: urban.nilsson@slu.se
Elfving, SLU, Forest Ecology and Management, Umeå, Sweden E-mail: be@nn.se
Karlsson, SLU, Unit of Field Based Research, Asa, Sweden E-mail: kk@nn.se

article id 53, category Research article

Saana Kataja-aho, Aino Smolander, Hannu Fritze, Sini Norrgård, Jari Haimi. (2012). Responses of soil carbon and nitrogen transformations to stump removal. Silva Fennica vol. 46 no. 2 article id 53. https://doi.org/10.14214/sf.53

Keywords: biofuel; boreal forest; carbon; nitrogen; nutrient dynamics; stump removal

Abstract | View details | Full text in PDF | Author Info

We studied in central Finland whether stump harvesting after clear felling of coniferous forest poses further short-term changes in soil carbon and nitrogen dynamics when compared to the traditional site preparation method, mounding. Exposed mineral soil patches in Norway spruce (Picea abies) dominated clear-cut stands were sampled 1–5 years after the treatments. The extent of the exposed mineral soil surface was significantly larger at the stump removal sites when compared to the mounding sites. No differences were found in soil pH, organic matter content or total concentration of soil C between the treatments or treatment years. Total concentration of soil N was consistently higher and C:N ratio lower in the stump removal plots than in the mounded plots. Further, both net N mineralisation and nitrification were clearly increased in the stump removal plots one year after the treatments. Soil microbial activity (CO₂ production) was higher in the stump removal plots but similar difference was not found in sieved soil samples incubated in the laboratory. Fluxes of other important greenhouse gases (CH₄ and N₂O) did not seem to be affected by stump removal. The differences between the stump removal and mounding procedures were most obviously attributed to more substantial soil disturbance by stump pulling and/or differences in the microbial communities and quality of soil organic matter in the differently treated soil.

Kataja-aho, University of Jyväskylä, Dept. of Biological and Environmental Science, Jyväskylä, Finland E-mail: saana.m.kataja-aho@jyu.fi
Smolander, Finnish Forest Research Institute, Vantaa, Finland E-mail: as@nn.fi
Fritze, Finnish Forest Research Institute, Vantaa, Finland E-mail: hf@nn.fi
Norrgård, University of Jyväskylä, Dept. of Biological and Environmental Science, Jyväskylä, Finland E-mail: sn@nn.fi
Haimi, University of Jyväskylä, Dept. of Biological and Environmental Science, Jyväskylä, Finland E-mail: jh@nn.fi

article id 69, category Research article

Tarja Wallenius, Risto Laamanen, Jussi Peuhkurinen, Lauri Mehtätalo, Annika Kangas. (2012). Analysing the agreement between an Airborne Laser Scanning based forest inventory and a control inventory – a case study in the state owned forests in Finland. Silva Fennica vol. 46 no. 1 article id 69. https://doi.org/10.14214/sf.69

Keywords: forest inventory; quality assessment; airborne laser scanning

Abstract | View details | Full text in PDF | Author Info

Airborne laser scanning based forest inventories have recently shown to produce accurate results. However, the accuracy varies according to the test area and used methodology and therefore, an unambiguous and practical quality assessment will be needed as a part of each inventory project. In this study, the accuracy of an ALS inventory was evaluated with a field sampling based control inventory. The agreement between the ALS inventory and the control inventory was analysed with four methods: 1) root mean square error (RMSE) and bias, 2) scatter plots with 95% confidence intervals, 3) Bland-Altman plots and 4) tolerance limits within Bland-Altman plots. Each method has its own special features which have to be taken into account when the agreement is analysed. The pre-defined requirements of the ALS inventory were achieved. A simplified control inventory approach with a slightly narrower focus is proposed to be used in the future. The Bland-Altman plots with the tolerance limits are proposed to be used in quality assessments of operational ALS inventories. Further studies to improve the efficiency of quality assessment are needed.

Wallenius, Metsähallitus, P.O. Box 94, FI-01301 Vantaa, Finland E-mail: tarja.wallenius@metsa.fi
Laamanen, Metsähallitus, P.O. Box 94, FI-01301 Vantaa, Finland E-mail: rl@nn.fi
Peuhkurinen, Oy Arbonaut Ltd, Helsinki, Finland E-mail: jp@nn.fi
Mehtätalo, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: lm@nn.fi
Kangas, University of Helsinki, Department of Forest Sciences, Helsinki, Finland E-mail: ak@nn.fi

article id 68, category Research article

Maria Villikka, Petteri Packalén, Matti Maltamo. (2012). The suitability of leaf-off airborne laser scanning data in an area-based forest inventory of coniferous and deciduous trees. Silva Fennica vol. 46 no. 1 article id 68. https://doi.org/10.14214/sf.68

Keywords: forest inventory; group-specific estimates; leaf-off data; LIDAR

Abstract | View details | Full text in PDF | Author Info

This study examined the suitability of airborne laser scanner (ALS) data collected under leaf-off conditions in a forest inventory, in which deciduous and coniferous trees need to be separated. All analyses were carried out with leaf-on and leaf-off ALS data collected from the same study area. Additionally, aerial photographs were utilized in the Nearest Neighbor (NN) imputations. An area-based approach was used in this study. Regression estimates of plot volume were more accurate in the case of leaf-off than leaf-on data. In addition, regression models were more accurate in coniferous plots than in deciduous plots. The results of applying leaf-on models with leaf-off data, and vice versa, indicate that leaf-on and leaf-off data should not be combined since this causes serious bias. The total volume and volume by coniferous and deciduous trees was estimated by the NN imputation. In terms of total volume, leaf-off data provided more accurate estimates than leaf-on data. In addition, leaf-off data discriminated between coniferous and deciduous trees, even without the use of aerial photographs. Accurate results were also obtained when leaf-off ALS data were used to classify sample plots into deciduous and coniferous dominated plots. The results indicate that the area-based method and ALS data collected under leaf-off conditions are suitable for forest inventory in which deciduous and coniferous trees need to be distinguished.

Villikka, University of Easten Finland, Department of Forest Sciences, Joensuu, Finland E-mail: mv@nn.fi
Packalén, University of Easten Finland, Department of Forest Sciences, Joensuu, Finland E-mail: petteri.packalen@uef.fi
Maltamo, University of Easten Finland, Department of Forest Sciences, Joensuu, Finland E-mail: mm@nn.fi

article id 65, category Research article

Kristóf Kelemen, Barbara Mihók, László Gálhidy, Tibor Standovár. (2012). Dynamic response of herbaceous vegetation to gap opening in a Central European beech stand. Silva Fennica vol. 46 no. 1 article id 65. https://doi.org/10.14214/sf.65

Keywords: continuous cover forestry; dispersal; gap colonization; herbs; seed bank type; species richness

Abstract | View details | Full text in PDF | Author Info

Herbaceous ground vegetation in artificially-created gaps was studied in a managed beech (Fagus sylvatica L.) forest over a period of eight years in Northern Hungary, Central Europe. These gaps were being used as an alternative to the regular shelterwood system to create uneven-aged stands. The effects of gap size (15 and 40 m diameter) and canopy openness on herbaceous species colonization and persistence were assessed in a systematic grid of 5 5 m. Overall, herbaceous cover was low before gap creation, increased soon afterwards, and continued to rise over time. The number of herb species increased in the gaps and, to a lesser extent, in adjacent areas under the remaining tree canopy. Colonization of gaps was rapid and there was substantial turnover of species i.e. various species disappeared from the gaps over time whilst others colonized. Species with both long-term persistent seed banks and long distance dispersal abilities were the most successful types colonizing gaps. Six species occurred preferentially in large gaps, while only one species was found to prefer small gaps. Species present before gap creation survived in both gap sizes. Smaller gaps with a diameter of half the height of canopy trees also tended to remain free of common weed species, whereas large cover of Rubus fruticosus L. and Calamagrostis epigejos (L.) Roth could hamper natural regeneration in larger gaps. For the successful regeneration of beech we recommend the use of small gaps complemented by few large gaps.

Kelemen, Loránd Eötvös University, Institute of Biology, Department of Plant Systematics, Ecology and Theoretical Biology, Budapest, Hungary E-mail: kk@nn.hu
Mihók, Loránd Eötvös University, Institute of Biology, Department of Plant Systematics, Ecology and Theoretical Biology, Budapest, Hungary E-mail: bm@nn.hu
Gálhidy, Loránd Eötvös University, Institute of Biology, Department of Plant Systematics, Ecology and Theoretical Biology, Budapest, Hungary E-mail: lg@nn.hu
Standovár, Institute of Biology, Department of Plant Systematics, Ecology and Theoretical Biology, Budapest, Hungary E-mail: standy@ludens.elte.hu

article id 63, category Research article

Leena Koivuranta, Tarja Latva-Karjanmaa, Pertti Pulkkinen. (2012). The effect of temperature on seed quality and quantity in crosses between European (Populus tremula) and hybrid aspens (P. tremula x P. tremuloides). Silva Fennica vol. 46 no. 1 article id 63. https://doi.org/10.14214/sf.63

Keywords: climate change; gene flow; germination; hybrid vigour

Abstract | View details | Full text in PDF | Author Info

Hybrid aspen (Populus tremula L. Populus tremuloides Michx.) plantations are expanding in Fennoscandia and the Baltic countries; however, the possible effects of plantations on the native European aspen (P. tremula) and the level of gene flow between European and hybrid aspen have not been investigated. We studied seed quantity and quality in intraspecific and interspecific crosses of the European and hybrid aspens over a two year period. In order to study whether elevated temperatures due to climate change would benefit the species differently, we performed the crosses in different temperatures. In both years, interspecific crosses produced more seeds with higher quality than intraspecific crosses. This result was most distinct in crosses between female hybrid aspen and male European aspen. In higher temperatures, relative germination difference between hybrid aspen seeds and seeds from P. tremula P. tremula crosses seems to increase. These results suggest that hybrid aspen may have a significant genetic impact on the European aspen, and this effect may be strengthened by climate warming.

Koivuranta, Finnish Forest Research Institute, Haapastensyrjä, Finland E-mail: lk@nn.fi
Latva-Karjanmaa, Finnish Forest Research Institute, Haapastensyrjä, Finland E-mail: tlk@nn.fi
Pulkkinen, Finnish Forest Research Institute, Haapastensyrjä, Finland E-mail: pertti.pulkkinen@metla.fi

article id 62, category Research article

Nadia Goué, Nathalie Noël-Boizot, Michel Vallance, Elisabeth Magel, Philippe Label. (2012). Microdissection to isolate vascular cambium cells in poplar. Silva Fennica vol. 46 no. 1 article id 62. https://doi.org/10.14214/sf.62

Keywords: fusiform cambial cells; microgenomics; Populus spp.; ray cambial cells

Abstract | View details | Full text in PDF | Author Info

Vascular cambium is the lateral meristem producing xylem cells inwards and phloem cells outwards in plant stem. Thus, in trees, the quality and quantity of wood is a result of highly regulated developmental process depending initially on the vascular cambium cell production. The availability of accurate transcriptomics technologies based on high coverage sequencing raises the level of expectations on tissue sampling to a very high degree. What is the benefit of top-level transcriptomics in wood formation studies if we are using these technologies on raw tissues, mixing cells at the organ level or even higher scale? The presented work describes a nine-step procedure, from standing tree to isolated ray and fusiform cells from cryolyophilized tangential sections of the poplar cambial zone. The aim of this paper is to present a step by step procedure including advices on how to select the optimal tree, how to fell the tree while securing its physiological parameters, how to cryolyophilize and microdissect under binocular, presenting the time schedule of the whole process and RNA analysis.

Goué, UMR5546 CNRS-Université Paul Sabatier, Castanet Tolosan, France; (INRA-UAGPF, 2163 Avenue de la Pomme de Pin, 45075 Orléans cedex 2, France) E-mail: goue@lrsv.ups-tlse.fr
Noël-Boizot, INRA-UAGPF, 2163 Avenue de la Pomme de Pin, 45075 Orléans cedex 2, France E-mail: nnb@nn.fr
Vallance, INRA-UAGPF, 2163 Avenue de la Pomme de Pin, 45075 Orléans cedex 2, France E-mail: mv@nn.fr
Magel, Universität Hamburg, Zentrum Holzwirtschaft, Deutschland E-mail: em@nn.de
Label, INRA-UAGPF, 2163 Avenue de la Pomme de Pin, 45075 Orléans cedex 2, France E-mail: pl@nn.fr

article id 89, category Research article

Russell Grenfell, Tuomas Aakala, Timo Kuuluvainen. (2011). Microsite occupancy and the spatial structure of understorey regeneration in three late-successional Norway spruce forests in northern Europe. Silva Fennica vol. 45 no. 5 article id 89. https://doi.org/10.14214/sf.89

Keywords: boreal forest; disturbance; microsite; spatial correlation; stand structure; natural forest

Abstract | View details | Full text in PDF | Author Info

We compared microsite occupancy and three spatial structure of regeneration in three primeval late-successional Norway spruce dominated forests. One area lay in the middle boreal zone in Russia (Dvina-Pinega) where larger-scale disturbance from bark beetles and drought had occurred; the other areas lay in the northern boreal zone, one in Finland (Pallas-Ylläs) had encountered only small-scale disturbance, and one in Russia (Kazkim) had been influenced by fire. We mapped all spruce (Picea abies) and birch (Betula pendula and Betula pubescens) trees with diameter at breast height (DBH) ≥ 10 cm on 40 m 400 m plots, and those with DBH < 10 cm on 2 m or 4 m 400 m subplots. On the subplots we also recorded microsite occupancy and estimated microsite availability. At all study areas small seedlings (h < 0.3 m) of both spruce and birch were found largely on disturbance-related microsites. Birch saplings (h ≥ 1.3 m, DBH < 10 cm) disproportionately occupied deadwood-related microsites at Dvina-Pinega. In contrast, spruce saplings at all study areas, and birch saplings at Kazkim and Pallas-Ylläs, showed less, or no, preference. Our results thus confirm the importance of disturbance-related microsites for regeneration establishment, but not necessarily for long-term survival. No spatial segregation between the overstorey (DBH ≥ 10 cm) and saplings (h ≥ 1.3 m, DBH < 10 cm) or seedlings (h < 1.3 m) was found at Pallas-Ylläs or Kazkim, and only three instances of very weak segregation were found at Dvina-Pinega. This suggests that the regeneration gap concept may not be useful for describing the regeneration dynamics of primeval boreal forests.

Grenfell, University of Helsinki, Dept of Forest Sciences, Helsinki, Finland E-mail: russell.grenfell@helsinki.fi
Aakala, University of Helsinki, Dept of Forest Sciences, Helsinki, Finland E-mail: ta@nn.fi
Kuuluvainen, University of Helsinki, Dept of Forest Sciences, Helsinki, Finland E-mail: tk@nn.fi

article id 88, category Research article

Seppo Rouvinen, Jari Kouki. (2011). Tree regeneration in artificial canopy gaps established for restoring natural structural variability in a Scots pine stand. Silva Fennica vol. 45 no. 5 article id 88. https://doi.org/10.14214/sf.88

Keywords: ecosystems; diversity; restoration

Abstract | View details | Full text in PDF | Author Info

In Finland and elsewhere in Europe, many protected forest areas include also stands that were previously managed and that lack several naturally occurring stand characteristics. In these areas, ecosystem restoration can be used to facilitate and accelerate the formation of structural and habitat features resembling those of natural forests. For example, by creating small gaps it could be possible to diversify forest structure and tree species composition and to produce dead wood while still maintaining mostly continous canopy coverage. We examined experimentally the effects of artificial gap formation on post-disturbance tree regeneration in the gaps in a young protected, but formerly commercially managed pine (Pinus sylvestris L.) dominated forest. In the experimental sites, gap size and the portion of girdled trees out of all treated trees (girdled and felled trees combined) in the gaps varied. Natural and artificial (direct seeding of silver birch Betula pendula Roth) tree regeneration and development was monitored both on disturbed (scarified soil patches) and undisturbed forest floor during three growing seasons. Results show that gaps can be valuable in diversifying stand structure but to be successful and rapid, tree regeneration needs disturbed forest floor. Pine regenerated numerously, but birch had clearly lower regeneration, especially on small-sized gaps. In conclusion, increasing tree diversity in young pine-dominated forests seems to be difficult when only small artificial gaps are used. But even small gaps can be used to create and maintain diverse cohort structure of the dominant species and thus they can contribute to restoration goals.

Rouvinen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: seppo.rouvinen@uef.fi
Kouki, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: jk@nn.fi

article id 84, category Research article

Asko Lõhmus, Piret Lõhmus. (2011). Old-forest species: the importance of specific substrata vs. stand continuity in the case of calicioid fungi. Silva Fennica vol. 45 no. 5 article id 84. https://doi.org/10.14214/sf.84

Keywords: forest management; conservation; continuity; habitat; lichen; limiting factor; structural diversity

Abstract | View details | Full text in PDF | Author Info

Appropriate conservation management of old-forest species depends on the causes of their old-forest affinity, which, however, are insufficiently known. Calicioid fungi are often considered old-forest dependent because of their special requirements for microhabitat, microclimate, and stand continuity for at least two tree generations. We demonstrate that, for several methodological or interpretational problems, published studies do not provide unequivocal evidence for such mechanisms and even for old-forest dependency of calicioids in general. We then analyse a large Estonian dataset (ca. 2300 records of 32 species) representing various management types and site types to answer whether old forests have more calicioid species, and any specific species, than could be expected for the substratum availability observed. Although old growth had more species and records than mature managed stands or cutover sites, those substratum types that occurred at roughly similar abundances also hosted comparable numbers of species in different management types. The characteristic substrata adding extra species to old growth were snags and root-plates of treefall mounds; wood surfaces in general comprised more than half of all calicioid records. Although substratum abundance did not fully explain the species-richness contrast between old growth and mature stands, additional evidence suggested that the unexplained variance is rather due to small-scale habitat characteristics than stand-scale continuity or microclimate. Finally, we review the evidence for old-forest affinity of calicioid species and distinguish a set of threatened species. We conclude that the availability of specific substrata is the main limiting factor for calicioid fungi in forests, and its quantitative and stochastic nature explains the large random and region-specific variation in the published lists of ‘old-forest species’.

Lõhmus, Department of Zoology, Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise st. 46, EE-51014, Tartu, Estonia E-mail: asko.lohmus@ut.ee
Lõhmus, Department of Botany, Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia E-mail: pl@nn.ee

article id 83, category Research article

Inari Ylläsjärvi, Håkan Berglund, Timo Kuuluvainen. (2011). Relationships between wood-inhabiting fungal species richness and habitat variables in old-growth forest stands in the Pallas-Yllästunturi National Park, northern boreal Finland. Silva Fennica vol. 45 no. 5 article id 83. https://doi.org/10.14214/sf.83

Keywords: species-area relationship; species richness; old-growth forest; indicators; northern Fennoscandia; polyporaceae; polypores

Abstract | View details | Full text in PDF | Author Info

Indicators for biodiversity are needed for efficient prioritization of forests selected for conservation. We analyzed the relationships between 86 wood-inhabiting fungal (polypore) species richness and 35 habitat variables in 81 northern boreal old-growth forest stands in Finland. Species richness and the number of red-listed species were analyzed separately using generalized linear models. Most species were infrequent in the studied landscape and no species was encountered in all stands. The species richness increased with 1) the volume of coarse woody debris (CWD), 2) the mean DBH of CWD and 3) the basal area of living trees. The number of red-listed species increased along the same gradients, but the effect of basal area was not significant. Polypore species richness was significantly lower on western slopes than on flat topography. On average, species richness was higher on northern and eastern slopes than on western and southern slopes. The results suggest that a combination of habitat variables used as indicators may be useful in selecting forest stands to be set aside for polypore species conservation.

Ylläsjärvi, Rovaniemi University of Applied Sciences, School of Forestry and Rural Industries, Jokiväylä 11 c, FI-96300 Rovaniemi, Finland E-mail: inari.yllasjarvi@ramk.fi
Berglund, University of Helsinki, Department of Forest Sciences, Helsinki, Finland E-mail: hb@nn.fi
Kuuluvainen, University of Helsinki, Department of Forest Sciences, Helsinki, Finland E-mail: tk@nn.fi

article id 82, category Research article

Nicole J. Fenton, Yves Bergeron. (2011). Dynamic old-growth forests? A case study of boreal black spruce forest bryophytes. Silva Fennica vol. 45 no. 5 article id 82. https://doi.org/10.14214/sf.82

Keywords: disturbances; old-growth forest; succession; boreal; bryophytes; climax; gap dynamics

Abstract | View details | Full text in PDF | Author Info

Old-growth forests have sparked significant interest over the last twenty years and definitions have evolved from structure based to process based, acknowledging the diversity of forests that could be considered old growth. However studies frequently group all forests over a certain age into a single type, negating the dynamic processes that create old growth. In this study we examine a 2350-year chronosequence in boreal black spruce forests in northwestern Quebec to determine whether continued community change can be observed in the bryophyte layer. Bryophytes dominate the understory of boreal forests and influence ecosystem functioning, particularly in paludified forests where production exceeds decomposition in the organic layer. Community composition and richness changed throughout the chronosequence with no evidence of a steady state associated with an old-growth phase. In contrast the bryophyte community continued to evolve with multiple phases being evident. These results suggest that old-growth forests on the Clay Belt of northwestern Quebec and northeastern Ontario, Canada, should be regarded as part of the continuous gradient in forest development rather than a single state. This complicates conservation of these forests as multiple phases should be considered when planning forest reserves.

Fenton, Université du Québec en Abitibi-Témiscamingue, 445 Boulevard de l’Université, Rouyn-Noranda, Québec, Canada J9X 4E5 E-mail: nicole.fenton@uqat.ca
Bergeron, Université du Québec en Abitibi-Témiscamingue, 445 Boulevard de l’Université, Rouyn-Noranda, Québec, Canada J9X 4E5 E-mail: yb@nn.ca

article id 80, category Research article

Mari T. Jönsson, Shawn Fraver, Bengt Gunnar Jonsson. (2011). Spatio-temporal variation of coarse woody debris input in woodland key habitats in central Sweden. Silva Fennica vol. 45 no. 5 article id 80. https://doi.org/10.14214/sf.80

Keywords: boreal forest; Picea abies; dendrochronology; disturbance dynamics; tree mortality; woodland key habitats; windstorms

Abstract | View details | Full text in PDF | Author Info

The persistence of many saproxylic (wood-living) species depends on a readily available supply of coarse woody debris (CWD). Most studies of CWD inputs address stand-level patterns, despite the fact that many saproxylic species depend on landscape-level supplies of CWD. In the present study we used dated CWD inputs (tree mortality events) at each of 14 Norway spruce (Picea abies) dominated woodland key habitat sites to analyze the spatial and temporal patterns of CWD additions between 1950 and 2002 within a small landscape in central Sweden. We found that inputs were episodic within sites, where local windstorms created pulses in CWD input. Pulses occurred simultaneously in many sites, yielding landscape-level synchrony of CWD input. These synchronous pulses, and importantly, the breaks between pulses, may have negative implications for saproxylic species that are dependent on large volume inputs of freshly killed Norway spruce. In addition, the inherent small size and relative isolation of these sites may further increase extinction risks due to stochastic events. However, background CWD input rates occurring between pulses varied substantially among sites, presumably the result of the sites’ varied histories and structural characteristics. This finding suggests that the different sites have varied abilities to provide habitat for saproxylic species during periods with low landscape-level input of CWD.

Jönsson, Department of Ecology, SLU, P.O. Box 7044, SE-750 07 Uppsala, Sweden (current); Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden E-mail: mari.jonsson@slu.se
Fraver, U.S. Forest Service, Northern Research Station, Grand Rapids, Minnesota, USA (current); Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden E-mail: sf@nn.us
Jonsson, Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden E-mail: bgj@nn.se

article id 76, category Research article

Alessandra Bottero, Matteo Garbarino, Vojislav Dukic, Zoran Govedar, Emanuele Lingua, Thomas A. Nagel, Renzo Motta. (2011). Gap-phase dynamics in the old-growth forest of Lom, Bosnia and Herzegovina. Silva Fennica vol. 45 no. 5 article id 76. https://doi.org/10.14214/sf.76

Keywords: disturbance regime; Lom; old-growth forest; canopy gaps; beech-spruce-fir; small-scale

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We investigated forest canopy gaps in the mixed beech (Fagus sylvatica L.), silver fir (Abies alba Miller), and Norway spruce (Picea abies (L.) Karst.) old-growth forest of Lom in the Dinaric Mountains of Bosnia and Herzegovina. Gap size, age, gap fraction, gapmaker characteristics and the structure and composition of gapfillers were documented to investigate gap dynamics. The percentages of forest area in canopy and expanded gaps were 19% and 41%, respectively. The median canopy gap size was 77 m², and ranged from 11 to 708 m². Although there were many single tree-fall gaps, the majority had multiple gapmakers that were often in different stages of decay, suggesting gap expansion is important at the study site. Of the gapmakers recorded, 14% were uprooted stems, 60% snapped stems, and 26% were standing dead trees. Dendroecological analysis suggests that gap formation varied in time. The density of gapfillers was not correlated to gap size, and the species composition of gapfillers varied between seedling, sapling, and tree life stages. The results suggest that gaps are mainly formed by endogenous senescence of single canopy trees. Exogenous disturbance agents, most likely related to wind and snow, act mainly as secondary agents in breaking weakened trees and in expanding previously established gaps. Although the findings are partially consistent with other studies of gap disturbance processes in similar old-growth forests in central Europe, the observed gap dynamic places the Lom core area at the end of a gradient that ranges from forests controlled by very small-scale processes to those where large, stand replacing disturbances predominate.

Bottero, University of Turin, Department Agroselviter, Via Leonardo da Vinci 44, 10095 Grugliasco (TO), Italy E-mail: alessandra.bottero@unito.it
Garbarino, University of Turin, Department Agroselviter, Via Leonardo da Vinci 44, 10095 Grugliasco (TO), Italy E-mail: mg@nn.it
Dukic, University of Banja Luka, Faculty of Forestry, Banja Luka, Bosnia and Herzegovina E-mail: vd@nn.ba
Govedar, University of Banja Luka, Faculty of Forestry, Banja Luka, Bosnia and Herzegovina E-mail: zg@nn.ba
Lingua, University of Padua, Department of TeSAF, Legnaro (PD), Italy E-mail: el@nn.it
Nagel, University of Ljubljana, Department of Forestry and Renewable Forest Resources, Ljubljana, Slovenia E-mail: tan@nn.si
Motta, University of Turin, Department Agroselviter, Via Leonardo da Vinci 44, 10095 Grugliasco (TO), Italy E-mail: rm@nn.it

article id 102, category Research article

Anne Toppinen, Katja Lähtinen, Leena A. Leskinen, Niklas Österman. (2011). Network co-operation as a source of competitiveness in medium-sized Finnish sawmills. Silva Fennica vol. 45 no. 4 article id 102. https://doi.org/10.14214/sf.102

Keywords: collaboration; social capital; strategic resources; competitive advantage; business processes

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In the Finnish sawmill industry, inter-firm collaboration has often been brought up as a means of creating a competitive edge in global markets by achieving economies of scale. According to the resource-based view (RBV), a firm can evaluate its current or potential partners by considering firm-level collaboration as a portfolio of complementary strategic resources. The specific focus of the study is on examining the types and forms of sawmill co-operation, how the co-operation emerged and which firm-specific resources are mainly related to co-operation. Based upon this, we can see how the managers of medium-sized sawmills perceive network co-operation as facilitating the achievement of a sustainable competitive advantage. The empirical data for this study were collected by interviewing 16 managers and employees in medium-sized non-integrated sawmills, a joint-venture marketing company and other co-operative partners. The findings of the study show that meaningful and beneficial co-operation partnerships exist in the Finnish sawmilling industry, but the sawmill managers do not perceive this collaboration as a strategic resource. The marketing company was the only firm in this study that relied on its co-operative networks in seeking a sustainable competitive advantage. To make more of co-operative partnerships, the principles of co-operative networking should be understood better in the sawmilling industry in order to know what to expect from co-operation. Furthermore, the managers should have the courage to engage in more extensive co-operation in order for strategic rents to materialize. Since the selection of the right partners is fundamental, further studies could be conducted on the reasons behind failed or terminated co-operative arrangements to gather further empirical knowledge in this subject area.

Toppinen, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: anne.toppinen@helsinki.fi
Lähtinen, Finnish Environment Institute (SYKE), Joensuu, Finland E-mail: kl@nn.fi
Leskinen, Rantalankuja 4, Joensuu, Finland E-mail: lal@nn.fi
Österman, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: no@nn.fi

article id 98, category Research article

Meeri Pearson, Markku Saarinen, Kari Minkkinen, Niko Silvan, Jukka Laine. (2011). Mounding and scalping prior to reforestation of hydrologically sensitive deep-peated sites: factors behind Scots pine regeneration success. Silva Fennica vol. 45 no. 4 article id 98. https://doi.org/10.14214/sf.98

Keywords: soil preparation; peatland forest regeneration; mound; scalp; Scots pine; OM decomposition; excess moisture

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Watering up typically ensues after clearcutting forestry-drained peatland forests. Thus, the effectiveness of maintenance drainage and soil preparation procedures becomes paramount for establishing a new generation of commercial forest. Mounding is the primary method of soil preparation applied in regeneration sites lying on deep peat. As raised planting spots, mounds are resistant to waterlogging and assumed to be beneficial for organic matter (OM) decomposition via, e.g., increased soil aeration and temperature, which would also enhance seedling growth. In recent years, however, less intensive and cheaper alternatives like scalping have been sought with some reported cases of success. Our case study investigated the survival and growth of Scots pine outplants in mounds, scalps, and unprepared microsites along a moisture gradient. After three growing seasons, mounding accelerated neither seedling growth nor OM decomposition relative to the unprepared treatment. Survival in mounds was nonetheless superior overall. Scalps behaved as water collecting depressions leading to a catastrophic regeneration result. Based on our findings, water table level (WTL) overrides other growth-controlling factors in excess moisture conditions. To combat watering up coupled with greater than normal rainfall, we recommend reforestation strategies which provide elevated, prepared planting spots (i.e., mounds) or utilize unprepared, higher microforms.

Pearson, Finnish Forest Research Institute, Western Finland Regional Unit, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: meeri.pearson@metla.fi
Saarinen, Finnish Forest Research Institute, Western Finland Regional Unit, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: ms@nn.fi
Minkkinen, University of Helsinki, Department of Forest Sciences, Helsinki, Finland E-mail: km@nn.fi
Silvan, Finnish Forest Research Institute, Western Finland Regional Unit, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: ns@nn.fi
Laine, Finnish Forest Research Institute, Western Finland Regional Unit, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: jl@nn.fi

article id 97, category Research article

Hannu Hökkä, Jaakko Repola, Mikko Moilanen, Markku Saarinen. (2011). Seedling survival and establishment in small canopy openings in drained spruce mires in Northern Finland. Silva Fennica vol. 45 no. 4 article id 97. https://doi.org/10.14214/sf.97

Keywords: Picea abies; canopy gaps; natural regeneration; drained peatlands; seedling establishment

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A large proportion of drained spruce mire stands is currently approaching regeneration maturity in Finland. Traditional regeneration methods with effective site preparation and planting generally result in satisfactory seedling stands also in spruce mires. However, natural regeneration methods may be more appropriate in protecting watercourses and minimizing regeneration costs. We studied the survival of advance growth and establishment of new seedlings in small canopy openings that were cut at three different diameters in two experimental drained spruce mire stands in Northern Finland (Tervola and Oulu) in 2004. The number of seedlings was repeatedly surveyed from five small circular plots (one 10 m² and four 5 m² plots in size) located within the opening. Advance growth which survived the cutting and new seedlings were separated in the surveys. The density of advance growth was on average 9000 ha^–1 after cutting, and it decreased by 30% during the five-year monitoring period (2006–2010) due to natural mortality. The number of new seedlings increased rapidly within the three years after cutting the openings. In 2010, 11 000–26 000 new seedlings ha^–1 in Tervola and 12 000–16 000 ha^–1 in Oulu on average were observed. The size of the opening had no clear effect on the regeneration result. The proportion of birch of the new seedlings increased with time and opening size in Tervola. The results show that Norway spruce regenerates naturally in small canopy openings cut in mature drained spruce mire stands.

Hökkä, Finnish Forest Research Institute, Rovaniemi Research Unit, FI-96301 Rovaniemi, Finland E-mail: hannu.hokka@metla.fi
Repola, Finnish Forest Research Institute, Rovaniemi Research Unit, FI-96301 Rovaniemi, Finland E-mail: jr@nn.fi
Moilanen, Finnish Forest Research Institute, Muhos Research Unit, Muhos, Finland E-mail: mm@nn.fi
Saarinen, Finnish Forest Research Institute, Parkano Research Unit, Parkano, Finland E-mail: ms@nn.fi

article id 93, category Research article

Pertti Pulkkinen, Saila Varis, Raimo Jaatinen, Aulis Leppänen, Anne Pakkanen. (2011). Increasing survival and growth of Scots pine seedlings with selection based on autumn coloration. Silva Fennica vol. 45 no. 4 article id 93. https://doi.org/10.14214/sf.93

Keywords: Pinus sylvestris; adaptation; field trials; harsh conditions; needles; nursery; selection

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This study evaluates the possibility of using autumn coloration of young Scots pine (Pinus sylvestris L.) seedlings as an indicator of adaptation to harsh climate conditions. One-year old seedlings from natural stands with different origins and seed orchards were classified as “red/reddish” and “green” based on the needle color after artificially increased night length in nursery and then measured after 14 years in field trials. In almost all the studied groups seedlings classified as “red/reddish” had significantly higher survival rate than seedlings classified as “green”. The survival of “red/reddish” was 14.2% higher than “green” among natural stand seed material and 56.2% among seed orchard material. During the study period the survival difference between “red/reddish” and “green” seedlings tended to increase. The seedling color had limited connection with the height growth, even though the trees classified as “red/reddish” were slightly taller than those classified as “green”. However, the total productivity over all field trials, described here as a heightsum, of “red/reddish” trees was 15% higher than productivity of “green” trees from natural stand material, and 61% higher than those from seed orchard material. It seems that controlled selection based on autumn color can be utilized within seed crops of different types with the aim to increase the adaptability of seed material to different environmental conditions.

Pulkkinen, Metla, Haapastensyrjä, Läyliäinen, Finland E-mail: pertti.pulkkinen@metla.fi
Varis, Metla, Haapastensyrjä, Läyliäinen, Finland E-mail: sv@nn.fi
Jaatinen, Metla, Haapastensyrjä, Läyliäinen, Finland E-mail: rj@nn.fi
Leppänen, Metla, Haapastensyrjä, Läyliäinen, Finland E-mail: al@nn.fi
Pakkanen, Metla, Haapastensyrjä, Läyliäinen, Finland E-mail: ap@nn.fi

article id 450, category Research article

Miaoer Lu, Pekka Nygren, Jari Perttunen, Stephen G. Pallardy, David R. Larsen. (2011). Application of the functional-structural tree model LIGNUM to growth simulation of short-rotation eastern cottonwood. Silva Fennica vol. 45 no. 3 article id 450. https://doi.org/10.14214/sf.450

Keywords: Populus deltoides; carbon allocation; L-system; photon flux interception; photosynthetic production; voxel model

Abstract | View details | Full text in PDF | Author Info

The functional-structural tree growth model LIGNUM was developed as a general research tool that can be applied to several tree species. The growth simulation of short-rotation eastern cottonwood (Populus deltoides Bartr. ex Marsh.) inherits the basic LIGNUM modeling concepts including modular tree structure, L-system-based description of structural development, and carbon budget. New developments of LIGNUM model in this study were the incorporation of a biochemically-derived photosynthesis submodel; nested time steps for simulating physiological processes, structural development, and annual biomass production; incorporation of field-measured weather data for modeling the response of physiological processes to environmental variation; and application of a Monte-Carlo voxel space submodel for simulating the stochasticity of tree growth and improving computational efficiency. A specific parameter system was applied for modeling P. deltoides growth in the central Missouri, USA, environment. This adaptation of LIGNUM was applied on modeling growth of P. deltoides in a short-rotation agroforestry practice. The simulated height and biomass growth were close to field observations. Visualization of simulation results closely resembled the trees growing in an open site. The simulated response of tree growth to variations in photon flux input was reasonable. The LIGNUM model may be used as a complement to field studies on P. deltoides in short-rotation forestry and agroforestry.

Lu, Deparment of Forestry, University of Missouri, Columbia, MO, USA E-mail: ml@nn.us
Nygren, The Finnish Society of Forest Science, P.O. 18, FI-01301 Vantaa, Finland E-mail: pekka.nygren@metla.fi
Perttunen, Finnish Forest Research Institute, Vantaa, Finland E-mail: jp@nn.fi
Pallardy, Deparment of Forestry, University of Missouri, Columbia, MO, USA E-mail: sgp@nn.us
Larsen, Deparment of Forestry, University of Missouri, Columbia, MO, USA E-mail: drl@nn.us

article id 449, category Research article

Thomas Wutzler, Ingolf Profft, Martina Mund. (2011). Quantifying tree biomass carbon stocks, their changes and uncertainties using routine stand taxation inventory data. Silva Fennica vol. 45 no. 3 article id 449. https://doi.org/10.14214/sf.449

Keywords: forest management; forest inventory; uncertainty; carbon stocks

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For carbon (C) trading or any other verifiable C reports, it would be reasonable to identify and quantify continuous changes in carbon stocks at regional scales without high investments into additional C-specific, time- and labor-intensive inventories. Our study demonstrates the potential of using routine stand taxation data from large scale forestry inventories for verifiable quantification of tree biomass C stocks, C stock change rates, and associated uncertainties. Empirical models, parameters, and equations of uncertainty propagation have been assembled and applied to data from a forest management unit in Central Germany (550 000 ha), using stand taxation inventories collected between 1993 and 2006. The study showed: 1) The use of stand taxation data resulted in a verifiable and sufficiently precise (cv = 7%) quantification of tree biomass carbon stocks and their changes at the level of growth-regions (1700 to 140 000 ha). 2) The forest of the test region accumulated carbon in tree biomass at a mean annual rate of 1.8 (–0.9 to 4.5) tC/ha/yr over the studied period. 3) The taxation inventory data can reveal spatial patterns of rates of C stock changes, specifically low rates of 0.4 tC/ha/yr in the northwest and high rates of 3.0 tC/ha/yr in the south of the study region.

Wutzler, Max Planck Institute for Biogeochemistry, Hans-Knöll-Strasse 10, 07745 Jena, Germany E-mail: twutz@bgc-jena.mpg.de
Profft, Max Planck Institute for Biogeochemistry, Hans-Knöll-Stra§e 10, 07745 Jena, Germany E-mail: ip@nn.de
Mund, Max Planck Institute for Biogeochemistry, Hans-Knöll-Stra§e 10, 07745 Jena, Germany E-mail: mm@nn.de

article id 110, category Research article

Erlend Nybakk, Pablo Crespell, Eric Hansen. (2011). Climate for innovation and innovation strategy as drivers for success in the wood industry: moderation effects of firm size, industry sector, and country of operation. Silva Fennica vol. 45 no. 3 article id 110. https://doi.org/10.14214/sf.110

Keywords: comparative management; innovations; organisational culture; strategy; wood industry; working climate

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This study examines the relationships between firm financial performance and a) the climate for innovation and b) innovation strategy in the wood products industry. The focus is on the moderator effects of firm size, country of operation, and industry sector. Using a sample of 460 responses from chief executive officers and top managers of Norwegian and US firms, we conducted a regression analysis to probe for interaction effects. The sample included primary and secondary manufacturers of various sizes. Consistent with previous studies, we found a positive impact for both a climate for innovation and an innovation strategy on firm performance. In terms of moderation, only one interaction was found to be significant, representing a moderator effect of industry size on the climate-performance relationship. Further testing showed that secondary, large manufacturers exhibited a weaker, yet still positive, relationship between climate for innovation and performance. This low level of significant interactions suggests stability of the relationship among the main factors depicted in the model, with important implications for managers and future research. These findings indicate that a positive climate for innovation and a management committed to innovation through an innovation strategy have a positive effect on the bottom line of wood products firms. This effect holds true regardless of industry, size, or country, so most firms can benefit from the implementation of these pro-innovation practices.

Nybakk, Norwegian Forest and Landscape Institute, P.O. Box 115, N-1431 Ås, Norway E-mail: nye@skogoglandskap.no
Crespell, FPInnovations (Forintek Division), Vancouver, BC, Canada E-mail: pc@nn.fi
Hansen, Oregon State University, College of Forestry, OR, USA E-mail: eh@nn.us

article id 105, category Research article

Jaana Luoranen, Risto Rikala. (2011). Nutrient loading of Norway spruce seedlings hastens bud burst and enhances root growth after outplanting. Silva Fennica vol. 45 no. 3 article id 105. https://doi.org/10.14214/sf.105

Keywords: Picea abies; late-season fertilization; nitrogen concentration; root growth capacity

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We studied the effects of late season nutrient loading (NLOAD) on the timing of bud burst, growth and changes in nitrogen (N) concentrations in the first growing season after seedlings were outplanted. Two-year-old Norway spruce (Picea abies (L.) Karst.) seedlings with three foliar nitrogen concentration levels (NLOAD levels 11.3, 22.5 and 27.5 g N kg^-1 for L, M- and H-seedlings, respectively) were examined in the following three experiments: root growth capacity test (RGC), rooting experiment in the field and soil fertility experiment (‘rich’ or ‘poor’ soil) in the field. Bud burst in RGC was monitored daily and foliar N concentration (field experiments), height and root growth (rooting experiment) at monthly intervals. With respect to the RGC test, no differences in root growth were observed among the three NLOAD levels, but buds of H-seedlings burst 2–6 days earlier than others. In the rooting experiment, nutrient loading increased height and root growth but did not affect the timing of height growth. In the soil fertility experiment, foliar N of H- and M-seedlings decreased rapidly, but the decline was slower in rich soil. Current-year needles had more N in seedlings growing in rich soil and the N concentration declined until height growth ceased whereafter it increased until autumn. Improved growth from nutrient loading seems to last only for the first season after planting and the greatest benefits are enjoyed by seedlings planted in poor soils.

Luoranen, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600, Suonenjoki, Finland E-mail: jaana.luoranen@metla.fi
Rikala, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600, Suonenjoki, Finland E-mail: rr@nn.fi

article id 116, category Research article

Eva-Maria Nordström, Ljusk Ola Eriksson, Karin Öhman. (2011). Multiple criteria decision analysis with consideration to place-specific values in participatory forest planning. Silva Fennica vol. 45 no. 2 article id 116. https://doi.org/10.14214/sf.116

Keywords: forest management; decision support; public participation; spatial planning

Abstract | View details | Full text in PDF | Author Info

The combination of multiple criteria decision analysis (MCDA) and participatory planning is an approach that has been applied in complex planning situations where multiple criteria of very different natures are considered, and several stakeholders or social groups are involved. The spatial character of forest planning problems adds further to the complexity, because a large number of forest stands are to be assigned different treatments at different points in time. In addition, experience from participatory forest planning indicates that stakeholders may think about the forest in terms of place-specific values rather than in forest-wide terms. The objective of this study was to present an approach for including place-specific values in MCDA-based participatory forest planning and illustrate the approach by a case study where the objective was to choose a multipurpose forest plan for an area of urban forest in northern Sweden. Stakeholder values were identified in interviews, and maps were used to capture place-specific spatial values. The nonspatial and nonplace-specific spatial values were formulated as criteria and used to build an objective hierarchy describing the decision situation. The place-specific spatial values were included in the creation of a map showing zones of different silvicultural management classes, which was used as the basis for creation of forest plan alternatives in the subsequent process. The approach seemed to work well for capturing place-specific values, and the study indicates that formalized methods for including and evaluating place-specific values in participatory forest planning processes should be developed and tested further.

Nordström, Swedish University of Agricultural Sciences, Department of Forest Resource Management, Skogsmarksgränd 1, SE-901 83 Umeå, Sweden E-mail: eva-maria.nordstrom@slu.se
Eriksson, Swedish University of Agricultural Sciences, Department of Forest Resource Management, Skogsmarksgränd 1, SE-901 83 Umeå, Sweden E-mail: loe@nn.se
Öhman, Swedish University of Agricultural Sciences, Department of Forest Resource Management, Skogsmarksgränd 1, SE-901 83 Umeå, Sweden E-mail: ko@nn.se

article id 115, category Research article

Marjut Turtiainen, Kauko Salo, Olli Saastamoinen. (2011). Variations of yield and utilisation of bilberries (Vaccinium myrtillus L.) and cowberries (V. vitis-idaea L.) in Finland. Silva Fennica vol. 45 no. 2 article id 115. https://doi.org/10.14214/sf.115

Keywords: bilberry; cowberry; total berry yield; yield variation; utilisation of wild berries

Abstract | View details | Full text in PDF | Author Info

So far, only rough estimates for the utilisation rates of wild berries in Finland have been available. One reason for this is that there has been a lack of empirical-knowledge-based studies concerning total yields of wild berries and their yield variations. This study had three aims: 1) total bilberry and cowberry yields of an average crop year were calibrated for different (abundant and poor) crop years using the inventory data on wild berries collected by the Finnish Forest Research Institute (1997–2008); 2) national utilisation rates of bilberries and cowberries were calculated for three different berry years 1997–1999; and 3) regional utilisation rates of these berry species were calculated for the year 1997. According to calculations, annual bilberry yields in Finland vary from 92 to 312 million kg. For cowberry, the range of variation in total berry yields is from 129 to 386 million kg. It was also found that approximately the same proportion of the total yield of bilberries (i.e. 5–6%) was collected between 1997 and 1999. Utilisation rates of cowberries were also quite constant varying from approximately 8% to nearly 10%. In 1997, bilberries and cowberries were utilised most intensively in the eastern parts of the country and in the Oulu-Kainuu region. The results of this present study describe the situation before the phenomenon of foreign pickers. It can be presumed that commercial wild berry picking by migrant collectors has so far affected both national and regional utilisation rates of wild berries.

Turtiainen, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: marjut.turtiainen@uef.fi
Salo, Finnish Forest Research Institute, Joensuu Research Unit, Joensuu, Finland E-mail: ks@nn.fi
Saastamoinen, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: os@nn.fi

article id 41, category Research article

Ying Hou, Jintao Qu, Zukui Luo, Chao Zhang, Kaiyun Wang. (2011). Morphological mechanism of growth response in treeline species Minjiang fir to elevated CO2 and temperature. Silva Fennica vol. 45 no. 2 article id 41. https://doi.org/10.14214/sf.41

Keywords: climate change; Abies faxoniana; crown architecture; leaf morphology; response ratio

Abstract | View details | Full text in PDF | Author Info

To test whether and how morphological traits are linked with growth responses of plants to temperature and CO₂ is important for understanding the mechanism underlying how plant growth will respond to global warming. In this study, using closed-top chambers to mimic future elevated CO₂ and temperature, the growth response, morphological traits of Minjiang fir (Abies faxoniana Rehd.et Wils.) and the relationship of the two were investigated after two years of exposure to the single and combined elevation of CO₂ and temperature. The results showed that biomass of Minjiang fir was 21%, 31%, and 35% greater than the control in elevated CO₂, elevated temperature and the combination of elevated CO₂ and temperature treatments, respectively. Elevated CO₂ and temperature significantly affected the morphology of Minjiang fir, and a few morphological traits were highly correlated with growth responses. Larger branch angles at the upper layer, crown volume, and relative crown length contributed to positive growth responses to elevated CO₂, while decreased specific leaf area (SLA) constricted any further growth response. Leaf morphological traits were more closely correlated with the response ratio than crown did in the elevated temperature, while in the combination of elevated CO₂ and temperature, crown was more correlated with the response ratio than the leaf morphological traits. Thus, our results indicate that morphological traits may contribute differently to growth responses under different experimental conditions.

Hou, Department of Life Sciences, Shangqiu Normal University, Shangqiu, China E-mail: yh@nn.cn
Qu, Department of Life Sciences, Shangqiu Normal University, Shangqiu, China E-mail: jq@nn.cn
Luo, School of Environment and Life Sciences, Kaili University, Kaili, China E-mail: zl@nn.cn
Zhang, Shanghai Key Laboratory of Urbanization and Ecological Restoration, East China Normal University, Shanghai, China, and University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: cz@nn.cn
Wang, Shanghai Key Laboratory of Urbanization and Ecological Restoration, East China Normal University, Shanghai, China, and University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: kywang@re.ecnu.edu.cn

article id 40, category Research article

Jorge Martín-García, Elba Espiga, Valentín Pando, Julio Javier Diez. (2011). Factors influencing endophytic communities in poplar plantations. Silva Fennica vol. 45 no. 2 article id 40. https://doi.org/10.14214/sf.40

Keywords: endophyte; poplar; management; site quality; foliar nutrients; forest health

Abstract | View details | Full text in PDF | Author Info

The fungal species associated with leaves and twigs from stands of Populus x euramericana in northern Spain were studied with the aim of evaluating the effects of several factors on endophytic communities in these plantations. Endophyte assemblages were analysed in 12 poplar plantations (clone I-214), chosen according to a factorial scheme with two factors: age and site quality. Crown condition, dendrometric variables and foliar nutrients were recorded in each sampled tree to evaluate their effects on endophytic communities. Fungal species richness and relative isolation frequency (RIF) were higher in young stands than in adult stands. Moreover, the age-related differences depended on site quality, with the lowest richness levels observed in adult stands located in poor sites. At stand level, endophyte assemblages varied among stands according to site quality and, to a lesser extent, stand age. On the other hand, crown discoloration, total height and foliar concentrations of iron and zinc may be key indicators of endophytic communities in poplar plantations, at tree level.

Martín-García, Sustainable Forest Management Research Institute, University of Valladolid – INIA, Avenida de Madrid 57, 34004 Palencia, Spain, and Forestry Engineering, University of Extremadura, Plasencia, Spain E-mail: jorgemg@pvs.uva.es
Espiga, Sustainable Forest Management Research Institute, University of Valladolid – INIA, Palencia, Spain E-mail: ee@nn.es
Pando, Statistics and Operations Research Department, University of Valladolid, Spain E-mail: vp@nn.es
Diez, Sustainable Forest Management Research Institute, University of Valladolid – INIA, Palencia, Spain E-mail: jjd@nn.es

article id 33, category Research article

Raffaele Spinelli, Natascia Magagnotti, Giuseppe Paletto, Christian Preti. (2011). Determining the impact of some wood characteristics on the performance of a mobile chipper. Silva Fennica vol. 45 no. 1 article id 33. https://doi.org/10.14214/sf.33

Keywords: chipping; productivity; biomass; fuel consumption

Abstract | View details | Full text in PDF | Author Info

A study was conducted to determine the effect of some wood characteristics such as species, moisture content and tree part on the performance and product quality offered by a mobile industrial chipper, of the type commonly used for roadside chipping. Two main species, two tree parts and two moisture content levels were combined in a factorial design yielding 8 treatments, each replicated 5 or 6 times. A flow meter was installed on the chipper engine, and all chips produced were weighed and sampled for moisture content and particle size distribution. The results indicated that some wood characteristics such as species and moisture content have a secondary effect on chipper productivity and fuel consumption, which are primarily controlled by piece size. In particular, fuel consumption per unit dry mass seem to be rather constant and in the range of 3.2 l per oven dry ton. Moisture content and tree part may have a significant effect on the particle size distribution of chips. Of course, these results were only verified for the species used in the test and for industrial chippers, and may change if substantially different species or machines are used.

Spinelli, CNR IVALSA, Via Madonna del Piano 10, Sesto Fiorentino (FI), Italy E-mail: spinelli@ivalsa.cnr.it
Magagnotti, CNR IVALSA, Via Biasi 75, S. Michele all’Adige (TN), Italy E-mail: nm@nn.it
Paletto, CNR IMAMOTER, Strada delle Cacce 73, Torino, Italy E-mail: gp@nn.it
Preti, CNR IMAMOTER, Strada delle Cacce 73, Torino, Italy E-mail: cp@nn.it

article id 32, category Research article

Susete Marques, Jordi Garcia-Gonzalo, José G. Borges, Brigite Botequim, M. Manuela Oliveira, José Tomé, Margarida Tomé. (2011). Developing post-fire Eucalyptus globulus stand damage and tree mortality models for enhanced forest planning in Portugal. Silva Fennica vol. 45 no. 1 article id 32. https://doi.org/10.14214/sf.32

Keywords: forest fires; forest management; Eucalyptus globulus Labill; damage model; post-fire mortality

Abstract | View details | Full text in PDF | Author Info

Forest and fire management planning activities are carried out mostly independently of each other. This paper discusses research aiming at the development of methods and tools that can be used for enhanced integration of forest and fire management planning activities. Specifically, fire damage models were developed for Eucalyptus globulus Labill stands in Portugal. Models are based on easily measurable forest characteristics so that forest managers may predict post-fire mortality based on forest structure. For this purpose, biometric data and fire-damage descriptors from 2005/2006 National Forest Inventory plots and other sample plots within 2006, 2007 and 2008 fire areas were used. A three-step modelling strategy based on logistic regression methods was used. In the first step, a model was developed to predict whether mortality occurs after a wildfire in a eucalypt stand. In the second step the degree of damage caused by wildfires in stands where mortality occurs is quantified (i.e. percentage of mortality). In the third step this mortality is distributed among trees. Data from over 85 plots and 1648 trees were used for modeling purposes. The damage models show that relative damage increases with stand basal area. Tree level mortality models indicate that trees with high diameters, in dominant positions and located in regular stands are less prone to die when a wildfire occurs.

Marques, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: smarques@isa.utl.pt
Garcia-Gonzalo, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: jgg@nn.pt
Borges, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: jgb@nn.pt
Botequim, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: bb@nn.pt
Oliveira, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: mmo@nn.pt
Tomé, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: jt@nn.pt
Tomé, Technical University of Lisbon, School of Agriculture, Forest Research Center, Tapada da Ajuda, 1349-017 Lisboa, Portugal E-mail: mt@nn.pt

article id 31, category Research article

Jeovanna Lowe, David Pothier, Jean-Pierre L. Savard, Ghislain Rompré, Mathieu Bouchard. (2011). Snag characteristics and cavity-nesting birds in the unmanaged post-fire northeastern Canadian boreal forest. Silva Fennica vol. 45 no. 1 article id 31. https://doi.org/10.14214/sf.31

Keywords: snags; cavity nesting birds; boreal forests; old-growth; long term chronosequence; time since fire; mortality rate; basal area

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We studied the availability and characteristics of snags and their use by cavity-nesting birds in the northeastern part of the Canadian boreal forest. We built up two long-term (> 200 years) chronosequences following time since the last fire in the unmanaged boreal forest of northeastern Québec, one in the balsam fir-white birch domain (southern region) and one in the spruce-mosses domain (northern region). We then sampled and characterized snags and live trees in 30 stands from each of these two chronosequences. We also looked for nest cavities on all sampled snags, performed bird inventories by point counts, and calculated tree mortality rate from permanent sample plots. Results show that mortality rates follow a U-shaped pattern, with more snags of large diameter (> 20 cm DBH) in young (< 50 years) and in old (> 200 years) forests. In the latter, we also found more nest cavities than in any other age classes. Although abundance of primary cavity nesters (excavating species) did not vary among age classes, secondary cavity nesters (using cavities already available) tend to be more numerous in older forests. Our results highlight the capacity for young and old-growth forests to provide quality habitat for species that are dependent on large snags. Proper forest management should maintain a mosaic of different age forest stands, including snags, to promote biodiversity and provide important resources for resident bird species.

Lowe, Centre d’étude de la foret, Département des sciences du bois et de la foret, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Université Laval, Québec, Québec, G1V 0A6, Canada E-mail: jeovannalowe@gmail.com
Pothier, Centre d’étude de la foret, Département des sciences du bois et de la foret, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Université Laval, Québec, Québec, G1V 0A6, Canada E-mail: dp@nn.ca
Savard, Wildlife Research, Science and Technology, Québec Region, 1141 Route de l’Église, P.O. Box 10100, Québec, Québec, G1V 4H5, Canada E-mail: jpls@nn.ca
Rompré, Centre d’étude de la foret, Département des sciences du bois et de la foret, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Université Laval, Québec, Québec, G1V 0A6, Canada & Department of Biology and Health Sciences, 84 West South Street, Wilkes University, PA 18766, USA E-mail: gr@nn.ca
Bouchard, Ministère des Ressources naturelles et de la Faune, Direction de l’Environnement et de la Protection des Forets, 880 Chemin Ste-Foy, Quebec, Québec, G1S 4X4, Canada E-mail: mb@nn.ca

article id 30, category Research article

Hilppa Gregow, Heli Peltola, Mikko Laapas, Seppo Saku, Ari Venäläinen. (2011). Combined occurrence of wind, snow loading and soil frost with implications for risks to forestry in Finland under the current and changing climatic conditions. Silva Fennica vol. 45 no. 1 article id 30. https://doi.org/10.14214/sf.30

Keywords: A1B-scenario; climate change; snow loads; soil frost; stem breakage; uprooting; wind

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This work focuses on the combined occurrence of wind, snow loading and soil frost with implications for risks to forestry in Finland under the current and changing climatic conditions. For this purpose, we employ meteorological datasets, available for the period of 1971–2009 and global climate model (GCM) simulations for the current climate 1971–2000, and periods 2046–65 and 2081–2100 applying the A1B-climate change scenario. Based on our results, the wind and snow induced risks to Finnish forests are projected to increase in the future although the change in the occurrence of strong winds is small. This is because soil frost depths that support tree anchorage from late autumn to early spring in Finland are projected to nearly disappear in the southern and central parts of the country. Heavy snow loads > 30 kg m^–2 are becoming more common in southern and eastern Finland despite that the average cumulative 5-day snow loads decrease in these areas by 18 to 50%, respectively. As a result of the changes in the combined occurrence of wind, snow loading and soil frost, the risk of climatic conditions making conifers liable to uprooting are projected to increase in southern, central and eastern Finland. In the north, the risk of stem breakage is becoming more pronounced under snow loading > 20 kg m^–2. Despite some uncertainties related to this work, we assume that the findings can serve as valuable support for the risk assessment of wind and snow induced damages to Finnish forests and for forestry, in general.

Gregow, Finnish Meteorological Institute, Helsinki, Finland E-mail: hilppa.gregow@fmi.fi
Peltola, University of Eastern Finland, Faculty of Forest Sciences, Joensuu, Finland E-mail: heli.peltola@uef.fi
Laapas, Finnish Meteorological Institute, Helsinki, Finland E-mail: ml@nn.fi
Saku, Finnish Meteorological Institute, Helsinki, Finland E-mail: ss@nn.fi
Venäläinen, Finnish Meteorological Institute, Helsinki, Finland E-mail: av@nn.fi

article id 29, category Research article

Piotr Androsiuk, Roman Zielinski, Kornelia Polok. (2011). B-SAP markers derived from the bacterial KatG gene differentiate populations of Pinus sylvestris and provide new insights into their postglacial history. Silva Fennica vol. 45 no. 1 article id 29. https://doi.org/10.14214/sf.29

Keywords: Pinus sylvestris; KatG gene; molecular markers; population differentiation; migrations

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The aim of the studies was to evaluate the efficiency of the KatG gene based B-SAP markers as a tool to distinguish morphologically diversified and geographically distant Scots pine populations and to track the routes of migrations. The 19 populations growing in the IUFRO 1982 provenance experiment and representing the natural distribution of the species in Europe were scored using 103 B-SAP loci. Among them 26% loci were polymorphic. The level of polymorphism was associated with the location of primers on the KatG template. The diversity was low, H_e = 0.086, and deposited mostly among populations. Seven unique markers were found that identified populations and likely they were associated with morphology. The overall genetic identity was relatively low, I = 0.933 (D = 0.069). The block of six B-SAP markers discriminated populations into two groups in agreement with their geographic origin and thereby further described as the North and the South. The North group was uniform with genetic diversity, H_e = 0.026 and the overall genetic distance D = 0.022. Presumably, it migrated from refugia in the Alps via France, northern Germany and Denmark, to Scandinavia and Russia. The South group was heterogeneous with H_e = 0.063 and D = 0.047. This group migrated from the Carpathians via Slovakia to Germany and Poland. The Balkans and Asian refugia did not take part in recolonization of Europe. The block of six B-SAP/KatG markers can be recommended for tracking postglacial history of Scots pine.

Androsiuk, University of Warmia and Mazury in Olsztyn, Department of Genetics, Plac Lodzki 3, 10-967 Olsztyn, Poland E-mail: pa@nn.pl
Zielinski, University of Warmia and Mazury in Olsztyn, Department of Genetics, Plac Lodzki 3, 10-967 Olsztyn, Poland E-mail: rz@nn.pl
Polok, University of Warmia and Mazury in Olsztyn, Department of Genetics, Plac Lodzki 3, 10-967 Olsztyn, Poland E-mail: kpolok@moskit.uwm.edu.pl

article id 125, category Research article

Juho Rantala, Tiina Laine. (2010). Productivity of the M-Planter tree-planting device in practice. Silva Fennica vol. 44 no. 5 article id 125. https://doi.org/10.14214/sf.125

Keywords: silviculture; cost-efficiency; mechanisation; planting; seedling; technology

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Need to mechanise tree-planting work have recently increased for many reasons. The newest planting and soil scarification device performing work in Nordic forests is the Finnish M-Planter. This study aims to clarify M-Planter’s productivity in practice and show how various factors affect it. The follow-up data set covers 607 work shifts, of 13 operators with, in total, five M-Planters. The average productivity figures for the operators were 143 and 169 seedlings per effective working hour during the first and second planting season, respectively. Overall, the measured average productivity was 34.2% lower than that observed in an earlier work study of the M-Planter based on an experimental study design. On average, the operators learned to use the combination of the M-Planter and a base machine more efficiently while their experience in using it increased during the follow-up. Increasing number of stones and stumps as well as a thicker humus layer decreased productivity of the M-Planter. The study concludes that utilisation of the full productivity potential of the M-Planter requires not only good operators but also development of the whole planting service supply chain.

Rantala, Finnish Forest Research Institute, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: juho.rantala@metla.fi
Laine, Finnish Forest Research Institute, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: tl@nn.fi

article id 122, category Research article

Benoit Lafleur, Nicole J. Fenton, David Paré, Martin Simard, Yves Bergeron. (2010). Contrasting effects of season and method of harvest on soil properties and the growth of black spruce regeneration in the boreal forested peatlands of eastern Canada. Silva Fennica vol. 44 no. 5 article id 122. https://doi.org/10.14214/sf.122

Keywords: soil disturbance; peatland; Picea mariana; careful logging; clearcutting; paludification; forest productivity

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It has been suggested that without sufficient soil disturbance, harvest in boreal forested peatlands may accelerate paludification and reduce forest productivity. The objectives of this study were to compare the effects of harvest methods (clearcutting vs. careful logging) and season (summer vs. winter harvest) on black spruce regeneration and growth in boreal forested peatlands of eastern Canada, and to identify the soil variables that favour tree growth following harvest. Moreover, we sought to determine how stand growth following harvest compared with that observed following fire. The average tree height of summer clearcuts was greater than that of summer carefully logged stands and that of all winter harvested sites. Summer clearcutting also resulted in a higher density of trees > 3 m and > 4 m tall and in a 50% reduction in Rhododendron groenlandicum cover, a species associated with reduced black spruce growth. Height growth of sample trees was related to foliar N and P concentrations, and to soil total N, pH and available Ca and Mg but not to harvest method or season. Our results also indicate that summer clearcutting could produce stand productivity levels comparable to those observed after high-severity soil burns. These results suggest that summer clearcutting could be used to restore forest productivity following harvest in forested peatlands, and offer further support to the idea that sufficient levels of soil disturbance may be required to restore productivity in ecosystems undergoing paludification.

Lafleur, NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada E-mail: benoit.lafleur@uqat.ca
Fenton, NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada E-mail: njf@nn.ca
Paré, Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P.O. Box 10380, Stn. Sainte-Foy, QC G1V 4C7, Canada E-mail: dp@nn.ca
Simard, Département de Géographie, Université Laval, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Québec, QC G1V 0A6, Canada E-mail: ms@nn.ca
Bergeron, NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, 445 boul. de l’Université, Rouyn-Noranda, QC J9X 5E4, Canada E-mail: yb@nn.ca

article id 111, category Research article

Ilona Pietilä, Annika Kangas, Antti Mäkinen, Lauri Mehtätalo. (2010). Influence of growth prediction errors on the expected losses from forest decisions. Silva Fennica vol. 44 no. 5 article id 111. https://doi.org/10.14214/sf.111

Keywords: growth prediction; uncertainty; forest information; updating; inoptimality loss

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In forest planning, forest inventory information is used for predicting future development of forests under different treatments. Model predictions always include some errors, which can lead to sub-optimal decisions and economic loss. The influence of growth prediction errors on the reliability of projected forest variables and on the treatment propositions have previously been examined in a few studies, but economic losses due to growth prediction errors is an almost unexplored subject. The aim of this study was to examine how the growth prediction errors affected the expected losses caused by incorrect harvest decisions, when the inventory interval increased. The growth models applied in the analysis were stand-level growth models for basal area and dominant height. The focus was entirely on the effects of growth prediction errors, other sources of uncertainty being ignored. The results show that inoptimality losses increased with the inventory interval. Average relative inoptimality loss was 3.3% when the inventory interval was 5 years and 11.6% when it was 60 years. Average absolute inoptimality loss was 230 euro ha^–1 when the inventory interval was 5 years and 860 euro ha^–1 when it was 60 years. The average inoptimality losses varied between development classes, site classes and main tree species.

Pietilä, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ip@nn.fi
Kangas, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: annika.kangas@helsinki.fi
Mäkinen, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: am@nn.fi
Mehtätalo, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: lm@nn.fi

article id 134, category Research article

Dan Bergström, Urban Bergsten, Tomas Nordfjell. (2010). Comparison of boom-corridor thinning and thinning from below harvesting methods in young dense Scots pine stands. Silva Fennica vol. 44 no. 4 article id 134. https://doi.org/10.14214/sf.134

Keywords: bioenergy; comparative time studies; energy wood; geometric thinning; pre-commercial thinnings; systematic thinnings

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At present, only a small proportion of the potential extractable bioenergy from young dense forests in Sweden is utilized. The conventional mechanized first thinning systems used in such stands suffer from low productivity, so the operation is only profitable in stands with bigger trees and high standing volumes. Conventional harvesters are used for this operation equipped with accumulating felling heads designed for handling several trees during each crane cycle. In thinning from below the felling and bunching work requires many time-consuming non-linear crane movements to avoid felling or damaging of future crop trees. However, higher productivity can be achieved when trees between strip roads are harvested in about 1 m-wide corridors with a length corresponding to the reach of the crane. We refer to this operation as boom-corridor thinning. The objective of this study was to compare felling and bunching productivity in young dense stands when employing thinning from below or boom-corridor thinning. Experiments were performed using a randomized block design involving between 4400 and 18 600 trees x ha^-1 with a corresponding average tree size of 7.2 and 3.2 cm dbh, respectively. Based on the average tree being removed at a dbh of 5.7 cm, the productivity (ODt x PW-hour^-1) was significant (almost 16%) higher for the boom-corridor thinning than for thinning from below treatment. At the same time, the time taken for the work element “Crane in-between” (the period between the loaded crane starting to move towards a tree and the felling head rapidly slowing down for positioning) was significantly reduced, by almost 17%. The positive results were achieved even though the operator was new to the method. To achieve a significantly higher efficiency during the felling and bunching operation, development of new harvesting equipment and operating techniques seems crucial.

Bergström, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden E-mail: dan.bergstrom@srh.slu.se
Bergsten, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden E-mail: ub@nn.se
Nordfjell, Swedish University of Agricultural Sciences, Dept of Forest Resource Management, Section of Planning and Operations Management, Umeå, Sweden E-mail: tn@nn.se

article id 132, category Research article

Mats Berlin, Lars Lönnstedt, Gunnar Jansson, Öje Danell, Tore Ericsson. (2010). Developing a Scots pine breeding objective: a case study involving a Swedish sawmill. Silva Fennica vol. 44 no. 4 article id 132. https://doi.org/10.14214/sf.132

Keywords: Pinus sylvestris; economic weights; bio-economic model; tree breeding; multi-trait selection

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The aim of this study was to develop a Scots pine (Pinus sylvestris L.) breeding objective for a vertically integrated sawmill in northern Sweden. The production system was defined as comprising the sawmill and the forests supplying it. Volume per hectare, wood density, survival and straightness were used as objective traits and the related selection criteria were measurements, collected at young tree age, of height, diameter, pilodyn penetration, vitality and straightness. A bio-economic model was used to calculate economic weights for the objective traits identified. We also investigated the efficiency of different selection indices based on these economic weights, in combination with available data on genetic parameters. Furthermore, we studied the effect of different discount rates on the calculated economic weights. The results showed that, compared to the full index (which included all selection criteria), omitting either vitality or straightness had a negligible effect, reducing predicted profit gain per hectare by less than one per cent. Height or diameter each had a greater effect, with a loss of predicted profit gain per hectare of up to 6%. Excluding pilodyn penetration from the selection index caused the largest reduction in predicted profit gain per hectare, amounting to over 10%. However, when both height and diameter were removed the predicted profit gain per hectare dropped to one-third of that based on the full index. Finally, ranking and genetic selection for the developed breeding objective was insensitive to changes in the discount rate.

Berlin, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: mats.berlin@skogsforsk.se
Lönnstedt, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: ll@nn.se
Jansson, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: gj@nn.se
Danell, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: od@nn.se
Ericsson, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: te@nn.se

article id 131, category Research article

Timo Pukkala, Tatu Hokkanen, Teijo Nikkanen. (2010). Prediction models for the annual seed crop of Norway spruce and Scots pine in Finland. Silva Fennica vol. 44 no. 4 article id 131. https://doi.org/10.14214/sf.131

Keywords: flowering; cone crops; seed years; mixed model

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Many studies indicate that the flowering abundance of boreal trees strongly correlates with the weather conditions of the previous summer. This study developed prediction models for the seed crops of Norway spruce and Scots pine using weather variables one and two years prior to flowering year as predictors. Weather data, systematically recorded at many weather stations, were obtained from the Finnish Meteorological Institute. Seed crop monitoring data came from 22 spruce stands and 44 pine stands. In every stand, seed crop has been monitored for many years, the longest continuous period being 45 years. Monthly mean temperatures, monthly rainfalls, and periodical temperature sums were used as predictors in the seed crop models. Generally, both tree species flowered abundantly one year after a warm summer and two years after a cool summer. While the models only explained about 45% of the variation in the annual seed crop, they accurately predicted good and bad seed years: when the models predicted good seed crops the likelihood to have at least a medium seed crop was very high and when the models predicted small seed crops, the likelihood to obtain medium or good seed crop was very low. Therefore, the models reliably predict if a particular year will be a good seed year or a poor seed year. These predictions can be used in forestry practice for proper timing of natural regeneration activities, and when activities in seed orchards are planned.

Pukkala, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: timo.pukkala@uef.fi
Hokkanen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: th@nn.fi
Nikkanen, Finnish Forest Research Institute, Finlandiantie 18, FI-58450 Punkaharju, Finland E-mail: tn@nn.fi

article id 145, category Research article

Jianbang Gan, C. T. Smith. (2010). Coupling greenhouse gas credits with biofuel production cost in determining conversion plant size. Silva Fennica vol. 44 no. 3 article id 145. https://doi.org/10.14214/sf.145

Keywords: bioethanol; production cost; carbon balance; feedstock supply radius; life-cycle analysis

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Biofuel plant size is one of the key variables in biofuel supply chain analysis as it plays a pivotal role in controlling the efficacy of both feedstock supply and feedstock-to-biofuel conversion. The unit production cost and greenhouse gas (GHG) balance of biofuels vary with plant size. We develop an analytical framework for integrating biofuel production costs and GHG balance derived from life-cycle analysis into supply chain optimization, followed by its application to ethanol production using forest biomass in the southern United States. We derive formulas for determining the optimal biofuel plant size and the corresponding feedstock supply radius based on the minimization of biofuel production costs less GHG benefits. Our results indicate that though biofuel plant size and feedstock supply radius should be augmented by considering GHG benefits, the GHG price will have a more significant impact on net biofuel production costs than on conversion plant size or feedstock supply radius. With a rise in the GHG price the net biofuel production cost tends to increase while the directions of change in plant size and feedstock supply radius are uncertain, depending upon the costs and GHG emissions of biomass transport and feedstock-to-fuel conversion. Combining GHG offset values with biofuel production costs enables us to more holistically examine the biofuel supply chain.

Gan, Department of Ecosystem Science and Management, Texas A&M University, Texas, USA E-mail: j-gan@tamu.edu
Smith, Faculty of Forestry, University of Toronto, Ontario, Canada E-mail: cts@nn.ca

article id 143, category Research article

Juha Laitila, Jani Heikkilä, Perttu Anttila. (2010). Harvesting alternatives, accumulation and procurement cost of small-diameter thinning wood for fuel in Central Finland. Silva Fennica vol. 44 no. 3 article id 143. https://doi.org/10.14214/sf.143

Keywords: biomass resources; multi-tree-handling; delimbed stemwood; whole trees; Finland; early thinnings; forest chips

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This study compared harvesting alternatives, accumulation and procurement costs of small-diameter thinning wood chips for fuel, when trees were harvested either as delimbed stemwood or whole trees. The calculation was made for a hypothetical plant located in Central Finland and the radius of the procurement area was 100 km via the existing road network. Cutting was done with conventional harvester head equipped with multi-tree-handling (MTH) accessories, with the logged trees being chipped at the roadside storage. The cost of delimbed stemwood chips at heating plant was 24% higher compared to the cost of whole tree chips. The availability analysis attested that delimbing lowered the regional cutting removal by 42% compared to the whole tree harvesting, when the minimum accumulation for the fuel fraction at the stand was set at 25 m³/ha. Delimbing diminishes the recovery rate at the site, resulting in a diminishing number of potential recovery sites meeting the threshold volume. However, the study showed that the forest energy potential is increased and procurement costs are reduced, if delimbed stemwood is harvested from stands where the whole tree harvesting is not acceptable due to nutrient loss or for other ecological reasons. Intelligent selection of cutting methods for different stands enables minimization of transport distance and control of procurement cost.

Laitila, The Finnish Forest Research Institute, Joensuu, Finland E-mail: juha.laitila@metla.fi
Heikkilä, L&T Biowatti Oy, Seinäjoki, Finland E-mail: jh@nn.fi
Anttila, The Finnish Forest Research Institute, Joensuu, Finland E-mail: pa@nn.fi

article id 142, category Research article

Helmer Belbo. (2010). Comparison of two working methods for small tree harvesting with a multi tree felling head mounted on farm tractor. Silva Fennica vol. 44 no. 3 article id 142. https://doi.org/10.14214/sf.142

Keywords: Norway spruce; cost functions; forest biomass harvesting; multi-tree handling; young stands

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In this study, the efficiency of a small multi-tree felling head, mounted on a farm tractor with a timber trailer was studied, when harvesting small trees for energy in thinnings. Both separate loading and direct loading of the felled trees was studied. Time studies were carried out in a mixed stand of Norway spruce (Picea abies (L.) Karst) and birch (Betula pubescens Ehrh.). The time consumption of the work elements in the different work methods was formulated by regression analysis, where the independent variables were tree size and degree of accumulation. The average size of the harvested trees was 0.035 m3. The time consumption for the harvesting and loading were similar for the two studied methods, 20 minutes per m3 at a tree size of 0.035 m3, but the two methods showed different characteristics for different tree sizes and level of accumulation. The direct loading method had the highest productivity when more than 0.1 m3 were collected in the felling cycle, whereas the separate loading method had the highest productivity when less than 0.05 m3 were collected in the felling cycle. The total effective time consumption for harvesting and forwarding the biomass 300 meters to roadside landing was 27 minutes per m3. The efficiency of the initial felling and collecting of the small trees was the main challenge. Both the harvesting technique and harvesting technology needs further development to provide a feasible production chain for woodfuel from energy thinning.

Belbo, Norwegian Forest and Landscape Institute, Box 115, 1431 Ås, Norway E-mail: helmer.belbo@skogoglandskap.no

article id 141, category Research article

Per Kristian Rørstad, Erik Trømborg, Even Bergseng, Birger Solberg. (2010). Combining GIS and forest modelling in estimating regional supply of harvest residues in Norway. Silva Fennica vol. 44 no. 3 article id 141. https://doi.org/10.14214/sf.141

Keywords: bioenergy; forestry; SGIS; supply functions

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New and ambitious targets for renewable energy production put attention to increased supply of biomass. Harvest residues are only to a limited extent demanded by the traditional forest industries and represent an unutilized resource for increased production of renewable energy in Norway. The overall objective of this paper is to study how GIS and forest modelling can be combined to improve estimates of the supply of harvest residues, taking different environmental and economic constraints into consideration. The analyses are based on a case study of a forest area of more than 40 000 ha in Southern Norway divided into about 500 private forest properties. The study was carried out by computations of timber harvest using the forestry scenario model SGIS based on extensive forest inventory data at stand level. In the studied area energy utilization of harvest residues is not profitable below an energy price of about EUR 3.2/GJ (NOK 0.10 /kWh) when the distance from roadside to industry is 20 km. Above this level supply increases rapidly over a rather narrow price range and is nearly inelastic above EUR 4.1/GJ (NOK 0.12/kWh). We did not find significant negative shifts in the residues supply caused by changes in location of roundwood harvest over time. Exclusion of collection from stands with a site index (H₄₀) below 14 reduced the potential supply of residues by 16–27%. The optimisation method combined selection of exogenous variables in order to map observed harvesting level and is probably the best approach to map future harvest.

Rørstad, Norwegian University of Life Sciences, Dept of Ecology and Natural Resource Management, Ås, Norway E-mail: per.kristian.rorstad@umb.no
Trømborg, Norwegian University of Life Sciences, Dept of Ecology and Natural Resource Management, Ås, Norway E-mail: et@nn.no
Bergseng, Norwegian University of Life Sciences, Dept of Ecology and Natural Resource Management, Ås, Norway E-mail: eb@nn.no
Solberg, Norwegian University of Life Sciences, Dept of Ecology and Natural Resource Management, Ås, Norway E-mail: bs@nn.no

article id 138, category Research article

Santiago Martín-Alcón, José Ramón González-Olabarría, Lluís Coll. (2010). Wind and snow damage in the Pyrenees pine forests: effect of stand attributes and location. Silva Fennica vol. 44 no. 3 article id 138. https://doi.org/10.14214/sf.138

Keywords: models; stand structure; conifers; Pyrenees; snow damages; stability; wind damages

Abstract | View details | Full text in PDF | Author Info

Wind and snow-induced damage have been analyzed at stand level for three pine forests in the Central-Eastern Pyrenees (Pinus nigra Arn. salzmanii, Pinus sylvestris L. and Pinus uncinata Ram.). Stand-level models have been then developed for the most affected two species, Pinus sylvestris L. and Pinus uncinata Ram., to describe damage severity. The models were based on data from national forest inventory plots. They included variables related to the spatial location and structure of the stands, being validated using a sub-set of the database (25% of the plots randomly selected). Mountain pine forests (Pinus uncinata Ram.) were the most heavily affected by wind and snow disturbances. For both mountain and Scots pine species, topographic exposure and the severity of the local storm regime had an important effect on the degree of damage. Stand’s resistance to wind and snow was found to be dependent on the combined effect of basal area and mean slenderness of the dominant trees. For a given slenderness ratio, damage increased strongly in lower-density stands, particularly in stands with basal areas below 15 m²/ha. Stand structure was particularly important to define the resistance of Scots pine stands, which presented a higher vulnerability to wind and snow under higher degree of even-agedness. The models presented in this study provide empirically-based information that can be used to implement silvicultural practices to minimize the risk of those forests to suffer wind and snow-related damages.

Martín-Alcón, Forest Technology Center of Catalonia, Solsona, Lleida, Spain E-mail: santiago.martin@ctfc.es
González-Olabarría, Forest Technology Center of Catalonia, Solsona, Lleida, Spain E-mail: jrgo@nn.es
Coll, Forest Technology Center of Catalonia, Solsona, Lleida, Spain E-mail: lc@nn.es

article id 137, category Research article

Alberto Bueno, Julio J. Diez, Mercedes M. Fernández. (2010). Ophiostomatoid fungi transported by Ips sexdentatus (Coleoptera; Scolytidae) in Pinus pinaster in NW Spain. Silva Fennica vol. 44 no. 3 article id 137. https://doi.org/10.14214/sf.137

Keywords: Spain; Ips sexdentatus; ophiostomatoid fungi; Pinus pinaster; mycangia

Abstract | View details | Full text in PDF | Author Info

Ips sexdentatus (Coleoptera; Scolytidae) is one of the main vectors of ophiostomatoid blue stain fungi that can cause mortality of healthy conifers. For this reason, our objective was to identify the fungal species carried by this bark beetle in Maritime pine (Pinus pinaster) in north-western Spain. We collected insects from naturally infected pines placed them on malt extract agar (MEA) and left to walk freely on culture plates. Plant tissues (phloem and xylem) from adult pines were cultivated in moist chambers and also on MEA. At the same time, we inoculated pine logs with living insects in the laboratory. Four ophiostomatoid fungi appeared: Ophiostoma ips, Ophiostoma brunneo-ciliatum, Ceratocystiopsis minuta and Ophiostoma sp., as well as Graphium and Sporothrix imperfect stages. Moreover there were seven saprophytic species: Penicillium sp., Trichoderma sp., Verticillium sp., Mucor sp., Aspergillus niger, Gliocladium viride and Scopulariopsis brevicaulis, and the pathogenic Ophiostoma ips. The fructification percentage of the ophiostomatoid species was low, however; its imperfect stage Sporothrix/Hyalorhinocladiella produced high quantity of conidiophores.

Bueno, University of Valladolid, Dept of Agroforestry Sciences, Palencia, Spain E-mail: ab@nn.es
Diez, University of Valladolid, Dept of Agroforestry Sciences, Palencia, Spain E-mail: jjd@nn.es
Fernández, University of Valladolid, Dept of Agroforestry Sciences, Palencia, Spain E-mail: mffernan@agro.uva.es

article id 455, category Research article

Seppo Kellomäki, Matti Maajärvi, Harri Strandman, Antti Kilpeläinen, Heli Peltola. (2010). Model computations on the climate change effects on snow cover, soil moisture and soil frost in the boreal conditions over Finland. Silva Fennica vol. 44 no. 2 article id 455. https://doi.org/10.14214/sf.455

Keywords: climate change; soil frost; precipitation; temperature; A2 climate scenario; snow accumulation; soil carrying capacity; soil moisture

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This study considered how climate change affects the accumulation of snow, the soil moisture and soil frost at sites without tree cover in boreal conditions in Finland (60°–70°N). An increase of 4.5 °C in annual mean temperature and 20 % in annual precipitation were assumed for Finland by the year 2100 according to A2 emission scenario. Along with climate, the soil type of the permanent inventory plots of the Finnish National Forest Inventory was used. Soil and climate data were combined by using a process-based ecosystem model. Calculations were done for four periods: current climate (1971–2000), near future (2001–2020), mid-term future (2021–2050) and long-term future (2071–2100). According to our simulations, the average monthly duration and depth of snow decreased over the simulation period. However, the increasing precipitation may locally increase the snow depths in the mid-term calculations. In the autumn and winter, the average volumetric soil moisture content slightly increased in southern Finland during the near future, but decreased towards the end of the century, but still remained on a higher level than presently. In northern Finland, the soil moisture in the autumn and winter increased by the end of this century. In the summertime soil moisture decreased slightly regardless of the region. Throughout Finland, the length and the depth of soil frost decreased by the end of the century. In the south, the reduction in the depth was largest in the autumn and spring, while in the mid-winter it remained relatively deep in the middle of the century. In the north, the depth tended to increase during the first two calculation periods, in some areas, even during the third calculation period (2071–2100) due to reduced insulation effects of snow during cold spells. The wintertime increase in soil moisture and reduced soil frost may be reflected to reduced carrying capacity of soil for timber harvesting.

Kellomäki, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: seppo.kellomaki@uef.fi
Maajärvi, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: mm@nn.fi
Strandman, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: hs@nn.fi
Kilpeläinen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: ak@nn.fi
Peltola, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: hp@nn.fi

article id 151, category Research article

Janne Miettinen, Pekka Helle, Ari Nikula, Pekka Niemelä. (2010). Capercaillie (Tetrao urogallus) habitat characteristics in north-boreal Finland. Silva Fennica vol. 44 no. 2 article id 151. https://doi.org/10.14214/sf.151

Keywords: forest management; forestry; grouse; thinnings; landscape composition

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This study aimed to identify tools for taking capercaillie habitats into consideration in forest management. This would provide new alternatives for ecologically more sustainable forest management. Capercaillie summer and winter locations, from wildlife monitoring counts (1998–2004) in northern Finland, and reference, non-capercaillie locations were combined with forest planning data, and the area proportions of different landscape classes in an 800-m radius circle surrounding capercaillie and reference locations were compared. Thinning stands (in summer and winter) and spruce mires (in summer) were more abundant in capercaillie habitats than in reference landscapes, whereas e.g. seedling stands, mature stands and waste land areas were less abundant. The relative habitat use was highest in mean tree diameter (DBH) classes from 10.5 to 14.5 cm in summer habitats of adult capercaillie in heath forests, whereas in peatland forests, in brood habitats and in winter habitats it peaked in diameter classes 14.5 to 18.5 cm. The tree layer density was positively associated with the relative habitat use. A trend of lower habitat use was detected in the largest diameters (17–40 cm) in comparison to middle-sized diameters (10–16 cm) in heath forests, but not in peatland forests. Relatively young managed forests (age 30–40 years or more) can form suitable capercaillie habitats in north-boreal forests. However, this suitability is not necessarily permanent. Understorey management, longer rotations and multicohort forest management are suitable tools for capercaillie habitat management, because they can increase the available cover close to the ground, canopy cover, overall forest cover at the landscape scale and bilberry cover.

Miettinen, Finnish Game and Fisheries Research Institute, Finland E-mail: janne.miettinen@rktl.fi
Helle, Finnish Game and Fisheries Research Institute, Finland E-mail: ph@nn.fi
Nikula, Finnish Forest Research Institute, Finland E-mail: an@nn.fi
Niemelä, University of Turku, Dept of Biology E-mail: pn@nn.fi

article id 150, category Research article

Sini Eräjää, Panu Halme, Janne S. Kotiaho, Anni Markkanen, Tero Toivanen. (2010). The volume and composition of dead wood on traditional and forest fuel harvested clear-cuts. Silva Fennica vol. 44 no. 2 article id 150. https://doi.org/10.14214/sf.150

Keywords: dead wood; forest fuel harvesting; fine woody debris (FWD); clear-cut

Abstract | View details | Full text in PDF | Author Info

Logging residue and cut stumps are increasingly used as a renewable energy source known as forest fuel. Forest fuel harvesting obviously reduces the volume of dead wood and is likely to alter the dead wood composition, but the magnitude of the change is not known. Such information is important for the evaluation of the effects of forest fuel harvesting on biodiversity because a large proportion of forest dwelling species are directly dependent on dead wood. We measured the volume and characteristics of all dead wood units with a minimum diameter of 2 cm and a minimum length of 20 cm on 10 forest-fuel harvested and 10 traditional (control) clear-cuts. The total volume of dead wood at forest fuel harvested and control clear-cuts was 26.0 and 42.3 m³/ha, respectively. The volumes were much greater than expected suggesting that the volume of dead wood on clear-cuts has been underestimated in previous studies. Forest fuel harvested clear-cuts had 42% less branches and 81% less cut stumps than control clear-cuts but there were no differences in the volume of logs and pieces of logs, snags or roots. The volume of fine woody debris was negatively affected by forest fuel harvesting. We conclude that fine woody debris and cut stumps form a considerable resource on clear-cuts that is reduced by forest fuel harvesting. These components of dead wood have potential to be of importance in managed forests and thus deserve more attention in future biodiversity studies.

Eräjää, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: se@nn.fi
Halme, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: panu.halme@jyu.fi
Kotiaho, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: jsk@nn.fi
Markkanen, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: am@nn.fi
Toivanen, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: tt@nn.fi

article id 458, category Research article

Sakari Tuominen, Kalle Eerikäinen, Anett Schibalski, Markus Haakana, Aleksi Lehtonen. (2010). Mapping biomass variables with a multi-source forest inventory technique. Silva Fennica vol. 44 no. 1 article id 458. https://doi.org/10.14214/sf.458

Keywords: National Forest Inventory; remote sensing; biomass models; biomass maps

Abstract | View details | Full text in PDF | Author Info

Map form information on forest biomass is required for estimating bioenergy potentials and monitoring carbon stocks. In Finland, the growing stock of forests is monitored using multi-source forest inventory, where variables are estimated in the form of thematic maps and area statistics by combining information of field measurements, satellite images and other digital map data. In this study, we used the multi-source forest inventory methodology for estimating forest biomass characteristics. The biomass variables were estimated for national forest inventory field plots on the basis of measured tree variables. The plot-level biomass estimates were used as reference data for satellite image interpretation. The estimates produced by satellite image interpretation were tested by cross-validation. The results indicate that the method for producing biomass maps on the basis of biomass models and satellite image interpretation is operationally feasible. Furthermore, the accuracy of the estimates of biomass variables is similar or even higher than that of traditional growing stock volume estimates. The technique presented here can be applied, for example, in estimating biomass resources or in the inventory of greenhouse gases.

Tuominen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: sakari.tuominen@metla.fi
Eerikäinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: ke@nn.fi
Schibalski, University of Potsdam, Karl-Liebknecht-Strasse 24–25, 14476 Potsdam, Germany E-mail: as@nn.de
Haakana, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mh@nn.fi
Lehtonen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: al@nn.fi

article id 166, category Research article

Kim Pingoud, Johanna Pohjola, Lauri Valsta. (2010). Assessing the integrated climatic impacts of forestry and wood products. Silva Fennica vol. 44 no. 1 article id 166. https://doi.org/10.14214/sf.166

Keywords: carbon stocks; managed forests; silvicultural guidelines; harvested wood products; energy and material substitution; displacement of fossil carbon emissions

Abstract | View details | Full text in PDF | Author Info

Managed forests serve as a store of carbon (C) and a renewable source of energy and materials. By using forest products as substitutes for fossil fuels or non-renewable materials, emissions from fossil C sources can be displaced. The efficiency of emissions displacement depends on the product, its lifecycle and the fossil-fuel based reference system that is substituted. Forest management practices have an impact on C stocks in biomass and on the annual supply of products and their mix. There are trade-offs between sequestering C stocks in forests and the climatic benefits obtained by sustainable forest harvesting and using wood products to displace fossil C emissions. This article presents an integrated, steady-state analysis comparing various equilibrium states of managed forests and wood product pools that represent sustainable long-term forestry and wood-use strategies. Two climatic indicators are used: the combined C stock in forests and wood products and the fossil C emissions displaced annually by harvested wood products. The study indicates that long-term strategies could be available that are better according to both indicators than forestry practices based on the existing silvicultural guidelines in Finland. These strategies would involve increasing the basal area and prolonging rotations to produce more sawlogs. Further, the climate benefits appear to be highest in case the sawlog supply is directed to production of long-lived materials substituting for fossil-emission and energy intensive materials and recycled after their useful life to bioenergy.

Pingoud, VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland E-mail: kim.pingoud@vtt.fi
Pohjola, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: jp@nn.fi
Valsta, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: lv@nn.fi

article id 164, category Research article

Aki Suvanto, Matti Maltamo. (2010). Using mixed estimation for combining airborne laser scanning data in two different forest areas. Silva Fennica vol. 44 no. 1 article id 164. https://doi.org/10.14214/sf.164

Keywords: airborne laser scanning; area-based method; mixed estimation; regression models

Abstract | View details | Full text in PDF | Author Info

Airborne laser scanning (ALS) data have become the most accurate remote sensing technology for forest inventories. When planning new inventories the costs of fieldwork could be reduced if datasets of old inventory areas are effectively reused in the new area. The aim of this study was to apply mixed estimation using a combination of existing and new field datasets in area-based approach. Additionally, combining datasets with mixed estimation was compared with constructing new local models with smaller datasets. The two forest study areas were in Juuka and Matalansalo, which are located about 120 km apart in eastern Finland. ALS-based regression models were constructed using datasets of Matalansalo (472 reference plots) and Juuka (10–212 reference plots). Models were developed for the basal area median tree diameter and height, mean tree height, stem number, basal area and volume. The work was based on a simulation approach which involved five methods for approximating the regression coefficients. The first method merged the datasets using ordinary least squares (OLS) regression models, whereas the second and third methods combined datasets using mixed estimation on different weighting principles, and the final two estimated local models with predetermined and new independent variables. The results indicate that mixed estimation can improve the accuracy of derived stand variables compared with basic OLS models. Additionally, a sample of 40–50 plots was enough to build local models for basal area and volume and produce at least the equal accuracy of results than any other methods in this study.

Suvanto, Blom Kartta Oy, Teollisuuskatu 18, FI-80100 Joensuu, Finland E-mail: aki.suvanto@blomasa.com
Maltamo, University of Eastern Finland, School of Forest Sciences, P.O. Box, FI-80101, Joensuu, Finland E-mail: mm@nn.fi

article id 162, category Research article

Ruut Rabinowitsch-Jokinen, Ilkka Vanha-Majamaa. (2010). Immediate effects of logging, mounding and removal of logging residues and stumps on coarse woody debris in managed boreal Norway spruce stands. Silva Fennica vol. 44 no. 1 article id 162. https://doi.org/10.14214/sf.162

Keywords: forest management; soil preparation; bioenergy; log; stump harvesting; CWD; logging residues; snag

Abstract | View details | Full text in PDF | Author Info

Wood fuel production has increased remarkably, but its environmental effects within the forest ecosystem have not yet been studied much. We investigated the immediate effects of two series of forest management treatments, which produce timber and forest chips, on the volume and decay classes of coarse woody debris (CWD). One of the treatment series included logging and residue harvesting (LRH) and mounding (M), while the other series included LRH and mounding combined with stump harvesting (MSH). We hypothesized that, i) LRH reduces CWD, excluding stumps; ii) the more intense the soil preparation treatment is, M vs. MSH, the more CWD is destroyed; iii) both LRH and soil preparation treatments (M and MSH) reduce the occurence of snags, highly decayed CWD and deciduous CWD in particular. Ten sample plots in mature managed Norway spruce (Picea abies (L.) H. Karst.) dominated forests were located in Southern Finland. The total volume of CWD on the sample plots was measured three times: before and after LRH, and after M or MSH. LRH significantly decreased the volume of snags and the combined volume of snags and logs. MSH significantly decreased the total volume of CWD, while M had no significant effect on the volume of CWD. The middle and highly decayed CWD were destroyed most easily in the treatments.

Rabinowitsch-Jokinen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301, Vantaa, Finland E-mail: rrj@nn.fi
Vanha-Majamaa, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301, Vantaa, Finland E-mail: ilkka.vanha-majamaa@metla.fi

article id 161, category Research article

Mika Nieminen, Erkki Ahti, Harri Koivusalo, Tuija Mattsson, Sakari Sarkkola, Ari Laurén. (2010). Export of suspended solids and dissolved elements from peatland areas after ditch network maintenance in south-central Finland. Silva Fennica vol. 44 no. 1 article id 161. https://doi.org/10.14214/sf.161

Keywords: drained peatlands; forestry; ditching; hydrochemistry; nutrient export; suspended solids

Abstract | View details | Full text in PDF | Author Info

In Finland nearly 6 million hectares of peatlands are drained for forestry purposes. Ditch network maintenance in the drained peatlands, i.e. cleaning old ditches or digging complementary ditches, deteriorates surface water quality by increasing the export of dissolved elements and suspended solids (SS). Effect of ditch network maintenance on the export of SS, dissolved organic carbon (DOC), and dissolved nitrogen (N), phosphorous (P), iron (Fe), aluminum (Al) and manganese (Mn) was studied in nine pairs of treated and control (no maintenance) catchments located in southern and central Finland. In this study we extended the paired catchment approach by combining data from several catchments and identifying the treatment effect on SS and element loads from the entire dataset. Following the method of Laurén et al. (2009) we identified how uncertainty in correlation between treatment and control catchments during pre-treatment period is reflected in the estimated treatment effect on SS and element loads. In the experiment, the export of SS increased significantly for the four year study period following the ditch network maintenance and Al export increased for one year. The export of N, P and Fe was not significantly changed and DOC and Mn export decreased after the ditch maintenance operation.

Nieminen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mika.nieminen@metla.fi
Ahti, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ea@nn.fi
Koivusalo, Department of Civil and Environmental Engineering, Aalto University School of Science and Technology, P.O. Box 15200, FI-00076 Aalto, Finland E-mail: hk@nn.fi
Mattsson, Finnish Environment Institute, P.O. Box 140, FI-00251 Helsinki, Finland E-mail: tm@nn.fi
Sarkkola, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ss@nn.fi
Laurén, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: al@nn.fi

article id 176, category Research article

María Pasalodos-Tato, Timo Pukkala, Antonio Rigueiro-Rodríguez, Esther Fernández-Nunez, María Rosa Mosquera-Losada. (2009). Optimal management of Pinus radiata silvopastoral systems established on abandoned agricultural land in Galicia (north-western Spain). Silva Fennica vol. 43 no. 5 article id 176. https://doi.org/10.14214/sf.176

Keywords: simulation; economic profitability; optimization; risk reduction; salvage

Abstract | View details | Full text in PDF | Author Info

Timber production has been the main objective in forest production in Galicia for a long time. Nevertheless, factors such as fire risk and the need to obtain non-timber benefits make other production alternatives like silvopastoral systems worth of consideration. Integration of grazing in the production system not only diversifies products and benefits, but also decreases fire risk by enhancing fuel control. Nonetheless, few studies have examined the economic profitability of these systems. This article analyses the economics of silvopastoral systems established on abandoned agricultural soils afforested with Pinus radiata D. Don. Different tree planting densities, discounting rates, grass values and fire risk scenarios were analysed. The technique employed is based on the combination of an optimization algorithm and a simulator of stand growth and grass yield. The most profitable schedules were obtained with initial stand densities of 1500 trees per hectare. However, with high unit values of pasture production (high value of grass), schedules with an initial stand density of 500 trees per hectare were the most profitable. When the risk of fire was included in the analyses, silvopastoral systems were always more profitable than timber production systems. With an assumption that grazing reduces fire risk thinnings should be done earlier and heavier to reduce the expected losses due to fire and to promote grass production. This lengthens the pasture period. In general, rotation lengt

Pasalodos-Tato, INIA, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria. Madrid, Spain E-mail: pasalodos.maria@inia.es
Pukkala, University of East Finland, Joensuu, Finland E-mail: tp@nn.fi
Rigueiro-Rodríguez, University of Santiago de Compostela, Lugo, Spain E-mail: arr@nn.es
Fernández-Nunez, University of Santiago de Compostela, Lugo, Spain E-mail: efn@nn.es
Mosquera-Losada, University of Santiago de Compostela, Lugo, Spain E-mail: mrml@nn.es

article id 175, category Research article

Heikki Hänninen, Jaana Luoranen, Risto Rikala, Heikki Smolander. (2009). Late termination of freezer storage increases the risk of autumn frost damage to Norway spruce seedlings. Silva Fennica vol. 43 no. 5 article id 175. https://doi.org/10.14214/sf.175

Keywords: Norway spruce; simulation; autumn frost damage; day degrees; freezer storage; growing season

Abstract | View details | Full text in PDF | Author Info

Over the last few years it has become increasingly common in artificial forest regeneration to extend the planting period by using freezer-stored seedlings for early summer plantings. Developmentally, however, planted freezer-stored seedlings lag behind seedlings planted earlier in the spring. As freezer-stored seedlings also start hardening later, they are more susceptible to early autumn frosts, especially in years when the thermal growing season ends and the first autumn frosts come earlier than usual. By means of computer simulations with a simple temperature sum model and long-term air-temperature data from three locations in Finland, we examined the effect of the freezer-storage termination date on the risk of autumn frost damage to the seedlings. The long-term simulations revealed a drastic effect of year-to-year variation in the thermal conditions during the growing season on the occurrence of autumn frost damage. Such results provide crucial information complementary to those obtained in field experiments, which are always restricted to a relatively short time period. Together with earlier field data, the present results suggest that at an average regeneration site in central Finland, the planting of seedlings whose storage has terminated on 15 June and 22 June involve autumn frost damage every tenth and every fifth year, respectively. The sensitivity analysis revealed that the temperature sum requirement of maturation has a great effect on the risk of autumn frost damage, thus pinpointing the need for experimental studies addressing this ecophysiological trait of the seedlings.

Hänninen, Plant Ecophysiology and Climate Change Group (PECC), Department of Biological and Environmental Sciences, Box 65, FI-00014 University of Helsinki, Finland E-mail: heikki.hanninen@helsinki.fi
Luoranen, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: jl@nn.fi
Rikala, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: rr@nn.fi
Smolander, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: hs@nn.fi

article id 174, category Research article

Akihiro Sumida, Taro Nakai, Masahito Yamada, Kiyomi Ono, Shigeru Uemura, Toshihiko Hara. (2009). Ground-based estimation of leaf area index and vertical distribution of leaf area density in a Betula ermanii forest. Silva Fennica vol. 43 no. 5 article id 174. https://doi.org/10.14214/sf.174

Keywords: allometry; leaf area density; LAI; leaf inclination angle; MacArthur–Horn method; pipe model; Betula ermanii

Abstract | View details | Full text in PDF | Author Info

We developed a ground-based method for estimating leaf area index (LAI) and vertical distribution of leaf area density (LAD) for two Betula ermanii plots, combining an allometric method for tree leaf area with the MacArthur–Horn (MH) method using a portable laser rangefinder, including a correction for changes in leaf inclination angle along the vertical gradient measured with a portable digital protractor from a canopy access tower in each plot. Vertical distribution of projected leaf area density obtained by the MH method (LADMH) was transformed to relative distribution for allotting fixed LAI to different heights. Hence, we first developed an allometric method for estimating tree leaf area for LAI determination. Trunk cross-sectional area at branching height (AB) was accurately estimated (r² = 0.97) from ground-based measurements of tree dimensions. We used this method to apply pipe model allometry between tree leaf area and AB, and estimated LAI (4.56 and 4.57 m² m^–2). We then examined how leaf inclination angle affected estimation of the vertical distribution of actual LAD. Leaf inclination angle measurements revealed that actual LAD in the upper canopy was 1.5–1.8-times higher than LADMH, because of steep leaf inclination, while the correction factor was 1.15–1.25 in the lower canopy. Due to the difference among heights, vertical distribution of LAD estimated with correction for vertical change in leaf inclination was more skewed to the upper canopy than that without correction. We also showed that error in LAD distribution can result if horizontal canopy heterogeneity is neglected when applying the MH method.

Sumida, Institute of Low Temperature Science, Hokkaido University, N19W8, Sapporo 060-0819, Japan E-mail: asumida@lowtem.hokudai.ac.jp
Nakai, International Arctic Research Center, University of Alaska Fairbanks, 930 Koyukuk Drive, P.O. Box 757340, Fairbanks, Alaska 99775-7340, USA E-mail: tn@nn.jp
Yamada, International Meteorological & Oceanographic Consultants Co., Ltd. Kawaguchi-cho 2-6528-87, Choshi, Chiba 288-0001, Japan E-mail: my@nn.jp
Ono, Institute of Low Temperature Science, Hokkaido University, N19W8, Sapporo 060-0819, Japan E-mail: ko@nn.jp
Uemura, Field Science Center for Northern Biosphere, Hokkaido University, Tokuda 250, Nayoro, Hokkaido 096-0071, Japan E-mail: su@nn.jp
Hara, Institute of Low Temperature Science, Hokkaido University, N19W8, Sapporo 060-0819, Japan E-mail: th@nn.jp

article id 173, category Research article

Erik Hellberg, Torbjörn Josefsson, Lars Östlund. (2009). The transformation of a Norway spruce dominated landscape since pre-industrial times in northern Sweden: the influence of modern forest management on forest structure. Silva Fennica vol. 43 no. 5 article id 173. https://doi.org/10.14214/sf.173

Keywords: birch; disturbance dynamics; forest history; deciduous forest; fire

Abstract | View details | Full text in PDF | Author Info

Logging history and the study of reference conditions in Scandinavian boreal forests has tended to focus on Scots pine dominated ecosystems. This paper presents a regional study of pre-industrial forest conditions and examines the effects of the industrial exploitation of ecosystems dominated by Norway spruce in northern Sweden. Historical records covering a period which preceded industrial logging in the study area (1917–1927) were used to obtain quantitative data on forest structure and influence of forest fires. These data were compared with a modern data set (2003) to analyse changes due to the industrial transformation of the forest. The early 20th century landscape was dominated by old, multi-cohorted spruce forests and mixed coniferous forests. It was found that fire affected both the structure and composition of the landscape. In post-burnt areas, even-aged forests dominated by deciduous species were the principal forest type. Between the early and modern data sets, profound changes in tree-species composition and age structure were documented. While the total volume of deciduous species increased substantially, the coverage of forests dominated by deciduous species decreased. There was also a significant increase in pine-dominated forests and in the total volume of pine. The industrial transformation of the studied landscapes has had profound effects on the structure of spruce forests, but much less so on deciduous forests. The study concludes that the present forest structure is a function of past management regimes, and that future transformations of the landscape will continue, thus affecting the natural variability and biodiversity of the forests.

Hellberg, Tunstigen 10, SE-831 43 Östersund, Sweden E-mail: eh@nn.se
Josefsson, Swedish University of Agricultural Sciences, Department of Forest Ecology and Management, SE-901 83 Umeå, Sweden E-mail: torbjorn.josefsson@svek.slu.se
Östlund, Swedish University of Agricultural Sciences, Department of Forest Ecology and Management, SE-901 83 Umeå, Sweden E-mail: lo@nn.se

article id 171, category Research article

Takuo Nagaike. (2009). Snag abundance and species composition in a managed forest landscape in central Japan composed of Larix kaempferi plantations and secondary broadleaf forests. Silva Fennica vol. 43 no. 5 article id 171. https://doi.org/10.14214/sf.171

Keywords: snags; long-rotation plantation; plantation age; species composition

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Larix kaempferi is the main plantation species in the low-snow, cool-temperate zone of Japan. I studied L. kaempferi plantations of various stand ages in central Japan to examine and compare the effect of stand age on the abundance, size, and species composition of snags (standing dead trees) compared to those in secondary broadleaf forests. Plantations that were older than the standard rotation age had more and larger snags than young plantations, and the species diversity of snags was positively correlated with stand age. Because the density of living planted L. kaempferi showed little correlation with snag variables, whereas that of naturally regenerated tree species was positively correlated with snag variables, the density dependence of snag occurrence was stronger in naturally regenerated trees than in planted L. kaempferi. Snag species that were positively correlated with stand age were the main species in secondary broadleaf forests in this area. Basal area, density, and number of species of snags in standard-rotation plantations were significantly lower than in long-rotation plantations and secondary broadleaf forests. Long-rotation plantations are useful for retaining snags compared to standard-rotation plantations.

Nagaike, Yamanashi Forest Research Institute, Masuho, Yamanashi 400-0502, Japan E-mail: nagaike-zty@pref.yamanashi.lg.jp

article id 187, category Research article

Tobias Biechele, Leif Nutto, Gero Becker. (2009). Growth strain in Eucalyptus nitens at different stages of development. Silva Fennica vol. 43 no. 4 article id 187. https://doi.org/10.14214/sf.187

Keywords: growth stress; growth strain; Eucalyptus nitens; stages of development; sawnwood

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Eucalypts are renowned for their high growth stress levels. These stresses cause splitting, warping and dimensional instability when cutting, processing and drying the wood. In Chile, large Eucalyptus nitens plantations can be found, which, due to these problems, are scarcely utilised for solid wood products (veneer, sawn wood). This study aims to determine the factors influencing growth stress at different stages of tree’s development, and to identify whether the factors influencing growth stress change over time. In five stands of different ages, growth strain, as an indicator of growth stress, was measured at different tree heights with the single hole drilling method. The tree variables DBH, tree height, slenderness (height/diameter ratio) and crown parameters also were measured. A correlation analysis of tree variables and growth strains was undertaken. The results obtained indicate a high variability in growth strain values. It was concluded that growth strain is not correlated with a single growth parameter, but with a combination of factors that variously influence it at different ages and tree heights.

Biechele, University of Freiburg, Institute of Forest Utilisation and Work Science, Werthmannstr. 6, DE-79085 Freiburg, Germany E-mail: tobias.biechele@fobawi.uni-freiburg.de
Nutto, University of Freiburg, Institute of Forest Utilisation and Work Science, Werthmannstr. 6, DE-79085 Freiburg, Germany E-mail: ln@nn.de
Becker, University of Freiburg, Institute of Forest Utilisation and Work Science, Werthmannstr. 6, DE-79085 Freiburg, Germany E-mail: gb@nn.de

article id 186, category Research article

Juho Rantala, Pertti Harstela, Veli-Matti Saarinen, Leo Tervo. (2009). A techno-economic evaluation of Bracke and M-planter tree planting devices. Silva Fennica vol. 43 no. 4 article id 186. https://doi.org/10.14214/sf.186

Keywords: productivity; cost-efficiency; mechanization; planting cost

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Techno-economically reasonable mechanization of tree planting has proved to be a difficult task in the Nordic working conditions. Although planting machines and combinations of base machine and planting device have been developed since the 1970s, mechanized planting has not been cost-competitive to manual planting. The aim of this study was to find out work time distributions, productivities, costs and effects of different work difficulty factors on productivities and costs of the state-of-the-art Nordic planting devices, Swedish Bracke and Finnish M-Planter, and to compare the devices with each other. The theory of comparative time studies was the base for the experimental design of this study. In the average working conditions, productivity (E15) of M-Planter (236 seedlings/hour) was 36.0% higher than that of Bracke (174 seedlings/hour). Here, M-Planter performed planting work 23.4% cheaper than Bracke. However, the difference depended greatly on the working conditions; the more stones or stumps the smaller the difference, and the more slash the bigger the difference.

Rantala, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: juho.rantala@metla.fi
Harstela, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: ph@nn.fi
Saarinen, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: vms@nn.fi
Tervo, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: lt@nn.fi

article id 183, category Research article

Stella Bogino, María José Fernández Nieto, Felipe Bravo. (2009). Climate effect on radial growth of Pinus sylvestris at its southern and western distribution limits. Silva Fennica vol. 43 no. 4 article id 183. https://doi.org/10.14214/sf.183

Keywords: Scots pine; dendroclimatology; tree ring; pulse and interpulse

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The associations between tree-ring width and climatic variables, the tree age effect on climate-growth relationship and the drought index impact on radial growth of Scots pine (Pinus sylvestris L.) were studied in Mediterranean environments in the Iberian Peninsula. Dendrochronological techniques were applied to construct six tree-ring width chronologies for P. sylvestris. The association between tree growth and climate was analysed with correlation coefficients and bootstrapped response functions. Drought index (DRI) was used to detect the effects of aridity. Tree-ring width was positively correlated with rainfall in the growing season but this association stated earlier at the lowest altitudinal sites. The effects of temperature varied according to the site. The response to climatic variables depended on the age of the trees: more of the variability was explained by climatic variables in young stands than in old stands. The significant association between radial growth and DRI suggests that drought is a determining factor in the radial growth of P. sylvestris. Climate forecast scenarios show an increase in rainfall irregularity in the Mediterranean region so the differential tree response to rainfall at different elevations can be used to predict tree growth for determining silvicultural treatments.

Bogino, Universidad de Valladolid, Departamento de Producción Vegetal y Recursos Forestales, Joint Unit UVa-INIA ‘Sustainable Forest Management’, Avda. de Madrid 44, 34004 Palencia, Spain E-mail: sbogino@fices.unsl.edu.ar
Fernández Nieto, Universidad de Valladolid, Departamento de Producción Vegetal y Recursos Forestales, Joint Unit UVa-INIA ‘Sustainable Forest Management’, Avda. de Madrid 44, 34004 Palencia, Spain E-mail: mjfn@nn.es
Bravo, Universidad de Valladolid, Departamento de Producción Vegetal y Recursos Forestales, Joint Unit UVa-INIA ‘Sustainable Forest Management’, Avda. de Madrid 44, 34004 Palencia, Spain E-mail: fb@nn.es

article id 182, category Research article

Janne Miettinen, Pekka Helle, Ari Nikula, Pekka Niemelä. (2009). Changes in landscape-scale habitat selection of capercaillie (Tetrao urogallus) in managed north-boreal forest. Silva Fennica vol. 43 no. 4 article id 182. https://doi.org/10.14214/sf.182

Keywords: forestry; landscape composition; capercaillie; wildlife triangle

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We studied changes in habitat selection of capercaillie in northern Finnish boreal forests at two spatial scales during two time periods, 1989–1992 and 2000–2003. We studied capercaillie densities and their changes between the study periods in relation to the landscape class proportions within 3-km buffer zones around the wildlife triangle center points. Furthermore, we compared the landscape class proportions in 800-meter buffer zones around capercaillie wildlife triangle count observations and around the counted wildlife triangle transects using t-tests and compositional analysis. At the local population scale (3 km) the change in adult density between the study periods was associated positively with the proportion of young thinning stands in 2003 and reversely with the mature stand (1992 and 2003) and clear-cut (1992) proportions. Capercaillie juvenile and pooled densities during 2000–2003 were positively associated with the advanced thinning stand proportion in 2003. At the capercaillie home range scale (800 m) habitats were rich in mature stands during 1989–1992 in relation to available habitats, but not during 2000–2003 when young thinning stands were more abundant in relation to available habitats. Relatively young managed forests can be suitable for capercaillie, but mature managed forests as capercaillie habitats may have deteriorated between the study periods. Spatial planning may help to form suitable areas that are large enough for the species, but the highest potential may lay in the forest stand scale, where increased cover on the ground could promote the habitat quality.

Miettinen, Kankurinhaka 14, FI-90450 Kempele, Finland E-mail: janne.miettinen@rktl.fi
Helle, Finnish Game and Fisheries Research Institute, Tutkijantie 2 E, FI-90570 Oulu, Finland E-mail: ph@nn.fi
Nikula, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-99600 Rovaniemi, Finland E-mail: an@nn.fi
Niemelä, University of Turku, Department of Biology, FI-20014 University of Turku, Finland E-mail: pn@nn.fi

article id 203, category Research article

Matti Maltamo, Jussi Peuhkurinen, Jukka Malinen, Jari Vauhkonen, Petteri Packalén, Timo Tokola. (2009). Predicting tree attributes and quality characteristics of Scots pine using airborne laser scanning data. Silva Fennica vol. 43 no. 3 article id 203. https://doi.org/10.14214/sf.203

Keywords: LIDAR; alpha shape; crown height; height metrics; k-MSN; timber quality

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The development of airborne laser scanning (ALS) during last ten years has provided new possibilities for accurate description of the living tree stock. The forest inventory applications of ALS data include both tree and area-based plot level approaches. The main goal of such applications has usually been to estimate accurate information on timber quantities. Prediction of timber quality has not been focused to the same extent. Thus, in this study we consider here the prediction of both basic tree attributes (tree diameter, height and volume) and characteristics describing tree quality more closely (crown height, height of the lowest dead branch and sawlog proportion of tree volume) by means of high resolution ALS data. The tree species considered is Scots pine (Pinus sylvestris), and the field data originate from 14 sample plots located in the Koli National Park in North Karelia, eastern Finland. The material comprises 133 trees, and size and quality variables of these trees were modeled using a large number of potential independent variables calculated from the ALS data. These variables included both individual tree recognition and area-based characteristics. Models for the dependent tree characteristics to be considered were then constructed using either the non-parametric k-MSN method or a parametric set of models constructed simultaneously by the Seemingly Unrelated Regression (SUR) approach. The results indicate that the k-MSN method can provide more accurate tree-level estimates than SUR models. The k-MSN estimates were in fact highly accurate in general, the RMSE being less than 10% except in the case of tree volume and height of the lowest dead branch.

Maltamo, University of Joensuu, Faculty of Forest Sciences, FI-80101 Joensuu, Finland E-mail: matti.maltamo@joensuu.fi
Peuhkurinen, University of Joensuu, Faculty of Forest Sciences, FI-80101 Joensuu, Finland E-mail: jp@nn.fi
Malinen, Finnish Forest Research Institute, Joensuu Research Unit, FI-80101 Joensuu, Finland E-mail: jm@nn.fi
Vauhkonen, University of Joensuu, Faculty of Forest Sciences, FI-80101 Joensuu, Finland E-mail: jv@nn.fi
Packalén, University of Joensuu, Faculty of Forest Sciences, FI-80101 Joensuu, Finland E-mail: pp@nn.fi
Tokola, University of Joensuu, Faculty of Forest Sciences, FI-80101 Joensuu, Finland E-mail: tt@nn.fi

article id 194, category Research article

Ane Zubizarreta Gerendiain, Heli Peltola, Pertti Pulkkinen. (2009). Growth and wood property traits in narrow crowned Norway spruce (Picea abies f. pendula) clones grown in southern Finland. Silva Fennica vol. 43 no. 3 article id 194. https://doi.org/10.14214/sf.194

Keywords: fibre length; stem volume; height; diameter; wood density; earlywood; latewood

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We investigated the growth, yield, wood density traits and fibre properties in 13 narrow crowned Norway spruce (Picea abies f. pendula) clones grown at a spacing of 2 m x 1.5 m (about 3300 seedlings/ha) in a field trial established in 1988 in southern Finland on a forest soil. For comparison, we used 3 normal crowned Norway spruce (Picea abies (L.) Karst.) genetic entries grown as a mixture in the same trial representing southern Finnish breeding regions. We found that wood density traits and fibre properties showed, on average, lower phenotypic variation than growth and yield traits regardless of crown type. Narrow crowned clones also had, on average, lower stem volume and fibre length, but higher overall wood density. More over, the phenotypic correlations between studied growth and wood properties ranged, on average, from moderate (normal crown) to high (narrow crown). These results were opposite to previous findings for narrow and normal crowned genetic entries grown in narrower spacing (1 m x 1 m) in southern Finland. Thus, this indicates lower plasticity of narrow crowned clones to the increasing growing space compared to normal crowned ones, so, they should be grown at denser spacing in order to fully utilise its space efficiency capacity. However, this field trial was established as a mixture of normal and narrow crown trees, so that 90% of genetic entries were narrow crowned ones, and therefore the crown competition would be much higher for normal crowned trees when the whole trial would consist of that entry alone. In the latter case, we could expect significantly lower productivity of normal crowned genetic entries with this spacing.

Zubizarreta Gerendiain, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: ane.zubizarreta@joensuu.fi
Peltola, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: hp@nn.fi
Pulkkinen, Finnish Forest Research Institute, Haapastensyrjä Breeding Station, FI-12600 Läyliäinen, Finland E-mail: pp@nn.fi

article id 191, category Research article

Katri Luostarinen, Noora Huotari, Eila Tillman-Sutela. (2009). Effect of regeneration method on growth, wood density and fibre properties of downy birch (Betula pubescens Ehrh.). Silva Fennica vol. 43 no. 3 article id 191. https://doi.org/10.14214/sf.191

Keywords: coppice; fibre length; fibre width; regeneration methods; wood properties

Abstract | View details | Full text in PDF | Author Info

Short rotation tree stands, established by coppicing, are nowadays used mainly for energy purposes in Fennoscandia, but their usage for pulp raw material may increase in the future. Downy birch (Betula pubescens), which is commonly used for pulp production in boreal zone, has good sprouting capacity. However, it is not known if the fibre properties of sprout-originated downy birches differ from those of seed-originated ones. Therefore, fibre length and width of sprout- and seed-originated downy birches grown on fertile soil were measured at a stand age of 25 years. Additionally annual ring width, stem height and diameter, and wood density were studied to compare the growth and wood properties of sprout- and seed-originated birches. Annual rings were slightly wider in sprout- than in seed-originated birches, whereas no differences were observed in wood density. Fibres, too, were slightly longer and wider in sprout- than in seed-originated trees. Still these minor differences observed here are hardly significant for the industries using birch wood. Consequently downy birch wood from coppiced stands is well suited for pulp. The advantages of coppice, i.e. rapidity and low costs of establishment, productivity, and the ability of downy birch to grow on untypical forest sites, may even increase the importance of the wood coming from coppiced birch stands in the future.

Luostarinen, Faculty of Forest Sciences, University of Joensuu, P.O. Box 111, FI-80101, Joensuu, Finland E-mail: katri.luostarinen@joensuu.fi
Huotari, Finnish Forest Research Institute, Muhos Research Unit, Kirkkosaarentie, FI-91500 Muhos, Finland E-mail: nh@nn.fi
Tillman-Sutela, Finnish Forest Research Institute, Muhos Research Unit, Kirkkosaarentie, FI-91500 Muhos, Finland E-mail: ets@nn.fi

article id 211, category Research article

Timo Pukkala. (2009). Population-based methods in the optimization of stand management. Silva Fennica vol. 43 no. 2 article id 211. https://doi.org/10.14214/sf.211

Keywords: Particle Swarm Optimization; differential evolution; evolution strategy; Nelder-Mead method; amoeba search; polytope search; evolutionary computing

Abstract | View details | Full text in PDF | Author Info

In Finland, the growth and yield models for tree stands are simulation programs that consist of several sub-models. These models are often non-smooth and non-differentiable. Direct search methods such as the Hooke-Jeeves algorithm (HJ) are suitable tools for optimizing stand management with this kind of complicated models. This study tested a new class of direct search methods, namely population-based methods, in the optimization of stand management. The tested methods were differential evolution, particle swarm optimization, evolution strategy, and the Nelder-Mead method. All these methods operate with a population of solution vectors, which are recombined and mutated to obtain new candidate solutions. The management schedule of 719 stands was optimized with all population-based methods and with the HJ method. The population-based methods were competitive with the HJ method, producing 0.57% to 1.74% higher mean objective function values than HJ. On the average, differential evolution was the best method, followed by particle swarm optimization, evolution strategy, and Nelder-Mead method. However, differences between the methods were small, and each method was the best in several stands. HJ was alone the best method in 7% of stands, and a population based method in 3% (Nelder-Mead) to 29% (differential evolution) of stands. All five methods found the same solution in 18% of stands.

Pukkala, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: timo.pukkala@joensuu.fi

article id 210, category Research article

Juha Heiskanen, Markku Lahti, Jaana Luoranen, Risto Rikala. (2009). Nutrient loading has a transitory effect on the nitrogen status and growth of outplanted Norway spruce seedlings. Silva Fennica vol. 43 no. 2 article id 210. https://doi.org/10.14214/sf.210

Keywords: nursery fertilization; plantation performance; soil fertility

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In recent years increased fertilization provided to tree seedlings in the nursery in the previous autumn has been introduced in order to promote good outplanting performance. In this paper this nutrient loading has been studied in order to determine how the increased seedling nutrient status with unaffected seedling size affects both the growth and the nutrient concentration, content and uptake of two-year-old Norway spruce container seedlings (Picea abies (L.) Karsten) after outplanting. Seedling development was monitored for three years at two contrasting soil fertility levels on a sandy test field in two planting years and on one natural forest outplanting site in central Finland. Nutrient loading was shown to increase shoot and root growth in a poor fertility soil during the first growing season after planting, while, after the first growing season, nutrient loading was not found to affect seedling performance. However, although nutrient loading cannot compensate for the availability of nutrients to the seedlings from the soil, it may provide an additional input for fast plantation establishment on poorer sites during the first crucial growing season after outplanting.

Heiskanen, The Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland E-mail: juha.heiskanen@metla.fi
Lahti, The Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland E-mail: ml@nn.fi
Luoranen, The Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland E-mail: jl@nn.fi
Rikala, The Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland E-mail: rr@nn.fi

article id 209, category Research article

Jaana Luoranen, Kyösti Konttinen, Risto Rikala. (2009). Frost hardening and risk of a second flush in Norway spruce seedlings after an early-season short-day treatment. Silva Fennica vol. 43 no. 2 article id 209. https://doi.org/10.14214/sf.209

Keywords: frost hardiness; Picea abies; bud formation; container seedlings; height growth cessation; second flush

Abstract | View details | Full text in PDF | Author Info

There have been years in Finland when container seedlings of Norway spruce (Picea abies (L.) Karsten) planted in the summer have been damaged by early-autumn frosts. For August and September plantings, the seedlings can be hardened by means of short-day (SD) treatment, but little information is available about its usability for earlier plantings. We studied the effects of early-season SD treatment on the frost hardiness and risk of a second flush of Norway spruce seedlings. In three successive years, second-year seedlings were grown in a greenhouse or outdoors in the spring and early summer and then subjected to two or three-week SD treatment beginning on the second, third, or fourth week of June. We monitored the height growth cessation, bud formation, and frost hardiness of the seedlings in the nursery. All SD treatments made the height growth cease, but the risk of a second flush increased if the temperature sum was less than 300 d.d. before the beginning of the SD treatment or more than 450 d.d. between the end of the treatment and mid-August. Clearly, then, SD treatment reduced the risk of a second flush in seedlings that had been grown in a greenhouse in the spring. Early-season SD treatment increased the frost hardiness of both needles and stems for late July to early September in comparison with untreated seedlings. Later in the autumn, however, the differences disappeared. Before recommending the use of early-season SD-treated seedlings for summer planting, the method has to be tested in practical field conditions.

Luoranen, The Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland E-mail: jaana.luoranen@metla.fi
Konttinen, The Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland E-mail: kk@nn.fi
Rikala, The Finnish Forest Research Institute, Suonenjoki Research Unit, FI-77600 Suonenjoki, Finland E-mail: rr@nn.fi

article id 208, category Research article

Mikko Räisänen, Tapani Repo, Tarja Lehto. (2009). Cold acclimation of Norway spruce roots and shoots after boron fertilization. Silva Fennica vol. 43 no. 2 article id 208. https://doi.org/10.14214/sf.208

Keywords: boron deficiency; dieback; freezing tolerance; mineral nutrition

Abstract | View details | Full text in PDF | Author Info

Boron deficiency, manifested as shoot dieback, is a problem in conifer stands growing on soils with high nitrogen availability in Fennoscandia. Earlier observations on Norway spruce (Picea abies L. Karst.) suggest that freezing tolerance is decreased by boron deficiency. Here, the effect of boron fertilization on cold acclimation of Norway spruce was studied in a young stand with initially low boron status two years after fertilization. Buds, stems, needles and roots were collected at five sampling times during cold acclimation and subsequently exposed to series of freezing temperatures. Lethal temperatures of organs were assessed by electrolyte leakage method (EL) and visual scoring of damage (VS). Freezing tolerance of buds was measured also by differential thermal analysis (DTA). The mean boron (B) concentration in needles was 4 mg kg–1 in unfertilized and 21 mg kg–1 in B-fertilized trees while critical level of B deficiency is considered to be 5 mg kg–1. The risk for increased freezing injuries in the low-B trees was not evident since all trees achieved cold hardiness that would be sufficient in central Finland. At two sampling times out of five, shoots or stem of B-fertilized trees were slightly more freezing tolerant than non-fertilized trees. However, the present study does not give strong evidence for the hypothesis that decreased freezing tolerance in B deficiency would be a triggering factor for leader dieback in Norway spruce at the B levels studied.

Räisänen, University of Joensuu, Faculty of Forest Sciences, P.O.Box 111, FI-80101 Joensuu, Finland; (present address), FAForest, FI-83480 Ahonkylä, Finland E-mail: mr@nn.fi
Repo, Finnish Forest Research Institute, Joensuu Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: tr@nn.fi
Lehto, University of Joensuu, Faculty of Forest Sciences, P.O.Box 111, FI-80101 Joensuu, Finland E-mail: tarja.lehto@joensuu.fi

article id 205, category Research article

Pekka Vakkari, Mari Rusanen, Katri Kärkkäinen. (2009). High genetic differentiation in marginal populations of European white elm (Ulmus laevis). Silva Fennica vol. 43 no. 2 article id 205. https://doi.org/10.14214/sf.205

Keywords: marginal populations; genetic differentiation; genetic conservation; Ulmus

Abstract | View details | Full text in PDF | Author Info

Studies on the amount of genetic variation in marginal populations and differentiation between them are essential for assessment of best gene conservation strategies and sampling schemes. Thirteen marginal populations of Ulmus laevis in southern Finland and one in Estonia were investigated for genetic variation in 20 allozyme loci. Population differentiation among Finnish stands was high, F_st = 0.290, and mean genetic diversity low, H_e = 0.088. The differentiation follows the isolation-by-distance structure within the core of the distribution area (lake Vanajavesi). Fairly high frequency of recurrent genotypes was observed, but this did not have an influence on the genetic parameters. The observed genetic structure is consistent with the central-marginal hypothesis. In the light of the results, the Finnish gene conservation strategy for U. laevis seems to be on a sound basis.

Vakkari, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: pekka.vakkari@metla.fi
Rusanen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mr@nn.fi
Kärkkäinen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: kk@nn.fi

article id 464, category Research article

Christian Kanzian, Franz Holzleitner, Karl Stampfer, Sarah Ashton. (2009). Regional energy wood logistics – optimizing local fuel supply. Silva Fennica vol. 43 no. 1 article id 464. https://doi.org/10.14214/sf.464

Keywords: logistics; energy wood; transport optimization; GIS

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The promotion of electric energy production from solid biomass by the Austrian government has lead to a boom in the construction of new combined heat and power plants. The current total demand for wood chips in the research area for energy purposes is 70 400 m³ of loose volume chips per year. The expected increase in demand due to these new plants is more than 4 times greater than current demand: up to 302 700 m³ of loose volume per year. Even if the energy wood feedstock potential is satisfactory, the design of the supply chain is still unresolved. The aim of this study is to give decision-makers a base for further development. To accomplish this, we designed and tested four different supply scenarios: one for 9 plants and one for 16 plants. The scenarios were developed using a combination of geographic information systems (GIS) and linear programming methods. The results indicate that direct transport of solid fuel wood as round wood and chipping at the plant is the cheapest supply system with a resulting cost of 5.6–6.6 EUR/m³ loose. Using harvesting residues can only be recommended for large plants because of poor fuel quality. In this case, residues would be chipped at or near the landing, piled and transported via self-loading trucks at a cost between 8.4 and 9.1 EUR/m³ loose. In order to meet increasing demand and to ensure a continuous supply, especially during the winter and spring seasons it is necessary to optimize the supply chain by including storage terminals. However, using terminals and increased demand both lead to higher logistical costs. For example, if the total volume is handled via terminals, the average supply costs including storage will increase by 26%. Higher demand increases the costs by 24%.

Kanzian, University of Applied Life Sciences Vienna, Institute of Forest Engineering, Peter Jordan Strasse 82, A-1190 Vienna, Austria E-mail: christian.kanzian@boku.ac.at
Holzleitner, University of Applied Life Sciences Vienna, Institute of Forest Engineering, Peter Jordan Strasse 82, A-1190 Vienna, Austria E-mail: fh@nn.at
Stampfer, University of Applied Life Sciences Vienna, Institute of Forest Engineering, Peter Jordan Strasse 82, A-1190 Vienna, Austria E-mail: ks@nn.at
Ashton, Southern Regional Extension Forestry, Forestry Bldg. 4-420, University of Georgia, Athens, GA 30602, USA E-mail: sa@nn.us

article id 220, category Research article

Jani Heikkilä, Matti Sirén, Anssi Ahtikoski, Jari Hynynen, Tiina Sauvula, Mika Lehtonen. (2009). Energy wood thinning as a part of stand management of Scots pine and Norway spruce. Silva Fennica vol. 43 no. 1 article id 220. https://doi.org/10.14214/sf.220

Keywords: energy wood thinning; stand management; MOTTI simulator

Abstract | View details | Full text in PDF | Author Info

The effects of combined production of industrial and energy wood on yield and harvesting incomes, as well as the feasibility of energy wood procurement, were studied. Data for 22 Scots pine (Pinus sylvestris L.) and 21 Norway spruce (Picea abies (L.) Karst.) juvenile stands in Central and Southern Finland were used to compare six combined production regimes to conventional industrial wood production. The study was based on simulations made by the MOTTI stand simulator, which produces growth predictions for alternative management regimes under various site and climatic conditions. The combined production regimes included precommercial thinning at 4–8 m dominant height to a density of 3000–4000 stems ha^–1 and energy wood harvesting at 8, 10 or 12 m dominant height. Combined production did not decrease the total yield of industrial wood during the rotation period. Differences in the mean annual increment (MAI) were small, and the rotation periods varied only slightly between the alternatives. Combined production regime can be feasible for a forest owner if the price of energy wood is 3–5 EUR m^–3 in pine stands, and 8–9 EUR m^–3 in spruce stands. Energy wood procurement was not economically viable at the current energy price (12 EUR MWh^–1) without state subsidies. Without subsidies a 15 EUR MWh^–1 energy price would be needed. Our results imply that the combined production of industrial and energy wood could be a feasible stand management alternative.

Heikkilä, L&T Biowatti Oy, P.O. Box 738, FI-60101 Seinäjoki, Finland E-mail: jani.heikkila@biowatti.fi
Sirén, Finnish Forest Research Institute, Vantaa Research Unit, P.O.Box 18, FI-01301 Vantaa, Finland E-mail: ms@nn.fi
Ahtikoski, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O.Box 16, FI-96301 Rovaniemi, Finland E-mail: aa@nn.fi
Hynynen, Finnish Forest Research Institute, Vantaa Research Unit, P.O.Box 18, FI-01301 Vantaa, Finland E-mail: jh@nn.fi
Sauvula, Seinäjoki University of Applied Sciences, School of Agriculture and Forestry, Tuomarniementie 55, FI-63700 Ähtäri, Finland E-mail: ts@nn.fi
Lehtonen, Finnish Forest Research Institute, Vantaa Research Unit, P.O.Box 18, FI-01301 Vantaa, Finland E-mail: ml@nn.fi

article id 219, category Research article

Arto Haara, Pekka Leskinen. (2009). The assessment of the uncertainty of updated stand-level inventory data. Silva Fennica vol. 43 no. 1 article id 219. https://doi.org/10.14214/sf.219

Keywords: uncertainty; measurement error; simulation; non-parametric methods; observed error; stand-level inventory

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Predictions of growth and yield are essential in forest management planning. Growth predictions are usually obtained by applying complex simulation systems, whose accuracy is difficult to assess. Moreover, the computerised updating of old inventory data is increasing in the management of forest planning systems. A common characteristic of prediction models is that the uncertainties involved are usually not considered in the decision-making process. In this paper, two methods for assessing the uncertainty of updated forest inventory data were studied. The considered methods were (i) the models of observed errors and (ii) the k-nearest neighbour method. The derived assessments of uncertainty were compared with the empirical estimates of uncertainty. The practical utilisation of both methods was considered as well. The uncertainty assessments of updated stand-level inventory data using both methods were found to be feasible. The main advantages of the two studied methods include that bias as well as accuracy can be assessed.

Haara, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: arto.haara@joensuu.fi
Leskinen, Finnish Environment Institute, Research Programme for Production and Consumption, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: pl@nn.fi

article id 214, category Research article

Michelle de Chantal, Hannu Rita, Urban Bergsten, Mikaell Ottosson Löfvenius, Harald Grip. (2009). Frost heaving of Picea abies seedlings as influenced by soil preparation, planting technique, and location along gap-shelterwood gradients. Silva Fennica vol. 43 no. 1 article id 214. https://doi.org/10.14214/sf.214

Keywords: deep planting; normal planting; mobile container; fixed container; HuMinMix; soil horizon

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The effects of soil preparation, planting technique and location along gap-shelterwood gradients (position and orientation) on frost heaving damage to seedlings were studied in Vindeln Experimental Forests, northern Sweden. The forest was harvested in a grid pattern in winter 2004–2005, forming gaps and shelterwood areas of 30 x 40 m each. Gap-shelterwood gradients were delimited in four orientations and subdivided into five positions: 7 m and 15 m into the gap and shelterwood, and at the gap edge. At each position, three replicates of three soil preparations were made: exposed E and B horizons and HuMinMix (milled vegetation and humus layers mixed with surface mineral soil). In early October 2005, one-year-old containerized Picea abies (L.) Karst. seedlings were planted using four techniques: normal and deep planting, and mobile and fixed experimental containers. After one winter, frost heaving damage was highest for seedlings on B horizon combined with the mobile container (51 ± 6%) and normal planting (43±6%). Normal- or deep-planted seedlings in HuMinMix had the least damage (5–6.6 ± 2.5%). Compared to normal planting, deep planting reduced frost heaving damage only on B horizon. When considering the orientation, seedlings in the experimental containers had more or similar frost heaving damage than normal- or deep-planted seedlings. Along the eastern gradient, seedlings incurred more frost heaving damage in the center of the gap than under the canopy.

Chantal, University of Helsinki, Dept of Forest Ecology & Dept of Forest Resource Management, Helsinki, Finland E-mail: michelle.dechantal@helsinki.fi
Rita, University of Helsinki, Dept of Forest Ecology & Dept of Forest Resource Management, Helsinki, Finland E-mail: hr@nn.fi
Bergsten, Swedish University of Agricultural Sciences, Dept of Forest Ecology and Management, Umeå, Sweden E-mail: ub@nn.se
Löfvenius, Swedish University of Agricultural Sciences, Dept of Forest Ecology and Management, Umeå, Sweden E-mail: mol@nn.se
Grip, Swedish University of Agricultural Sciences, Dept of Forest Ecology and Management, Umeå, Sweden E-mail: hg@nn.se

article id 467, category Research article

Annika Kangas, Ruut Haapakoski, Liisa Tyrväinen. (2008). Integrating place-specific social values into forest planning – Case of UPM-Kymmene forests in Hyrynsalmi, Finland. Silva Fennica vol. 42 no. 5 article id 467. https://doi.org/10.14214/sf.467

Keywords: collaborative planning; experienced values of forests; social value mapping; survey

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In participatory forest management planning, the perceived values of local inhabitants concerning the area under planning are collected. The results may, however, depend on the methods used. In this study, values of residents of Hyrynsalmi municipality concerning the nearby forests owned by UPM-Kymmene Ltd. were evaluated with a questionnaire consisting of general value questions and mapping of social values of forests. The data was collected from a public meeting and from a mailed survey from randomly sampled people and from members of municipal council. The aims of the study were to 1) test the social value mapping method in commercial forests in a rural-urban interface as well as to examine the benefits and drawbacks 2) in place-specific and non-specific data collection, and 3) in different data collection methods, from the viewpoint of forest management planning. We noted that while all respondents can claim to represent local values, different data collection methods produced statistically significantly different local values. This needs to be accounted for when planning a participatory process. In operational forest planning, place-specific information is more useful than questions concerning the general values, while the latter may help in defining forest policy goals. The social values mapping method is also relatively easy for the participants. However, in the studied case about one fifth of the area was delineated by the participants per each positive value. The answers were quite scattered, suggesting that most of the area had some social values for local people. This indicates that utilising a social values mapping method in planning needs further development in rural areas, where distinctive patches can not be easily detected.

Kangas, University of Helsinki, Department of Forest Management, P.O. Box 27, FI-00014 University of Helsinki E-mail: annika.kangas@helsinki.fi
Haapakoski, University of Helsinki, Department of Forest Management, P.O. Box 27, FI-00014 University of Helsinki E-mail: rh@nn.fi
Tyrväinen, Finnish Forest Research Institute, P.O. Box 16, FI-96301 Rovaniemi, Finland. E-mail: lt@nn.fi

article id 466, category Research article

Ilkka Korpela, Tuukka Tuomola, Timo Tokola, Bo Dahlin. (2008). Appraisal of seedling stand vegetation with airborne imagery and discrete-return LiDAR – an exploratory analysis. Silva Fennica vol. 42 no. 5 article id 466. https://doi.org/10.14214/sf.466

Keywords: silviculture; remote sensing; forest regeneration; classification; species

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The potential for combined use of airborne discrete-return LiDAR and digital imagery in the classification and measurement of common seedling stand vegetation was examined in southern Finland (61°50’N, 24°20’E). Classification was based on spectral and textural image features in addition to geometric and radiometric features of the LiDAR. The accuracy of leaf-on, LiDAR-based terrain elevation models was tested as well as the accuracy of LiDAR in the measurement of vegetation heights. LiDAR-based canopy height and the range-normalized intensity of the LiDAR were strong explanatory variables in vegetation classification. Interspecies variation was observed in the height measurement accuracy of LiDAR for different tree, shrub and low vegetation canopies. Elevation models derived with 1–15 pulses per m² showed an inherent noise of app. 15–25 cm, which restricts the use of LiDAR in regeneration assessment of very young stands. The spatial pattern of the competing vegetation was reproduced in classification-based raster surfaces, which could be useful in deriving meaningful treatment proposals.

Korpela, University of Helsinki, Dept of Forest Management, P.O. Box 27, FI-00014 University of Finland E-mail: ilkka.korpela@helsinki.fi
Tuomola, University of Helsinki, Dept of Forest Management, P.O. Box 27, FI-00014 University of Finland E-mail: tt@nn.fi
Tokola, University of Helsinki, Dept of Forest Management, P.O. Box 27, FI-00014 University of Finland E-mail: tt@nn.fi
Dahlin, University of Helsinki, Dept of Forest Management, P.O. Box 27, FI-00014 University of Finland E-mail: bd@nn.fi

article id 227, category Research article

Ola Lindroos. (2008). The effects of increased mechanization on time consumption in small-scale firewood processing. Silva Fennica vol. 42 no. 5 article id 227. https://doi.org/10.14214/sf.227

Keywords: comparative time study; fuelwood; blade saw; wedge splitter; processor; senior worker; operator effects

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Firewood, which is mainly processed by the consumer, is still an important source of energy for heating houses in industrialised countries. Possibilities to compare the mechanization’s impact on efficiency of firewood processing are limited, due to variations between working conditions in previous studies. Therefore, the objective was to compare time consumption for two small-scale firewood processing systems with different levels of mechanisation under identical conditions. The systems were tested on two classes of wood: one with a homogeneous and medium-sized diameter of logs and one with a mixture of small and large-diameter-logs. Differences in time consumption were analysed for correlations with physical workloads, deviations to routine operations, operator influences and operator perceptions. Twelve operators (60–79 years old) were studied and they showed large variation in time consumption. However, the within-operator time consumption patterns were consistent. In other words, operators all responded similarly to the different combinations of systems and wood classes, but at different absolute levels. The time required to process a unit volume of wood was 25–33% lower when the more highly mechanised system was used, and the time required was 13–22% lower for the homogeneous wood class. Physical work load, deviations and perceptions of the work varied between operators, but were weakly correlated with time consumption. The results’ implications for analyses of investments in equipment for firewood-processing for self-sufficiency purposes are discussed.

Lindroos, Swedish University of Agricultural Sciences, Department of Forest Resource Management, SE-901 83 Umeå, Sweden E-mail: ola.lindroos@srh.slu.se

article id 225, category Research article

Johan Bergh, Urban Nilsson, Harald Grip, Per-Ola Hedwall, Tomas Lundmark. (2008). Effects of frequency of fertilisation on production, foliar chemistry and nutrient leaching in young Norway spruce stands in Sweden. Silva Fennica vol. 42 no. 5 article id 225. https://doi.org/10.14214/sf.225

Keywords: boreal; sludge; wood-ash; N; P; K

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There is a great need to increase the production in Swedish forests to meet future demand from the forest industry and the bio-energy sector. One option to increase the production is to supply nutrients to young stands of Norway spruce. For the practical application it is important to develop and optimise fertilisation regimes in terms of production, economy and leaching of nutrients. The frequency of fertilisation is one important variable in the fertilisation regime, and this study aimed to study effects of different fertilisation frequencies on production and leaching of nitrogen. In 2001, five field experiments were established in southern, central and northern Sweden. Young stands of Norway spruce were fertilised every year, every second year and every third year. In addition, fertilisation with sludge pellets and wood-ash combined with nitrogen was investigated. The current annual increment after five years of treatment was significantly larger in fertilised than in unfertilised treatments. The difference in production between fertilisation every year and every second year was insignificant, while fertilisation every third year resulted in lower production. Sludge pellets and wood-ash fertilisation gave significantly lower production than fertilisation every second year even though approximately the same amount of nitrogen was applied. There was relatively little leaching of nitrate to ground water in all treatments; 0.6–1 kg N ha^–1 a^–1 from plots with fertilisation every year or every second year; and 2.7 kg N ha^–1 a^–1 from plots with fertilisation every third year. Most of the leaching was after the first fertilisation, in all treatments at all sites.

Bergh, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: johan.bergh@ess.slu.se
Nilsson, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: un@nn.se
Grip, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: hg@nn.se
Hedwall, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: poh@nn.se
Lundmark, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: tl@nn.se

article id 237, category Research article

Jussi Peuhkurinen, Matti Maltamo, Jukka Malinen. (2008). Estimating species-specific diameter distributions and saw log recoveries of boreal forests from airborne laser scanning data and aerial photographs: a distribution-based approach. Silva Fennica vol. 42 no. 4 article id 237. https://doi.org/10.14214/sf.237

Keywords: diameter distribution; non-parametric estimation; pre-harvest measurement; stem data bank

Abstract | View details | Full text in PDF | Author Info

The low-density airborne laser scanning (ALS) data based estimation methods have been shown to produce accurate estimates of mean forest characteristics and diameter distributions, according to several studies. The used estimation methods have been based on the laser canopy height distribution approach, where various laser pulse height distribution -derived predictors are related to the stand characteristics of interest. This approach requires very delicate selection methods for selecting the suitable predictor variables. In this study, we introduce a new nearest neighbor search method that requires no complicated selection algorithm for choosing the predictor variables and can be utilized in multipurpose situations. The proposed search method is based on Minkowski distances between the distributions extracted from low density ALS data and aerial photographs. Apart from the introduction of a new search method, the aims of this study were: 1) to produce accurate species-specific diameter distributions and 2) to estimate factual saw log recovery, using the estimated height-diameter distributions and a stem data bank. The results indicate that the proposed method is suitable for producing species-specific diameter distributions and volumes at the stand level. However, it is proposed, that the utilization of more extensive and locally emphasized reference data and auxiliary variables could yield more accurate saw log recoveries.

Peuhkurinen, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: jp@nn.fi
Maltamo, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: mm@nn.fi
Malinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jm@nn.fi

article id 234, category Research article

Enni Flykt, Sari Timonen, Taina Pennanen. (2008). Variation of ectomycorrhizal colonisation in Norway spruce seedlings in Finnish forest nurseries. Silva Fennica vol. 42 no. 4 article id 234. https://doi.org/10.14214/sf.234

Keywords: Picea abies; nursery; containerised seedlings; ectomycorrhiza; fungal diversity

Abstract | View details | Full text in PDF | Author Info

Ectomycorrhizal (ECM) colonisation patterns and seedling growth of containerised spruce seedlings were studied in five typical Finnish forest nurseries by morphotyping and molecular characterisation. ECM colonisation degree of 1-year-old spruce seedlings was below 20% in all studied Finnish forest nurseries. In 2-year-old spruce seedlings the ECM colonisation degree was ca. 50–60% in three of the nurseries, but negligible in others. The ECM fungal species richness varied from 0.1 to 3.8 types per seedling. Altogether seven ECM morphotypes were distinguished. The clearest factors associated with ECM colonisation patterns were nitrogen and phosphorus fertilisation. Particularly fertilisation in the early stage of seedling development appeared to diminish the degree of colonisation and species richness of ECM fungi. Root/shoot ratio was positively correlated with high colonisation degree and species richness of ECM fungi. Higher fertilisation inputs in these overall fertilisation levels did not increase the size of the seedlings. According to these results moderate fertilisation levels particularly in the beginning of seedling cultivation are critical for generating higher root/shoot ratios and sufficient ECM colonisation degree of the roots.

Flykt, University of Helsinki, Department of Applied Chemistry and Microbiology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ef@nn.fi
Timonen, University of Helsinki, Department of Applied Chemistry and Microbiology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: st@nn.fi
Pennanen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: tp@nn.fi

article id 233, category Research article

Raija Laiho, Sakari Sarkkola, Seppo Kaunisto, Jukka Laine, Kari Minkkinen. (2008). Macroscale variation in peat element concentrations in drained boreal peatland forests. Silva Fennica vol. 42 no. 4 article id 233. https://doi.org/10.14214/sf.233

Keywords: drainage; peat soil; nutrient deficiencies; spatial variation; soil nutrients

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Information on the variation in soil element concentrations at different spatial scales is needed for, e.g., designing efficient sampling strategies, upscaling the processes related to carbon cycling, and planning land use and management. In spite of intensive land use, such information concerning peat soils is still scarce. We analyzed the variation in peat mineral element concentrations in boreal peatland forests drained 50–60 years earlier. We wanted to quantify the proportions of variation deriving from differences between regions and peatland basins and from within-peatland heterogeneity, and to model the variation using relatively easily measurable site and soil characteristics. We utilized 878 peat samples representing the 0–20 cm layer and collected from 289 sites in 79 peatland basins. The sites represented three different drained peatland forest site types. The two strongest gradients in the element composition captured by principal component analysis were correlated with both the North-South gradient and the site type variation, and the East-West gradient. In general, most of the variation in the element concentrations was contributed by differences among peatland basins, and variation within the floristically determined sites. Most of the element concentrations were best modeled when either the bulk density or the ash content of the peat, or both, were used in addition to site type and geographical location. The explanatory power remained modest for most element concentrations. As for the P concentrations in soil, however, our models provide means for estimating a large part of the variation among drained pine mire sites.

Laiho, University of Helsinki, Department of Forest Ecology, FI-00014 University of Helsinki, Finland E-mail: raija.laiho@helsinki.fi
Sarkkola, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ss@nn.fi
Kaunisto, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland E-mail: sk@nn.fi
Laine, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland E-mail: jl@nn.fi
Minkkinen, University of Helsinki, Department of Forest Ecology, FI-00014 University of Helsinki, Finland E-mail: km@nn.fi

article id 232, category Research article

Thomas Wutzler. (2008). Effect of the aggregation of multi-cohort mixed stands on modeling forest ecosystem carbon stocks. Silva Fennica vol. 42 no. 4 article id 232. https://doi.org/10.14214/sf.232

Keywords: stand structure; thinning; inventory; scale; model; stratification; bias; inventorystand structure

Abstract | View details | Full text in PDF | Author Info

Studies of the carbon sink of forest ecosystems often stratify the studied stands by the dominating species and thereby abstract from differences in the mixed-species, multi-cohort structure of many forests. This case study infers whether the aggregation of forestry data introduces a bias in the estimates of carbon stocks and their changes at the scale of individual stands and the scale of a forest district. The empirical TreeGrOSS-C model was applied to 1616 plots of a forest district in Central Germany to simulate carbon dynamics in biomass, woody debris, and soil. In a first approach each stand was explicitly simulated with all cohorts. In three other approaches the forest inventory data were aggregated in several ways, including a stratification of the stands to 110 classes according to the dominating species, age class, and site conditions. A small but significant bias was confirmed. At stand scale the initial ecosystem carbon stocks by the aggregated approach differed from that of the detailed approach by 2.3%, but at the district scale only by 0.05%. The differences in age between interspersed and dominant cohorts as well as differences in litter production were important for the differences in initial carbon stocks. The amounts of wood extracted by thinning operations were important for the differences in the projection of the carbon stocks over 100 years. Because of the smallness of bias, this case study collects evidence that the approaches, that represent stands or stratums by a single cohort, are valid at the scale of a forest district or larger.

Wutzler, Max Planck Institute for Biogeochemistry, Hans Knöll Str. 10, DE-07745, Jena, Germany E-mail: thomas.wutzler@bgc-jena.mpg.de

article id 248, category Research article

Tuula Jyske, Harri Mäkinen, Pekka Saranpää. (2008). Wood density within Norway spruce stems. Silva Fennica vol. 42 no. 3 article id 248. https://doi.org/10.14214/sf.248

Keywords: Picea abies; wood density; inter-ring variation; intra-ring variation; maturation

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We studied the variation in average wood density of annual rings, earlywood density, and latewood density in addition to ring width and latewood percentage within Norway spruce (Picea abies (L.) Karst.) stems from the pith to the bark, and from the stem base towards the stem apex. Moreover, the variation in wood density within annual rings was studied at the different heights and radial positions in the stem. The material consisted of 85 trees from central and south-eastern Finland. Variation between the annual rings accounted for 11–27% of the total variation in wood density. Only small differences (3–6%) in wood density were found between different heights in the stem. The largest (49–80%) variation in wood density was found within the annual rings. The difference in wood density between earlywood and latewood was smaller in the rings near the pith than in the outer rings. The increasing wood density from the pith outwards was related to increasing latewood density and latewood percentage, whereas the earlywood density increased only slightly from the pith outwards. In a given cambial age (i.e., given rings from the pith), the average wood density of annual rings increased with increasing stem height. In contrast, in the rings formed in the same calendar years (i.e., given rings from the bark), the average wood density of annual rings decreased with increasing stem height. The results of this study verify our knowledge of wood density variation and can further contribute to creating models to predict wood density.

Jyske, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: tuula.jyske@metla.fi
Mäkinen, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: hm@nn.fi
Saranpää, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ps@nn.fi

article id 245, category Research article

Saija Huuskonen, Jari Hynynen, Risto Ojansuu. (2008). Stand characteristics and external quality of young Scots pine stands in Finland. Silva Fennica vol. 42 no. 3 article id 245. https://doi.org/10.14214/sf.245

Keywords: Scots pine; growth and yield; precommercial thinning; external stem quality; young stand management

Abstract | View details | Full text in PDF | Author Info

The effects of silvicultural practices (regeneration method and young stand management) on the stand characteristics of young Scots pine (Pinus sylvestris (L.)) stands were studied. Stand density, mean diameter, crown ratio and external quality of young Scots pine stands were analysed on the basis of extensive inventory data. The study material consisted of 181 stands containing inventory growth plots, representing the most common site types for Scots pine and covering all the important wood production areas in Finland. Intensive management practices, i.e. artificial regeneration and precommercial thinning, clearly enhanced mean diameter development of the stand. The overall stand density of the crop trees was relatively low in the material (1925 trees ha–1). In more than one third of the stands, the stem number of crop trees was below 1500 trees ha–1. Stand density was not affected by forest management, but it was slightly higher in Southern than in Northern Finland. The geographical location, in terms of annual effective temperature sum, affected the average slenderness and crown ratio. At a given mean stand diameter, the dominant height of the stand was lower, and the mean crown ratio was higher, in Northern than in Southern Finland. The average external quality of the Scots pine trees was relatively low. The proportion of trees without any observed defects was 54%. The most common external defects were curved stems (23%) and branchiness (9%). Branchiness was more frequent among the largest trees, while curved stems were more common in smaller trees. Defects were the most frequent in planted stands, and in stands growing on fresh sites. The defects were more frequent in Northern Finland than in Southern Finland. The relatively low stand density and poor external quality of the young stands emphasize the importance of stem quality as a tree selection criterion in commercial thinnings of Scots pine stands, if the goal is to produce high quality timber.

Huuskonen, University of Helsinki, Department of Forest Ecology, Helsinki, Finland E-mail: saija.huuskonen@helsinki.fi
Hynynen, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland E-mail: jh@nn.fi
Ojansuu, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland E-mail: ro@nn.fi

article id 242, category Research article

Jyrki Hytönen, Paula Jylhä. (2008). Fifteen-year response of weed control intensity and seedling type on Norway spruce survival and growth on arable land. Silva Fennica vol. 42 no. 3 article id 242. https://doi.org/10.14214/sf.242

Keywords: Norway spruce; afforestation; frost damage; seedling size; seedling type; vegetation control

Abstract | View details | Full text in PDF | Author Info

The effects of seedling type (2-year-old container seedlings vs. 4-year-old bare-rooted seedlings) and post-planting vegetation control intensity on the growth and survival of Norway spruce (Picea abies (L.) Karst.) seedlings were compared based on 15-year data from a field experiment established on arable land. Vegetation control treatments with terbuthylazine and glyphosate were carried out 1–3 times on successive years, either as overall or spot applications. The highest stand volumes were obtained with the combination of large bare-rooted seedlings and effective vegetation control. Volume of bare-rooted seedlings was greater than that of container seedlings in all treatments (e.g. on the control plots 9.5 m³/ha vs. 4.1 m³/ha). The best results were obtained with the most intensive weed control treatments (spot treatment repeated twice and overall application repeated three times). These treatments increased both bare-rooted and containerised seedlings’ survival by 33–40% units and their height, breast height diameter, and volume by 45–49%, 17–47%, and 249–279%, respectively. In terms of survival, the container seedlings, in due part to their smaller size, benefited from vegetation control more than the bare-rooted seedlings. Successive early summer frosts damaged the seedlings and significantly retarded their growth. The frequency of frost damage was not affected by vegetation control nor was it attributed to seedling type.

Hytönen, Finnish Forest Research Institute, Kannus Research Unit, P.O. Box 44, FI-69101, Kannus, Finland E-mail: jyrki.hytonen@metla.fi
Jylhä, Finnish Forest Research Institute, Kannus Research Unit, P.O. Box 44, FI-69101, Kannus, Finland E-mail: pj@nn.fi

article id 468, category Research article

Antti Lännenpää, Tuomas Aakala, Heikki Kauhanen, Timo Kuuluvainen. (2008). Tree mortality agents in pristine Norway spruce forests in northern Fennoscandia. Silva Fennica vol. 42 no. 2 article id 468. https://doi.org/10.14214/sf.468

Keywords: Picea abies; northern Fennoscandia; Coniophora; mortality agent; pristine forest

Abstract | View details | Full text in PDF | Author Info

We examined tree mortality agents in pristine old Norway spruce (Picea abies (L.) Karst.) forests in northern Finland and northwestern Russia. The data was collected on nine 40 m 400 m transects. The primary mortality agents of recently dead trees were recorded and their frequencies were calculated. The pattern of tree growth prior to death was studied based on increment core samples and compared with the growth of healthy dominant trees. Of all recently dead trees, 72% could be associated with a primary mortality agent. In both study areas the most common primary mortality agent was a Coniophora (Mérat) DC. -genus fungi, which was found on average in 33% of trees sampled. The fungi Phellinus chrysoloma (Fr.) Don and Onnia leporina (Fr.) H. Jahn as mortality agents were more common in the Finnish area compared to the Russian area. Analysis on the growth patterns indicated weak differences between different pathogens’ influence on prior-to-death growth of trees, so that fungi rotting the whole tree decreased tree growth more rapidly than fungi rotting only the heart wood. The results demonstrated that in old Norway spruce forests of northern Fennoscandia the most common primary tree mortality agents were wood rotting fungi, which weaken the mechanical stability of tree stems until they fall due to snow or wind, which should be considered only as secondary mortality agents. It is evident that tree death in pristine forest typically results from a long-lasting process involving both biotic and abiotic factors.

Lännenpää, Department of Forest Ecology, University of Helsinki, Finland E-mail: al@nn.fi
Aakala, Department of Forest Ecology, University of Helsinki, Finland E-mail: tuomas.aakala@helsinki.fi
Kauhanen, Kolari Research Unit, Finnish Forest Research Institute, Finland E-mail: hk@nn.fi
Kuuluvainen, Department of Forest Ecology, University of Helsinki, Finland E-mail: tk@nn.fi

article id 259, category Research article

Jani Laturi, Jarmo Mikkola, Jussi Uusivuori. (2008). Carbon reservoirs in wood products-in-use in Finland: current sinks and scenarios until 2050. Silva Fennica vol. 42 no. 2 article id 259. https://doi.org/10.14214/sf.259

Keywords: climate change; wood products; carbon pool; present value; decay function

Abstract | View details | Full text in PDF | Author Info

This study addresses the question of how much carbon will be sequestered in wood products during the coming decades in Finland. Using sawnwood and other wood material consumption data since the 1950s and inventory data of carbon reservoirs of wood products in the Finnish construction and civil engineering sector, we first derive estimates for the carbon reservoirs in wood products-in-use in that sector. We then extend the estimate to include all wood products-in-use. We find that the carbon pool of wood products in the Finnish construction and civil engineering sector grew by about 12% since an inventory for 2000, and that the overall estimate for carbon reservoirs of Finnish wood products in 2004 was 26.6 million tons of carbon. In building the scenarios until 2050, econometric time series models accounting for the relationship between wood material consumption and the development of GDP were used. The results indicate that the range of carbon reservoirs of wood products in Finland will be 39.6–64.2 million tons of carbon in the year 2050. The impacts of different forms of the decay function on the time-path of a carbon sink and its value in wood products were also studied. When a logistic decay pattern is used, the discounted value of the predicted carbon sink of wood products in Finland is between EUR850 and EUR1380 million – at the price level of EUR15/CO₂ ton – as opposed to 440–900 million euros, if a geometric decay pattern is used.

Laturi, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: jani.laturi@metla.fi
Mikkola, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: jm@nn.fi
Uusivuori, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ju@nn.fi

article id 253, category Research article

Riitta Väänänen, Mika Nieminen, Martti Vuollekoski, Hannu Nousiainen, Tapani Sallantaus, Eeva-Stiina Tuittila, Hannu Ilvesniemi. (2008). Retention of phosphorus in peatland buffer zones at six forested catchments in southern Finland. Silva Fennica vol. 42 no. 2 article id 253. https://doi.org/10.14214/sf.253

Keywords: peatland; buffer zone area; phosphorus; retention

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Our current knowledge of the P retention efficiency of peatland buffer zone areas used to reduce sediment and nutrient leaching from forestry areas is insufficient. Especially the role of P sorption by soil in buffer zones needs closer examination as there is considerable variation in the efficiency of P retention. Six sites in southern Finland were chosen for the study. The buffer zone areas varied between 0.1–4.9% of the catchment area. A total of 10 kg of solute PO₄–P was added to the inflow of the buffer zone areas and the concentrations of PO₄–P in inflow and outflow were measured for 2–4 years. P retention characteristics of the surface peat were determined with sorption-desorption isotherms before and after PO₄–P addition and the effective buffer zone area over which the added P was spread was determined from soil water samples. P retention in the two largest buffer zone areas was complete (100% retention), and the third largest buffer retained 94%. Retention in the three smallest buffer zones was 24%, 95% and 95% of the added P. As a result of P addition reduction in peat P retention capacity was detected in three out of four cases. The effective buffer zone area varied from 67% to 100% of the total buffer zone area. Factors contributing to efficient P retention were large buffer size and low hydrological load whereas high hydrological load combined with the formation of preferential flow paths, especially during early spring or late autumn was disadvantageous. High P retention capacity in peat contributed to the sustainability of P retention. The study showed that even relatively small buffer zone areas are able to efficiently reduce P load.

Väänänen, Department of Forest Ecology, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: riitta.vaananen@helsinki.fi
Nieminen, Finnish Forest Research Institute, Vantaa Research Unit, Finland E-mail: mn@nn.fi
Vuollekoski, Finnish Forest Research Institute, Vantaa Research Unit, Finland E-mail: mv@nn.fi
Nousiainen, Finnish Forest Research Institute, Vantaa Research Unit, Finland E-mail: hn@nn.fi
Sallantaus, Finnish Environment Institute, Nature Division, Helsinki, Finland E-mail: ts@nn.fi
Tuittila, Department of Forest Ecology, University of Helsinki, Finland E-mail: est@nn.fi
Ilvesniemi, Finnish Forest Research Institute, Vantaa Research Unit, Finland E-mail: hi@nn.fi

article id 252, category Research article

Tuomo Kalliokoski, Pekka Nygren, Risto Sievänen. (2008). Coarse root architecture of three boreal tree species growing in mixed stands. Silva Fennica vol. 42 no. 2 article id 252. https://doi.org/10.14214/sf.252

Keywords: Pinus sylvestris; Betula pendula; Picea abies; site type; branching pattern; influence area; developmental stage

Abstract | View details | Full text in PDF | Author Info

Root system architecture determines many of the vital functions of a tree, e.g. stability of anchorage and resource uptake. The shoot:root ratio is determined through the allocation of resources. Studies on below-ground architectural elements in boreal mixed forests are relatively scarce despite the fact that knowledge on below-ground interactions and allocation changes in relation to stand developmental stage and soil fertility is needed both in ecological and silvicultural research. In this study, sixty tree root systems of three different tree species, Betula pendula, Picea abies and Pinus sylvestris, were excavated in five mixed forest stands in order to quantify differences between the species and sites in terms of rooting behaviour. Root architecture differed greatly between the species, implying different solutions for the functions of root systems. Half of the P. sylvestris had developed a taproot as a response to anchorage needs, while P. abies correspondingly had pronounced secondary growth of proximal roots. Betula pendula had the most extensive root system, illustrating the greater demand of deciduous trees for water. Betula pendula was also the most sensitive to soil fertility: it favoured exploration on the poorest site, as illustrated by the high total root length, whereas on the most fertile site its strategy was to efficiently exploit soil resources through increased branching intensity. The results obtained in this study provide basic knowledge on the architectural characteristics of boreal tree root systems for use by forestry professionals and modellers.

Kalliokoski, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: tuomo.kalliokoski@metla.fi
Nygren, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: pn@nn.fi
Sievänen, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: rs@nn.fi

article id 251, category Research article

Lina R. Steinke, Andrea C. Premoli, Cintia P. Souto, Mikael Hedrén. (2008). Adaptive and neutral variation of the resprouter Nothofagus antarctica growing in distinct habitats in north-western Patagonia. Silva Fennica vol. 42 no. 2 article id 251. https://doi.org/10.14214/sf.251

Keywords: isozymes; morphological variation; leaf traits; South America; temperate forest

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N. antarctica occurs in the widest range of habitat types among all South American Notho–fagus. The aim of this study is to investigate adaptive responses by variation in morphological (tree form and leaf characters), and environmental traits (soils) of the polymorphic N. ant–arctica. Also we analyze the effect of genetic drift and limited gene flow in such predominantly apomict by means of neutral variation (isozymes). We studied four potentially different morphological variants each associated with a separate habitat 1) an arboreal variant growing in optimal environments; 2) a sparsely branched variant of temporarily flooded basins or flats; 3) a dwarf variant growing at high elevation, and 4) a shrub-like variant inhabiting matorral environments. The study was restricted latitudinally to Nahuel Huapi National Park, Argentina. For each habitat type we investigated two sites. Nothofagus antarctica shows locally occurring phenotypes. The forest and the high elevation variants were morphologically distinct from the matorral and the basin types. The latter were undistinguishable except for more profuse branching in the matorral type as a result of sprouting due to recent fires. Isozyme evidence indicates a great deal of within-population genetic diversity which is maintained by outcrossing and significant among-site divergence (F_ST = 18%) that reflects limited gene flow.The apparent high phenotypic and genetic variability in N. antarctica is due to both plasticity and genotypic effects as a result of stable population structure and long periods of isolation which may be reinforced by selection at diverse biotopes.

Steinke, Plant Ecology and Systematics, Lund University, Ecology Department, 223 62 Lund, Sweden E-mail: lks@nn.se
Premoli, Universidad Nacional del Comahue, Laboratorio Ecotono – CRUB, Quintral 1250, 8400 Bariloche, Argentina E-mail: apremoli@crub.uncoma.edu.ar
Souto, Universidad Nacional del Comahue, Laboratorio Ecotono – CRUB, Quintral 1250, 8400 Bariloche, Argentina E-mail: cps@nn.ar
Hedrén, Plant Ecology and Systematics, Lund University, Ecology Department, 223 62 Lund, Sweden E-mail: mh@nn.se

article id 250, category Research article

Saara Lilja-Rothsten, Michelle de Chantal, Chris Peterson, Timo Kuuluvainen, Ilkka Vanha-Majamaa, Pasi Puttonen. (2008). Microsites before and after restoration in managed Picea abies stands in southern Finland: effects of fire and partial cutting with dead wood creation. Silva Fennica vol. 42 no. 2 article id 250. https://doi.org/10.14214/sf.250

Keywords: biodiversity; boreal forest; regeneration; coarse woody debris; disturbance dynamics; CWD; managed forest

Abstract | View details | Full text in PDF | Author Info

Different types of microsites, e.g. CWD (coarse woody debris), mounds, and uprooting pits, are important for tree regeneration and biodiversity. However, microsite diversity is greatly reduced in managed stands. We studied how restoration treatments changed microsite distribution in mature managed Picea abies stands. Four cutting treatments were used: uncut, low-CWD (5 m³ ha^–1 of down retention trees, DRT, and 50 m³ ha^–1 of standing retention trees), intermediate-CWD (as previous but leaving 30 m³ ha^–1 of DRT), and high-CWD (as previous but with 60 m³ ha^–1 of DRT). Timber harvested from stands ranged from 108–168 m³ ha^–1. Half of the stands were burned, and half remained unburned. Sampling was stratified into upland and paludified biotopes within each stand. The pre-treatment microsite distributions were dominated by level ground in both biotopes; mounds and microsites on or next to CWD or a stump were slightly more abundant in the paludified than in the upland biotopes. Microsites were more diverse after cutting, with and without fire. The cutting treatment increased the relative abundances of microsites on or next to CWD. Fire consumed small diameter dead wood and flattened mounds. Microsites were more diverse in paludified than in upland biotopes. The results demonstrate that microsite diversity can rapidly be restored to structurally impoverished managed Picea stands despite a large portion of wood volume being harvested.

Lilja-Rothsten, University of Helsinki, Dept. of Forest Ecology, Finland E-mail: saara.lilja@helsinki.fi
Chantal, University of Helsinki, Dept. of Forest Ecology, Finland E-mail: mdc@nn.fi
Peterson, Dept. of Plant Biology, University of Georgia, Athens, GA, USA E-mail: cp@nn.us
Kuuluvainen, University of Helsinki, Dept. of Forest Ecology, Finland E-mail: tk@nn.fi
Vanha-Majamaa, The Finnish Forest Research Institute, Vantaa Unit, Finland E-mail: ivm@nn.fi
Puttonen, The Finnish Forest Research Institute, Vantaa Unit, Finland E-mail: pp@nn.fi

article id 264, category Research article

Yrjö Nuutinen, Kari Väätäinen, Jaakko Heinonen, Antti Asikainen, Dominik Röser. (2008). The accuracy of manually recorded time study data for harvester operation shown via simulator screen. Silva Fennica vol. 42 no. 1 article id 264. https://doi.org/10.14214/sf.264

Keywords: accuracy of timing; mixed effects models; time studies

Abstract | View details | Full text in PDF | Author Info

The aim of the study was to investigate the effect of work experience on the accuracy and variation of observers recording the operation time of a harvester. A simulated thinning operation using a harvester, shown as video via a television screen in laboratory conditions, was observed by 20 inexperienced students and 10 experienced work study researchers. All the observers timed the different work elements of the harvester work with special fieldwork timers. The duration of different work elements measured by the human observers were compared to the corresponding recordings by the harvester’s automated data collector. Although the inexperienced students made more measurement mistakes than the experienced researchers, the differences in measurement error averages were not statistically significant between the groups. However, the variances of tree specific errors were significantly higher in the measurements done by the students. As inexperienced recorders, the students were not able to properly record short work elements, which lasted a maximum of 4 seconds. Due to systematic measurement errors, there was a large variation in the timing structures of the work elements among all observers. Observers’ skills and experience seems to affect measurement accuracy and thus the derived results, especially in intensive time studies. Therefore, the recorder should receive detailed training and practical experience in timing of different work elements of forest operations. In the future, with the use of automated data collectors time studies with large, detailed and accurate data will be implemented. However, due to the varying timing conditions in the forest, manual data collection is still required because of its greater flexibility.

Nuutinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: yrjo.nuutinen@metla.fi
Väätäinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: kv@nn.fi
Heinonen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jh@nn.fi
Asikainen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: aa@nn.fi
Röser, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: dr@nn.fi

article id 263, category Research article

Aksel Granhus, Dag Fjeld. (2008). Time consumption of planting after partial harvests. Silva Fennica vol. 42 no. 1 article id 263. https://doi.org/10.14214/sf.263

Keywords: planting; work study; mechanical site preparation; partial cutting; scarification

Abstract | View details | Full text in PDF | Author Info

Partial harvesting combined with underplanting may be a means to reduce the risk of regeneration failure when e.g. unfavourable microclimatic conditions or severe damage by bark-feeding insects may be expected after clear-cutting, and to maintain or establish certain stand structures or tree species mixture. In this study, we performed time studies of manual planting with and without prior site preparation (patch scarification, inverting) in partially harvested stands of Norway spruce (Picea abies (L.) Karst.). The harvest treatments included basal area removals of approx. 35, 45, and 55%, and a patch clear-cut treatment that was assumed to provide the same conditions for planting as conventional clear-cutting. Site preparation had a much larger influence on time consumption plant^–1 (main time) than the harvest treatment. The lowest time consumption was found with inverting and the highest without site preparation. The time spent on walking between planting spots increased with decreasing harvest intensity, reflecting a lower density of planted seedlings in the partially harvested stands. A corresponding increase in main time per plant only occurred after site preparation, since the time spent on clearing the planting spot (removal of logging residue and humus) on untreated plots was higher at the higher harvest strengths. The variation in time consumption attributed to the six replicate stands was large and mainly due to the difference among stands planted by different workers.

Granhus, Norwegian University of Life Sciences, Dept. of Ecology and Natural Resource Management (INA), P.O.Box 5003, NO-1432 Ås, Norway E-mail: aksel.granhus@umb.no
Fjeld, Swedish University of Agricultural Sciences, Dept. of Forest Resource Management, SE-901 83 Umeå, Sweden E-mail: df@nn.se

article id 469, category Research article

Henri Vanhanen, Timo O. Veteli, Sonja Päivinen, Seppo Kellomäki, Pekka Niemelä. (2007). Climate change and range shifts in two insect defoliators: gypsy moth and nun moth – a model study. Silva Fennica vol. 41 no. 4 article id 469. https://doi.org/10.14214/sf.469

Keywords: insects; forest pests; CLIMEX; Lymantria monacha; Lymantria dispar; poleward shift; geographical range

Abstract | View details | Full text in PDF | Author Info

Environmental factors influenced by global climate change determine the distribution ranges of organisms. Especially ectothermic animals are expected to shift their distribution ranges northwards in the next hundred years or so. In this study simulations made with CLIMEX-modelling software were used to predict the future distribution ranges of two Central European serious forest pest species: the nun moth (Lymantria monacha L. (Lepidoptera: Lymantriidae)) and the gypsy moth (L. dispar L). The software calculates an ecoclimatic index based on the life cycle requirements of a species and thus represents the probability of a viable population to exist at a certain location. Three different climate warming scenarios were considered: temperature increase of 1.4, 3.6 and 5.8°C. Simulations generated with the current climate conditions corresponded well to the current distributions of the species. The climate warming scenarios shifted the northern boundary of the distribution for both of these species north by c. a. 500–700 km. Also the southern edge of the ranges retracted northwards by 100–900 km. The results of this study are in agreement with the results of empirical studies on other species. Being serious pest species, these species pose a potential threat to silviculture and therefore, have to be considered in the planning of forest management practices.

Vanhanen, Faculty of Forestry, University of Joensuu, P.O.B. 111, FI-80101 Joensuu, Finland E-mail: hv@nn.fi
Veteli, Faculty of Biosciences, University of Joensuu, P.O.B. 111, FI-80101, Joensuu, Finland E-mail: timo.veteli@joensuu.fi
Päivinen, Faculty of Forestry, University of Joensuu, P.O.B. 111, FI-80101 Joensuu, Finland E-mail: sp@nn.fi
Kellomäki, Faculty of Forestry, University of Joensuu, P.O.B. 111, FI-80101 Joensuu, Finland E-mail: sk@nn.fi
Niemelä, Faculty of Forestry, University of Joensuu, P.O.B. 111, FI-80101 Joensuu, Finland E-mail: pn@nn.fi

article id 278, category Research article

Katri Luostarinen. (2007). The effect of annual ring orientation and drying method on deformations, casehardening and colour of silver birch (Betula pendula) boards. Silva Fennica vol. 41 no. 4 article id 278. https://doi.org/10.14214/sf.278

Keywords: wood; timber quality; dimensional stability; distortion; drying schedules; kiln drying; L*a*b* coordinates

Abstract | View details | Full text in PDF | Author Info

Deformations of timber, caused mainly by anisotropic shrinkage, can be partially directed by controlling annual ring orientation through different sawing patterns. Ring orientation also affects the movement of water from within the board to its surface, with rapidity of drying having implications for the wood colour. Here sawn silver birch (Betula pendula Roth) timber was classed into two groups according to ring orientation. Two drying methods were used. The final moisture content was lower and the colour lighter in dried boards with radial than with tangential flats, but deformations were larger in radial than in tangential boards. Both drying and ring orientation affected the final moisture content and moisture gradient of the boards. Very small differences in board sizes or shape had an effect on both colour and deformations. The results support the need for accurate sawing and for classing silver birch timber sawn into parquet billets according to ring orientation in order to optimise the drying quality.

Luostarinen, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: katri.luostarinen@joensuu.fi

article id 277, category Research article

Laura Koskela, Bikas K. Sinha, Tapio Nummi. (2007). Some aspects of the sampling distribution of the Apportionment Index and related inference. Silva Fennica vol. 41 no. 4 article id 277. https://doi.org/10.14214/sf.277

Keywords: harvesting; bucking; dissimilarity index; multinomial distribution; overlapping coefficient

Abstract | View details | Full text in PDF | Author Info

As customer-oriented production strategies have gained ground in the sawmill industry, proper measurement of the fit between the log demand and log output distributions has become of crucial importance. The prevailing means of measuring the outcome is the so-called Apportionment Index (AI), which is calculated from the relative proportions of the observed and required distributions. Although some statistical properties of the AI have recently been examined and alternative means of measuring the bucking outcome have been suggested, properties of the sampling distribution of the AI have not yet been widely studied. In this article we examine the asymptotic sampling distribution for the AI by assuming a multinomial distribution for the outcome. Our results are based mainly on large-sample normal approximations. Also some studies of the determination of the number of logs needed to obtain a specified level of accuracy of the AI have been carried out.

Koskela, University of Tampere, Dept of Mathematics, Statistics and Philosophy, FI-33014 University of Tampere, Finland E-mail: laura.koskela@uta.fi
Sinha, Indian Statistical Institute, Kolkata, India E-mail: bks@nn.in
Nummi, University of Tampere, Dept of Mathematics, Statistics and Philosophy, FI-33014 University of Tampere, Finland E-mail: tn@nn.fi

article id 274, category Research article

Timo Saksa, Jari Miina. (2007). Cleaning methods in planted Scots pine stands in southern Finland: 4-year results on survival, growth and whipping damage of pines. Silva Fennica vol. 41 no. 4 article id 274. https://doi.org/10.14214/sf.274

Keywords: Pinus sylvestris; birch; competition; tending of sapling stand

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The effects of four cleaning treatments on the survival, growth of, and whipping damage to Scots pine (Pinus sylvestris L.) main stems were studied in young planted pine stands in southern Finland. Treatments were: no cleaning, point-cleaning of broadleaves (mainly birch, Betula pendula Roth and B. pubescens Ehrh.) within a radius of 1 m from the pine, topping of competing broadleaves, and total cleaning of broadleaves. A randomised complete block design with three replicates was established in five sapling stands: the mean height of the pines was 1.5 m in the three younger stands (6 or 7 years old), and 3 m in the two older stands (9 years old). Measurements taken four growing seasons later showed that in the younger stands, all cleaning treatments significantly (P < 0.05) decreased the mortality and increased the diameter increment of the pines. The height increment of the pines on point-cleaned and topped plots was significantly greater than on totally cleaned plots. In the older stands, the effects of cleaning treatments on the mortality and increment of pines were non-significant. In the younger and older stands, point-cleaning and total cleaning significantly reduced the whipping damage to pines, whereas the topping of competing broadleaves did not. The preliminary results support the use of point-cleaning in planted Scots pine stands when the mean height of the pines is about 1.5 m.

Saksa, Finnish Forest Research Institute, Suonenjoki Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: timo.saksa@metla.fi
Miina, Finnish Forest Research Institute, Joensuu Unit, P.O.Box 68, FI-80101 Joensuu, Finland E-mail: jm@nn.fi

article id 273, category Research article

Stefan Mattson, Urban Bergsten, Tommy Mörling. (2007). Pinus contorta growth in boreal Sweden as affected by combined lupin treatment and soil scarification. Silva Fennica vol. 41 no. 4 article id 273. https://doi.org/10.14214/sf.273

Keywords: biomass; wood density; cultivation; lodgepole pine; lupinus; nitrogen inputs

Abstract | View details | Full text in PDF | Author Info

Effects of combining lupin (Lupinus nootkatensis L.) establishment and soil scarification on stem volume and stem biomass yield of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) were studied on a poor boreal site in Sweden 18 years after plantation. A field randomized block experiment was established with three different scarification techniques (disc trenching, moulding and ploughing) followed by establishment of lupins by either seeds or roots. There were three blocks without and two blocks with lupins. Overall, on average for the three soil scarification techniques, the lupin treatment significantly increased the volume per hectare by 102%.The lupin treatment significantly increased the stem volume per hectare by 236% for mounding and 139% for disc trenching, whereas the 55% increase for ploughing was not significant. The increase in the total stem biomass yield per tree was more pronounced for larger trees; 46% for average trees and 106% for dominant trees. However, there were no significant differences between scarification techniques for the lupin treatment in total stem biomass yield. Over the 18-year period, the increased growth rate following the lupin treatment resulted in a significantly decreased average stem basic wood density (on average 6%) for the sample trees. Because lupin is a nitrogen-fixing plant species, the large increase in tree growth following the lupin treatment was probably an effect of increased amount of nitrogen in the soil. The results indicate that use of lupin is a possible alternative to increase site productivity of lodgepole pine on poor boreal sites.

Mattson, Swedish University of Agricultural Sciences, Dept of Forest Ecology and Management, SE-901 83 Umeå, Sweden E-mail: sm@nn.se
Bergsten, Swedish University of Agricultural Sciences, Dept of Forest Ecology and Management, SE-901 83 Umeå, Sweden E-mail: ub@nn.se
Mörling, Swedish University of Agricultural Sciences, Dept of Forest Ecology and Management, SE-901 83 Umeå, Sweden E-mail: tommy.morling@ssko.slu.se

article id 284, category Research article

Tuomo Nurminen, Jaakko Heinonen. (2007). Characteristics and time consumption of timber trucking in Finland. Silva Fennica vol. 41 no. 3 article id 284. https://doi.org/10.14214/sf.284

Keywords: logistics; cut-to-length operations; time study; work phases; log-normal distribution

Abstract | View details | Full text in PDF | Author Info

Cost efficiency and flexibility have become increasingly important in the logistics of cut-to-length harvesting operations. At the same time, the operating conditions for long-distance transportation have become more demanding and variable. Since the number of log products has increased and the size of harvesting sites has decreased, loads of timber must increasingly be collected from several log decks, increasing the time consumption and costs of the trucking operation. The objectives of this study were to formulate time-consumption models for typical timber transportation activities in Finland and introduce a statistical procedure for examining the variation in time consumption during the trucking phases. The study used a combination of time studies and follow-up studies based on empirical data for 368 loads (a total volume of nearly 18 000 m³) collected from one wood procurement district in central Finland. The model included the following explanatory factors: driving distance, number of log decks, log product and load volume. Since transportation includes several phases and since many factors affect the work performance, significant variation in the total transportation time was observed. This makes planning and cost accounting more difficult. The models developed in this study are a promising initial tool to support route planning and optimization, and cost and profitability calculations for trucking entrepreneurs and the forest industry.

Nurminen, University of Joensuu, Faculty of Forest Sciences; Forest Agency Tuomo Nurminen, Joensuuntie 5 B 8, FI-41800 Korpilahti, Finland E-mail: tn@nn.fi
Heinonen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jh@nn.fi

article id 283, category Research article

Ilkka Korpela, Tuukka Tuomola, Esko Välimäki. (2007). Mapping forest plots: an efficient method combining photogrammetry and field triangulation. Silva Fennica vol. 41 no. 3 article id 283. https://doi.org/10.14214/sf.283

Keywords: remote sensing; least squares adjustment; intertree positioning; spatial resection; trilateration

Abstract | View details | Full text in PDF | Author Info

Intra stand spatial information is often collected in ecological investigations, when functioning or interactions in the ecosystem are studied. Local relative accuracy is often given priority in such cases. Forest maps with accurate absolute positions in a global coordinate system are needed in remote-sensing applications for validation and calibration purposes. Establishing the absolute position is particularly difficult under a canopy as is creating undistorted coordinate systems for large plots in the forest. We present a method that can be used for the absolute mapping of point features under a canopy that is efficient for large forest plots. In this method, an undistorted network of control points is established in the forest using photogrammetric observations of treetops. These points are used for the positioning of other points, using redundant observations of interpoint distances and azimuths and a least squares adjustment. The method provides decimetre-level accuracy and only one person is required to conduct the work. An estimate of the positioning accuracy of each point is readily available in the field. We present the method, a simulation study that explores the potential of the method and results from an experiment in a mixed boreal stand in southern Finland.

Korpela, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ilkka.korpela@helsinki.fi
Tuomola, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: tt@nn.fi
Välimäki, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ev@nn.fi

article id 282, category Research article

Annika Kangas, Lauri Mehtätalo, Matti Maltamo. (2007). Modelling percentile based basal area weighted diameter distribution. Silva Fennica vol. 41 no. 3 article id 282. https://doi.org/10.14214/sf.282

Keywords: stand structure; diameter distribution; prediction; interpolation

Abstract | View details | Full text in PDF | Author Info

In percentile method, percentiles of the diameter distribution are predicted with a system of models. The continuous empirical diameter distribution function is then obtained by interpolating between the predicted values of percentiles. In Finland, the distribution is typically modelled as a basal-area weighted distribution, which is transformed to a traditional density function for applications. In earlier studies it has been noted that when calculated from the basal-area weighted diameter distribution, the density function is decreasing in most stands, especially for Norway spruce. This behaviour is not supported by the data. In this paper, we investigate the reasons for the unsatisfactory performance and present possible solutions for the problem. Besides the predicted percentiles, the problems are due to implicit assumptions of diameter distribution in the system. The effect of these assumptions can be somewhat lessened with simple ad-hoc methods, like increasing new percentiles to the system. This approach does not, however, utilize all the available information in the estimation, namely the analytical relationships between basal area, stem number and diameter. Accounting for these, gives further possibilities for improving the results. The results show, however, that in order to achieve further improvements, it would be recommendable to make the implicit assumptions more realistic. Furthermore, height variation within stands seems to have an important contribution to the uncertainty of some forest characteristics, especially in the case of sawnwood volume.

Kangas, Department of Forest Resources Management, P.O.Box 27, FI-00014 University of Helsinki, Finland E-mail: ak@nn.fi
Mehtätalo, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: lm@nn.fi
Maltamo, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: mm@nn.fi

article id 280, category Research article

Mika Nieminen, Mikko Moilanen, Sirpa Piirainen. (2007). Phosphorus allocation in surface soil of two drained peatland forests following wood and peat ash application – why effective adsorption on low sorptive soils? Silva Fennica vol. 41 no. 3 article id 280. https://doi.org/10.14214/sf.280

Keywords: forestry; ash fertilization; peat; aluminium; iron; phosphorus adsorption; phosphorus fractionation

Abstract | View details | Full text in PDF | Author Info

Fertilization of drained peatland forests with wood ash and different commercial phosphorus fertilizers (calcium phosphates) generally give similar stand growth responses. However, it has been shown that use of calcium phosphate fertilizers generally lead to highly increased P release to recipient water courses. On the other hand, no corresponding release has been reported after ash fertilization. Soil samples from the surface peats from a nutrient poor and a fertile drained peatland site were collected before and 1–4 years after application of five different types of ash products. The changes over time in the different chemical forms of P in the substrate were studied. The results indicated that the reason for the low liability to leaching of ash fertilizers was that significant amounts of P are adsorbed by Al and Fe during weathering of the ash fertilizers. However, further studies are needed to clarify whether the adsorption of P occurs with the Al and Fe of the ash or the native Al and Fe compounds present in soil before ash fertilization.

Nieminen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mika.nieminen@metla.fi
Moilanen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mm@nn.fi
Piirainen, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: sp@nn.fi

article id 303, category Research article

Lars Lönnstedt. (2007). Industrial timberland ownership in the USA: arguments based on case studies. Silva Fennica vol. 41 no. 2 article id 303. https://doi.org/10.14214/sf.303

Keywords: forest management; backward vertical integration; pricing; secured supply; owner structure

Abstract | View details | Full text in PDF | Author Info

The forest product companies’ ownership of timberland is decreasing in the United States as in many other countries. In aggregate the forest product industry owned 26.5 million hectares (11.6% of the U.S. timberland) in 2002 compared with 28.5 million hectares in 1987 (FIA 2006). Reasons for this decrease of timberland ownership are several and complex. This article presents four case studies of U.S.-based forest product companies. The vertical integration theory and empirical studies about timberland ownership give a base for the study. Four hypotheses are formulated on the basis of the literature. The results give support to two of them. An important reason for timberland ownership is a wish to secure deliveries. Market conditions are important for the need of owning timberland. Two of the companies did not own timberland, the main reason being more profitable alternative uses of capital. The ownership structure of the company, tradition, and culture are other important explanations for timberland ownership. This study did not show the advantage of timberland ownership for information and coordination.

Lönnstedt, SLU, Department of Forest Products, P.O. Box 7060, SE 750 07 Uppsala, Sweden E-mail: lars.lonnstedt@spm.slu.se

article id 296, category Research article

Samuel Roturier, Sofia Bäcklund, Maria Sundén, Urban Bergsten. (2007). Influence of ground substrate on establishment of reindeer lichen after artificial dispersal. Silva Fennica vol. 41 no. 2 article id 296. https://doi.org/10.14214/sf.296

Keywords: mineral soil; bark; Cladina mitis; image analysis; lichen colonization; moss; thallus; twigs

Abstract | View details | Full text in PDF | Author Info

Methods to improve the recovery of reindeer lichen after soil disturbance or overgrazing are being sought for areas where reindeer are herded. The effects of four substrates – mineral soil, moss, twigs and pine bark – on the establishment of lichen fragments after total removal of the vegetation were thus studied in a middle-aged pine stand and a clear-cut, both located in a lichen-rich pine-heath. Cladina mitis fragments of two sizes were manually dispersed in 1 m² quadrats and their movements from their respective dispersal points were registered after one year. The natural re-establishment of lichens in the quadrats was monitored over three years by using digital pictures. In the forest stand, no significant differences were detected in either the fragment movement or the lichen establishment between the different substrates, but the fragment size had positive effects on both parameters. In the clear-cut, the moss substrate was the most suitable not only for the artificially dispersed lichens to fasten to, but also for the natural settlement of lichens from the surrounding lichen mat. More lichen thalli fastened to the bark and twigs substrates than to the mineral soil, but the settlement of lichens from the surrounding was greater on bare mineral soil substrate. The results indicate that artificial dispersal of lichen thalli on an appropriate substrate could be a successful strategy for promoting lichen recovery.

Roturier, SLU, Vindeln Experimental Forests, Svartberget Fältstation, SE-922 91 Vindeln, Sweden E-mail: samuel.roturier@esf.slu.se
Bäcklund, E-mail: sb@nn.se
Sundén, E-mail: ms@nn.se
Bergsten, SLU, Dept of Forest Ecology, SE-901 83 Umeå, Sweden E-mail: ub@nn.se

article id 294, category Research article

Ülle Püttsepp, Krista Lõhmus, Andres Koppel. (2007). Decomposition of fine roots and α-cellulose in a short rotation willow (Salix spp.) plantation on abandoned agricultural land. Silva Fennica vol. 41 no. 2 article id 294. https://doi.org/10.14214/sf.294

Keywords: decomposition; α-cellulose; fine roots; acid detergent lignin; short rotation forest; Salix spp.

Abstract | View details | Full text in PDF | Author Info

Decomposition of fine roots (<1 mm in diameter) of the clones of Salix viminalis, S. dasyclados and α-cellulose sheets (50 x 10 x 1 mm) was studied in a 6-years old Salix spp. plantation established on abandoned agricultural land in Estonia. The substrates were incubated in litterbags (mesh size 0.14 mm) in 5–10 cm topsoil, in non-fertilised plots for one year. Changes in the ash-free weight of the fine roots were best described by negative exponential models (S. viminalis R² = 0.98, S. dasyclados R² = 0.96), and by a linear model for α-cellulose (R² = 0.63). The sheets of α-cellulose decomposed roughly twice as rapidly as the fine roots (S. viminalis k = 0.325, S. dasyclados k = 0.165). The remaining (of the initial) ash-free weights of the fine roots were 73.3 ± 0.8% (mean ± SE) and 85.8 ± 2.2% respectively, and of the α-cellulose 35.9 ± 8.5%, in the end of the one year of decomposition. The amount of acid detergent (AD) lignin in the fine-roots of S. viminalis increased significantly and did not change in S. dasyclados, suggesting higher activity of microbial decomposers in the first substrate. Of the studied quality parameters, the AD lignin was the major factor determining the different rate of decomposition of the fine roots of S. viminalis and S. dasyclados. Nitrogen was recycled in the fine root sub-system in both Salix species. This knowledge can be applied in the management of Salix plantations, aimed at bioenergy production.

Püttsepp, Department of Ecology, Swedish University of Agricultural Sciences, P.O. Box 7072, SE-75007 Uppsala, Sweden; Estonian University of Life Sciences, Kreuzwaldi 64, Tartu 51014, Estonia E-mail: ulle.puttsepp@ekol.slu.se
Lõhmus, Institute of Geography, University of Tartu, Vanemuise 46, Tartu 51014, Estonia E-mail: kl@nn.ee
Koppel, Estonian University of Life Sciences, Kreuzwaldi 64, Tartu 51014, Estonia E-mail: ak@nn.ee

article id 292, category Research article

Sanna Susiluoto, Frank Berninger. (2007). Interactions between morphological and physiological drought responses in Eucalyptus microtheca. Silva Fennica vol. 41 no. 2 article id 292. https://doi.org/10.14214/sf.292

Keywords: photosynthesis; chlorophyll fluorescence; root/shoot ratio; RuBP; xylem permeability

Abstract | View details | Full text in PDF | Author Info

We studied the response of Eucalyptus microtheca to drought in a greenhouse experiment. As a result of the drought the growth of the seedlings decreased and allocation patterns changed so that allocation to the roots increased. However, changes in photosynthesis and stomatal conductance under drought were rather modest. We showed, using chlorophyll fluorescence and measurements of photosynthesis under high CO₂ that the biochemical capacity of photosynthesis increased under drought. The results suggest that changes in root/shoot ratio are the primary reactions that initiate a series of compensatory reactions that mitigate the effects of drought in Eucalyptus microtheca.

Susiluoto, University of Helsinki, Department of Forest Ecology, PL 27, 00014 University of Helsinki, Finland E-mail: sannamaija.susiluoto@helsinki.fi
Berninger, Departement des Sciences biologiques, Université du Québec à Montréal, CP 8888 Succ Centre Ville, Montreal, Canada E-mail: fb@nn.ca

article id 291, category Research article

Yildiray Lise, Zeki Kaya, Fikret Isik, Rumi Sabuncu, Irfan Kandemir, Sertaç Önde. (2007). The impact of over-exploitation on the genetic structure of Turkish red pine (Pinus brutia Ten.) populations determined by RAPD markers. Silva Fennica vol. 41 no. 2 article id 291. https://doi.org/10.14214/sf.291

Keywords: Pinus brutia Ten.; RAPD-PCR; human over-exploitation; genetic structure; inbreeding

Abstract | View details | Full text in PDF | Author Info

To determine the possible impact of over-exploitation on the genetic structure of Turkish red pine (Pinus brutia Ten.) populations, three natural and three over-exploited (human degraded) populations of the species in the Mediterranean region of Turkey were investigated with Randomly Amplified Polymorphic DNA (RAPD). With the 80 RAPD primers tested, 12 of them yielded 137 polymorphic RAPD fragments. Four of the studied populations maintained unique fragments. The mean proportion of polymorphic fragments for all populations ranged from 89.8 to 98.9% and there were no significant differences between natural (94.8%) vs. over-exploited populations (92.7%). The estimated heterozygosity values suggested that Turkish red pine maintains high levels of genetic diversity (range 0.24–0.28) though studied populations and grouped ones as natural (H_e = 0.28) vs. over-exploited (0.27) did not differ significantly. The mean F_ST value indicated that the large portion of the total genetic diversity was within populations (93%), but this value was lower in the natural populations (92%) than in the over-exploited ones (94%). In over-exploited populations, excess of homozygosity was observed (about 6% higher) as compared to natural populations, indicating impacts of inbreeding in P. brutia.

Lise, Department of Biological Sciences, Middle East Technical University, 06531, Ankara, Turkey E-mail: yl@nn.tr
Kaya, Department of Biological Sciences, Middle East Technical University, 06531, Ankara, Turkey E-mail: kayaz@metu.edu.tr
Isik, North Carolina State University, Raleigh, USA E-mail: fi@nn.us
Sabuncu, Southwest Anatolia Forest Research Institute, Antalya, Turkey E-mail: rs@nn.tr
Kandemir, Department of Biology, Zonguldak Karaelmas University, 67100, Zonguldak, Turkey E-mail: ik@nn.tr
Önde, Department of Biological Sciences, Middle East Technical University, 06531, Ankara, Turkey E-mail: so@nn.tr

article id 307, category Research article

Jacqueline C. Bolli, Andreas Rigling, Harald Bugmann. (2007). The influence of changes in climate and land-use on regeneration dynamics of Norway spruce at the treeline in the Swiss Alps. Silva Fennica vol. 41 no. 1 article id 307. https://doi.org/10.14214/sf.307

Keywords: tree growth; dendroecology; microsites; subalpine meadow succession; tree invasion

Abstract | View details | Full text in PDF | Author Info

Recent changes of climate and land-use are often regarded to affect the European Alpine region substantially and to trigger an increase in the elevation of the upper treeline. The patterns of tree invasion on a subalpine meadow at 1900 m a.s.l. in Sedrun, Canton Grisons, Switzerland, were studied in order 1) to reconstruct the process of tree establishment and tree–growth dynamics in space and time, and 2) to evaluate the influence of site properties, land-use change and climate on these processes. Dendroecological analysis of 105 Norway spruce combined with an assessment of 48 vegetation plots and 17 soil profiles revealed that the trees were established in one main period (1965–1980s), starting 15 years after the abandonment of the agricultural use of the meadow, and that there is a pronounced environmental gradient along the forest-meadow ecotone. Tree establishment and height growth were favoured close to the former forest edge, but all saplings irrespective of their distance to the forest edge and their age showed increased radial growth since 1990, coinciding with a period of higher summer temperatures in the region. Therefore, we conclude that the observed tree-line dynamics in Sedrun are the result of both land-use and climate change: Tree establishment was triggered by the abandonment of the agricultural use of the meadow, and strongly favoured by particularly good growing conditions in a warm decade, which illustrates the sensitivity of conifers near the alpine tree-line to temperature fluctuations.

Bolli, Swiss Federal Research Institute, Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland E-mail: jacqueline.bolli@wsl.ch
Rigling, Swiss Federal Research Institute, Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland E-mail: ar@nn.ch
Bugmann, Swiss Federal Institute of Technology (ETH) Zürich, Universitätstrasse 16, CH-8092 Zürich, Switzerland E-mail: hb@nn.ch

article id 306, category Research article

Niina Tanskanen, Hannu Ilvesniemi. (2007). Spatial distribution of fine roots at ploughed Norway spruce forest sites. Silva Fennica vol. 41 no. 1 article id 306. https://doi.org/10.14214/sf.306

Keywords: Picea abies; forest soil; fine roots; ploughing; spatial distribution; specific root length; understorey roots

Abstract | View details | Full text in PDF | Author Info

We examined the spatial distribution of fine roots at two forest sites that were ploughed 20 (site K1) and 33 years (site K2) before sampling and planted with Norway spruce (Picea abies (L.) Karst.) seedlings. Soil core samples were taken from the tilt and beneath the tilt, the furrow and the intermediate undisturbed soil to a depth of 0.4 m for fine root biomass, length and necromass determinations. Norway spruce fine roots were found throughout the ploughed forest sites. The fine roots were, however, unevenly distributed: the fine root biomass was highest in the tilt (624 and 452 g m^–2 at sites K1 and K2, respectively) and lowest in the undisturbed soil at site K1 (79 g m^–2) and in the furrow at site K2 (145 g m^–2). The estimated average fine root biomass at the ploughed forest sites (268 and 248 g m^–2 at sites K1 and K2, respectively) was, however, similar to those presented in other studies concerning sites that had not been ploughed. In the tilt, a substantial proportion of the fine roots was in the inverted mineral soil horizons and in the new organic horizon above the tilt. Consistent with the fine root biomass findings, the Norway spruce necromass was highest in the tilt but the vertical distribution of the dead roots was different: the necromass was highest in the buried O_BT horizon. The results of this study suggest that at the ploughed forest sites, a substantial part of Norway spruce nutrient and water uptake occured in the tilt during the first 20 or 33 years after plantation.

Tanskanen, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: niina.tanskanen@helsinki.fi
Ilvesniemi, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: hi@nn.fi

article id 323, category Research article

Simo Kyllönen, Alfred Colpaert, Hannu Heikkinen, Mikko Jokinen, Jouko Kumpula, Mika Marttunen, Kari Muje, Kaisa Raitio. (2006). Conflict management as a means to the sustainable use of natural resources. Silva Fennica vol. 40 no. 4 article id 323. https://doi.org/10.14214/sf.323

Keywords: sustainability; conflict management; resource management; deliberative participation; frame analysis; assurance game; prisoner’s dilemma

Abstract | View details | Full text in PDF | Author Info

Democratic societies’ emphasis on individual rights and freedoms inevitably opens them up to political disputes. Conflict management should thus be seen as an integral part of democratic institutional design. The evolution and management of policy disputes concerning the use of different natural resources in Finland is analysed by using the theoretical models of frame analysis and strategic interaction. The studied disputes include lake fisheries, watercourse regulation, reindeer herding, and forestry. The institutional design in the case studies varies. Despite the differences, many common features are identified that could explain their successes or difficulties in achieving sustainable and cooperative use of the resources. Among these are problems involving complex and uncertain knowledge, differences in frames held by multiple users of a resource, and distrust between the users and other parties. The analysis concludes with preliminary conclusions on how various disputes related to sustainable resource use could be managed. These include addressing the knowledge and frame problems in order to initiate a learning process; establishing sub-processes in which mutual trust between the parties – including a managing authority or a third party – can emerge; giving explicit roles and a clear division of entitlement to the parties; and providing a credible alternative for co-operation that affects the parties’ payoff assessments during the process. Finally, the conflict management process shouldn’t be regarded as a distinct phase of dispute resolution, but as an essential aspect of ongoing co-management practices of resource use.

Kyllönen, Department of Social and Moral Philosophy, P.O. Box 9, FI-00014 University of Helsinki, Finland E-mail: simo.kyllonen@helsinki.fi
Colpaert, University of Joensuu, Department of Geography, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: ac@nn.fi
Heikkinen, Taida, P.O. Box 1000, FI-90014 University of Oulu, Finland E-mail: hh@nn.fi
Jokinen, Finnish Forest Research Institute, Kolari Research Unit, Muoniontie 21 A, FI-95900 Kolari, Finland E-mail: mj@nn.fi
Kumpula, Finnish Game and Fisheries Research Institute, Reindeer Research Station, Toivoniementie 246, FI-99910 Kaamanen, Finland E-mail: jk@nn.fi
Marttunen, Finnish Environment Institute, P.O. Box 140, FI-00251 Helsinki, Finland E-mail: mk@nn.fi
Muje, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: km@nn.fi
Raitio, Department of Social and Policy, University of Joensuu, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: kr@nn.fi

article id 322, category Research article

Jaakko Repola. (2006). Models for vertical wood density of Scots pine, Norway spruce and birch stems, and their application to determine average wood density. Silva Fennica vol. 40 no. 4 article id 322. https://doi.org/10.14214/sf.322

Keywords: Norway spruce; Scots pine; silver birch; wood density; downy birch; mixed models

Abstract | View details | Full text in PDF | Author Info

The purpose of this study was to investigate the vertical dependence of the basic density of Scots pine, Norway spruce, and birch stems, and how such dependence could be applied for determining the average stem wood density. The study material consisted of 38 Scots pine (Pinus sylvestris), 39 Norway spruce (Picea abies [L.] Karst.) and 15 birch (Betula pendula and Betula pubescens) stands located on mineral soil sites in southern Finland. The stem material mainly represented thinning removal from stands at different stages of development. The linear mixed model technique, with both fixed and random effects, was used to estimate the model. According to the fixed part of the model, wood density was dependent on the vertical location along the stem in all three tree species. Wood density in pine decreased from the butt to the top, and the gradient in wood density was steep at the butt but decreased in the upper part of the stem. The vertical dependence was similar in birch, but the density gradient was much smaller. For spruce the vertical dependence of the basic density was moderate. The model can be calibrated for a tree stem when one or more sample disks are measured at freely selected heights. Using treewise calibrated predictions of the vertical density dependence and measured stem diameters, almost unbiased estimates, and lower prediction errors than with traditional methods, were obtained for the average stem wood density. The advantages of the method were greater for pine with a strong vertical dependence in basic density, than for spruce and birch.

Repola, Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-96300 Rovaniemi, Finland E-mail: jaakko.repola@metla.fi

article id 321, category Research article

Jori Uusitalo, Anne Puustelli, Veli-Pekka Kivinen, Tapio Nummi, Bikas K. Sinha. (2006). Bayesian estimation of diameter distribution during harvesting. Silva Fennica vol. 40 no. 4 article id 321. https://doi.org/10.14214/sf.321

Keywords: diameter distribution; Bayesian statistics; tree harvesting

Abstract | View details | Full text in PDF | Author Info

This research aims to combine two different data sets with Bayesian statistics in order to predict the diameter distribution of trees at harvest. The parameters of prior distribution are derived from the forest management plans supplemented by additional ocular information. We derive the parameters for the sample data from the first trees harvested, and then create the posterior distribution within the Bayesian framework. We apply the standard normal distribution to construct diameter (dbh) distributions, although many other theoretical distributions have been proved better with dbh data available. The methodology developed is then tested on nine mature spruce (Picea abies) dominated stands, on which the normal distribution seems to work well in mature spruce stands. The tests indicate that prediction of diameter distribution for the whole stand based on the first trees harvested is not wise, since it tends to give inaccurate predictions. Combining the first trees harvested with prior information seems to increase the reliability of predictions.

Uusitalo, The Finnish Forest Research Institute, Parkano unit, FI-39700 Parkano, Finland E-mail: jori.uusitalo@metla.fi
Puustelli, University of Tampere, Department of Mathematics, Statistics and Philosophy, FI-33014 University of Tampere, Finland E-mail: ap@nn.fi
Kivinen, University of Helsinki, Department of Forest Resource Management, Box 27, FI-00014 University of Helsinki, Finland E-mail: vpk@nn.fi
Nummi, University of Tampere, Department of Mathematics, Statistics and Philosophy, FI-33014 University of Tampere, Finland E-mail: tn@nn.fi
Sinha, Stat-Math Division, Indian Statistical Institute, 203 B.T. Road, Kolkata - 700 108, India E-mail: bks@nn.in

article id 319, category Research article

Ulises Diéguez-Aranda, José Antonio Grandas-Arias, Juan Gabriel Álvarez-González, Klaus von Gadow. (2006). Site quality curves for birch stands in north-western Spain. Silva Fennica vol. 40 no. 4 article id 319. https://doi.org/10.14214/sf.319

Keywords: site quality; Betula pubescens; generalized algebraic difference approach; base-age invariant dynamic equation; Hossfeld model; Galicia

Abstract | View details | Full text in PDF | Author Info

A model for predicting the height growth of even-aged, birch (Betula pubescens Ehrh.) dominated stands in Galicia (north-western Spain) was developed. Data from stem analysis of 214 trees were used for model construction. Two dynamic site equations derived with the generalized algebraic difference approach (GADA) were tested, which combine compatible site index and height models in one common equation. Both equations are base-age invariant and directly estimate height and site index from any height and age. The fittings were done in one stage using the base-age-invariant dummy variables method. A second-order continuous-time autoregressive error structure was used to correct the inherent autocorrelation of the longitudinal data used in this study. Cieszewski’s model best described the data. This model is therefore recommended for height growth prediction and site classification of birch stands in Galicia.

Diéguez-Aranda, Departamento de Ingeniería Agroforestal, Universidad de Santiago de Compostela. Escuela Politécnica Superior, Campus universitario, 27002 Lugo, Spain E-mail: udieguez@lugo.usc.es
Grandas-Arias, Departamento de Ingeniería Agroforestal, Universidad de Santiago de Compostela. Escuela Politécnica Superior, Campus universitario, 27002 Lugo, Spain E-mail: jaga@nn.es
Álvarez-González, Departamento de Ingeniería Agroforestal, Universidad de Santiago de Compostela. Escuela Politécnica Superior, Campus universitario, 27002 Lugo, Spain E-mail: jgag@nn.es
Gadow, Institut fur Waldinventur und Waldwachstum, George-Auguts-Universität Göttingen. Büsgenweg 5, D-37077 Göttingen, Germany E-mail: kg@nn.de

article id 316, category Research article

Sonja Vospernik. (2006). Probability of bark stripping damage by red deer (Cervus elaphus) in Austria. Silva Fennica vol. 40 no. 4 article id 316. https://doi.org/10.14214/sf.316

Keywords: logistic regression; bark stripping; red deer

Abstract | View details | Full text in PDF | Author Info

Bark stripping by red deer (Cervus elaphus) causes considerable damage to Austrian forests, however, the incidence of bark stripping was never examined from large scale survey data. In this manuscript we present a logistic regression model for bark stripping damage (static model) and a model for recent (5-year period) bark stripping damage to previously undamaged trees (dynamic model) developed from Austrian National Forest Inventory data. Both models showed bark stripping damage to be most frequent in core red deer habitat areas and less frequent in less suitable habitat. Damage was concentrated at elevations of 400–1200 m and in alluvial forests (only static model). Norway spruce (Picea abies), European ash (Fraxinus excelsior), Sweet chestnut (Castanea sativa) and Sorbus spp. had 11–12 times more injuries than all the other species. Red deer preferred the smallest trees with a breast height diameter of 5 cm for bark stripping and damage probability decreased rapidly for trees with a breast height diameter greater than 25 cm. Our static model showed a maximum of bark stripping damage in stands with a mean height of 20 m. In the dynamic model the probability for bark stripping damage decreased with decreasing mean height. Also, in the static model the probability for bark stripping damage increased with increasing spruce proportion and with increasing stand density whereas in the dynamic model the proportion of previous bark stripping damage was a good predictor. Goodness of fit and discrimination of both models were good. In combination with forest growth models, the bark stripping models can be used to predict the risk of damage associated with different forest and habitat management options.

Vospernik, University of Natural Resources and Applied Life Sciences, Institute of Forest Growth Research, Department of Forest and Soil Sciences, Peter-Jordan-Stra§e 82, A-1190 Vienna, Austria E-mail: sonja.vospernik@boku.ac.at

article id 332, category Research article

Marc Palahí, Timo Pukkala, Antoni Trasobares. (2006). Calibrating predicted tree diameter distributions in Catalonia, Spain. Silva Fennica vol. 40 no. 3 article id 332. https://doi.org/10.14214/sf.332

Keywords: calibration estimation; Weibull function; parameter prediction

Abstract | View details | Full text in PDF | Author Info

Several probability density functions have been used in describing the diameter distributions of forest stands. In a case where both the stand basal area and number of stems per hectare are assessed, the fitted or predicted distribution is scaled using only one of these variables, with the result that the distribution often gives incorrect values for the other variable. Using a distribution that provides incorrect values for known characteristics means wasting information. Calibrating the distribution so that it is compatible with the additional information on stand characteristics is a way to avoid such wasting. This study examined the effect of calibration on the accuracy of the predicted diameter distributions of the main tree species of Catalonia. The distributions were calibrated with and without considering the prediction errors of the frequencies of diameter classes. When prediction errors were assumed, the calibration was done with and without making allowance for estimation errors in the stand level calibration variables. Calibrated distributions were more accurate than non-calibrated in terms of sums of different powers of diameters. The set of calibration variables that gave the most accurate results included six stand variables: number of trees per hectare, stand basal area, basal-area-weighted mean diameter, non-weighted mean diameter, median diameter, and basal area median diameter. Of the tested three-variable combinations the best was: number of trees per hectare, stand basal area, and basal-area-weighted mean diameter. Means were more useful calibration variables than medians.

Palahí, Centre Tecnológic Forestal de Catalunya. Passeig Lluis Companys, 23, 08010, Barcelona, Spain E-mail: marc.palahi@ctfc.es
Pukkala, University of Joensuu, Faculty of Forestry, P.O. Box 111, 80101 Joensuu, Finland E-mail: tp@nn.fi
Trasobares, Foreco Technologies, Av. Diagonal 416, Estudio 2, Barcelona 08037, Spain E-mail: at@nn.es

article id 326, category Research article

Xuejiang Zhang, Helena Korpelainen, Chunyang Li. (2006). Microsatellite variation of Quercus aquifolioides populations at varying altitudes in the Wolong Natural Reserve of China. Silva Fennica vol. 40 no. 3 article id 326. https://doi.org/10.14214/sf.326

Keywords: genetic differentiation; genetic variation; altitudinal gradients; microsatellites; Quercus aquifolioides

Abstract | View details | Full text in PDF | Author Info

Genetic variation and differentiation were investigated among five natural populations of Quercus aquifolioides occurring along an altitudinal gradient that varied from 2000 to 3600 m above sea level in the Wolong Natural Reserve of China, by analyzing variation at six microsatellite loci. The results showed that the populations were characterized by relatively high intra-population variation with the average number of alleles equaling 11.33 per locus and the average expected heterozygosity (H_E) being 0.779. The amount of genetic variation varied only little among populations, which suggests that the influence of altitude factors on microsatellite variation is limited. However, there is a significantly positive correlation between altitude and the number of low-frequency alleles (R² = 0.97, P < 0.01), which indicates that Q. aquifolioides from high altitudes has more unique variation, possibly enabling adaptation to severe conditions. F statistics showed the presence of a slight deficiency of heterozygosity (F_IS = 0.136) and a low level of differentiation among populations (F_ST = 0.066). The result of the cluster analysis demonstrated that the grouping of populations does not correspond to the altitude of the populations. Based on the available data, it is likely that the selective forces related to altitude are not strong enough to significantly differentiate the populations of Q. aquifolioides in terms of microsatellite variation.

Zhang, Chengdu Institute of Biology, Chinese Academy of Sciences, P.O. Box 416, Chengdu 610041, P. R. China; Graduate School of the Chinese Academy of Sciences, Beijing 100039, P. R. China E-mail: xz@nn.cn
Korpelainen, Department of Applied Biology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: hk@nn.fi
Li, Chengdu Institute of Biology, Chinese Academy of Sciences, P.O. Box 416, Chengdu 610041, P. R. China E-mail: licy@cib.ac.cn

article id 341, category Research article

Sanni Raiskila, Pekka Saranpää, Kurt Fagerstedt, Tapio Laakso, Mia Löija, Riitta Mahlberg, Leena Paajanen, Anne-Christine Ritschkoff. (2006). Growth rate and wood properties of Norway spruce cutting clones on different sites. Silva Fennica vol. 40 no. 2 article id 341. https://doi.org/10.14214/sf.341

Keywords: Norway spruce; density; growth rate; mechanical strength; modulus of elasticity; modulus of rupture

Abstract | View details | Full text in PDF | Author Info

The effect of growth rate on weight density and strength properties of three Norway spruce cutting clones growing on three different sites in different geographic locations was studied. The purpose was to follow variation in wood physical and mechanical properties and in quality between fast-growing clones grown in environments differing in nutritional and soil properties and climate within the boreal zone. The cloned trees had been selected on grounds of good growth, health and quality. The cuttings were collected from three-year-old seedlings and rooted. The rooted cuttings were planted in the 1970’s and they were on average 26 years old at a time of felling. The variation of weight density was studied within the annual ring and within the stem between the juvenile and mature wood from the pith to the bark with an X-ray densitometric method. The average annual ring width (and latewood proportion, %) varied between the clones from 2.92±1.36 mm (15.34%) to 3.30±1.25 mm (11.80%) and between the sites from 2.76±1.07 mm (14.71%) to 3.70±1.22 mm (13.29%). The mean weight density was 0.461±0.077 g cm–3 and latewood density 0.750±0.125 g cm–3 in this material. The mean modulus of elasticity was 9.88±1.43 GPa, modulus of rupture 67.51±11.50 MPa and weight density of the test samples (ρ12) 414±44 kg m–3 in mature wood. The parameters studied showed clearly that the environment had a large effect while the three clones differed from each other similarly in the different sites, e.g. the fastest growing clone was fastest on all sites.

Raiskila, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: sr@nn.fi
Saranpää, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: pekka.saranpaa@metla.fi
Fagerstedt, Department of Biological and Environmental Sciences, Plant Biology, P.O. Box 65, FI-00014 University of Helsinki, Finland E-mail: kf@nn.fi
Laakso, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: tl@nn.fi
Löija, VTT Building and Transport, P.O. Box 1806, FI-02044 VTT, Finland E-mail: lm@nn.fi
Mahlberg, VTT Building and Transport, P.O. Box 1806, FI-02044 VTT, Finland E-mail: rm@nn.fi
Paajanen, VTT Building and Transport, P.O. Box 1806, FI-02044 VTT, Finland E-mail: lp@nn.fi
Ritschkoff, VTT Building and Transport, P.O. Box 1806, FI-02044 VTT, Finland E-mail: acr@nn.fi

article id 340, category Research article

Petteri Muukkonen, Raisa Mäkipää, Raija Laiho, Kari Minkkinen, Harri Vasander, Leena Finér. (2006). Relationship between biomass and percentage cover in understorey vegetation of boreal coniferous forests. Silva Fennica vol. 40 no. 2 article id 340. https://doi.org/10.14214/sf.340

Keywords: upland soils; peatlands; biomass models; ground vegetation

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In the present study, the aboveground biomass of the understorey vegetation of boreal coniferous forests was modelled according to the percentage cover. A total of 224 observations from 22 stands in upland forests and 195 observations from 14 different studies in peatland forests were utilized for the present analyses. The relationships between biomass and percentage cover can be used in ecosystem and carbon-cycle modelling as a rapid nondestructive method for estimation of the aboveground biomass of lichens, bryophytes, herbs and grasses, and dwarf shrubs in upland forests and bottom and field layers in peatland forests.

Muukkonen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: petteri.muukkonen@metla.fi
Mäkipää, Finnish Forest Research Institute, Unioninkatu 40 A, FI-00170 Helsinki, Finland E-mail: rm@nn.fi
Laiho, Department of Forest Ecology, P.O. Box 24, FI-00014 University of Helsinki, Finland E-mail: rl@nn.fi
Minkkinen, Department of Forest Ecology, P.O. Box 24, FI-00014 University of Helsinki, Finland E-mail: km@nn.fi
Vasander, Department of Forest Ecology, P.O. Box 24, FI-00014 University of Helsinki, Finland E-mail: hv@nn.fi
Finér, Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: lf@nn.fi

article id 339, category Research article

John W. McCarthy, Gordon Weetman. (2006). Age and size structure of gap-dynamic, old-growth boreal forest stands in Newfoundland. Silva Fennica vol. 40 no. 2 article id 339. https://doi.org/10.14214/sf.339

Keywords: boreal forests; old-growth forests; gap dynamics; age and size structure; rotated sigmoid; Newfoundland

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The age and size structure of trees in old Abies-Picea-Betula forests on Newfoundland’s Great Northern Peninsula were examined. It was hypothesized that the size and age structure of both the tree and regeneration “strata” of these stands display the complex structural heterogeneity characteristic of classic, self-regenerating, uneven-aged old-growth stands, and that the development and dynamics of such structures occur over long periods of time. With all tree species combined, dbh (diameter at breast height) and height distributions exhibited a strong reverse-J character, with well-defined, semi-logarithmic rotated sigmoid height and size frequencies. Seedling height and basal diameter frequency distributions were reverse-J in character. Live tree ages for all species, except white birch (Betula papyrifera Marsh), ranged from 25 to 269 years, and were characterized by all-age frequency distributions. Tree age and size were poorly correlated. On average, balsam fir (Abies balsamea (L.) Mill.) required 62 years to reach breast height (1.3 m), with black spruce (Picea mariana (Mill.) B.S.P.) and white spruce (Picea glauca (Moench) Voss) requiring 40 and 48 years, respectively. Total age of dead standing trees ranged from 45 to 232 years. Reverse-J age frequencies characterized the seedling bank, with balsam fir seedlings present in nearly all age classes up to 110, 120 and 85 years in three sample stands. Seedling size (height and basal diameter)-age relationships were characteristic of decades-long suppression. The combination of tree and seedling bank size and age structure provide strong evidence of quasi-equilibrium, small-scale, gap dynamic old-growth boreal forest stands.

McCarthy, University of British Columbia, Forest Sciences Department, 2424 Main Mall, Vancouver, B.C., Canada V6T 1Z4 E-mail: jmccarthy@jesuits.ca
Weetman, University of British Columbia, Forest Sciences Department, 2424 Main Mall, Vancouver, B.C., Canada V6T 1Z4 E-mail: gw@n.ca

article id 338, category Research article

Andrea Vajda, Ari Venäläinen, Pekka Hänninen, Raimo Sutinen. (2006). Effect of vegetation on snow cover at the northern timberline: a case study in Finnish Lapland. Silva Fennica vol. 40 no. 2 article id 338. https://doi.org/10.14214/sf.338

Keywords: climate; snow; forest-tundra; Lapland; radar; tree-line; wind modelling

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The presence of permanent snow cover for 200–220 days of the year has a determining role in the energy, hydrological and ecological processes at the climate-driven spruce (Picea abies) timberline in Lapland. Disturbances, such as forest fires or forest harvesting change the vegetation pattern and influence the spatial variation of snow cover. This variability in altered snow conditions (in subarctic Fennoscandia) is still poorly understood. We studied the influence of vegetation on the small-scale spatial variation of snow cover and wind climate in the Tuntsa area that was disturbed by a widespread forest fire in 1960. Radar was applied to measure snow thickness over two vegetation types, the spruce-dominant fire refuge and post-fire treeless tundra. Wind modelling was used to estimate the spatial variation of wind speed and direction. Due to the altered surface roughness and the increased wind velocity, snow drifting was more vigorous on the open tundra, resulting in a 30-cm thinner snow cover and almost half the water equivalent compared to the forest values. The changes in local climate after the fire, particularly in snow cover, may have played an important role in the poor recovery of vegetation: a substantial area is still unforested 40 years after the fire.

Vajda, Finnish Meteorogical Institute, Climate and Global Change, P.O. Box 503, FI-00101 Helsinki, Finland E-mail: andrea.vajda@fmi.fi
Venäläinen, Finnish Meteorogical Institute, Climate and Global Change, P.O. Box 503, FI-00101 Helsinki, Finland E-mail: av@nn.fi
Hänninen, Geological Survey of Finland, P.O. Box 96, FI-02151 Espoo, Finland E-mail: ph@nn.fi
Sutinen, Geological Survey of Finland, P.O. Box 77, FI-96101 Rovaniemi, Finland E-mail: rs@nn.fi

article id 337, category Research article

Hannu Salminen, Risto Jalkanen. (2006). Modelling variation of needle density of Scots pine at high latitudes. Silva Fennica vol. 40 no. 2 article id 337. https://doi.org/10.14214/sf.337

Keywords: Pinus sylvestris; needles; dendroclimatology; NTM; precipitation; temperature; fascicles

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The relationship between apical extension and needle density and the effect of temperature and precipitation on needle density was modelled using data gathered from forty-nine felled sample trees in five stands of Scots pine (Pinus sylvestris L.) located along a latitudinal transect from the Arctic Circle up to the northern timberline. The lengths were measured and needle densities assessed from all annual shoots located above 1.3 metres using the Needle Trace Method (NTM), resulting, on average, in 39-year-long chronologies. The mean overall needle density was 7.8 short shoots per shoot centimetre. Needle-density variation in the measured data was mostly due to within-tree differences. Of the total variance, within-tree variation yielded 46%, between-tree 21%, and between-year 27%. The dependence of needle density on annual height growth was studied by fitting a multilevel model with random stand-, tree- and year-intercepts, the independent variables being tree age and height growth. There was a very strong negative correlation between height growth and needle density, and the proportion of between-year variance explained solely by height growth and age was 50%. The stand-wise residual variations and their correlations with the temperature and precipitation time series were further analysed with cross-correlation analysis in order to screen for additional independent variables. The only possible additional independent variable found was the precipitation of April–May (precipitation of May in the two northernmost stands). When it was added to the multi-level model, the proportion of explained between-year needle-density variance was 55%, but the overall fit of the model improved only slightly. The effect of late winter and early spring precipitation indicates the role of snow coverage and snowmelt on the growing conditions in the three southernmost stands. In general, stand-level needle-density variation is mostly due to changes in height growth.

Salminen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: hannu.salminen@metla.fi
Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: rj@nn.fi

article id 359, category Research article

Paula Horne. (2006). Forest owners’ acceptance of incentive based policy instruments in forest biodiversity conservation – a choice experiment based approach. Silva Fennica vol. 40 no. 1 article id 359. https://doi.org/10.14214/sf.359

Keywords: forest owners; heterogeneity; incentive based policy mechanism; choice experiment method

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Finland has launched a new policy programme (METSO) to enhance conservation of forest biodiversity. In non-industrial private forests, the policy is based on economic incentives and voluntarism on the part of forest owners. While biodiversity conservation is the main target of the policy, social acceptability is considered to be of great importance. This study examined the factors that affect the acceptability of biodiversity conservation contracts among private forest owners, and the amount of compensation needed to keep the forest owners at least as well off as before the contract. Choice experiment method was used to analyse the data that were collected by surveying 3000 Finnish private forest owners. Analysing separately those respondents who were willing to enter into a conservation contract allowed an assessment of the impact of forest owners’ heterogeneity on compensation amount. The results show how the welfare of forest owners shifts when the contract terms are changed. In a base scenario the forest owner was assumed to be the initiator of the contract that would require only small patches of forest to be protected, and would also bind new forest owners over its duration of ten years. For all respondents, the average demand for compensation would be around 224 euros annually. When those always choosing the “no additional conservation” alternative were excluded, the average welfare impact of the base scenario was positive.

Horne, Finnish Forest Research Institute, Unioninkatu 40 A, FI-00170 Helsinki, Finland E-mail: paula.horne@metla.fi

article id 357, category Research article

Elizabeth Dodson Coulter, John Sessions, Michael G. Wing. (2006). Scheduling forest road maintenance using the analytic hierarchy process and heuristics. Silva Fennica vol. 40 no. 1 article id 357. https://doi.org/10.14214/sf.357

Keywords: decision support; simulated annealing; threshold accepting; road environmental impacts; AHP

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The management of low-volume roads has transitioned from focusing on maintenance designed to protect a capital investment in road infrastructure to also include environmental effects. In this study, two models using mathematical programming are applied to schedule forest road maintenance and upgrade activities involving non-monetary benefits. Model I uses a linear objective function formulation that maximizes benefit subject to budgetary constraints. Model II uses a non-linear objective function to maximize the sum of benefits divided by the sum of all costs in a period. Because of the non-linearity of the constraints and the requirements that the decision variables be binary, the solutions to both problem formulations are found using two heuristics, simulated annealing and threshold accepting. Simulated annealing was found to produce superior solutions as compared to threshold accepting. The potential benefit for completing a given road maintenance or upgrade project is determined using the Analytic Hierarchy Process (AHP), a multi-criterion decision analysis technique. This measure of benefit is combined with the economic cost of completing a given project to schedule maintenance and upgrade activities for 225 km (140 miles) of road in forested road systems within western Oregon. This combination of heuristics, cost-benefit analysis, environmental impacts, and expert judgment produces a road management schedule that better fits the current road management paradigm.

Coulter, College of Forestry and Conservation, University of Montana, 32 Campus Drive, Missoula, MT 59812, USA E-mail: elizabeth.coulter@cfc.umt.edu
Sessions, Department of Forest Engineering, College of Forestry, Oregon State University, 204 Peavy Hall, Corvallis, OR 97331-5706, USA E-mail: js@nn.us
Wing, Department of Forest Engineering, College of Forestry, Oregon State University, 204 Peavy Hall, Corvallis, OR 97331-5706, USA E-mail: mgw@nn.us

article id 355, category Research article

Ilkka Korpela. (2006). Geometrically accurate time series of archived aerial images and airborne lidar data in a forest environment. Silva Fennica vol. 40 no. 1 article id 355. https://doi.org/10.14214/sf.355

Keywords: vegetation; canopy; monitoring; laser scanning; change detection; photogrammetry; 3D; aerial triangulation; direct georeferencing

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Reconstructing three-dimensional structural changes in the forest over time is possible using archived aerial photographs and photogrammetric techniques, which have recently been introduced to a larger audience with the advent of digital photogrammetry. This paper explores the feasibility of constructing an accurate time-series of archived aerial photographs spanning 42 years using different types of geometric data and estimation methods for image orientation. A recent airborne laser scanning (lidar) data set was combined with the image block and assessed for geometric match. The results suggest that it is possible to establish the multitemporal geometry of an image block to an accuracy that is better than 0.5 m in 3D and constant over time. Even geodetic ground control points can be omitted from the estimation if the most recent images have accurate direct sensor orientation, which is becoming a standard technique in aerial photography. This greatly reduces the costs and facilitates the work. An accurate multitemporal image block combined with recent lidar scanning for the estimation of topography allows accurate monitoring and retrospective analysis of forest vegetation and management operations.

Korpela, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ilkka.korpela@helsinki.fi

article id 354, category Research article

Mervi Talvitie, Olli Leino, Markus Holopainen. (2006). Inventory of sparse forest populations using adaptive cluster sampling. Silva Fennica vol. 40 no. 1 article id 354. https://doi.org/10.14214/sf.354

Keywords: coarse woody debris; adaptive cluster sampling; simple random sampling; drought damage; efficiency

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In many studies, adaptive cluster sampling (ACS) proved to be a powerful tool for assessing rare clustered populations that are difficult to estimate by means of conventional sampling methods. During 2002 and 2003, severe drought-caused damage was observed in the park forests of the City of Helsinki, Finland, especially in barren site pine and spruce stands. The aim of the present study was to examine sampling and measurement methods for assessing drought damage by analysing the effectiveness of ACS compared with simple random sampling (SRS). Horvitz-Thompson and Hansen-Hurwitz estimators of the ACS method were used for estimating the population mean and variance of the variable of interest. ACS was considerably more effective than SRS in assessing rare clustered populations such as those resulting from drought damage. The variances in the ACS methods were significantly smaller and the inventory efficiency in the field better than in SRS.

Talvitie, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: mervi.talvitie@helsinki.fi
Leino, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ol@nn.fi
Holopainen, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ah@nn.fi

article id 351, category Research article

Jiaojun Zhu, Xiufen Li, Zugen Liu, Wei Cao, Yutaka Gonda, Takeshi Matsuzaki. (2006). Factors affecting the snow and wind induced damage of a montane secondary forest in northeastern China. Silva Fennica vol. 40 no. 1 article id 351. https://doi.org/10.14214/sf.351

Keywords: stem breakage; uprooting; stand structure; snow and wind damages; secondary forests; mixed forests

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In order to understand the processes of snow and wind induced damage in a natural montane, secondary forest in northeastern China, we examined the impacts of site conditions on the snow and wind damage; analyzed if the dominant tree species differed in their susceptibilities to the damage; and established the relationships between the characteristics of tree and stand and the damage. The results indicated that in regard to the topography factors, slope steepness and soil depth played a relatively important role for the damage. Damage ratios of all types combined were positively related with the composition of dominant tree species. The stand density was also important in determining resistance to the damage, i.e., the densely populated stand exhibited less overall damage ratios; however, the dominant tree species were commonly damaged easily by the snow and wind. Four damage modes found (uprooting, stem breakage, canopy damage and bending) were closely related to the stem taper (p < 0.05), and they could be ranked in following order: bending (92.0 ) > uprooting (85.3) > stem breakage (80.1) > canopy damage (65.0). In regard to differences in tree species’ susceptibilities to the damage, Betula costata exhibited the most uprooting, bending and overall damage ratios; while Quercus mongolica showed the highest breakage (both stem breakage and canopy damage) ratio, and Fraxinus mandshurica exhibited the least damage ratio (overall). The major six tree species could also be divided into two groups according to the overall damage ratios, i.e., more susceptible ones (B. costata, Ulmus laciniata and Q. mongolica), and less susceptible ones (F. mandshurica, Acer mono and Juglans mandshurica) to the snow and wind damage.

Zhu, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China E-mail: zrms29@yahoo.com
Li, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China; Graduate School of Chinese Academy of Sciences, Yuquan Road 19-A, Beijing, 100039, China E-mail: xfl@nn.cn
Liu, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China; Graduate School of Chinese Academy of Sciences, Yuquan Road 19-A, Beijing, 100039, China E-mail: zgl@nn.cn
Cao, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China E-mail: wc@nn.cn
Gonda, Faculty of Agriculture, Niigata University, Ikarashi 2-8050, Niigata, 950-2181, Japan E-mail: yg@nn.jp
Matsuzaki, Faculty of Agriculture, Niigata University, Ikarashi 2-8050, Niigata, 950-2181, Japan E-mail: tm@nn.jp

article id 348, category Research article

Chunyang Li, Xuejiang Zhang, Xingliang Liu, Olavi Luukkanen, Frank Berninger. (2006). Leaf morphological and physiological responses of Quercus aquifolioides along an altitudinal gradient. Silva Fennica vol. 40 no. 1 article id 348. https://doi.org/10.14214/sf.348

Keywords: carbon isotope composition; leaf nitrogen content; specific leaf area; stomata

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Quercus aquifolioides Rehder & E.H. Wilson, an evergreen alpine and subalpine shrub species, occupies a wide range of habitats on the eastern slopes of the Himalaya in China. In this study, we measured leaf morphology, nitrogen content and carbon isotope composition (as an indicator of water use efficiency) of Q. aquifolioides along an altitudinal gradient. We found that these leaf morphological and physiological responses to altitudinal gradients were non-linear with increasing altitude. Specific leaf area, stomatal length and index increased with increasing altitude below 2800 m, but decreased with increasing altitude above 2800 m. In contrast, leaf nitrogen content per unit area and carbon isotope composition showed opposite change patterns. Specific leaf area seemed to be the most important parameter that determined the carbon isotope composition along the altitudinal gradient. Our results suggest that near 2800 m in altitude could be the optimum zone for growth and development of Q. aquifolioides, and highlight the importance of the influence of altitude in research on plant physiological ecology.

Li, Chengdu Institute of Biology, Chinese Academy of Sciences, P.O. Box 416, Chengdu 610041, P. R. China E-mail: licy@cib.ac.cn
Zhang, Chengdu Institute of Biology, Chinese Academy of Sciences, P.O. Box 416, Chengdu 610041, P. R. China; Graduate School of the Chinese Academy of Sciences, Beijing 100039, P.R. China E-mail: xz@nn.cn
Liu, Sichuan Academy of Forestry, Chengdu 610081, P. R. China E-mail: xl@nn.cn
Luukkanen, Viikki Tropical Resources Institute, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ol@nn.fi
Berninger, Département des sciences biologiques, Cp 8888 succ centre ville, Université du Québec à Montréal, Montréal (QC) H3C 3P8, Canada E-mail: fb@nn.ca

article id 367, category Research article

Sakari Tuominen, Markus Haakana. (2005). Landsat TM imagery and high altitude aerial photographs in estimation of forest characteristics. Silva Fennica vol. 39 no. 4 article id 367. https://doi.org/10.14214/sf.367

Keywords: multi-source forest inventory; satellite imagery; high-altitude aerial photographs; image texture

Abstract | View details | Full text in PDF | Author Info

Satellite sensor data have traditionally been used in multi-source forest inventory for estimating forest characteristics. Their advantages generally are large geographic coverage and large spectral range. Another remote sensing data source for forest inventories offering a large geographic coverage is high altitude aerial photography. In high altitude aerial photographs the spectral range is very narrow but the spatial resolution is high. This allows the extraction of texture features for forest inventory purposes. In this study we utilized a Landsat 7 ETM satellite image, a photo mosaic composed of high altitude panchromatic aerial photographs, and a combination of the aforementioned in estimating forest attributes for an area covering approximately 281 000 ha in Forestry Centre Häme-Uusimaa in Southern Finland. Sample plots of 9th National Forest Inventory (NFI9) were used as field data. In the estimation, 6 Landsat 7 ETM image channels were used. For aerial photographs, 4 image channels were composed from the spectral averages and texture features. In combining both data sources, 6 Landsat channels and 3 aerial image texture channels were selected for the analysis. The accuracy of forest estimates based on the Landsat image was better than that of estimates based on high altitude aerial photographs. On the other hand, using the combination of Landsat ETM spectral features and textural features on high altitude aerial photographs improved the estimation accuracy of most forest attributes.

Tuominen, Finnish Forest Research Institute, Unioninkatu 40 A, FI-00170 Helsinki, Finland E-mail: sakari.tuominen@metla.fi
Haakana, Finnish Forest Research Institute, Unioninkatu 40 A, FI-00170 Helsinki, Finland E-mail: mh@nn.fi

article id 366, category Research article

Lars Eliasson. (2005). Effects of forwarder tyre pressure on rut formation and soil compaction. Silva Fennica vol. 39 no. 4 article id 366. https://doi.org/10.14214/sf.366

Keywords: soil density; cone penetrometer; final felling; till soil

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In Swedish forestry, final felling is usually done by a harvester and a forwarder. These machines are heavy and the risk for rutting and soil compaction can be considerable under unfavourable soil conditions. The aim of this study was to evaluate effects of forwarder tyre inflation pressure on rutting and soil compaction after final felling. Three levels of forwarder tyre pressure were studied, 300, 450 and 600 kPa, after 2 and 5 machine passages. The first passage was driven with a 19.7 Mg harvester, and the second to fifth passages with a fully loaded forwarder totalling 37.8 Mg. Rut depths were not significant affected by tyre pressures but increased significantly with the number of machine passages. Soil density was significantly increased by 0.075 Mg m–3 by the harvester passage. Soil density increased significantly with increasing number of forwarder passages, and tyre pressure did not significantly influence this increase but the interaction between number of forwarder passages and tyre pressure was almost significant. Data suggest that density increases occur earlier in the 600 kPa treatment than in the other treatments. Only parts of an area harvested are trafficked in a normal harvesting operation. Outside the research area approximately 12.5 per cent of the area harvested was covered with ruts. On primary strip roads, which are heavily trafficked, soil compaction cannot be avoided by reducing the tyre pressure. On secondary strip roads, not passed more than once by the forwarder, a low forwarder tyre pressure may reduce soil compaction.

Eliasson, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: lars.eliasson@norraskogsagarna.se

article id 365, category Research article

Raffaele Spinelli, Carla Nati, Natascia Magagnotti. (2005). Harvesting and transport of root biomass from fast-growing poplar plantations. Silva Fennica vol. 39 no. 4 article id 365. https://doi.org/10.14214/sf.365

Keywords: productivity; biomass; logistics; harvesting; root recovery; cost

Abstract | View details | Full text in PDF | Author Info

Recovery of tree root biomass can be attractive, since the stump-root system represents a substantial portion of the tree mass and its removal may prove instrumental to re-cultivation. Most available studies concern Nordic technologies, particularly suited to mature conifer stands. Unlike spruce, plantation poplar develops a deep taproot, whose extraction requires completely different methods. The aim of the study was to investigate poplar root recovery operations in plantations with time studies, and to determine the productivity and delivery costs of the operations. Seven operation systems developed to work with poplar plantations in Italian conditions were studied. Extraction and cleaning units were based on general-purpose prime movers. Under favourable conditions extraction and cleaning units achieved a very high productivity: 150 stumps per hour for the extraction unit and 170 for the cleaning unit. Delivered cost varied widely, ranging from 28 to 66 Euros Mg^–1. Transportation was the most expensive single work task. It accounted for about 40% of the total recovery cost. Extraction and cleaning contributed approximately 25% each to the total cost, and loading 9%. Guidelines to recovery system improvement and efficient operation are provided.

Spinelli, CNR/IVALSA, Via Madonna del Piano - Palazzo F, I-50019 Sesto Fiorentino (FI), Italy E-mail: spinelli@ivalsa.cnr.it
Nati, CNR/IVALSA, Via Madonna del Piano - Palazzo F, I-50019 Sesto Fiorentino (FI), Italy E-mail: cn@nn.it
Magagnotti, CNR/IVALSA, Via Madonna del Piano - Palazzo F, I-50019 Sesto Fiorentino (FI), Italy E-mail: nm@nn.it

article id 360, category Research article

Timo Kurkela, Tarmo Aalto, Martti Varama, Risto Jalkanen. (2005). Defoliation by the common pine sawfly (Diprion pini) and subsequent growth reduction in Scots pine: a retrospective approach. Silva Fennica vol. 39 no. 4 article id 360. https://doi.org/10.14214/sf.360

Keywords: height growth; NTM; defoliation; insect attack; needle density; needle production; needle retention; radial growth; herbivory

Abstract | View details | Full text in PDF | Author Info

The foliage status in the main stem of Scots pines (Pinus sylvestris) was studied retrospectively using the needle trace method (NTM) on a stand, seriously defoliated by the pine sawfly (Diprion pini) in the 1980s. Needle density increased abruptly in the seasons following the defoliation. The strongest reduction in annual needle production occurred one year later. As a consequence of lower needle production, the annual number of attached needles decreased three to five years after the defoliation. Needle retention and the average age of attached needles tended to increase after defoliation. In analyses of covariance with the NTM variables, needle density (logarithmic transformed values) and average age of attached needles, had the highest, significant, negative relationship with radial and height increments both in the period prior to the defoliation and in the time when the trees were suffering from defoliation. The relationships between height increment and the number of needles and needle loss were positive and significant. Also radial increment had a positive relationship with the number of needles but not with needle loss. Interestingly, an abrupt increase in the needle density gave a good indication of the effects of a sudden defoliation in pines.

Kurkela, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: timo.kurkela@metla.fi
Aalto, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: ta@nn.fi
Varama, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mv@nn.fi
Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: rj@nn.fi

article id 479, category Research article

Ken Olaf Storaunet, Jørund Rolstad, Ivar Gjerde, Vegard S. Gundersen. (2005). Historical logging, productivity, and structural characteristics of boreal coniferous forests in Norway. Silva Fennica vol. 39 no. 3 article id 479. https://doi.org/10.14214/sf.479

Keywords: boreal forest; stand structure; decaying wood; forest history; naturalness; selective logging; dead trees

Abstract | View details | Full text in PDF | Author Info

Conservation of forest biodiversity has brought about an interest in evaluating the naturalness of forests, and to locate and protect semi-natural and old-growth forests in the Fennoscandian countries. However, it is not always clear how natural these forests really are, and how the past management history has affected their present structural composition. We studied the relationships between cut stumps from historical logging activity (50–100 years ago) and forest structural characteristics of today in a total of 385 0.25 ha plots in three boreal coniferous forests which are parts of National Nature Reserves in Norway. We also studied how forest productivity influenced these relationships. In plots with negligible logging impact we found the amount of living trees, dead wood, and size of the oldest trees mainly to increase with increasing productivity, whereas the age of the oldest trees decreased. The amount of deciduous trees was generally low irrespective of productivity. The intensity of logging did not consistently influence most of these forest structural variables, neither at low- nor at high-productive sites. The only consistent relationship in all study areas was a decreasing amount of dead wood with increasing logging intensity at high-productive sites. Also, the decay class distribution of dead wood was more right-skewed (indicating on-going accumulation of dead wood) the more logging had occurred at high-productive sites. Except from the effects on dead wood, previous logging does not show up as a major determinant of other stand structures of today.

Storaunet, Norwegian Forest Research Institute, Høgskolevegen 8, NO-1432 Ås, Norway E-mail: ken.storaunet@skogforsk.no
Rolstad, Norwegian Forest Research Institute, Høgskolevegen 8, NO-1432 Ås, Norway E-mail: jr@nn.no
Gjerde, Norwegian Forest Research Institute, Fanaflaten 4, NO-5244 Fana, Norway E-mail: ig@nn.no
Gundersen, Norwegian Forest Research Institute, Fanaflaten 4, NO-5244 Fana, Norway E-mail: vsg@nn.no

article id 377, category Research article

Saara Lilja, Timo Kuuluvainen. (2005). Structure of old Pinus sylvestris dominated forest stands along a geographic and human impact gradient in mid-boreal Fennoscandia. Silva Fennica vol. 39 no. 3 article id 377. https://doi.org/10.14214/sf.377

Keywords: disturbances; restoration; stand structure; managed forest; old growth forest

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Stand structural characteristics were examined in old Pinus sylvestris dominated sites in three regions along a broad geographic and human impact gradient in mid-boreal Fennoscandia. The study regions were: 1) Häme in south-western Finland, with a long history of forest utilization, 2) Kuhmo in north-eastern Finland, with a more recent history of intensive forest utilization, and 3) Vienansalo in Russian Karelia, still characterized by a large near-natural forest landscape. Within each region the sampled sites were divided into three human impact classes: 1) near-natural stands, 2) stands selectively logged in the past, and 3) managed stands treated with thinnings. The near-natural and selectively logged stands in Häme and Kuhmo had a significantly higher Picea proportion compared to stands in Vienansalo. In comparison, the proportions of deciduous tree volumes were higher in near-natural stands in Vienansalo compared to near-natural stands in Häme. The pooled tree diameter distributions, both in near-natural and selectively logged stands, were descending whereas managed stands had a bimodal diameter distribution. Structural diversity characteristics such as broken trunks were most common in near-natural stands and in stands selectively logged in the past. The results demonstrate the higher structural complexity of near-natural stands and stands selectively logged in the past compared to managed stands, and highlight that old near-natural stands and stands selectively logged in the past vary widely in their structures. This obviously reflects both their natural variability but also various combinations of pre-industrial land use and human impact on fire disturbance. These factors need to be acknowledged when using “natural” forest structures as a reference in developing strategies for forest management, restoration and nature conservation.

Lilja, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: saara.lilja@helsinki.fi
Kuuluvainen, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: tk@nn.fi

article id 372, category Research article

Ulf Sikström. (2005). Pre-harvest soil acidification, liming or N fertilization did not significantly affect the survival and growth of young Norway spruce. Silva Fennica vol. 39 no. 3 article id 372. https://doi.org/10.14214/sf.372

Keywords: Picea abies; regeneration; limestone; sulphur powder; urea

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Acidification, liming, and N fertilization affect a number of soil properties. Such changes may have an impact on forest regeneration and yield. The aim of this study was to investigate the survival and growth of Picea abies (L.) Karst. planted on plots that had been acidified (in 12 annual treatments totalling 600 or 1200 kg S ha–1 in the form of elemental sulphur), limed (12 x 500 = 6000 kg lime ha–1 in the form of CaCO3) or N-fertilized (3 x 200 = 600 kg N ha–1 in the form of urea) prior to harvest. Trees growing on plots treated with a combination of the N plus the lower S application were also tested. None of the treatments, applied in three replicate stands, significantly influenced either survival or growth of Picea abies trees during the first 11 growing seasons after planting.

Sikström, SkogForsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: ulf.sikstrom@skogforsk.se

article id 371, category Research article

Mika Nieminen, Erkki Ahti, Hannu Nousiainen, Samuli Joensuu, Martti Vuollekoski. (2005). Capacity of riparian buffer zones to reduce sediment concentrations in discharge from peatlands drained for forestry. Silva Fennica vol. 39 no. 3 article id 371. https://doi.org/10.14214/sf.371

Keywords: ditching; suspended solids; peatlands; erosion; riparian buffer zones; water quality protection

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In 1995–2001, the efficiency of riparian buffer zone areas to reduce the concentrations of suspended solids in discharge from peatlands drained for forestry purposes was studied at 7 locations in south-central Finland. The two largest buffer zones reduced the concentrations of suspended solids by > 70%. The efficiency of the three medium-sized buffer zones to reduce through-flow sediment concentrations was 50–60%, but no reduction occurred at the smallest two buffer areas. Thus, the capacity of buffer zones to reduce sediment concentrations was strongly related to their size. However, significant correlations were also found between reduction capacity and inflow water sediment concentrations, although the correlations at the two smallest buffer zones were low. The use of buffer zones in reducing sediment load from peatlands drained for forestry purposes is recommended, but relatively large areas for efficient removal capacity are needed.

Nieminen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mika.nieminen@metla.fi
Ahti, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ea@nn.fi
Nousiainen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: hn@nn.fi
Joensuu, Forestry Development Centre Tapio, Soidinkuja 4, FI-00700 Helsinki, Finland E-mail: sj@nn.fi
Vuollekoski, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mv@nn.fi

article id 370, category Research article

Pekka Tamminen, John Derome. (2005). Temporal trends in chemical parameters of upland forest soils in southern Finland. Silva Fennica vol. 39 no. 3 article id 370. https://doi.org/10.14214/sf.370

Keywords: soil chemistry; acidification; time series

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Changes in chemical soil properties during periods of 12 to 28 years were studied in 54 stands in southern Finland. Relative slopes (%/year) were calculated for the changes in soil variables in order to utilise all the sampling occasions (2–6) covered by the study period. Only the results of new analyses made on the soil samples could be used owing to unpredictable differences between the results of the original and new analyses. During the study period the acidity (pH, exchangeable acidity) of the organic layer had decreased, and the mineral soil had become more acidic only in terms of increased exchangeable aluminium concentrations. An increasing trend in the amount of soil organic matter best explained the acidity variables: it lowered acidity in the organic layer, but increased it in the mineral soil. Acid ammonium acetate extractable nutrients showed decreasing trends over time, apart from an increasing trend for sulphur in the 0–30 cm mineral soil layer. Total concentrations of most elements in the organic layer, including nitrogen and sulphur, also showed a decreasing trend. Changes in the soil variables could not be firmly connected to deposition, wood production or the amount of nutrients accumulated in woody tissues. However, the decrease in sulphur concentrations in the organic layer was clearly linked with the decrease in sulphur deposition in recent years.

Tamminen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: pekka.tamminen@metla.fi
Derome, Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: jd@nn.fi

article id 388, category Research article

Jacob Edlund, Mats Warensjö. (2005). Repeatability in automatic sorting of curved Norway spruce saw logs. Silva Fennica vol. 39 no. 2 article id 388. https://doi.org/10.14214/sf.388

Keywords: Picea abies; compression wood; stem form; bow; scanner; sorting

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Sawn wood from curved logs is prone to have cross grain and contain compression wood, both of which affect the dimensional stability. Different types of curvature can, however, have different effects on both the sawing process and board quality, which is why a standard measure of bow height alone is not enough to sort logs or set the log quality. The aim of this study was to evaluate the repeatability when sorting curved saw logs using a 3D log scanner. In the study, 56 logs were categorized into five different curvature types and four different degrees of curvature severity. The logs were run through a Rema 3D log scanner four times, and the external geometry was recorded. From the geometry data, variables describing log shapes were calculated and used to develop models using linear discriminant analysis, which was used to classify the logs according to curvature type. The accuracy and repeatability were evaluated for the classifications with Cohen’s simple Kappa coefficient. The results of this study showed that it is possible to sort logs by curve type using a 3D log scanner, although sorting by curve type was largely dependent on curve severity. The repeatability test determined that the chance of a curved log being graded identically two consecutive times was 0.40, measured as kappa.

Edlund, SLU, Department of Forest Products and Markets, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: jacob.edlund@spm.slu.se
Warensjö, SLU, Department of Forest Products and Markets, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: mw@nn.se

article id 387, category Research article

Sanna Laukkanen, Teijo Palander, Jyrki Kangas, Annika Kangas. (2005). Evaluation of the multicriteria approval method for timber-harvesting group decision support. Silva Fennica vol. 39 no. 2 article id 387. https://doi.org/10.14214/sf.387

Keywords: group decision support; multicriteria approval; timber-harvesting planning; voting methods

Abstract | View details | Full text in PDF | Author Info

The decision support methods most often used in timber-harvesting planning are based on a single criterion. In this study, a voting-theory-based method called multicriteria approval (MA) is introduced to the group decision support of timber-harvesting. The use of voting methods alleviates the problems caused by the multitude of decision objectives involved in forestry decision-making and by the poor quality of information concerning both the preferences of decision-makers and the evaluation of decision alternatives with respect to the objectives often faced in practical timber-harvesting planning. In the case study, the tactical forest management plan of a forest holding jointly owned by three people was specified at the operative timber-harvesting level. The task was to find the best actual operative alternatives for the harvesting that had been proposed in the tactical plan. These timber-harvesting alternatives were combinations of treatment, timber-harvesting system and the timing of logging. Forest owners established multiple criteria under which the alternatives were evaluated. Two versions of MA were tested, one of them based on individual decision analyses and other one based on a composite analysis. The first was markedly modified from the original MA, combining properties of MA and Borda count voting. The other was an original MA with the order of importance for criteria estimated either using Borda count or cumulative voting. The results of the tested MA versions produced were very similar to each other. MA was found to be a useful tool for the group decision support of timber-harvesting.

Laukkanen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: sanna.laukkanen@joensuu.fi
Palander, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: tp@nn.fi
Kangas, UPM-Kymmene Forest, P.O. Box 32, FI-37601 Valkeakoski, Finland E-mail: jk@nn.fi
Kangas, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ak@nn.fi

article id 386, category Research article

Jouni Kalliovirta, Timo Tokola. (2005). Functions for estimating stem diameter and tree age using tree height, crown width and existing stand database information. Silva Fennica vol. 39 no. 2 article id 386. https://doi.org/10.14214/sf.386

Keywords: forest inventory; modeling; crown diameter; stem diameter

Abstract | View details | Full text in PDF | Author Info

The aim was to investigate the relations between diameter at breast height and maximum crown diameter, tree height and other possible independent variables available in stand databases. Altogether 76 models for estimating stem diameter at breast height and 60 models for tree age were formulated using height and maximum crown diameter as independent variables. These types of models can be utilized in modern remote sensing applications where tree crown dimensions and tree height are measured automatically. Data from Finnish national forest inventory sample plots located throughout the country were used to develop the models, and a separate test site was used to evaluate them. The RMSEs of the diameter models for the entire country varied between 7.3% and 14.9% from the mean diameter depending on the combination of independent variables and species. The RMSEs of the age models for entire country ranged from 9.2% to 12.8% from the mean age. The regional models were formulated from a data set in which the country was divided into four geographical areas. These regional models reduced local error and gave better results than the general models. The standard deviation of the dbh estimate for the separate test site was almost 5 cm when maximum crown width alone was the independent variable. The deviation was smallest for birch. When tree height was the only independent variable, the standard deviation was about 3 cm, and when both height and maximum crown width were included it was under 3 cm. In the latter case, the deviation was equally small (11%) for birch and Norway spruce and greatest (13%) for Scots pine.

Kalliovirta, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: jk@nn.fi
Tokola, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: timo.tokola@helsinki.fi

article id 399, category Research article

Torjus F. Bolkesjø. (2005). Projecting pulpwood prices under different assumptions on future capacities in the pulp and paper industry. Silva Fennica vol. 39 no. 1 article id 399. https://doi.org/10.14214/sf.399

Keywords: paper industry; Norway; capacity; partial equilibrium model; pulpwood; prices

Abstract | View details | Full text in PDF | Author Info

Capacity changes in the pulp and paper industry affect demand for pulpwood and thus pulpwood prices. This paper analyzes the impacts on roundwood prices in Norway of two possible capacity changes (one new machine and one close-down) that currently are high on the agenda in the Norwegian paper industry, and assesses the generality of the results obtained from these case studies. The two cases are implemented exogenously into a regionalized partial equilibrium forest sector model, and the capacity change scenarios are compared with a business as usual scenario assuming no demand shocks. The projected pulpwood prices change significantly in regions near mills where capacity shifts, at least for the close-down case, but only moderately at an aggregated national level. The reduction in prices under the close-down studied is higher than the price increase from the possible capacity increase case. The asymmetric price responses projected for the two case studies are supported by sensitivity analyses on other regions and cases (technologies). For the capacity increase case it is shown that the level of the projected pulpwood price is sensitive to assumptions on base-year prices and transport costs of imported roundwood, but the magnitudes of the price increases projected as a result of increased demand are less affected by these assumptions.

Bolkesjø, Norwegian University of Life Sciences, Dept. of Ecology and Natural Resource Management, Høyskoleveien 14, NO-1432 Ås, Norway E-mail: torjus.bolkesjo@umb.no

article id 398, category Research article

Heikki Ovaskainen. (2005). Comparison of harvester work in forest and simulator environments. Silva Fennica vol. 39 no. 1 article id 398. https://doi.org/10.14214/sf.398

Keywords: time study; single-grip harvester; harvester simulator; working technique; PlusCan

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Harvester simulators offer a safe and cost-saving method for studying the basics of harvester controls and working technique. Therefore, harvester simulators are increasingly being used in the education of harvester operators. In this study, the objective was to compare harvester work in real and simulator environments, and to determine how a professional harvester operator’s working technique may have changed in the simulator environment. Specific features of the simulator that encumbered operators’ normal work are also presented; and the correspondence of the simulator to reality is evaluated. The work of six professional harvester operators was studied in thinning and in clear cutting stands in both environments: first in the real forest and thereafter on the simulator. The results indicate that the operators’ working technique on the simulator was mainly the same as in the real forest. This means that the same restrictions are valid on the simulator as in the forest. The basic principles of harvesting must be known so that high productivity and good quality can be obtained. However, certain simulator-specific features encumbered the work of harvester operators. Limited visibility to the side increased the need to reverse and the 3D-visualization caused failed catches. Improvements in software would remove some of the defects, e.g. failed felling and cheating in the felling phase. These results also indicate that simulators can be used for research purposes.

Ovaskainen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: heikki.ovaskainen@joensuu.fi

article id 397, category Research article

Nuutti Kiljunen. (2005). Pricing the risk of the quality-guarantee in a stand establishment service. Silva Fennica vol. 39 no. 1 article id 397. https://doi.org/10.14214/sf.397

Keywords: quality; forest regeneration; risk; guarantee

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A stand-establishment service concept with quality guarantee was analysed. Here, the quality of stand establishment was assessed as the density of good quality seedlings evenly distributed on the plantation three years after planting. The amount of adequate premiums for the guarantee service and the risks accumulating to the service provider were studied. Monte Carlo simulation was used as a tool for analyzing the risks accumulating to the service provider of the stand-establishment in operational environments of different sizes. The premiums calculated to cover the expected amount of claims caused by the plantations not meeting the pre-set criteria were about 4–8% in addition to the approximated costs of stand establishment. The criteria used for determining the success or failure in a stand have a marked effect on the amount of premiums with a reasonable risk of ruin.

Kiljunen, Finnish Forest Research Institute, Suonenjoki Research Station, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: nuutti.kiljunen@metla.fi

article id 396, category Research article

Timo Pukkala, Mikko Kurttila. (2005). Examining the performance of six heuristic optimisation techniques in different forest planning problems. Silva Fennica vol. 39 no. 1 article id 396. https://doi.org/10.14214/sf.396

Keywords: genetic algorithms; simulated annealing; ecological planning; habitat suitability index (HSI); Hero; random search; tabu search

Abstract | View details | Full text in PDF | Author Info

The existence of multiple decision-makers and goals, spatial and non-linear forest management objectives and the combinatorial nature of forest planning problems are reasons that support the use of heuristic optimisation algorithms in forest planning instead of the more traditional LP methods. A heuristic is a search algorithm that does not necessarily find the global optimum but it can produce relatively good solutions within reasonable time. The performance of different heuristics may vary depending on the complexity of the planning problem. This study tested six heuristic optimisation techniques in five different, increasingly difficult planning problems. The heuristics were evaluated with respect to the objective function value that the techniques were able to find, and the time they consumed in the optimisation process. The tested optimisation techniques were 1) random ascent (RA), 2) Hero sequential ascent technique (Hero), 3) simulated annealing (SA), 4) a hybrid of SA and Hero (SA+Hero), 5) tabu search (TS) and 6) genetic algorithm (GA). The results, calculated as averages of 100 repeated optimisations, were very similar for all heuristics with respect to the objective function value but the time consumption of the heuristics varied considerably. During the time the slowest techniques (SA or GA) required for convergence, the optimisation could have been repeated about 200 times with the fastest technique (Hero). The SA+Hero and SA techniques found the best solutions for non-spatial planning problems, while GA was the best in the most difficult problems. The results suggest that, especially in spatial planning problems, it is a benefit if the method performs more complicated moves than selecting one of the neighbouring solutions. It may also be beneficial to combine two or more heuristic techniques.

Pukkala, University of Joensuu, Faculty of Forestry, P.O. BOX 111, FI-80101 Joensuu, Finland E-mail: timo.pukkala@forest.joensuu.fi
Kurttila, Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: mk@nn.fi

article id 395, category Research article

Lauri Mehtätalo. (2005). Height-diameter models for Scots pine and birch in Finland. Silva Fennica vol. 39 no. 1 article id 395. https://doi.org/10.14214/sf.395

Keywords: mixed model; longitudinal analysis; random parameter; stand development

Abstract | View details | Full text in PDF | Author Info

Height-Diameter (H-D) models for two shade-intolerant tree species were estimated from longitudinal data. The longitudinal character of the data was taken into account by estimating the models as random effects models using two nested levels: stand and measurement occasion level. The results show that the parameters of the H-D equation develop over time but the development rate varies between stands. Therefore the development of the parameters is not linked to the stand age but to the median diameter of the basal-area weighted diameter distribution (DGM). Models were estimated with different predictor combinations in order to produce appropriate models for different situations. The estimated models can be localized for a new stand using measured heights and diameters, presumably from different points in time, and the H-D curves can be projected into the future.

Mehtätalo, Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: lauri.mehtatalo@metla.fi

article id 393, category Research article

Seppo Rouvinen, Anne Rautiainen, Jari Kouki. (2005). A relation between historical forest use and current dead woody material in a boreal protected old-growth forest in Finland. Silva Fennica vol. 39 no. 1 article id 393. https://doi.org/10.14214/sf.393

Keywords: Populus tremula; Pinus sylvestris; Picea abies; coarse woody debris; forest utilization; historical ecology; land-use history; nature conservation; spatial pattern analysis

Abstract | View details | Full text in PDF | Author Info

Assessing the human impact on the naturalness and vegetation characteristics of protected areas is one of the key issues when designing forest conservation networks in Fennoscandia. We studied the small-scale, detailed relationship between forest utilization history and the current availability of dead woody material in a protected old-growth forest area in North Karelia, eastern Finland. From the study area of 32.4 ha, all the stumps (diameter ≥ 5 cm and height < 1.3 m, classified as natural, man-made and of undetermined origin) were measured using 25 x 25 m sub-plots. Standing and fallen dead trees (dbh ≥ 5 cm) were measured on 50 x 50 m plots in an area of 7.8 ha. The average number of stumps was 130 per ha, and over half of the stumps were classified as man-made. However, the historical documents since the 1910s showed no logging in the area: some of the largest man-made stumps probably originated from an earlier time, but most of those stumps were made considerably later. The variation in the total number of stumps (per ha) was great (range 0–560/ha, 0–16 m2/ha), with no clear clustering in space. However, clustering of man-made stumps was detected. The average volume of pooled standing and fallen trees was 84 m3/ha, with a range of 37–146 m3/ha. The other noticeable man-made disturbance besides logging was notching of aspens, which has a scatteredly significant influence on the amount of dead trees. In conclusion, the protected old-growth forest was not as a whole in a natural state but showed different degrees of human impact from virtually untouched patches to quite heavily managed patches. The results suggest that the number of man-made stumps may be a relatively quick and easy method of assessing the naturalness of woody biomass structure in the Fennoscandian boreal forests.

Rouvinen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: seppo.rouvinen@joensuu.fi
Rautiainen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: ar@nn.fi
Kouki, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: jk@nn.fi

article id 408, category Research article

Sakari Sarkkola, Hannu Hökkä, Timo Penttilä. (2004). Natural development of stand structure in peatland Scots pine following drainage: results based on long-term monitoring of permanent sample plots. Silva Fennica vol. 38 no. 4 article id 408. https://doi.org/10.14214/sf.408

Keywords: Pinus sylvestris; peatland; tree mortality; stand structure; drainage; dbh distribution

Abstract | View details | Full text in PDF | Author Info

We studied the dynamics of stand structure on drained peatland sites in Scots pine dominated stands untreated with thinnings. The data consisted of consecutive stand measurements in 10 permanent sample plots where the monitoring periods varied from 29 to 66 years. We assumed that the stand’s structural development was driven by the natural processes of regeneration, growth, and mortality, all related to inter-tree competition within the stand. The DBH distributions of live and dead trees at different times of post-drainage stand development – smoothed by Weibull function – were analysed to characterise the change in stand structure. The initial uneven-sized structure of the natural, widely-spaced stands became more uneven during the first decades following drainage due to enhanced regeneration. Later, as stand density and mean tree size continuously increased, the DBH distributions approached bell-shaped distributions. Accordingly, the suppressed trees showed their highest mortality rate during the first decades, but the peak of the mortality distribution shifted to larger trees along stand succession. The change in structure was faster in southern Finland than in northern Finland. We assumed the changes in stand dynamics reflected increased inter-tree competition, initiated by enhanced site productivity and increased stand stocking resulting from the ditching operation.

Sarkkola, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: sakari.sarkkola@helsinki.fi
Hökkä, Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: hh@nn.fi
Penttilä, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: tp@nn.fi

article id 405, category Research article

Timo Saksa. (2004). Regeneration process from seed crop to saplings – a case study in uneven-aged Norway spruce-dominated stands in southern Finland. Silva Fennica vol. 38 no. 4 article id 405. https://doi.org/10.14214/sf.405

Keywords: boreal forest; Picea abies; regeneration; uneven-aged

Abstract | View details | Full text in PDF | Author Info

The dynamics of spruce regeneration, from seed crop to saplings, was studied based on five permanent plots in uneven-aged, spruce-dominated, boreal forest stands, cut with single-tree selection in the beginning of the 1990’s. The annual fluctuation of the spruce seed crop was very similar in uneven-aged and even-aged stands. The correlation between seed crop and number of germinants was significant; but stem number, basal area or volume of the stand did not influence on seedling emergence. The effects of good seed crops were seen as peaks or an increase in the number of germinants and smallest seedlings. The mean number of ‘stabilised’ spruce seedlings (height 11 cm to 130 cm) varied from 6000 ha^–1 to over 25 000 spruce seedlings ha^–1 from one monitoring plot to another. On a monitoring plot the number of ‘stabilised’ spruce seedlings was stable over time. Neither stand basal area nor stand volume influenced the number of ‘stabilised’ spruce seedlings, but the height of these seedlings was higher on subplots with lower stand volume and smaller basal area. In this study the monitoring period, 5–10 years, was too short to obtain reliable figures for ingrowth, i.e. the transition of seedlings to the sapling stage (h > 130 cm). The adjusted mean ingrowth was 26 stems ha^–1 year^–1.

Saksa, Finnish Forest Research Institute, Suonenjoki Research Station, FI-77600 Suonenjoki, Finland E-mail: timo.saksa@metla.fi

article id 404, category Research article

William L. Mason, Colin Edwards, Sophie E. Hale. (2004). Survival and early seedling growth of conifers with different shade tolerance in a Sitka spruce spacing trial and relationship to understorey light climate. Silva Fennica vol. 38 no. 4 article id 404. https://doi.org/10.14214/sf.404

Keywords: seedling growth; light regime; stand density; irregular silviculture

Abstract | View details | Full text in PDF | Author Info

Alternative silvicultural systems to clearfelling are being adopted in Great Britain as a means of increasing the species and structural diversity of conifer plantation forests. One area where knowledge is lacking is the critical level of below-canopy light for survival and growth of young seedlings. This was investigated by planting seedlings of European larch Larix decidua (Mill.), Scots pine Pinus sylvestris L., Sitka spruce Picea sitchensis (Bong.(Carr.)), Douglas fir Pseudotsuga menziesii (Mirb.(Franco.)), and western hemlock Tsuga heterophylla (Raf. (Sarg.)) in a Sitka spruce plantation thinned to 3 different spacings. The incident light intensity beneath the canopy ranged from about 2 to over 60 per cent of full light. Planting in an adjoining open area provided an indication of growth under full light. Growth and survival of these seedlings were followed for 4 growing seasons. The highest seedling survival was found under the widest spacing and declined with closer spacing and lower light intensity. Only Douglas fir and western hemlock seedlings survived at the closest spacing, and in low percentages. The tallest seedlings of each species were found in the open grown conditions but survival was variable due to increased weed competition. Species-specific growth responses showed little difference under high light conditions but performance at low light was generally consistent with shade tolerance rankings in the literature except that Sitka spruce shade tolerance was slightly lower than expected. Minimum light requirements for these species increased from 10 to 30 per cent of full light with decreasing shade tolerance. Other studies of incident light in Sitka spruce plantations indicated that target basal areas in the range 25–30 m2 ha–1 are required if these light conditions are to be met, which suggests an irregular shelterwood system with frequent interventions should be favoured.

Mason, Forest Research, Northern Research Station, Roslin, Midlothian, Scotland, UK, EH25 9SY E-mail: bill.mason@forestry.gsi.gov.uk
Edwards, Forest Research, Northern Research Station, Roslin, Midlothian, Scotland, UK, EH25 9SY E-mail: ce@nn.uk
Hale, Forest Research, Northern Research Station, Roslin, Midlothian, Scotland, UK, EH25 9SY E-mail: seh@nn.uk

article id 419, category Research article

Tero Heinonen, Timo Pukkala. (2004). A comparison of one- and two-compartment neighbourhoods in heuristic search with spatial forest management goals. Silva Fennica vol. 38 no. 3 article id 419. https://doi.org/10.14214/sf.419

Keywords: simulated annealing; Hero; tabu search; 2-optimal heuristic; spatial optimisation; random ascent

Abstract | View details | Full text in PDF | Author Info

This study presents a comparison of the performance of four heuristic techniques with one- and two-compartment neighbourhoods in harvest scheduling problems including a spatial objective variable. The tested heuristics were random ascent, Hero, simulated annealing and tabu search. All methods seek better solutions by inspecting the neighbourhood solutions, which are combinations that can be obtained by changing the treatment schedule in one (one-compartment neighbourhood) or two (two-compartment neighbourhood) compartments. The methods and neighbourhoods were examined in one artificial and four real landscapes ranging from 700 to 981 ha in size. The landscapes had 608 to 900 stand compartments, and the examined planning problems had 2986 to 4773 binary decision variables. The objective function was a multi-objective utility function. The spatial objective variable was the percentage of compartment boundary that joins two compartments, both of which are to be cut during the same 20-year period. The non-spatial objectives were net incomes of three consecutive 20-year management periods and the remaining growing stock volume at the end of the third 20-year period. In another problem formulation, the total harvest of the first 20-year period was used as an objective variable together with the spatial objective. The results showed that a two-compartment neighbourhood was systematically and often clearly better than a one-compartment neighbourhood. The improvements were greatest with the simplest heuristics, random ascent and Hero. Of the four heuristics, tabu search and simulated annealing proved to be the best methods, but with a two-compartment neighbourhood the differences between methods were negligible.

Heinonen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: th@nn.fi
Pukkala, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: timo.pukkala@joensuu.fi

article id 413, category Research article

Mika Nieminen, Timo Penttilä. (2004). Inorganic and organic phosphorus fractions in peat from drained mires in northern Finland. Silva Fennica vol. 38 no. 3 article id 413. https://doi.org/10.14214/sf.413

Keywords: tree growth; drained peatland forests; phosphorus availability; sequential fractionation; site type classification

Abstract | View details | Full text in PDF | Author Info

Soil samples from 15 eutrophic, 26 herb-rich, 15 tall-sedge, and 11 low-sedge drained peatland sites were analysed for easily soluble and aluminum, iron, and calcium bound phosphorus (P) using the Chang and Jackson sequential fractionation method. Compared to earlier investigations, where only total and easily soluble P contents (e.g. NH4OAc or dilute H2SO4 extractable P) in peat have been analysed, significantly higher differences between sites were observed. The eutrophic sites were characterized by four to six-fold greater Ca-bound organic P and two to three-fold greater Ca-bound inorganic P contents than on the other three site type groups, whereas the average Al-bound inorganic P content of the eutrophic sites was only one-third of that at the other site types. Substantial differences between sites were also observed for Fe-bound inorganic P, i.e. two to four-fold greater Fe-P contents were measured at the herb-rich sites compared with the other three site type groups. The stand volume growth in the 67 studied drained peatland sites correlated significantly with Al-bound organic P and Fe-bound inorganic and organic P. The study showed that a detailed fractionation and discrimination of different forms of soil P is important in increasing the understanding of the relationship between P availability and vegetation community types and stand growth on drained peatlands.

Nieminen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mika.nieminen@metla.fi
Penttilä, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: tp@nn.fi

article id 430, category Research article

Mårten Hugosson, Fredrik Ingemarson. (2004). Objectives and motivations of small-scale forest owners; theoretical modelling and qualitative assessment. Silva Fennica vol. 38 no. 2 article id 430. https://doi.org/10.14214/sf.430

Keywords: forest management; small-scale forest owners; professional foresters; forest owners’ objectives; forest owners’ motivations; forest owners’ values

Abstract | View details | Full text in PDF | Author Info

Forest management changes with societal change, and it has been debated if economic development in society places material objectives in a less preferable position: it is assumed this is also the case as regards forest management. The aims of this study were to propose a theoretical model for empirical studies of objectives and motivations within this field and to depict motivations and objectives of small-scale forest owners in Sweden. Comparative literature studies were undertaken and qualitative methodology was used for the empirical studies. Firstly, to depict general trends among forest owners, interviews with professional foresters were conducted. Secondly, forest owners throughout Sweden were interviewed to compare the results of the interviews with the professional foresters on the motivations and objectives of small-scale forest owners. Within the literature, there were no consistent views on the subjective grounds for owning and managing small-scale forest estates. The proposed theoretical model originated from the cultural concept. Sets of interpretive and normative qualities were seen as underlying people’s actions, and such sets were related to basic values. The ‘objectives’ were clustered into groups creating four clusters i.e. ‘motivations’. The four motivations depicted were: Conservation; Utilities; Amenities and Economic Efficiency. The empirical results highlighted that the objectives and motivations of forest-owners covered a broad field and a move towards conservation interests was indicated. The theoretical model presented here is suggested a suitable tool for both depicting the motivations and objectives of forest owners and for making future comparisons.

Hugosson, Department of Forest Products and Markets, Swedish University of Agricultural Sciences, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: mh@nn.se
Ingemarson, Department of Forest Products and Markets, Swedish University of Agricultural Sciences, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: fredrik.ingemarson@spm.slu.se

article id 429, category Research article

Juho Rantala. (2004). Optimizing the supply chain strategy of a multi-unit Finnish nursery company. Silva Fennica vol. 38 no. 2 article id 429. https://doi.org/10.14214/sf.429

Keywords: economies of scale; supply chain management; optimization; mixed integer programming; seedling production

Abstract | View details | Full text in PDF | Author Info

This paper introduces a capacitated mixed integer programming (CMIP) model for solving an integrated production-distribution system design problem (PDSDP) in the seedling supply chain management (SCM) of a multi-unit Finnish nursery company. The model was originally developed from a strategic perspective in which a company desires to evaluate the expansion or closure of its facilities. Nevertheless, the model is also used for solving operational and tactical level problems by applying applicable constraints. The data were collected from the company studied. The results proved that economies of scale could be exploited in seedling production more than the company does today; Compared to the company’s current supply chain strategy with 5 nursery units producing seedlings, when other supply chain strategies were applied the number of nursery units decreased by 2–4 units, and cost savings in the supply chain varied from 11.3% to 21.3%.

Rantala, Finnish Forest Research Institute, Suonenjoki Research Station, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: juho.rantala@metla.fi

article id 428, category Research article

Jonny Andersson, Lars Eliasson. (2004). Effects of three harvesting work methods on Harwarder productivity in final felling. Silva Fennica vol. 38 no. 2 article id 428. https://doi.org/10.14214/sf.428

Keywords: forwarder; harvester; work method

Abstract | View details | Full text in PDF | Author Info

During the last ten years interest in the harwarder has increased, however, studies have concentrated on effects of technical improvements on machine productivity. It has been noted that there is a large potential to increase the productivity through development of suitable work methods. To find efficient work patterns for a harwarder with a turnable loading area, three different harvesting methods were studied in final felling. Three work methods were used. Method 1: the harwarder drove backwards into the stand making a strip road, strip road trees were felled and left on the ground, on the way out of the stand the harwarder cut and processed the trees on both sides of the machine directly into the loading area. Method 2: the harwarder drove forward along the edge of the cut, cutting and processing trees directly into the loading area. Method 3: the harwarder drove forward into the stand and cut and processed strip road trees and trees standing on both sides of the machine directly into the loading area. The most efficient work method was method 2 where the productivity was 13.0 m3 u.b. per E0h (cubic metre under bark per effective hour). The productivities for method 1 and 3 were 12.1 and 11.9 m3 u.b. per E0h, respectively. In addition to work method harwarder productivity was shown to be dependent on load volume, average tree size and hauling distance. The only work elements significantly affected by work methods were processing and movement during processing. The operator had only a few weeks to get used to the machine and even less time to practise on the work methods. Thus, it is probable that the productivity for the studied methods will increase with increasing work experience. Furthermore, as only three work methods were studied, there are still untested work methods. The potential to further improve harwarder work methods is considerable.

Andersson, Swedish University of Agricultural Sciences, Department of Silviculture, S-901 83 Umeå, Sweden E-mail: je@nn.se
Eliasson, Swedish University of Agricultural Sciences, Department of Silviculture, S-901 83 Umeå, Sweden E-mail: lars.eliasson@ssko.slu.se

article id 427, category Research article

Scott A. Weyenberg, Lee E. Frelich, Peter B. Reich. (2004). Logging versus fire: how does disturbance type influence the abundance of Pinus strobus regeneration? Silva Fennica vol. 38 no. 2 article id 427. https://doi.org/10.14214/sf.427

Keywords: disturbance refugia; interspecific competition; Minnesota; seedling dispersion; seed source; white pine

Abstract | View details | Full text in PDF | Author Info

Eastern white pine (Pinus strobus) has decreased in abundance over the past century throughout the Great Lakes Region of North America, but the relative constraints placed on recruitment under contrasting disturbance regimes are not well understood. The objectives of this study were to determine the extent to which white pine could invade areas recently disturbed by fire or logging (within 10–28 years), and assess the relative limitations placed on recruitment by seed supply, microsite habitat, and competition. We compared white pine regeneration on 61 sites disturbed by fire or logging that were adjacent to intact mature stands that provided a seed source. White pine seedling and sapling densities declined with increasing distance from a seed source, and the rate of decrease was determined by the interaction between seed supply and variation in number and quality of safe sites. For a given combination of seed source and site, white pine seedlings were three times more abundant on burned than logged sites. White pine seedlings grew into the sapling size class more often on burned than logged sites due to lower shrub cover on burned sites. At 25 years after disturbance, regeneration densities of white pine sufficient to achieve eventual future dominance occurred up to 80 m and 20 m from the edge of mature white pine stands after fire and logging, respectively. To attain a similar level of white pine stocking after disturbance, three to four times as many patches of mature white pine need to be left after logging than after fire.

Weyenberg, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: saw@nn.us
Frelich, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: freli001@umn.edu
Reich, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: pbr@nn.us

article id 425, category Research article

Petteri Vanninen. (2004). Allocation of above-ground growth in Pinus sylvestris – impacts of tree size and competition. Silva Fennica vol. 38 no. 2 article id 425. https://doi.org/10.14214/sf.425

Keywords: Scots pine; allocation; growth efficiency

Abstract | View details | Full text in PDF | Author Info

The effect of tree age, size and competition on above ground growth allocation was studied with 69 Pinus sylvestris trees. Competition was described by tree-level indicators (needle density, crown ratio and height-diameter ratio). The stem, branch and needle growth were determined by stem and branch radial increments and tree level biomass analysis. Combined growth of compartments was strongly correlated with needle mass. Furthermore, tree age, size and competition indicators affected the allocation of growth among the compartments. The allocation of growth to stem and needle increased with tree age and size while the allocation of growth to branch decreased. The increasing crown ratio increased allocation of growth to branches. The combined growth of the components and separate growth of needles, branches and stem were related to needle mass. However, competition and tree size were significant additional explanatory variables when the stem, branch and needle growth were estimated according to needle mass. The growth efficiency increased with relative tree height and decreased with increasing needle density.

Vanninen, University of Helsinki, Department of Forest Ecology; mailing address: SAIMA – Centre for Environmental Sciences, Linnankatu 11, FIN-57130 Savonlinna, Finland E-mail: petteri.vanninen@helsinki.fi

article id 424, category Research article

Mats Warensjö, Göran Rune. (2004). Stem straightness and compression wood in a 22-year-old stand of container-grown Scots pine trees. Silva Fennica vol. 38 no. 2 article id 424. https://doi.org/10.14214/sf.424

Keywords: Pinus sylvestris; stem form; eccentricity; reaction wood

Abstract | View details | Full text in PDF | Author Info

The distribution of compression wood in relation to eccentric growth and development of stem straightness was studied in a 22-year-old Scots pine (Pinus sylvestris L.) stand in central Sweden that was established with container-grown seedlings. Stem straightness was measured on the same 440 trees in 1986 and 1997. The number of stems with straight base sections increased from 60% in 1986 to 89% in 1997. Measurements of 72 sample trees in 2001 showed that 96% of the trees had developed straight stem bases. External geometry data of the logs was obtained with a Rema 3D log scanner. A sub-sample of 16 trees was randomly selected for analysis of compression wood distribution and eccentricity measurements. From each tree, 11 discs were cut at every 60 cm along the stem. All discs, except one, contained compression wood. Compression wood and pith eccentricity was most pronounced near the stem base but not significantly correlated to basal sweep. Severe compression wood content was correlated to pith eccentricity and bow height. In general, correlations were better for the basal sections of the logs. Even though most trees were straight, they contained large amounts of compression wood. It is evident that eccentric growth and compression wood formation play major roles in the development of stem straightness. In several stems, a spiral compression wood distribution pattern was found. Reasons for this are discussed.

Warensjö, Department of Forest Products and Markets, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden E-mail: mats.warensjo@spm.slu.se
Rune, Department of Forestry and Wood Technology, Dalarna University, SE-776 98 Garpenberg, Sweden E-mail: gr@nn.se

article id 422, category Research article

Mika Nieminen. (2004). Export of dissolved organic carbon, nitrogen and phosphorus following clear-cutting of three Norway spruce forests growing on drained peatlands in southern Finland. Silva Fennica vol. 38 no. 2 article id 422. https://doi.org/10.14214/sf.422

Keywords: hydrochemistry; forest regeneration; peatland forestry; leaching; nutrient losses

Abstract | View details | Full text in PDF | Author Info

The effect of clear-cutting on the concentrations of dissolved organic carbon (DOC), organic nitrogen (DON), NH4+, NO3–, and P in outflow water from three productive, Norway spruce dominated drained peatlands (RCC, VCC-1, VCC-2) were studied. Changes in runoff and transport loads (concentration x runoff) at two of the catchments during the frost-free period are also presented. Approximately 40% of the area was cut at RCC and VCC-2, and 72% at VCC-1. The volume removed was 250 m3 ha–1 at RCC, 259 m3 ha–1 at VCC-1, and for VCC-2, 317 m3 ha–1. The mean annual increase in outflow concentrations of DOC during the first four years after clear-cutting was 9.0 mg l–1 at RCC, 22.8 mg l–1 at VCC-1 and 8.4 mg l–1 at VCC-2. Corresponding increases in the forms of nitrogen were: 0.23, 0.51 and 0.16 mg DON l–1; 0.06, 0.31 and 0.04 mg NH4+-N l–1; and 0.05, 0.12 and 0.22 mg NO3–-N l–1. Clear-cutting did not significantly (p > 0.05) increase P concentrations. The increase in non-frost season runoff over the first three years after clear-cutting was 107 mm at RCC and 207 mm at VCC-1. The export loads of DOC during the non-frost season increased by 80 kg ha–1 at RCC and by 184 kg ha–1 at VCC-1 over the first three years. Corresponding increases for the other studied solutes were: 1.78 and 3.98 kg DON ha–1; 0.39 and 1.49 kg NH4+-N ha–1; 0.45 and 0.48 kg NO3–-N ha–1, and 0.09 and 0.06 kg P ha–1. The study demonstrated that clear-cutting may significantly increase the export of DOC and different forms of nitrogen from drained productive peatlands while only small increases in phosphorus export may occur.

Nieminen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: mika.nieminen@metla.fi

article id 439, category Research article

Christina Lundgren. (2004). Microfibril angle and density patterns of fertilized and irrigated Norway spruce. Silva Fennica vol. 38 no. 1 article id 439. https://doi.org/10.14214/sf.439

Keywords: ring width; growth rate; juvenile wood; MoE; X-ray diffraction

Abstract | View details | Full text in PDF | Author Info

Two Norway spruce nutrient optimisation trials, one in the north of Sweden and one in the south, were used to study the effects of intensive growth and fertilization on wood density and microfibril angle. Three different treatments and a control were available; daily irrigation, daily liquid fertilization and solid fertilization. The nutrient optimisation was based on foliage analysis and the solid fertilization essentially comprised the same amount of nutrients but was applied annually in solid form. Measurements of density and microfibril angle (MFA) were performed using X-ray diffraction. Growth rate, expressed as a transformation of annual ring width, was very important at the southern site when the effect of cambial maturation had been taken into account. Effects of both fertilization and irrigation remained strong and significant for density, and irrigation was a significant factor explaining MFA. At the northern site distance from pith was the dominant factor but the effect of growth rate was also strong and the treatment effect was significant for both density and MFA. The combination of higher MFA and decrease in density for fertilized trees resulted in a lower calculated strength of the wood. An over 100% increase in ring width only corresponded to approximately a 20% decrease in wood density and the production of wood dry matter was hence increased by treatments.

Lundgren, SLU, Dept. of Forest Products and Markets, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: christina.lundgren@spm.slu.se

article id 436, category Research article

Martti Varmola, Hannu Salminen, Mauri Timonen. (2004). Thinning response and growth trends of seeded Scots pine stands at the arctic timberline. Silva Fennica vol. 38 no. 1 article id 436. https://doi.org/10.14214/sf.436

Keywords: Pinus sylvestris; thinning; growth and yield; northern timberline

Abstract | View details | Full text in PDF | Author Info

Growth patterns and reactions of Scots pine (Pinus sylvestris L.) to thinning in extremely harsh climatic conditions were studied in two seeded Scots pine stands located on the arctic timberline. Coniferous trees usually do not form closed stands at the timberline, but occur only in scattered tree groups. The trial was established in two stands in 1985–1986 when the trees were at an age of 47 and 56 years and an average dominant height of 6.0–6.9 m. The trial was remeasured in 1998. The thinning treatments reduced the stem number for five different levels; final density of 300, 550, 800, 1050, and 1300 stems ha–1 and unthinned. The experiment had a randomised block design with four replications in each stand. The increased growing space provided by thinning accelerated diameter growth after a delay of 2–3 years. The differences between the radial growth of the thinning treatments were very clear during the whole 13- to 14-year observation period. Annual increment of the mean diameter was regularly the higher, the larger the spacing. Dominant diameter was less influenced by treatments. There were no significant differences in dominant height between any of the treatments. Both basal area and volume were regularly the greater the higher the stem number was. Even a relatively light thinning had a distinct positive effect on tree growth, i.e. not carrying out thinning resulted in a production loss of merchantable wood. According to the results, seeded stands on the arctic timberline can grow surprisingly well in favourable conditions and reach a dominant height of 12–14 m in 100 years and a mean annual increment of 1.0–1.5 m3 ha–1 y–1 over a rotation period of 130–160 years. Based on increment figures and thinning reactions, a spacing of ca. 1000 stems ha–1 can be recommended.

Varmola, The Finnish Forest Research Institute, Rovaniemi Research Station, P.O.Box 16, FIN-96301 Rovaniemi, Finland E-mail: martti.varmola@metla.fi
Salminen, The Finnish Forest Research Institute, Rovaniemi Research Station, P.O.Box 16, FIN-96301 Rovaniemi, Finland E-mail: hs@nn.fi
Timonen, The Finnish Forest Research Institute, Rovaniemi Research Station, P.O.Box 16, FIN-96301 Rovaniemi, Finland E-mail: mt@nn.fi

article id 432, category Research article

Bo Långström, Claes Hellqvist, Jan Cedervind. (2004). Comparison of methods for estimation of needle losses in Scots pine following defoliation by Bupalus piniaria. Silva Fennica vol. 38 no. 1 article id 432. https://doi.org/10.14214/sf.432

Keywords: Pinus sylvestris; pine looper; undefoliated foliage; needle biomass; CIR-pictures

Abstract | View details | Full text in PDF | Author Info

In 1996, ca. 7000 hectares of pine forests at Hökensås in SW Sweden were defoliated by the pine looper, Bupalus piniara (L.) (Lepidoptera. Geometridae). Following an aerial damage survey using CIR (colour infra red) photography, and estimation of pupal densities in the soil, ca 4000 ha of the most defoliated pine stands were sprayed in early August 1997 with Bacillus thuringiensis var. kurstaki. The control operation was succeessful but probably redundant, as no further defoliation occurred in unsprayed reference areas. In order to assess defoliation levels in different damage classes for later growth loss studies, 47 circular study plots were laid out in pine stands representing different damage and age classes. The remaining foliage was recorded for each tree using the following classes: 0, 10, 30, 50, 70, 90 and 100%. The defoliation levels in 1996 were estimated by disregarding the 1997 needle age class. Thirteen ca. 40-year-old sample trees representing different damage classes were felled, and the remaining foliage of all branches was estimated by needle age class using the above-mentioned scale. One branch in each of the whorls 1996, 1991, 1986 and 1981 was sampled and its needle dry weight was determined. The sample branch data confirmed the field observations that virtually no additional defoliation took place in 1997. The damage classes estimated from the CIR-pictures only agreed with the field damage estimates at the higher end of the damage scale. In contrast, the field estimate correlated well with plot means derived from tree-wise estimates (R2 = 0.93), and with with the calculated needle biomasses per tree (R2 = 0.90). Thus, the field damage classification was supported by the more detailed defoliation estimates, and hence forms a relevant basis for later growth loss studies.

Långström, SLU, Dept. of Entomology, P.O.Box 7044, S-750 07 Uppsala, Sweden. Fax +46 18 672 890 E-mail: bo.langstrom@entom.slu.se
Hellqvist, SLU, Dept. of Entomology, P.O.Box 7044, S-750 07 Uppsala, Sweden. Fax +46 18 672 890 E-mail: ch@nn.se
Cedervind, SLU, Dept. of Entomology, P.O.Box 7044, S-750 07 Uppsala, Sweden. Fax +46 18 672 890 E-mail: jc@nn.se

article id 431, category Research article

Pauline Stenberg, Miina Rautiainen, Terhikki Manninen, Pekka Voipio, Heikki Smolander. (2004). Reduced simple ratio better than NDVI for estimating LAI in Finnish pine and spruce stands. Silva Fennica vol. 38 no. 1 article id 431. https://doi.org/10.14214/sf.431

Keywords: Landsat ETM ; Leaf Area Index; spectral vegetation indices; boreal coniferous forests

Abstract | View details | Full text in PDF | Author Info

Estimation of leaf area index (LAI) using spectral vegetation indices (SVIs) was studied based on data from 683 plots on two Scots pine and Norway spruce dominated sites in Finland. The SVIs studied included the normalised difference vegetation index (NDVI), the simple ratio (SR), and the reduced simple ratio (RSR), and were calculated from Landsat ETM images of the two sites. Regular grids of size 1 km2 with gridpoints placed at 50 m intervals were established at the sites and measurements of LAI using the LAI-2000 instrument were taken at the gridpoints. SVI-LAI relationships were examined at plot scale, where the plots were defined as circular areas of radius 70 m around each gridpoint. Plotwise mean LAI was computed as a weighted average of LAI readings taken around the gridpoints belonging to the plot. Mean LAI for the plots ranged from 0.36 to 3.72 (hemisurface area). All of the studied SVIs showed fair positive correlation with LAI but RSR responded more dynamically to LAI than did SR or NDVI. Especially NDVI showed poor sensitivity to changes in LAI. RSR explained 63% of the variation in LAI when all plots were included (n = 683) and the coefficient of determination rose to 75% when data was restricted to homogeneous plots (n = 381). Maps of estimated LAI using RSR showed good agreement with maps of measured LAI for the two sites.

Stenberg, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: pauline.stenberg@helsinki.fi
Rautiainen, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: mr@nn.fi
Manninen, Finnish Meteorological Institute, Meteorological research, Ozone and UV radiation research, P.O. Box 503, FIN-00101 Helsinki, Finland E-mail: tm@nn.fi
Voipio, Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland E-mail: pv@nn.fi
Smolander, Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland E-mail: hs@nn.fi

article id 486, category Research article

Arto Haara. (2003). Comparing simulation methods for modelling the errors of stand inventory data. Silva Fennica vol. 37 no. 4 article id 486. https://doi.org/10.14214/sf.486

Keywords: measurement error; simulation; stand-level inventory; non-parametric estimation; Monte Carlo methods

Abstract | View details | Full text in PDF | Author Info

Forest management planning requires information about the uncertainty inherent in the available data. Inventory data, including simulated errors, are infrequently utilised in forest planning studies for analysing the effects of uncertainty on planning. Usually the errors in the source material are ignored or not taken into account properly. The aim of this study was to compare different methods for generating errors into the stand-level inventory data and to study the effect of erroneous data on the calculation of specieswise and standwise inventory results. The material of the study consisted of 1842 stands located in northern Finland and 41 stands located in eastern Finland. Stand-level ocular inventory and checking inventory were carried out in all study stands by professional surveyors. In simulation experiments the methods considered for error generation were the 1nn-method, the empirical errors method and the Monte Carlo method with log-normal and multivariate log-normal error distributions. The Monte Carlo method with multivariate error distributions was found to be the most flexible simulation method. This method produced the required variation and relations between the errors of the median basal area tree characteristics. However, if the reference data are extensive the 1nn-method, and in certain conditions also the empirical errors method, offer a useful tool for producing error structures which reflect reality.

Haara, Finnish Forest Research Institute, Joensuu Research Centre, P.O.Box 68, FIN-80101 Joensuu, Finland E-mail: arto.haara@metla.fi

article id 483, category Research article

Staffan Jacobson. (2003). Addition of stabilized wood ashes to Swedish coniferous stands on mineral soils - effects on stem growth and needle nutrient concentrations. Silva Fennica vol. 37 no. 4 article id 483. https://doi.org/10.14214/sf.483

Keywords: Pinus sylvestris; Norway spruce; Picea abies; Scots pine; foliar analysis; N fertilization; recycling

Abstract | View details | Full text in PDF | Author Info

Increasing use of forest fuels for energy production is generating increasing quantities of wood ash. A common understanding is that this ash should be spread in forests to counteract soil acidification and potential future nutrient deficiencies, and thus help sustain long-term forest productivity. A series of seven field experiments was established in Sweden in 1988–1995 to study the stem growth and needle nutrient concentrations of 30–60-year-old Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands on mineral soil after additions of wood ash in different doses or a combination of wood ash and N. The results showed that the most pronounced growth responses occurred when N was added, either alone or in combination with wood ash. The stem growth responses to additions of wood ash without N were small and variable, and not statistically significant at any of the studied experimental sites. However, there were indications that the addition of wood ash may increase stem-wood growth on fertile sites and decrease it on less fertile sites. In the short term, the addition of wood ash tended to increase the needle nutrient concentrations of most analyzed elements, except for N, but this could not be correlated to responses in stem growth.

Jacobson, The Forestry Research Institute of Sweden, Uppsala Science Park, SE-75183 Uppsala, Sweden E-mail: staffan.jacobson@skogforsk.se

article id 482, category Research article

Yaye Kène Gassama-Dia, Djibril Sané, Mansor N'Doye. (2003). Reproductive biology of Faidherbia albida (Del.) A. Chev. Silva Fennica vol. 37 no. 4 article id 482. https://doi.org/10.14214/sf.482

Keywords: flowering; selfing; Faidherbia albida; fructification; polyad; allogamy

Abstract | View details | Full text in PDF | Author Info

Phenology, flowering and fructification were studied in 5 natural populations of Faidherbia albida in a semi-arid zone in Senegal. In this species, the inflorescence acts as the reproductive unit; the basal flowers, opening first, have a low rate of fertilisation; the maximum rate of fertilisation (65%) was obtained in the apical flowers. Stigmatic receptivity, tested by esterasic reaction, was maximal immediately after anthesis. Stigmata of F. albida can bear simultaneously 2 or 3 polyads. Controlled pollination revealed that allogamy is the dominant reproductive system (ISI = 0.2) in natural populations of F. albida. Intra-specific variability in selfing (ISI ranging from 0 to 0.54) was also observed. Despite of the complete reproductive mechanism during flowering, only a small number of ripe pods (1.25%) is produced, and an average of 70% of the ovules per carpel are fertilized.

Gassama-Dia, Université Cheikh Anta Diop de Dakar, Faculté des Sciences et Techniques, Département de biologie végétale, Dakar, Sénégal E-mail: ykdia@ucad.sn
Sané, Université Cheikh Anta Diop de Dakar, Faculté des Sciences et Techniques, Département de biologie végétale, Dakar, Sénégal E-mail: ds@nn.sn
N'Doye, Université Cheikh Anta Diop de Dakar, Faculté des Sciences et Techniques, Département de biologie végétale, Dakar, Sénégal E-mail: mnd@nn.sn

article id 496, category Research article

Hampus Holmström, Hans Kallur, Göran Ståhl. (2003). Cost-plus-loss analyses of forest inventory strategies based on kNN-assigned reference sample plot data. Silva Fennica vol. 37 no. 3 article id 496. https://doi.org/10.14214/sf.496

Keywords: uncertainty; data acquisition; imputation; forestry planning

Abstract | View details | Full text in PDF | Author Info

The usefulness of kNN (k Nearest Neighbour)-assigned reference sample plot data as a basis for forest management planning was studied. Cost-plus-loss analysis was applied, whereby the inventory cost for a specific method is added to the expected loss due to non-optimal forestry activities caused by erroneous descriptions of the forest state. Four different strategies for data acquisition were evaluated: 1) kNN imputation of sample plots based on traditional stand record information, 2) imputation based on plot-wise aerial photograph interpretation in combination with stand record information, 3) sample plot inventory in the field with 5 plots per stand, and 4) sample plot inventory with 10 plots per stand. Expected losses were derived as mean values of differences between the maximum net present value and the corresponding value obtained when the treatment schedule believed to be optimal (based on data simulated according to method 1–4) was selected. The optimal choice of method was found to depend on factors such as stand maturity, stand area, and time to next treatment (thinning or clearcutting). In general, the field sample plot methods were competitive in large mature stands, especially when the time to the next (optimal) treatment was short. By in each stand (within an estate) employing the method with the lowest cost-plus-loss rather than choosing the method that performed best on average for the entire estate, the total cost for inventory at the estate level could be decreased by 15–50%. However, it was found difficult to identify what method should optimally be employed in a stand based on general stand descriptions.

Holmström, Regional Board of Forestry of Västra Götaland, P.O. Box 20008, SE-50420 Borås, Sweden E-mail: hampus.holmstrom@svsvg.svo.se
Kallur, ÖKA Skogsplan, Kopparvägen 45 O, SE-90750 Umeå, Sweden E-mail: hk@nn.se
Ståhl, Swedish Univ. of Agricultural Sciences, Dept. of Forest Resource Management and Geomatics, SE-90183 Umeå, Sweden E-mail: gs@nn.se

article id 495, category Research article

Christopher Dean. (2003). Calculation of wood volume and stem taper using terrestrial single-image close-range photogrammetry and contemporary software tools. Silva Fennica vol. 37 no. 3 article id 495. https://doi.org/10.14214/sf.495

Keywords: biomass; branches; terrestrial; photography; rectification; volume; taper

Abstract | View details | Full text in PDF | Author Info

A method of estimating trunk and branch volumes of single trees is presented that uses a combination of elementary field measurements, terrestrial photography, image rectification and on-screen digitising using commercial software packages and automated volume calculation. The method is applicable to a variety of different sized trees in situations where the trunks are clearly visible. Results for taper measurement and wood volume calculation are presented for Eucalyptus regnans F. von Muell., Sequoiadendron giganteum (Lindley) Buchholz and Quercus robur L. Branch allometrics are provided for E. regnans. The largest errors arose from field observations. If the trees are asymmetrical in cross-section (e.g. due to irregular buttressing or forked stems), or if there is no vantage point perpendicular to the direction of lean, then photographs from more than one side are recommended. Accuracy and precision of geometric reproduction by the image rectification process, and the volume calculation, were tested using mathematically generated tree components. The errors in the branch volumes of the virtual tree showed complex trends due to interacting factors. Volumes were underestimated by an average 0.5% for stems and 4% for branches. Due to the area deficit resulting from non-circular cross-sections of the buttress, overestimation of stem volumes could be as high as 10% on average for mature trees. However, the area deficit was known for E. regnans and incorporated into the volume calculation. The underestimation of volumes would help counteract over-estimation due to the area deficit. The application of this method to carbon accounting in forests and woodlands is explained.

Dean, CRC for Greenhouse Accounting, The Australian National University, GPO Box 475, Canberra, ACT 2601, Australia E-mail: cdean@rsbs.anu.edu.au

article id 506, category Research article

Teijo Palander, Katja Turunen, Sanna Laukkanen. (2003). Attitude of Finnish timber buyers towards implementation of a forest computer visualisation. Silva Fennica vol. 37 no. 2 article id 506. https://doi.org/10.14214/sf.506

Keywords: change resistance; competence; forest computer visualisation; timber trade

Abstract | View details | Full text in PDF | Author Info

Timber buyers’ opinions as regards forest computer visualisation are studied. The results indicated that timber buyers are still rather conventional in their computer use since they mainly use only the information system of their own company. The majority of the buyers perceived computer visualisation to be slightly useful for their work, or they had no opinion concerning the usefulness of it. One third of the buyers considered computer visualisation to be a quality factor for timber trade, and the majority were willing to use it if a program is going to adopt by their company. In analysis, different personal characteristics were found for three timber buyer groups: qualified, neutral and reluctant. Qualified buyers were the largest one, about half of the buyers belonging to this group. The greatest barriers to adopting a positive attitude to computer visualisation turned out to be weak computer skills and a general lack of interest in computer use. On the other side, it was found that organisational factors did not influence the buyers’ computer skills or attitudes towards visualisation. The results of this study can be utilised by timber buying organisation in ensuring the successful adoption of a new computer system.

Palander, Faculty of Forestry, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: teijo.palander@joensuu.fi
Turunen, Faculty of Forestry, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: kt@nn.fi
Laukkanen, Faculty of Forestry, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: sl@nn.fi

article id 505, category Research article

Jari Kärnä, Eric Hansen, Heikki Juslin. (2003). Environmental activity and forest certification in marketing of forest products – a case study in Europe. Silva Fennica vol. 37 no. 2 article id 505. https://doi.org/10.14214/sf.505

Keywords: environmental marketing; green marketing; European forest industry

Abstract | View details | Full text in PDF | Author Info

Forest industries and their industrial customers from four European countries were surveyed by interviews to study the environmental emphasis and the role of timber certification in their marketing planning. Most of the Finnish, Swedish, German and British companies have begun to integrate environmental issues in their strategic, structural and functional level marketing decisions. They see forest certification as a necessary tool for marketing forest products. The level of environmental activity (greenness) of the companies was studied by creating a one dimensional factor score rating. The logic of marketing planning was tested by using one functional level marketing tool – forest certification – as an example to examine how well the level of greenness explains the importance of forest certification for the company. The results show that in the surveyed companies the level of greenness has more explanatory power than background factors such as country or industry sector. The integration of environmental issues into marketing planning and the interest in forest certification by these companies can provide meaningful insights for the forest industries worldwide as they confront similar issues.

Kärnä, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: jari.karna@metla.fi
Hansen, Oregon State University, Department of Wood Science and Engineering, Richardson Hall 108, 97331-5751 Corvallis, OR, USA E-mail: eh@nn.us
Juslin, University of Helsinki, Department of Forest Economics, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: hj@nn.fi

article id 503, category Research article

Jyrki Hytönen. (2003). Effects of wood, peat and coal ash fertilization on Scots pine foliar nutrient concentrations and growth on afforested former agricultural peat soils. Silva Fennica vol. 37 no. 2 article id 503. https://doi.org/10.14214/sf.503

Keywords: wood ash; afforestation; Scots pine; vegetation control; herbicides; coal ash; peat ash; peat soils

Abstract | View details | Full text in PDF | Author Info

The effects of ash and commercial fertilizers on the foliar nutrient concentrations and stand growth of Scots pine were studied in four field experiments established on former cultivated peat soils. The aims were to compare ash types (wood, peat and coal ash), study the effects of ash treatment (pelletization), compare ash fertilization with commercial fertilizers, and to study the interaction between ash fertilization and weed control. Foliar samples were collected 1–3 years and 7–8 years after fertilization. In the unfertilized plots, the foliar nitrogen and phosphorus concentrations were fairly high, while those of potassium were low in all the experiments. The boron levels were low in three out of the four experiments. Application of either loose or pelletized wood ash, as well as of commercial fertilizers, increased foliar potassium and boron concentrations, and thus successfully remedied the existing nutrient imbalances and deficiencies. Since phosphorus deficiencies are rarely encountered on field afforestation sites, poor-quality wood ash with low phosphorus concentration could be used. Peat ash containing phosphorus, but only small amounts of potassium and boron, was not found to be very suitable for soil amelioration in connection with field afforestation. Coal ash, containing only small amounts of potassium, was a good source of boron for pine even when used in small amounts, and thus it can be used in cases where boron deficiencies alone are encountered. Wood ash significantly increased the height growth of Scots pines in two of the experiments, but peat ash and coal ash had no statistically significant effect. Wood ash increased the number of healthy seedlings. Vegetation control decreased seedling mortality by 24%, increased the growth of pine and decreased the proportion of trees damaged by elk and by deciduous trees.

Hytönen, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: jyrki.hytonen@metla.fi

article id 500, category Research article

Jarkko Hantula, Eeva Vainio. (2003). Specific primers for the differentiation of Heterobasidion annosum (s.str.) and H. parviporum infected stumps in northern Europe. Silva Fennica vol. 37 no. 2 article id 500. https://doi.org/10.14214/sf.500

Keywords: IS group S; IS group P; molecular identification; root and butt rot

Abstract | View details | Full text in PDF | Author Info

Two separate amplification products from random amplified microsatellite fingerprints of Heterobasidion annosum (s.str.) and H. parviporum were converted to specific markers. The markers were tested to be species specific and combined to a single PCR-reaction, which allowed the detection and identification of the two fungi directly from wood samples.

Hantula, Finnish Forest Research Institute. Fax +358 9 8570 5531 E-mail: jarkko.hantula@metla.fi
Vainio, Finnish Forest Research Institute. Fax +358 9 8570 5531 E-mail: ev@nn.fi

article id 515, category Research article

Juho Rantala, Kari Väätäinen, Nuutti Kiljunen, Pertti Harstela. (2003). Economic evaluation of container seedling packing and disinfection machinery. Silva Fennica vol. 37 no. 1 article id 515. https://doi.org/10.14214/sf.515

Keywords: economies of scale; nursery technology; mechanisation; container seedlings; packing;

Abstract | View details | Full text in PDF | Author Info

Productivity and costs of packing container seedlings were studied in a mechanised line for packing and disinfecting seedling trays. The hypothesis was that adequate cost-efficiency could be achieved when some common principles of mechanisation were applied. Results indicated that the unit costs are lower than those of manual packing, if these principles were applied and the annual number of packed seedlings exceeded 6 million. However, most of the nurseries in Finland are still too small to gain a real advantage from large-scale production.

Rantala, Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland E-mail: juho.rantala@metla.fi
Väätäinen, Finnish Forest Research Institute, Joensuu Research Centre, FIN-80101 Joensuu, Finland E-mail: kv@nn.fi
Kiljunen, Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland E-mail: nk@nn.fi
Harstela, Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland E-mail: ph@nn.fi

article id 514, category Research article

Jukka Malinen. (2003). Locally adaptable non-parametric methods for estimating stand characteristics for wood procurement planning. Silva Fennica vol. 37 no. 1 article id 514. https://doi.org/10.14214/sf.514

Keywords: stand characteristics; local non-parametric estimation; MSN method; wood procurement planning

Abstract | View details | Full text in PDF | Author Info

The purpose of this study was to examine the use of the local adaptation of the non-parametric Most Similar Neighbour (MSN) method in estimating stand characteristics for wood procurement planning purposes. Local adaptation was performed in two different ways: 1) by selecting local data from a database with the MSN method and using that data as a database in the basic k-nearest neighbour (k-nn) MSN method, 2) by selecting a combination of neighbours from the neighbourhood where the average of the predictor variables was closest to the target stand predictor variables (Locally Adaptable Neighbourhood (LAN) MSN method). The study data used comprised 209 spruce dominated stands located in central Finland and was collected with harvesters. The accuracy of the methods was analysed by estimating the tree stock characteristics and the log length/diameter distribution produced by a bucking simulation. The local k-nn MSN method was not notably better than the k-nn MSN method, although it produced less biased estimates on the edges of the input space. The LAN MSN method was found to be a more accurate method than the k-nn methods.

Malinen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: jukka.malinen@joensuu.fi

article id 509, category Research article

Michelle de Chantal, Laura Eskola, Hannu Ilvesniemi, Kari Leinonen, Carl Johan Westman. (2003). Early establishment of Pinus sylvestris and Picea abies sown on soil freshly prepared and after stabilisation. Silva Fennica vol. 37 no. 1 article id 509. https://doi.org/10.14214/sf.509

Keywords: Norway spruce; site preparation; Scots pine; direct seeding; soil properties

Abstract | View details | Full text in PDF | Author Info

The aim of this study is to investigate the early establishment of Pinus sylvestris L. (Scots pine) and Picea abies (L.) Karst. (Norway spruce) seedlings on soil freshly prepared and soil left to stabilise for one year after preparation. Three site preparation treatments were studied: exposed C horizon, mound (broken O/E/B horizon piled upside down over undisturbed forest floor), and exposed E/B horizon. The years investigated were different in terms of weather, one being rainy and the other one dry. As such, emergence was very low in the dry year. Content of fine silt particles, bulk density, water retention, air-filled porosity, loss-on-ignition, and near saturated hydraulic conductivity did not differ statistically between fresh and stabilised soil. Nevertheless, early establishment of P. sylvestris seedlings was improved on exposed C and E/B horizon after one year of soil stabilisation. In contrast, early establishment of P. sylvestris on mounds, and that of P. abies on all types of site preparation treatments were not improved by soil stabilisation. In addition, mortality due to frost heaving did not differ significantly between freshly prepared and stabilised soil. Considering the fact that growing season climate had a great influence on the sowing outcome, and that early establishment is also affected by other factors that vary yearly, such as predation, seedbed receptivity, and competition from vegetation, it may not be advantageous to wait for soil to stabilise before regenerating from seeds.

Chantal, University of Helsinki, Dept. of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: michelle.dechantal@helsinki.fi
Eskola, University of Helsinki, Dept. of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: le@nn.fi
Ilvesniemi, University of Helsinki, Dept. of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: hi@nn.fi
Leinonen, University of Helsinki, Dept. of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: kl@nn.fi
Westman, University of Helsinki, Dept. of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: cjw@nn.fi

article id 508, category Research article

Kai Vellak, Jaanus Paal, Jaan Liira. (2003). Diversity and distribution pattern of bryophytes and vascular plants in a boreal spruce forest. Silva Fennica vol. 37 no. 1 article id 508. https://doi.org/10.14214/sf.508

Keywords: boreal forests; correlation; general linear models; Estonia; field layer; ground layer; spatial patterns

Abstract | View details | Full text in PDF | Author Info

Small scale pattern of bryophyte communities is one of the remarkable sources of diversity in species-poor boreal forests. By means of correlation and general linear model approaches, the relationships between bryophyte vegetation and upper layers, as well as the response of ground and field layer species to several environmental factors, was analyzed in a boreal spruce forest in South-East Estonia. Of the studied factors, the strongest influence on the diversity and spatial distribution of ground and field layer species was found for ‘distance from nearest tree’. Species from different layers react differently to the proximity of trees. Species richness of bryophytes is higher further from trees, whereas more vascular plant species prefer to grow in the vicinity of tree trunks. For bryophyte species richness, the pH of the decay horizon is also important; fewer bryophyte species occur in more acid conditions.

Vellak, Institute of Zoology and Botany, Estonian Agricultural University, 181 Riia str., 51014 Tartu, Estonia; Institute of Botany and Ecology, University of Tartu, 40 Lai Str., 51005 Tartu, Estonia E-mail: kvellak@zbi.ee
Paal, Institute of Botany and Ecology, University of Tartu, 40 Lai Str., 51005 Tartu, Estonia E-mail: jp@nn.ee
Liira, Institute of Botany and Ecology, University of Tartu, 40 Lai Str., 51005 Tartu, Estonia E-mail: jl@nn.ee

article id 525, category Research article

Thomas Knoke. (2002). Value of complete information on red heartwood formation in beech (Fagus sylvatica). Silva Fennica vol. 36 no. 4 article id 525. https://doi.org/10.14214/sf.525

Keywords: value of information; economics of beech; red heartwood; silvicultural treatment

Abstract | View details | Full text in PDF | Author Info

Beech (Fagus sylvatica L.) is the most important deciduous tree species in Germany. The wood of beech shows normally a bright colour (white beech) as long as no coloured heartwood has been formed. The facultative heartwood formation is induced when oxygen enters central parts of older trees, where dead or at least less vital parenchyma exist. The coloured heartwood is usually called ‘red heartwood’. Beech without red heartwood can preferably be found in younger trees which show a high water content even in central parts of the stem. The presence of red heartwood is regarded as a severe reduction of timber quality. Numerous studies have investigated opportunities to derive information on the presence and characteristics of red heartwood of standing beech trees. But until now it has not been tested whether such information could be helpful to improve the economics of beech-silviculture. This paper investigates whether complete information on the heartwood of standing beech could be useful to control the proportion of discoloured timber harvested during one rotation. It is also examined, which kind of information on the heartwood could be used to improve the economic results. To verify this, simulations based on simple algorithms were conducted. The general assumption was made that all information on the heartwood would be available. The results show that information which is restricted on the mere existence of red heartwood is neither suited to significantly reduce the amount of coloured timber nor is it possible to improve economic results based on this information. Only based on information on the recent formation of red heartwood of beech, which is actually still white the amount of discoloured timber can be reduced significantly. Consequently the discounted cash flows can only be substantially improved based on information on an expected formation of recent red heartwood.

Knoke, Institute of Silviculture and Forest Management, Technische Universität München, Am Hochanger 13, D-85354 Freising, Germany E-mail: knoke@wbfe.forst.tu-muenchen.de

article id 523, category Research article

Heli Peltola, Jari Miina, Ismo Rouvinen, Seppo Kellomäki. (2002). Effect of early thinning on the diameter growth distribution along the stem of Scots pine. Silva Fennica vol. 36 no. 4 article id 523. https://doi.org/10.14214/sf.523

Keywords: Scots pine; early thinnings; thinning responses; diameter growth; growth distribution

Abstract | View details | Full text in PDF | Author Info

The absolute and relative effects of the first thinning on the diameter growth distribution along the stems were studied in 98 Scots pines (Pinus sylvestris L.) at heights of 1.3, 4, 6 and 8 m. The data cover one 3-year pre-thinning period and four 3-year post-thinning periods in plots with densities varying from 575 to 3400 stems ha–1. A shift in the point of maximum diameter growth down the bole was found during the first 3 years after thinning, with a shift back up the stem later. The thinning response over the whole 12-year post-thinning period was strongest the nearer the stem base and the heavier the thinning. The largest trees had the highest diameter growth after thinning in absolute terms, and the growth was greater the heavier the thinning. The absolute thinning response over the 12-year post-thinning period was highest in the medium tree size and in the largest trees, especially on the heavily thinned and lightly thinned plots. Whereas in the moderately thinned stand the smaller and larger trees responded more than did those of medium size on average. In relative sense, however, the small trees on heavily or moderately thinned plots responded more rapidly and more strongly than the medium-sized or large trees over the whole stem. The small trees on the lightly thinned plots responded only slightly to thinning. The results suggest that it is possible to affect the uniformity of wood properties (such as ring width) both within and between trees by thinning.

Peltola, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: heli.peltola@forest.joensuu.fi
Miina, Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: jm@nn.fi
Rouvinen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: ir@nn.fi
Kellomäki, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: sk@nn.fi

article id 522, category Research article

Annika Kangas, Matti Maltamo. (2002). Anticipating the variance of predicted stand volume and timber assortments with respect to stand characteristics and field measurements. Silva Fennica vol. 36 no. 4 article id 522. https://doi.org/10.14214/sf.522

Keywords: diameter distribution; timber assortment; prediction; calibration estimation; volume; accuracy; measurement combination

Abstract | View details | Full text in PDF | Author Info

Several models and/or several variable combinations could be used to predict the diameter distribution of a stand. Typically, a fixed model and a fixed variable combination is used in all conditions. The calibration procedure, however, makes it possible to choose the measurement combination from among many possibilities, although the model used is fixed. In this study, the usefulness of utilizing additional stand characteristics for calibrating the predicted diameter distribution is examined. Nine measurement strategies were tested in predicting the total stand volume, sawlog volume and pulpwood volume. The observed errors of these variables under each strategy were modeled as a function of basal area, basal area median diameter and number of stems. The models were estimated in three steps. First, an Ordinary Least Squares (OLS) model was fitted to the observed errors. Then, a variance function was estimated using the OLS residuals. Finally, a weighted Seemingly Unrelated Regression (SUR) analysis was used to model the observed errors, using the estimated variance functions as weights. The estimated models can be used to anticipate the precision and accuracy of predicted volume characteristics for each stand with different variable combinations and, consequently, to choose the best measurement combination in different stands.

Kangas, University of Helsinki, Dept. of Forest Resources Management, P.O. Box 27, 00014 University of Helsinki, Finland E-mail: annika.kangas@helsinki.fi
Maltamo, University of Joensuu, Faculty of Forestry, P.O. Box 111, 80101 Joensuu, Finland E-mail: mm@nn.fi

article id 533, category Research article

Anna Liisa Ruotsalainen, Juha Tuomi, Henry Väre. (2002). A model for optimal mycorrhizal colonization along altitudinal gradients. Silva Fennica vol. 36 no. 3 article id 533. https://doi.org/10.14214/sf.533

Keywords: alpine gradient; mycorrhiza; nutrient uptake kinetics; photosynthetic nutrient use efficiency

Abstract | View details | Full text in PDF | Author Info

Mycorrhizal associations are generally favourable for vascular plants in nutrient-poor conditions. Still, non-mycorrhizal plants are common in high arctic and alpine areas, which are often poor in nitrogen and phosphorus. The relative proportion of mycorrhizal plants has been found to decrease along with increasing altitude, suggesting that the advantage of the mycorrhizal symbiosis may change along an altitudinal gradient. This may be related to the environmental factors that possibly constrain the amount of photosynthesized carbon to be shared with mycorrhizal fungi. We propose a simple optimization model for root colonization by fungal symbionts and analyze the advantages of mycorrhizas in relation to the nutrient use efficiency of photosynthesis (PNUE), the kinetics of nutrient uptake and the soil nutrient levels. Our model suggests that mycorrhizas are not usually favoured at low PNUE values. At low nutrient levels, mycorrhizas may be advantageous if they have a lower threshold concentration of nutrient uptake (xmin) compared to non-mycorrhizal roots. If mycorrhizal roots have a higher maximum capacity of nutrient uptake (Vmax), mycorrhizas can be favourable for the host plant even at relatively low nutrient concentrations and at relatively low PNUE. Consequently, the possible patterns along altitudinal gradients essentially depend on PNUE. If the soil nutrient concentration is constant and PNUE decreases, the advantage of mycorrhizal symbiosis declines independently of the nutrient uptake kinetics. If PNUE remains constant and the soil nutrient concentration decreases along with increasing altitude, the emerging colonization pattern (either increasing, decreasing or intermediate) depends on the nutrient uptake kinetics. Additionally, if both PNUE and the soil nutrient concentration decrease, several patterns may emerge, depending on the nutrient uptake kinetics.

Ruotsalainen, Department of Biology, Botanical Museum, Box 3000, FIN-90014 University of Oulu, Finland E-mail: annu.ruotsalainen@oulu.fi
Tuomi, Department of Biology, Box 3000, FIN-90014 University of Oulu, Finland E-mail: jt@nn.fi
Väre, Botanical Museum, Finnish Museum of Natural History, Box 7, FIN-00014 University of Helsinki, Finland E-mail: hv@nn.fi

article id 531, category Research article

Thomas N. Buckley, Jeffrey M. Miller, Graham D. Farquhar. (2002). The mathematics of linked optimisation for water and nitrogen use in a canopy. Silva Fennica vol. 36 no. 3 article id 531. https://doi.org/10.14214/sf.531

Keywords: stomatal conductance; optimality theory; nitrogen allocation; NUE; WUE

Abstract | View details | Full text in PDF | Author Info

We develop, and discuss the implementation of, a mathematical framework for inferring optimal patterns of water and nitrogen use. Our analysis is limited to a time scale of one day and a spatial scale consisting of the green canopy of one plant, and we assume that this canopy has fixed quantities of nitrogen and water available for use in photosynthesis. The efficiencies of water and nitrogen use, and the interactions between the two, are strongly affected by physiological and physical properties that can be modeled in different ways. The thrust of this study is therefore to discuss these properties and how they affect the efficiencies of nitrogen and water use, and to demonstrate, qualitatively, the effects of different model assumptions on inferred optimal strategies. Preliminary simulations suggest that the linked optimisation of nitrogen and water use is particularly sensitive to the level of detail in canopy light penetration models (e.g., whether sunlit and shaded fractions are pooled or considered independently), and to assumptions regarding nitrogen and irradiance gradients within leaves (which determine how whole-leaf potential electron transport rate is calculated from leaf nitrogen content and incident irradiance).

Buckley, Environmental Biology Group, Research School of Biological Sciences, The Australian National University, GPO Box 475, Canberra City, ACT 2601, Australia and Cooperative Research Centre for Greenhouse Accounting, RSBS, ANU E-mail: tom_buckley@alumni.jmu.edu
Miller, Environmental Biology Group, Research School of Biological Sciences, The Australian National University, GPO Box 475, Canberra City, ACT 2601, Australia E-mail: jmm@nn.au
Farquhar, Environmental Biology Group, Research School of Biological Sciences, The Australian National University, GPO Box 475, Canberra City, ACT 2601, Australia and Cooperative Research Centre for Greenhouse Accounting, RSBS, ANU E-mail: gdf@nn.au

article id 529, category Research article

Tuula Aalto, Pertti Hari, Timo Vesala. (2002). Comparison of an optimal stomatal regulation model and a biochemical model in explaining CO2 exchange in field conditions. Silva Fennica vol. 36 no. 3 article id 529. https://doi.org/10.14214/sf.529

Keywords: photosynthesis; Scots pine; optimization; Pinus sylvestris L.; CO2 exchange; biochemical model

Abstract | View details | Full text in PDF | Author Info

Gas exchange of Pinus sylvestris L. was studied in subarctic field conditions. Aspects on optimal control of the gas exchange were examined using approach by Hari et al. (Tree Phys. 2: 169–175, 1986). Biochemical model by Farquhar et al. (Planta 149: 78–90, 1980) was utilized to describe the photosynthetic production rate of needles. The model parameters were determined from field measurements. The results from the optimization approach and biochemical model were compared and their performance was found quite similar in terms of R2 calculated using measured exchange rates (0.89 for optimization model and 0.85 for biochemical model). Minor differences were found in relation to responses to intercellular carbon dioxide concentration and temperature.

Aalto, Finnish Meteorological Institute, Air Quality Research, Sahaajankatu 20 E, FIN-00810 Helsinki, Finland E-mail: tuula.aalto@fmi.fi
Hari, University of Helsinki, Dept. of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: ph@nn.fi
Vesala, University of Helsinki, Dept. of Physics, P.O. Box 64, FIN-00014 University of Helsinki, Finland E-mail: tv@nn.fi

article id 542, category Research article

Håkan Lindström. (2002). Intra-tree models of juvenile wood in Norway spruce as an input to simulation software. Silva Fennica vol. 36 no. 2 article id 542. https://doi.org/10.14214/sf.542

Keywords: Picea abies; image analysis; juvenile wood; growth conditions

Abstract | View details | Full text in PDF | Author Info

Juvenile wood found in the first 5–25 growth rings of a conifer has a structure and properties that differ from mature wood. Juvenile wood is therefore said to influence processing and the end-use of sawn products. Consequently, models describing the juvenile wood content, within and between trees, could be useful in improving the utilisation and value of wood as an industrial raw material. The objective of the present study was to develop juvenile wood models, based on Norway spruce trees, which could be used within a model system for conversion simulation studies. Nineteen stands of Norway spruce (Picea abies [L.] Karst.) were selected throughout Sweden. Based on DBH, two small, two medium, and two large diameter timber trees were taken from each stand. DBH varied between 180–470 mm, tree height between 17–34 m, and total age between 51–152 years. Each selected tree was cross-cut into logs; discs were prepared from the large end of each log and from the top end of the top log. Image analysis was used to determine growth ring development on sampled discs. Using tree and growth variables, the juvenile core radius and the logarithmic value of juvenile wood percentage were modelled. The two models had an R2Adj of 0.71 and 0.88 respectively.

Lindström, University of Canterbury, School of Forestry, Private Bag 4800, Christchurch, New Zealand E-mail: lindstromhakan@netscape.net

article id 541, category Research article

Azim U. Mallik, F. Wayne Bell, Yanli Gong. (2002). Effectiveness of delayed brush cutting and herbicide treatments for vegetation control in a seven-year-old jack pine plantation in northwestern Ontario, Canada. Silva Fennica vol. 36 no. 2 article id 541. https://doi.org/10.14214/sf.541

Keywords: species richness; Pinus banksiana; species diversity; conifer release treatments; glyphosate; brushsaw; competition index

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Efficacy of three conifer release treatments, i) single application of glyphosate (Vision™) herbicide, ii) multiple application of glyphosate herbicide, and iii) motor-manual brush cutting for controlling competing plants, particularly trembling aspen (Populus tremuloides), pin cherry (Prunus pensylvanica), green alder (Alnus viridis spp. crispa), and beaked hazel (Corylus cornuta spp. cornuta), was studied in a seven-year-old jack pine (Pinus banksiana) plantation in northwestern Ontario, Canada. The single and multiple glyphosate applications were equally effective in controlling trembling aspen and pin cherry, causing over 90% stem mortality. The brushsaw treatment caused an initial decrease followed by an increase in stem density of these two species. A high degree of stem thinning by natural mortality in the untreated control plots was observed in trembling aspen (23–46%) and pin cherry (41–69%) over four years. As with trembling aspen and pin cherry, stem density of green alder and beaked hazel initially decreased and then increased following the brushsaw treatment, mainly due to resprouting. Stem mortality in green alder and beaked hazel was 45% and 97%, respectively, two years after the operational glyphosate treatment. Competition index (CI) was low (mean CI = 52, ranging from 18 to 115) in all the plots including the untreated control. There was a significant increase in basal diameter of jack pine in the brushsaw and herbicide-treated plots compared to the control three years after the treatments. Jack pine seedlings in the brushsaw and glyphosate treated plots were taller compared to that of control but differences were not significant. Lower species richness and diversity were recorded in the herbicide-treated plots compared to the brushsaw and control plots in the third growing season following treatment.

Mallik, Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada P7B 5E1 E-mail: azim.mallik@lakeheadu.ca
Bell, Ontario Forest Research Institute, Ontario Ministry of Natural Resources, Sault Ste. Marie, Ontario, Canada P6A 2E5 E-mail: fwb@nn.ca
Gong, Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada P7B 5E1 E-mail: yg@nn.ca

article id 540, category Research article

Finn H. Brække, Nagwa Salih. (2002). Reliability of foliar analyses of Norway spruce stands in a Nordic gradient. Silva Fennica vol. 36 no. 2 article id 540. https://doi.org/10.14214/sf.540

Keywords: Norway spruce; Picea abies; needle analyses; diagnostic methods; nutrient status; imbalanced nutrition; fertilisation; volume growth

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Norway spruce stands at eleven sites in Finland, Norway and Sweden have been studied under various climates, atmospheric deposition of N and S and fertilisation regimes. Nitrogen was growth restricting at eight inland sites, while P was growth restricting at three coastal sites. Liming and N fertilisation caused serious B deficiency on some of the inland sites. It is likely that liming affects uptake of B, whereas N fertilisation causes a dilution due to increased growth. Application of S combined with N probably caused K deficiency at one of the sites. The reliability of foliar analyses as a method to diagnose nutrient status and the likely changes after nutrient input to spruce forests in the Nordic countries, are discussed. The CR- and the DOP-method are evaluated for diagnostic purposes. Both methods seem to give reliable conclusions even if the CR-method often produces more specific results. Interpretation based on both current and one year old foliage improved the diagnostic prognoses. The accuracy of diagnosis also relies on knowledge and ability of the interpreter. Based on the results it is reason to be cautious about recommendations of single element fertilisations, e.g. with N alone, because the demand of other elements beyond available pools frequently occurs. Forest trees in the boreal region are probably well adapted to N deficiency, which means that they can handle the physiological consequences rather well, while deficiencies of other elements usually are more detrimental to growth vigour and stress related diseases.

Brække, Department of Forest Sciences, Agricultural University of Norway (AUN), P.O. Box 5044, N-1432 Ås, Norway E-mail: finn.braekke@isf.nlh.no
Salih, Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences (SLU), P.O. Box 7072, S-750 07 Uppsala, Sweden E-mail: ns@nn.se

article id 539, category Research article

Martti Venäläinen, Seppo Ruotsalainen. (2002). Procedure for managing large-scale progeny test data: a case study of Scots pine in Finland. Silva Fennica vol. 36 no. 2 article id 539. https://doi.org/10.14214/sf.539

Keywords: Pinus sylvestris; selection; progeny testing; performance level; reliability coefficient

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Large progeny test networks are typical for conventional forest tree breeding programmes. The individual progeny tests differ with respect to age, composition and ability to screen the breeding values of the parent trees. Several approaches have been introduced to manage the unbalanced and diverse nature of the data generated by progeny tests. This report presents a procedure for ranking breeding material on the basis of ‘messy’ data. Plot means were used as input values and missing plots were estimated from least squares. The differences between test means and variances were standardised by the performance level method. The different precision of the tests was quantified through the reliability coefficient. In order to facilitate the selection of plus trees for different purposes, all the available test results were combined into a single variable that was used for ranking. Three different kinds of ranking variable were calculated and each of them proved to be more useful for the selection of plus trees than an arithmetic or weighted mean. One of them, WMEAN, relied on the reliability and number of the progeny tests, while the others, WCONF0.50 and WCONF0.10, relied on the standard error of the plus tree mean, thus emphasising the precision of the values obtained. The analyses were carried out with SAS® procedures, which require only moderate skills in statistics, programming and data processing technology. The procedure has functioned well throughout an eight-year development phase. Nearly three thousand Scots pine (Pinus sylvestris) plus trees have been ranked for various characters, and the results have been used for roguing the seed orchards, to establish new ones, and to select plus trees for breeding populations.

Venäläinen, Finnish Forest Research Institute, Punkaharju Research Station, FIN-58450 Punkaharju, Finland E-mail: martti.venalainen@metla.fi
Ruotsalainen, Finnish Forest Research Institute, Punkaharju Research Station, FIN-58450 Punkaharju, Finland E-mail: sr@nn.fi

article id 538, category Research article

Seppo Nevalainen. (2002). The incidence of Gremmeniella abietina in relation to topography in southern Finland. Silva Fennica vol. 36 no. 2 article id 538. https://doi.org/10.14214/sf.538

Keywords: Pinus sylvestris; forest inventory; Gremmeniella abietina; topography; digital elevation models

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Field data of the 8th National Forest Inventory (NFI) from southern Finland and digital elevation models (DEMs) were used in this study. Damage due to Gremmeniella abietina increased slightly with an increase in absolute elevation in mineral soils. Severe damage increased almost linearly with an increase in elevation in mineral soil plots. The mean elevation in the tract area (the 7 km x 8 km area surrounding the plot) was more strongly correlated with the disease than the elevation of individual plots. The relative altitude of the plot was important: the disease was most severe in the plots situated lower than the mean elevation of the tract area, especially in the peatland plots. In this group, the damage increased linearly with an increase in absolute elevation. According to detailed DEMs in the most diseased areas, steepness of the slope was negatively correlated with the disease. The aspect of the slope had a weak influence. On mineral soils, the disease was most common in south-facing slopes. The microtopography was not as important for the disease occurrence as the relative elevation of the plot. The disease frequencies were very similarly related to the three most common types of surface features (channels, ridges and planar regions) within the 50-m scale. At the cell size of 100 metres, the disease was more common in channels than in ridges, except in mineral soil plots. Topographic variables only partly explained the regional patterns in the occurrence of this disease. The disease was frequent on upland areas, but, on the other hand, it was also common on lowland areas. The most diseased areas studied in detail differed very much from each other with respect to topography and the disease incidence.

Nevalainen, Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: seppo.nevalainen@metla.fi

article id 568, category Research article

Minna Malmivaara, Irja Löfström, Ilkka Vanha-Majamaa. (2002). Anthropogenic effects on understorey vegetation in Myrtillus type urban forests in southern Finland. Silva Fennica vol. 36 no. 1 article id 568. https://doi.org/10.14214/sf.568

Keywords: fragmentation; GNMDS; trampling; vegetation monitoring; wear

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The growth of urban population in Finland has resulted in increased fragmentation of urban forests and consequently increased recreational pressure on these forests. The effects of fragmentation and trampling on the ground and field layer vegetation were studied in mesic Myrtillus type Norway spruce-dominated urban forest stands of varying size in the greater Helsinki area. The number of residents living in the vicinity of the forest stands was an important factor affecting the understorey vegetation in urban forests. The cover of understorey vegetation in urban forests was remarkably lower than in rural areas, especially the ground layer cover, e.g. cover of Pleurozium schreberi, was significantly lower in urban forests than in the reference areas. Thus, the ground layer proved to be most susceptible to trampling. In the field layer, the cover of dwarf shrubs, especially of Vaccinium myrtillus, was lower in deteriorated than in undeteriorated urban forest stands.

Malmivaara, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: minna.malmivaara@metla.fi
Löfström, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: il@nn.fi
Vanha-Majamaa, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: ivm@nn.fi

article id 565, category Research article

Sybille Haeussler, Lorne Bedford, Alain Leduc, Yves Bergeron, J. Marty Kranabetter. (2002). Silvicultural disturbance severity and plant communities of the southern Canadian boreal forest. Silva Fennica vol. 36 no. 1 article id 565. https://doi.org/10.14214/sf.565

Keywords: site preparation; species composition; species diversity; ecosystem integrity; degradation; biodiversity indicators; life history strategies

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Boreal forest ecosystems are adapted to periodic disturbance, but there is widespread concern that conventional forest practises degrade plant communities. We examined vegetation diversity and composition after clearcut logging, mechanical and chemical site preparation in eight 5- to 12-yr old studies located in southern boreal forests of British Columbia and Quebec, Canada to find useful indicators for monitoring ecosystem integrity and to provide recommendations for the development and testing of new silvicultural approaches. Community-wide and species-specific responses were measured across gradients of disturbance severity and the results were explained in terms of the intermediate disturbance hypothesis and a simple regeneration model based on plant life history strategies. Species richness was 30 to 35% higher 5 to 8 years after clearcut logging than in old forest. Total and vascular species diversity generally peaked on moderately severe site treatments, while non-vascular diversity declined with increasing disturbance severity. On more-or-less mesic sites, there was little evidence of diversity loss within the range of conventional silvicultural disturbances; however, there were important changes in plant community composition. Removing soil organic layers caused a shift from residual and resprouting understory species to ruderal species regenerating from seeds and spores. Severe treatments dramatically increased non-native species invasion. Two important challenges for the proposed natural dynamics-based silviculture will be 1) to find ways of maintaining populations of sensitive non-vascular species and forest mycoheterotrophs, and 2) to create regeneration niches for disturbance-dependent indigenous plants without accelerating non-native species invasion.

Haeussler, C2 Site 81 RR#2 Monckton Rd., Smithers, B.C., Canada V0J 2N0 E-mail: skeena@bulkley.net
Bedford, B.C. Ministry of Forests, P.O. Box 9513 Stn. Prov. Govt., Victoria, B.C., Canada, V8W 9C2 E-mail: lb@nn.ca
Leduc, Groupe de recherche en écologie forestière interuniversitaire, Université du Québec à Montréal, CP 8888, Succursale A, Montréal, Québec, Canada, H3C 3P8 E-mail: al@nn.ca
Bergeron, Groupe de recherche en écologie forestière interuniversitaire, Université du Québec à Montréal, CP 8888, Succursale A, Montréal, Québec, Canada, H3C 3P8 E-mail: yb@nn.ca
Kranabetter, B.C. Ministry of Forests, Bag 5000, Smithers, B.C., Canada, V0J 2N0 E-mail: jmk@nn.ca

article id 563, category Research article

Timo Pakkala, Ilkka Hanski, Erkki Tomppo. (2002). Spatial ecology of the three-toed woodpecker in managed forest landscapes. Silva Fennica vol. 36 no. 1 article id 563. https://doi.org/10.14214/sf.563

Keywords: three-toed woodpecker; territory quality; landscape quality; critical threshold value; metapopulation theory; metapopulation capacity; Finnish National Forest Inventory

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The effects of landscape structure and forestry on the abundance and dynamics of boreal forest bird species have been studied widely, but there are relatively few studies in which the spatial structure and quality of the landscape have been related to the spatial ecology of bird species. In this paper, we present methods to measure territory and landscape quality for the three-toed woodpecker (Picoides tridactylus) and similar territorial forest bird species based on data from the Finnish multi-source national forest inventory and metapopulation theory. The three-toed woodpecker was studied with territory mapping within an area of 340 square km in southern Finland in 1987–2000. Altogether 195 breeding territory sites were observed. The spatial occurrence of the territories was aggregated, and the highest densities were observed in spruce-dominated old-growth forest areas. Both territory and landscape quality had significant consequences for the occurrence of the three-toed woodpecker. The spatial patterning and permanence of breeding and non-breeding territories were influenced by a combination of spatial dynamics of the species and the quality of the landscape, the latter being much influenced by forestry. The landscape-level spatial occurrence of the three-toed woodpecker in the study area may represent source-sink dynamics. The results of this paper suggest the presence of threshold values at different spatial scales, which may determine the occurrence of the three-toed woodpecker and similar species in managed forest landscapes.

Pakkala, Finnish Museum of Natural History, University of Helsinki, P.O. Box 17, FIN-00014 University of Helsinki, Finland E-mail: timo.pakkala@helsinki.fi
Hanski, Department of Ecology and Systematics, University of Helsinki, P.O. Box 47, FIN-00014 University of Helsinki, Finland E-mail: ih@nn.fi
Tomppo, Finnish Forest Research Institute, Unioninkatu 40 A, FIN-00170 Helsinki, Finland E-mail: et@nn.fi

article id 562, category Research article

Tero Kokkila, Annikki Mäkelä, Eero Nikinmaa. (2002). A method for generating stand structures using Gibbs marked point process. Silva Fennica vol. 36 no. 1 article id 562. https://doi.org/10.14214/sf.562

Keywords: spatial distribution; stand simulation; Gibbs point process; Markov chain Monte Carlo

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Stand growth modelling based on single tree responses to their surroundings requires a description of the spatial structure of a stand. While such detailed information is rarely available from field measurements, a method to create it from more general stand variables is needed. A marked Gibbs point potential theory combined with Markov chain Monte Carlo (MCMC) random process was used to create a spatial configuration for any given number of trees. The trees are considered as charges rejecting each other and building ‘potential energy’. As an analogue of the potential energy in physical systems, the potential of a stand is defined in terms of size-dependent tree-to-tree interactions that can be thought of as related to resource depletion and competition. The idea that bigger trees induce larger potentials brings 3-dimensional effects into the system. Any feasible spatial structure is a state of the system, and the related potential can be calculated. The probability that a certain state occurs is assumed to be a decreasing function of its potential. Because more regular structures have lower potentials, by adjusting the steepness of the probability distribution the spatial structure can be allowed to have a lot of randomness (naturally regenerated stands) or forced to be very regular (planted stands). The MCMC algorithm is a numerical method of finding stand configurations that correspond to the expected level of the potential, given the size distribution of trees and the shape of the probability density function. The method also allows us to take into account spatial variation in the terrain. Some spots can be defined to have lower basic potential than others (ditch, planting furrow, etc.) in order to create areas of higher than average stocking density. A preliminary test of the method was conducted on two measured stands. The results suggest that the method could provide an efficient and flexible means of mimicking variable stand structures.

Kokkila, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FIN-00014 Helsingin yliopisto, Finland E-mail: tero.kokkila@helsinki.fi
Mäkelä, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FIN-00014 Helsingin yliopisto, Finland E-mail: am@nn.fi
Nikinmaa, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FIN-00014 Helsingin yliopisto, Finland E-mail: en@nn.fi

article id 560, category Research article

Christopher P. Quine, Jonathan W. Humphrey, Karen Purdy, Duncan Ray. (2002). An approach to predicting the potential forest composition and disturbance regime for a highly modified landscape: a pilot study of Strathdon in the Scottish Highlands. Silva Fennica vol. 36 no. 1 article id 560. https://doi.org/10.14214/sf.560

Keywords: restoration; wind disturbance; site suitability; catchment planning

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The existing native forests of Scotland are fragmented and highly modified and none are ‘natural’. There is considerable interest in expanding the area of this oceanic boreal forest and restoring forest habitat networks to benefit biodiversity. However, unlike regions with substantial remaining natural forest, it is difficult to provide reference values for forest composition and structure using methods related to historical variability. An alternative approach is to combine models that predict woodland type from knowledge of site conditions, and disturbance regime from knowledge of the disturbance agents (particularly abiotic agents). The applicability of this approach was examined as part of a public participatory planning exercise in a highly managed landscape in Eastern Scotland. Models of site suitability (Ecological Site Classification) and wind disturbance (ForestGALES) were combined to determine potential woodland composition and structure, and derive options for native woodland expansion. The land use of the upper Strathdon catchment is currently dominated by agriculture and planted forests of non-native species, and only small fragments of semi-natural woodland remain (< 0.5% of the land area). Model results indicated that a very substantial proportion of the land area could support woodland (> 90%) but of a restricted range of native woodland types, with Scots pine communities predominant. Structural types likely to be present included wind-induced krummholz (treeline) forest, forest with frequent stand replacement by wind, and also a large area where gap phase (or some other disturbance) would predominate. The merits of the approach are discussed, together with the difficulties of validation, and the implications for the management of existing forests.

Quine, Forestry Commission, Northern Research Station, Roslin, Midlothian EH25 9SY, United Kingdom E-mail: chris.quine@forestry.gsi.gov.uk
Humphrey, Forestry Commission, Northern Research Station, Roslin, Midlothian EH25 9SY, United Kingdom E-mail: jwh@nn.uk
Purdy, Forestry Commission, Northern Research Station, Roslin, Midlothian EH25 9SY, United Kingdom E-mail: kp@nn.uk
Ray, Forestry Commission, Northern Research Station, Roslin, Midlothian EH25 9SY, United Kingdom E-mail: dr@nn.uk

article id 558, category Research article

Tuomo Wallenius. (2002). Forest age distribution and traces of past fires in a natural boreal landscape dominated by Picea abies. Silva Fennica vol. 36 no. 1 article id 558. https://doi.org/10.14214/sf.558

Keywords: boreal forest; disturbance dynamics; fire refugia; tree age

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Forest age distribution and occurrence of traces of past fires was studied in a natural Picea abies -dominated landscape in the Onega peninsula in north-west Russia. Forest age (maximum tree age) was determined and charcoal and fire scars were searched for in 43 randomly located study plots. In 70% of the study plots (30/43) trees older than 200 years existed. The largest 50-year age class consisted of plots with 251–300 year old forests. Traces of fires were found in all types of study plots, in forests on mineral soil as well as on peatlands. However, fire has been a rare disturbance factor, as traces of fires could not be found in 35% of the study plots (15/43). Estimated from the forest age class distribution, the fire rotation time for the whole area has been at least 300 years, but possibly considerably longer. This fire rotation time is much longer than fire history studies (largely based on examination of fire scars) commonly have reported for the average time between successive fires in Fennoscandia and Northwest Russia. The results suggest that the often stated generalisations about the importance and natural frequency of fire disturbance in boreal forests do not apply in landscapes dominated by Picea abies.

Wallenius, Department of Ecology and Systematics, University of Helsinki, P.O. Box 56, FIN-00014 University of Helsinki, Finland E-mail: tuomo.wallenius@helsinki.fi

article id 557, category Research article

Tuomo Wallenius, Timo Kuuluvainen, Raimo Heikkilä, Tapio Lindholm. (2002). Spatial tree age structure and fire history in two old-growth forests in eastern Fennoscandia. Silva Fennica vol. 36 no. 1 article id 557. https://doi.org/10.14214/sf.557

Keywords: Pinus sylvestris; Picea abies; disturbance dynamics; spatial autocorrelation; spatial pattern

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Two near natural old-growth forests, one dominated by Picea abies and the other by Pinus sylvestris, were studied for their fire history, and spatial patterns of trees and tree ages. The spatial tree age structure and the disturbance history of the forests were examined by drawing age class maps based on mapped and aged trees and by dating fires based on fire scars, and by using spatial analyses at tree scale. The tree age structures of the Picea and Pinus dominated forests were different, mainly due to differences in fire history and sensitivity of the dominant tree species to fire. Fire histories and tree age structures of both sites have probably been affected by human in the ancient past. However, in the Picea dominated site, the fires had been severe, killing most of the trees, whereas in the Pinus dominated site the severity of fires had been more variable, leaving some Pinus and even Picea trees alive. In the Pinus dominated site, the tree age distribution was multimodal, consisting of two Pinus cohorts, which were established after fires and a later Picea regeneration. The Picea dominated site was composed of four patches of different disturbance history. In the oldest patch, the tree age distribution was unimodal, with no distinct cohorts, while a single cohort that regenerated after severe fire disturbances dominated the three other patches. In both sites the overall spatial patterns of living and dead trees were random and the proportion of spatially autocorrelated variance of tree age was low. This means that trees of different age grew more or less mixed in the forest without forming spatially distinct regeneration patches, even in the oldest patch of Picea dominated Liimatanvaara, well over 200 years after a fire. The results show that detail knowledge of disturbance history is essential for understanding the development of tree age structures and their spatial patterns.

Wallenius, Department of Ecology and Systematics, University of Helsinki, P.O. Box 65, FIN-00014, Helsinki, Finland E-mail: tuomo.wallenius@helsinki.fi
Kuuluvainen, Department of Forest Ecology, University of Helsinki, P.O. Box 27, FIN-00014, Helsinki, Finland E-mail: tk@nn.fi
Heikkilä, Research Centre of Friendship Park, Tönölä, FIN-88900 Kuhmo, Finland E-mail: rh@nn.fi
Lindholm, Finnish Environment Institute, Nature and Land Use Division, P.O. Box 140, FIN-00251 Helsinki, Finland E-mail: tl@nn.fi

article id 556, category Research article

Timo Kuuluvainen, Juha Mäki, Leena Karjalainen, Hannu Lehtonen. (2002). Tree age distributions in old-growth forest sites in Vienansalo wilderness, eastern Fennoscandia. Silva Fennica vol. 36 no. 1 article id 556. https://doi.org/10.14214/sf.556

Keywords: forest dynamics; boreal forest; regeneration; age structure; fire disturbance

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The age and size of trees was sampled and measured on eight sample plots (0.2 ha each) within a Pinus sylvestris -dominated boreal forest landscape in Vienansalo wilderness, Russian Karelia. The fire history of these plots was obtained from a previous dendrochronological study. All the studied sample plots showed a wide and uneven distribution of tree ages, but the shape of the age distributions of trees as well as tree species composition varied substantially. Trees over 250 years of age occurred in every studied plot, despite its small size. This suggests that old Pinus were common and rather evenly distributed in the landscape matrix. The oldest Pinus tree was 525 years of age. The correlations between tree age and size were often weak or even nil. In Pinus the correlation between age and diameter was stronger than that between age and height. In the dominant tree species Pinus and Picea, the largest trees were not the oldest trees. The tree age distributions together with the fire history data indicated that the past fires have not been stand replacing, as many of the older Pinus had survived even several fires. Tree age classes that had regenerated after the last fire were most abundant and dominated by Picea and/or deciduous trees, while the trees established before the last fire were almost exclusively Pinus. The results suggest that periodic occurrence of fire is important for the maintenance of the Pinus-dominated landscape. This is because fire kills most Picea and deciduous trees and at the same time enhances conditions for Pinus regeneration, facilitated by available seed from the continuous presence of old fire-tolerant Pinus trees.

Kuuluvainen, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: timo.kuuluvainen@helsinki.fi
Mäki, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: jm@nn.fi
Karjalainen, Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: lk@nn.fi
Lehtonen, Faculty of Forestry, University of Joensuu, P.O. Box 24, FIN-80101 Joensuu, Finland E-mail: hl@nn.fi

article id 555, category Research article

Leena Karjalainen, Timo Kuuluvainen. (2002). Amount and diversity of coarse woody debris within a boreal forest landscape dominated by Pinus sylvestris in Vienansalo wilderness, eastern Fennoscandia. Silva Fennica vol. 36 no. 1 article id 555. https://doi.org/10.14214/sf.555

Keywords: forest dynamics; disturbances; dead wood; Scots pine; tree death

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The amount, variability, quality and spatial pattern of coarse woody debris (CWD) on mineral soil sites was studied within a natural Pinus sylvestris L. dominated boreal forest landscape in Russian Viena Karelia. Data on the total CWD was collected on 27 sample plots (20 m x 100 m) and data on large CWD was surveyed along four transects (40 m wide and up to 1000 m long). The mean volume of CWD (standing and down combined) was 69.5 m3 ha–1, ranging from 22.2 m3 ha–1 to 158.7 m3 ha–1 from plot to plot. On average, 26.9 m3 ha–1 (39%) of CWD was standing dead wood and 42.7 m3 ha–1 (61%) down dead wood. The CWD displayed a wide range of variation in tree species, tree size, stage of decay, dead tree type and structural characteristics, creating a high diversity of CWD habitats for saproxylic organisms. Large CWD was almost continuously present throughout the landscape and its overall spatial distribution was close to random, although a weak autocorrelation pattern was found at distances less than about 50 m. On small spatial scales total CWD showed wide variation up to a sample area of about 0.1 ha, beyond which the variation stabilized. The fire history variables of the sample plots were not related to the amount of CWD. This and the spatial pattern of CWD suggest that the CWD dynamics in this landscape was not driven by fire, but by more or less random mortality of trees due to autogenic causes of death.

Karjalainen, Department of Forest Ecology, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: lk@nn.fi
Kuuluvainen, Department of Forest Ecology, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: timo.kuuluvainen@helsinki.fi

article id 554, category Research article

Seppo Rouvinen, Timo Kuuluvainen, Juha Siitonen. (2002). Tree mortality in a Pinus sylvestris dominated boreal forest landscape in Vienansalo wilderness, eastern Fennoscandia. Silva Fennica vol. 36 no. 1 article id 554. https://doi.org/10.14214/sf.554

Keywords: dead wood; disturbance dynamics; spatial pattern analysis; mortality agent; forest structure; temporal variation

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Tree mortality and its causes and spatial pattern were examined along four transects (width 40 m, length 2550–3960 m), with a total length of 12 190 m and area of 48.8 ha, in a Pinus sylvestris L. dominated, boreal forest landscape. Tree mortality was determined within a time window of 3 years by identifying those trees (dbh ≥ 10 cm) along the transects that fitted into one of the three categories: 1) current mortality: trees that had died during the year of survey (1998), 2) recent mortality: trees that had died during the year (1997) before the survey year, and 3) predicted mortality: trees that were expected to die during the year (1999) following the survey year. Long-term tree mortality was studied on 10 plots (20 m x 100 m) by dating 87 dead trees using dendrochronological methods. The mean current mortality was 1.4 m3 ha–1 (3.7 trees ha–1). Both the recent and predicted mortalities were also 1.4 m3 ha–1. Mortality was, on the average, higher on peatlands than on mineral soils. The highest mortality was found within an area recently flooded by beavers. Over half of the examined trees (52%) were judged to die without any visible signs of an external abiotic cause. At the landscape scale, tree mortality was continuous although somewhat aggregated in space. Of the 66 dated standing dead Pinus trees, 23 (35%) had died during the 19th century and two during the 18th century, demonstrating that dead Pinus can remain standing for long periods of time before falling. Our results show that autogenic mortality of individual trees or small groups of trees was the predominant mode of disturbance in this Pinus dominated landscape.

Rouvinen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: seppo.rouvinen@forest.joensuu.fi
Kuuluvainen, University of Helsinki, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: tk@nn.fi
Siitonen, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: juha.siitonen@metla.fi

article id 578, category Research article

Kevin Boston, Pete Bettinger. (2001). Development of spatially feasible forest plans: a comparison of two modeling approaches. Silva Fennica vol. 35 no. 4 article id 578. https://doi.org/10.14214/sf.578

Keywords: forest planning; heuristics; linear programming; wildlife goals

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Spatial goals are becoming more frequent aspects of forest management plans as regulatory and organizational policies change in response to fisheries and wildlife concerns. The combination of green-up constraints (harvesting restrictions that prevent the cutting of adjacent units for a specified period of time) and habitat requirements for red-cockaded woodpeckers (RCW) in the southeastern U.S. suggests that spatially feasible forest plans be developed to guide management activities. We examined two modeling approaches aimed at developing management plans that had both harvest volume goals, RCW habitat, and green-up constraints. The first was a two-stage method that in one stage used linear programming to assign volume goals, and in a second stage used a tabu search – genetic algorithm heuristic technique to minimize the deviations from the volume goals while maximizing the present net revenue and addressing the RCW and green-up constraints. The second approach was a one-stage procedure where the entire management plan was developed with the tabu search – genetic algorithm heuristic technique, thus it did not use the guidance for timber volume levels provided by the LP solution. The goal was to test two modeling approaches to solving a realistic spatial harvest scheduling problem. One is where to volume goals are calculated prior to developing the spatially feasible forest plan, while the other approach simultaneously addresses the volume goals while developing the spatially feasible forest plan. The resulting forest plan from the two-stage approach was superior to that produced from the one-stage approach in terms of net present value. The main point from this analysis is that heuristic techniques may benefit from guidance provided by relaxed LP solutions in their effort to develop efficient forest management plans, particularly when both commodity production and complex spatial wildlife habitat goals are considered. Differences in the production of forest products were apparent between the two modeling approaches, which could have a significant effect on the selection of wood processing equipment and facilities.

Boston, Forest Fibre Solutions, Carter Holt Harvey, Tokoroa, New Zealand E-mail: kevin.boston@chh.co.nz
Bettinger, Department of Forest Resources, Oregon State University, Corvallis, OR 97331 E-mail: pb@nn.us

article id 577, category Research article

Jouni Siipilehto. (2001). Effect of weed control with fibre mulches and herbicides on the initial development of spruce, birch and aspen seedlings on abandoned farmland. Silva Fennica vol. 35 no. 4 article id 577. https://doi.org/10.14214/sf.577

Keywords: Populus tremula; Betula pendula; Picea abies; glyphosate; dichlobenile; herbicide; mulching; terbuthylazine; weed control

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Post-planting weed control methods on abandoned farmland were studied in three field trials in southern Finland using a completely randomized design with four treatments and 30 to 40 replications. Mulches of 60 x 60 cm [sheet mulch – strips of plane waste and plastic fibre, newspaper – waste paper slurry, wood chips, pure wood fibre slurry], herbicides [i.e. glyphosate or terbuthylazine alone or mixed and dichlobenile applied to 1 m2 spots] and hoeing treatments were compared to an untreated control plot. The study material consisted of two-year-old containerized aspen (Populus tremula L.), silver birch (Betula pendula (L.) Roth) and Norway spruce (Picea abies (L.) Karst.) seedlings planted in spring 1996. The ground vegetation was dominated by Elymys repens, Deschampsia cespitosa, Cirsium arvense and Epilobium angustifolium. Monitoring of the trials over a 3-year period showed a moderate effect of weed control, which varied according to the method used and by the crop species. Significant growth responses were found with herbicide in spruce, wood chips in spruce and birch and with sheet mulch in aspen seedlings. Sheet mulch also encouraged vole nesting thus increasing damages. Generally, slurry mulches proved to be insufficiently durable. Mulching had a clear insulating effect, which may increase the risk of winter drought.

Siipilehto, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: jouni.siipilehto@metla.fi

article id 590, category Research article

Anna Saarsalmi, Eino Mälkönen, Sirpa Piirainen. (2001). Effects of wood ash fertilization on forest soil chemical properties. Silva Fennica vol. 35 no. 3 article id 590. https://doi.org/10.14214/sf.590

Keywords: Pinus sylvestris; wood ash; Picea abies; nutrients; acidity; neutralization; pH

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The effects of wood ash fertilization on soil chemical properties were studied in three young Scots pine (Pinus sylvestris L.) plantations and a Norway spruce (Picea abies (L.) Karst.) plantation with different site fertility in southern Finland. The dose of 3 t ha–1 of loose wood ash was applied to 4 replicate plots (25 x 25 m) at each experiment. Humus layer and mineral soil samples were taken before the treatment and 7 and 16 years after wood ash application. Results showed that neutralization as well as fertilization effects of wood ash on forest soil were of long duration. An ash-induced pH increase of 0.6–1.0 pH units and exchangeable acidity (EA) decrease of 58–83% were detected in the humus layer 16 years after wood ash application. The decrease in acidity was most pronounced on the Calluna site with initially the lowest pH and highest EA. In the mineral soil the increase in pH was observed later than in the humus layer. After 16 years, the mineral soil pH was increased (0.2–0.3 pH units) on the Vaccinium and Myrtillus sites. A corresponding and in most cases a significant increase in the extractable Ca and Mg concentrations was detected in both the humus layer and in the mineral soil. Wood ash significantly increased the effective cation exchange capacity (CECe) and base saturation (BS) but decreased the concentration of exchangeable Al in both soil layers on all the sites. No response of N availability to wood ash application could be found.

Saarsalmi, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: anna.saarsalmi@metla.fi
Mälkönen, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: em@nn.fi
Piirainen, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: sp@nn.fi

article id 588, category Research article

Marjut Ihalainen, Timo Pukkala. (2001). Modelling cowberry (Vaccinium vitis-idaea) and bilberry (Vaccinium myrtillus) yields from mineral soils and peatlands on the basis of visual field estimates. Silva Fennica vol. 35 no. 3 article id 588. https://doi.org/10.14214/sf.588

Keywords: Vaccinium myrtillus; Vaccinium vitis-idaea; non-wood forest products

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This study presents new models for predicting bilberry and cowberry yields from site and stand characteristics. These models enable one to evaluate the future states of forests in terms of berry yields. The modelling data consisted of visual field estimates of site and tree stand characteristics, as well as berry yields from 627 forest stands. Berry yields were estimated using a scale from 0 to 10. Using these data, models were prepared which predict the berry yield scores from those site and stand characteristics which are usually known in forest planning calculations. The model predictions correlated positively and often quite strongly with earlier models. The results were in line with previous studies on the effects of site and tree cover on berry production. According to the models, sites of medium and rather poor fertility produce the highest bilberry yields. Increasing tree height increases, and the basal area of spruce and proportion of deciduous trees decrease, bilberry yield. With mineral soils, cowberry yields are best on poor sites. A high proportion of pine improves cowberry yields. The yields are the highest in open areas and very young stands, on the one hand, and in sparsely populated stands of large and old trees, on the other hand. In pine swamps, the yields are best on rather poor sites. Increasing basal area of deciduous trees decreases cowberry yields.

Ihalainen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: marjut.ihalainen@forest.joensuu.fi
Pukkala, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: tp@nn.fi

article id 586, category Research article

Tuula Nuutinen, Seppo Kellomäki. (2001). A comparison of three modelling approaches for large-scale forest scenario analysis in Finland. Silva Fennica vol. 35 no. 3 article id 586. https://doi.org/10.14214/sf.586

Keywords: MELA; carbon budget; forestry model; scenario modelling; EFISCEN; SIMA

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Forests play an important role in the sequestration of carbon dioxide and the storage of carbon. The potential and efficiency of mitigation options in forestry have been studied using large-scale forestry scenario models. In Finland, three models have been applied in attempts to estimate timber production and related carbon budgets. In this study, these models are compared. The oldest, MELA, was designed in the 1970s for the regional and national analysis of timber production. The European Forest Information Scenario Model, EFISCEN, originally a Swedish area matrix model, was developed in the early 1980s. SIMA, a gap-type ecosystem model, was utilised in the 1990s for regional predictions on how the changing climate may affect forest growth and timber yield in Finland. In EFISCEN, only the development of growing stock is endogeneous because the assumptions on growth, and the removal and rules for felling are given exogeneously. In the SIMA model, the rules for felling are exogeneous but the growth is modelled based on individual trees reacting to their environment. In the MELA model, the management of forests is endogeneous, i.e. the growth, felling regimes and the development of growing stock are the results of the analysis. The MELA approach integrated with a process-based ecosystem model seems most applicable in the analyses of effective mitigation measures compatible with sustainable forestry under a changing climate. When using the scenarios for the estimation of carbon budget, the policy makers should check that the analyses cover the whole area of interest, and that the assumptions on growth and management together with the definitions applied correspond with the forestry conditions in question.

Nuutinen, Finnish Forest Research Institute, Joensuu Research Centre, Box 68, FIN-80101 Joensuu, Finland E-mail: tuula.nuutinen@metla.fi
Kellomäki, University of Joensuu, Box 111, FIN-80101 Joensuu, Finland E-mail: sk@nn.fi

article id 585, category Research article

Meinrad Rohner, Klaus Böswald. (2001). Forestry development scenarios: timber production, carbon dynamics in tree biomass and forest values in Germany. Silva Fennica vol. 35 no. 3 article id 585. https://doi.org/10.14214/sf.585

Keywords: carbon balance; forestry scenario modeling; forest valuation

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The dynamics of the age class structure stands at the center of modeling long-run forestry scenarios. This insight has been applied to the construction of the Forest Development and Carbon Budget Simulation Model (ForCaBSiM), a model which is used for the study of several interrelated questions: the development of timber stocks and the potential level of sustainable harvests, the stocks and fluxes of tree carbon in managed forests, the economy-wide effects of management practices on the value of forest lands and timber stocks. The combined study of these issues allows to assess development scenarios with regard to the productive potential of forestry, the carbon cycle, and forest values. At present, the model is adapted to German data, but it is designed for use with other data sets as well. This paper provides a description of core mechanisms in ForCaBSiM. On this background, the choice and impact of crucial assumptions is examined. Illustrative results are used to demonstrate the use of the model. The paper focuses on the impact of varying rotation ages and the tree species composition. Particular attention is given to the concept of steady states.

Rohner, Renewable Resource Modeling, D-63477 Maintal, Germany E-mail: rohner@rrmodeling.de
Böswald, Factor Consulting + Management AG, CH-8045 Zurich, Switzerland E-mail: kb@nn.ch

article id 593, category Research article

Anneli Jalkanen. (2001). The probability of moose damage at the stand level in southern Finland. Silva Fennica vol. 35 no. 2 article id 593. https://doi.org/10.14214/sf.593

Keywords: National Forest Inventory; Alces alces; multilevel logistic regression; risk management

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The probability of moose damage was studied in sapling stands and young thinning stands in southern Finland. Data from the eighth National Forest Inventory in 1986–92 were used for modelling. The frequency of damage was highest at the height of two to five meters and at the age of ten to twenty years (at the time of measurement). Moose preferred aspen stands the most and least preferred Norway spruce stands. Scots pine and silver birch were also susceptible to damage. Logistic regression models were developed for predicting the probability that moose damage is the most important damaging agent in a forest stand. The best predictive variables were the age and dominant species of the stand. Variables describing the site were significant as cluster averages, possibly characterizing the area as a food source (fertility and organic soil), as well as the lack of shelter (wall stand). When sample plot, cluster and municipality levels were compared, it was found that most of the unexplained variance was at the cluster level. To improve the model, more information should be obtained from that level. The regression coefficients for aspen as supplementary species, and for pine as dominant species, had significant variance from cluster to cluster (area to area). It was also shown that the occurrence of aspen is closely connected to the occurrence of moose damage in pine sapling stands.

Jalkanen, Finnish Forest Research Institute, Unioninkatu 40 A, FIN-00170 Helsinki, Finland E-mail: anneli.jalkanen@metla.fi

article id 592, category Research article

Marja-Liisa Juntunen. (2001). Use of pesticides in Finnish forest nurseries in 1996. Silva Fennica vol. 35 no. 2 article id 592. https://doi.org/10.14214/sf.592

Keywords: herbicides; fungicides; insecticides; seedlings; survey study

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In 1996 a questionnaire on seedling production and use of pesticides was sent to 33 forest nurseries in Finland. Twenty-eight nurseries answered the questionnaire; thus the survey covered about 80% of the Finnish production of forest seedlings. According to this study, the Finnish nurseries together are using about 1000 kilograms of pesticides (as active ingredient, a.i.) annually. The most used herbicide was terbutylazine (Gardoprim-Neste®), and half of the total amount of fungicide used was chlorothalonil (Bravo 500®). Three fourths of the insecticide products had permethrin as the active ingredient. The nurseries applied, on average, 1.7 kg pesticides (a.i.)/ha annually, although the amount varied considerably between nurseries. In production of container seedlings the highest mean amounts of pesticides were applied to pine seedlings (9.5 kg/ha) and the lowest to spruce seedlings (0.9 kg/ha). To the fields of bareroot seedlings the nurseries applied, on average, 3.9 kg pesticides (a.i.)/ha. Mean amounts of pesticide (a.i.) per 1000 seedlings grown in containers were almost the same for birch and pine production, 1.6 and 1.7 grams, respectively; for production of spruce seedlings the comparable values were less than 0.5 grams. For production of bareroot seedlings the nurseries used about four times more pesticides than for container seedlings.

Juntunen, The Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland E-mail: marja-liisa.juntunen@metla.fi

article id 606, category Research article

Pekka Leskinen, Jyrki Kangas. (2001). Modelling future timber price development by using expert judgments and time series analysis. Silva Fennica vol. 35 no. 1 article id 606. https://doi.org/10.14214/sf.606

Keywords: forest planning; uncertainty; expert knowledge; forecasting; price peaks; price trend; price variation

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Timber prices belong to the most important variables affecting the optimality of forest management. On the other hand, forecasting of timber prices is very uncertain. One difficulty when using past time series data in forecasting future timber price development is the possibility of changes in the markets and in the society at large. Expert knowledge can be applied in forecasting of timber prices as information additional to that provided by time series modelling. This paper presents an approach utilising both time series data and expert judgments in modelling future timber prices. A time series model is used as the basis for the approach. Parameters describing future timber price trends, variation in future timber prices, and the probabilities of price peaks taking place in the future are estimated with expert judgments as the basis. A case study involving 12 experts was carried out in Finland, and models were estimated for all the six major timber assortments in the country. The model produced can be utilised in the optimisation calculations of forest planning.

Leskinen, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: pekka.leskinen@metla.fi
Kangas, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: jk@nn.fi

article id 602, category Research article

Teijo Nikkanen. (2001). Reproductive phenology in a Norway spruce seed orchard. Silva Fennica vol. 35 no. 1 article id 602. https://doi.org/10.14214/sf.602

Keywords: Picea abies; flowering; receptive period; pollination; reproductive synchronisation

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Reproductive phenology was studied in a Norway spruce seed orchard, located in southern Finland (62°13’N, 25°24’E), consisting of 67 clones from northern Finland (64°–67°N). Timing of flowering was determined on the basis of data recorded by a pollen catch meter during 1984–1995, and visual observations made on grafts in 1989, 1992, 1993 and 1995. The genetic and environmental factors affecting female and male phenology, and reproductive synchronisation were studied. The between-year variation in the timing of flowering was more than three weeks. However, when it was defined on the basis of the effective temperature sum, the variation was smaller. No phenological reproductive isolation was found between the seed orchard and surrounding natural forests. The duration of the receptive period of the seed orchard varied from 5 to 8 days, and anthesis determined on the basis of airborne pollen from 5 to 10 days. The receptive period started about one day earlier than anthesis, except in one abnormally warm flowering period when female and male flowering started simultaneously. In general, the flowering periods of the different clones overlapped. The clonal differences in the phenology of receptivity were in most cases statistically significant, but in pollen shedding they were not. The broad-sense heritability estimates were higher for female than for male phenology. Environmental factors, conversely, had a stronger effect on male phenology. A wide graft spacing and a graft position that favoured solar radiation on the lower parts of the crown promoted early pollen shedding and, subsequently, better reproductive synchronisation between female and male flowering.

Nikkanen, Finnish Forest Research Institute, Punkaharju Research Station, FIN-58451 Punkaharju, Finland E-mail: teijo.nikkanen@metla.fi

article id 622, category Research article

Håkan Lindström. (2000). Intra-tree models of basic density in Norway spruce as an input to simulation software. Silva Fennica vol. 34 no. 4 article id 622. https://doi.org/10.14214/sf.622

Keywords: Picea abies; wood density; image analysis; basic density; growth conditions

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Basic density is said to influence aspects of conversion, properties, and end-use of forest products. Consequently, it is argued that accurate models of basic density variation, within and between trees, could be used to improve the utilisation of wood as an industrial raw material. The objective of the present study was to develop basic density models based on Norway spruce trees, that could be used within a model system for conversion simulation studies. Nineteen stands of Norway spruce (Picea abies (L.) Karst.) were selected throughout Sweden. Based on dbh, two small, two moderate, and two large timber trees were taken from each stand. Dbh varied between 180–470 mm, tree height between 17–34 m, and total age between 51–152 years. Each selected tree was cross-cut into logs; discs were prepared from the butt end of each log and from the top end of the top log. Computed tomography scanning and image analysis were used to determine basic density and growth ring development on sampled discs. Basic density development in 20-mm segments from pith outwards was modelled in models based on ring width, tree and growth condition data. The resulting models had an adjusted R2 of 0.37–0.51 and a RMSE of 37–41 kg/m3.

Lindström, University of Canterbury, School of Forestry, Private Bag 4800, Christchurch, New Zealand E-mail: lindstromhakan@netscape.net

article id 621, category Research article

Jyrki Kangas, Pekka Leskinen, Timo Pukkala. (2000). Integrating timber price scenario modeling with tactical management planning of private forestry at forest holding level. Silva Fennica vol. 34 no. 4 article id 621. https://doi.org/10.14214/sf.621

Keywords: decision support; optimization; adaptive behaviour; non-industrial private forestry; tactical planning; timber price modelling

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In forest management planning, deterministic timber prices are typically assumed. However, real-life timber prices vary in the course of time, and also price peaks, i.e. exceptionally high timber prices, might occur. If land-owners can utilise the price variation by selling timber with the high prices, they are able to increase their net revenues correspondingly. In this study, an approach is presented to study the timber price variation and its significance in the optimization of forest management. The approach utilizes stochastic timber price scenario modelling, simulation of forest development, and optimization of forest management. The approach is presented and illustrated by means of a case study. It is shown how the degree of uncertainty due to variation in timber prices can be analyzed in tactical forest planning of private forestry, and how the potential benefits of adaptive timber-selling behaviour for a forest landowner can be computed by using the approach. The effects of stochastic timber prices on the choice of forest plan are studied at the forest holding level considering also the spacing and type of cuttings and the optimal cutting order. A forest plan prepared under the assumption of constant timber price very seldom results in optimal forest management. Through studying the effects of stochastic timber prices, forest landowners and other decision makers obtain valuable information about the significance of adaptive timber selling behaviour. The presented methodology can also be used in analysing the land-owners’ economic risks as a function of time-price structure.

Kangas, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: jyrki.kangas@metla.fi
Leskinen, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: pl@nn.fi
Pukkala, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: tp@nn.fi

article id 620, category Research article

Annika Kangas, Matti Maltamo. (2000). Performance of percentile based diameter distribution prediction and Weibull method in independent data sets. Silva Fennica vol. 34 no. 4 article id 620. https://doi.org/10.14214/sf.620

Keywords: stand structure; calibration estimation; Weibull function; diameter distribution prediction; distribution-free method; nearest neighbour method

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Diameter distribution is used in most forest management planning packages for predicting stand volume, timber volume and stand growth. The prediction of diameter distribution can be based on parametric distribution functions, distribution-free parametric prediction methods or purely non-parametric methods. In the first case, the distribution is obtained by predicting the parameters of some probability density function. In a distribution-free percentile method, the diameters at certain percentiles of the distribution are predicted with models. In non-parametric methods, the predicted distribution is a linear combination of similar measured stands. In this study, the percentile based diameter distribution is compared to the results obtained with the Weibull method in four independent data sets. In the case of Scots pine, the other methods are also compared to k-nearest neighbour method. The comparison was made with respect to the accuracy of predicted stand volume, saw timber volume and number of stems. The predicted percentile and Weibull distributions were calibrated using number of stems measured from the stand. The information of minimum and maximum diameters were also used, for re-scaling the percentile based distribution or for parameter recovery of Weibull parameters. The accuracy of the predicted stand characteristics were also compared for calibrated distributions. The most reliable results were obtained using the percentile method with the model set including number of stems as a predictor. Calibration improved the results in most cases. However, using the minimum and maximum diameters for parameter recovery proved to be inefficient.

Kangas, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: annika.kangas@metla.fi
Maltamo, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: mm@nn.fi

article id 617, category Research article

Jouni Siipilehto. (2000). A comparison of two parameter prediction methods for stand structure in Finland. Silva Fennica vol. 34 no. 4 article id 617. https://doi.org/10.14214/sf.617

Keywords: Pinus sylvestris; Picea abies; parameter prediction; dbh and height distribution; Johnson’s SBB distribution; Näslund’s height curve

Abstract | View details | Full text in PDF | Author Info

The objective of this paper was to predict a model for describing stand structure of tree heights (h) and diameters at breast height (dbh). The research material consisted of data collected from 64 stands of Norway spruce (Picea abies Karst.) and 91 stands of Scots pine (Pinus sylvestris L.) located in southern Finland. Both stand types contained birch (Betula pendula Roth and B. pubescent Ehrh.) admixtures. The traditional univariate approach (Model I) of using the dbh distribution (Johnson’s SB) together with a height curve (Näslund’s function) was compared against the bivariate approaches, Johnson’s SBB distribution (Model II) and Model Ie. In Model Ie within-dbh-class h-variation was included by transforming a normally distributed homogenous error of linearized Näslund’s function to concern real heights. Basal-area-weighted distributions were estimated using the maximum likelihood (ML) method. Species-specific prediction models were derived using linear regression analysis. The models were compared with Kolmogorov-Smirnov tests for marginal distributions, accuracy of stand variables and the dbh-h relationship of individual trees. The differences in the stand characteristics between the models were marginal. Model I gave a slightly better fit for spruce, but Model II was better for pine stands. The univariate Model I resulted in clearly too narrow marginal h-distribution for pine. It is recommended applying of a constrained ML method for reasonable dbh-h relationship instead of using a pure ML method when fitting the SBB model.

Siipilehto, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: jouni.siipilehto@metla.fi

article id 627, category Research article

Joseph Buongiorno, Audra Kolbe, Mike Vasievich. (2000). Economic and ecological effects of diameter-limit and BDq management regimes: simulation results for northern hardwoods. Silva Fennica vol. 34 no. 3 article id 627. https://doi.org/10.14214/sf.627

Keywords: diversity; hardwoods; simulation; uneven-aged management; economics; mixed-species stands

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The long-term financial and ecological effects of diameter-limit regimes and basal-area-diameter-q-ratio (BDq) regimes were compared by simulation in the case of northern hardwood forests. Varying the cutting cycle between 10 and 20 years had little effect on returns or stand structure. A 28-cm diameter-limit cut gave the highest production and financial returns, and the highest species diversity, but considerably lower size diversity. A 38-cm diameter-limit cut and a heavy BDq selection harvest gave high returns, while maintaining high levels of diversity. On lands of equal site quality, Michigan’s stands were more productive than Wisconsin’s. The results suggest that it is possible to manage northern hardwood stands sustainably with diameter-limit cuts, combined with removal of poorly performing understory trees. Adjusting the diameter limit gave rise to stands similar in productivity and structure to those obtained by BDq cutting regimes. Given their simplicity of implementation and monitoring, more attention should be given to diameter-limit cutting regimes, with attendant stand improvement measures, as a practical means for uneven-aged management of northern hardwoods.

Buongiorno, Department of Forest Ecology and Management, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI 53705, USA E-mail: Jbuongio@facstaff.wisc.edu
Kolbe, Department of Forest Ecology and Management, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI 53705, USA E-mail: ak@nn.us
Vasievich, USDA Forest Service, North Central Forest Experiment Station, 1407 S. Harrison Road, Suite 220, East Lansing, MI 48823, USA E-mail: mv@nn.us

article id 626, category Research article

Teijo Nikkanen, Seppo Ruotsalainen. (2000). Variation in flowering abundance and its impact on the genetic diversity of the seed crop in a Norway spruce seed orchard. Silva Fennica vol. 34 no. 3 article id 626. https://doi.org/10.14214/sf.626

Keywords: Picea abies; clone; ramet; status number; census number

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The variation in flowering abundance was studied in a Norway spruce seed orchard, located in southern Finland (62°13'N, 25°24'E), consisting of 67 clones from northern Finland (64°–67°N). The flowering variation in 1984–1996 was studied at the annual, clonal and graft level. In addition, the genetic diversity of an imaginary seed crop was estimated using a concept of status number. The between-year variation was large in both female and male flowering. Differences in flowering abundance among the clones were large and statistically significant in all the years studied. The average broad-sense heritability values for female and male flowering were 0.37 and 0.38, respectively, but varied considerably from year to year. The correlations between the flowering abundance of the clones in different years were usually positive and significant. However, the correlations for two pairs of successive good flowering years showed that the same clones usually flowered well in the first year in both pairs of years, and the other clones in the second year. The clonal differences in flowering could not be explained by geographic origin, but were more dependent on the graft size. Our results demonstrate that the variation in the ramet number, flowering abundance and pollen contamination must be included when estimating the genetic diversity of the seed crop in a seed orchard. The relative status number of the seed orchard was 84% of the number of clones when the variation in the ramet number was included. The relative status numbers after adjusting for the variation in female and male flowering were on the average 46 and 55%, respectively, and 59% when adjusting for both genders together. Pollen contamination increased the status number considerably.

Nikkanen, Finnish Forest Research Institute, Punkaharju Research Station, FIN-58450 Punkaharju, Finland E-mail: teijo.nikkanen@metla.fi
Ruotsalainen, Finnish Forest Research Institute, Punkaharju Research Station, FIN-58450 Punkaharju, Finland E-mail: sr@nn.fi

article id 625, category Research article

Hans-Örjan Nohrstedt. (2000). Effects of soil scarification and previous N fertilisation on pools of inorganic N in soil after clear-felling of a Pinus sylvestris (L.) stand. Silva Fennica vol. 34 no. 3 article id 625. https://doi.org/10.14214/sf.625

Keywords: boreal forest; mound; Sweden; furrow; nitrogen mineralisation; podsol

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Previous analyses of soil water beneath mounds resulting from scarification have implied that this forestry measure increases leaching of inorganic N. However, more recent soil-water studies have not confirmed this assumption. The soil study presented here examined the pools of inorganic N in different microsites emanating from a simulated disc trenching, i. e. the mound with underlying soil, the furrow bottom and the undisturbed soil. The study was made five years after scarification. The mound itself with underlying soil had a larger pool of inorganic N than the undisturbed soil. This was mainly because of an increase in the embedded humus layer, thus implying a larger net N mineralisation and/or lower losses. However, when pools of inorganic N per hectare were calculated, taking into consideration that a scarified area comprises 25% mounds, 25% furrows and 50% undisturbed soil, there was no increase in pools of inorganic N when compared with an area not subjected to scarification. This observation supports the finding of the more recent soil-water studies mentioned, i. e., that leaching seems not to be influenced by soil scarification. The scarification was made as a split-plot treatment on main-plots in an old experiment with different N doses. Thus, the effect of the previous N fertilisation could also be evaluated. Two N doses were tested beside the unfertilised control: 720N (3 x 240 kg N ha–1 yr–1) and 1800N (3 x 600 kg N ha–1 yr–1). The last fertiliser application was made six years before the clearcutting and 13 years before the soil sampling. The previously fertilised main-plots had larger pools of inorganic N than the control plots.

Nohrstedt, The Forestry Research Institute of Sweden, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: hans-orjan.nohrstedt@skogforsk.se

article id 635, category Research article

Manfred J. Lexer, Karl Hönninger, Helfried Scheifinger, Christoph Matulla, Nikolaus Groll, Helga Kromp-Kolb. (2000). The sensitivity of central European mountain forests to scenarios of climatic change: methodological frame for a large-scale risk assessment. Silva Fennica vol. 34 no. 2 article id 635. https://doi.org/10.14214/sf.635

Keywords: climate change; potential natural vegetation; alpine forests; risk assessment; patch model; multi-attribute decision making

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The methodological framework of a large-scale risk assessment for Austrian forests under scenarios of climatic change is presented. A recently developed 3D-patch model is initialized with ground-true soil and vegetation data from sample plots of the Austrian Forest Inventory (AFI). Temperature and precipitation data of the current climate are interpolated from a network of more than 600 weather stations to the sample plots of the AFI. Vegetation development is simulated under current climate (‘control run’) and under climate change scenarios starting from today's forest composition and structure. Similarity of species composition and accumulated biomass between these two runs at various points in time were used as assessment criteria. An additive preference function which is based on Saaty’s AHP is employed to synthesize these criteria to an overall index of the adaptation potential of current forests to a changing climate. The presented methodology is demonstrated for a small sample from the Austrian Forest Inventory. The forest model successfully simulated equilibrium species composition under current climatic conditions spatially explicit in a heterogenous landscape based on ground-true data. At none of the simulated sites an abrupt forest dieback did occur due to climate change impacts. However, substantial changes occured with regard to species composition of the potential natural vegetation (PNV).

Lexer, Institute of Silviculture, University of Agricultural Sciences, Peter-Jordanstrasse 70, A-1190 Vienna, Austria E-mail: lexer@edv1.boku.ac.at
Hönninger, Institute of Silviculture, University of Agricultural Sciences, Peter-Jordanstrasse 70, A-1190 Vienna, Austria E-mail: kh@nn.at
Scheifinger, Institute of Meteorology and Physics, University of Agricultural Sciences, Türkenschanzstrasse 18, A-1180 Vienna, Austria E-mail: hs@nn.at
Matulla, Institute of Meteorology and Physics, University of Agricultural Sciences, Türkenschanzstrasse 18, A-1180 Vienna, Austria E-mail: cm@nn.at
Groll, Institute of Meteorology and Physics, University of Agricultural Sciences, Türkenschanzstrasse 18, A-1180 Vienna, Austria E-mail: ng@nn.at
Kromp-Kolb, Institute of Meteorology and Physics, University of Agricultural Sciences, Türkenschanzstrasse 18, A-1180 Vienna, Austria E-mail: hkk@nn.at

article id 642, category Research article

Jonas Rönnberg. (2000). Logging operation damage to roots of clear-felled Picea abies and subsequent spore infection by Heterobasidion annosum. Silva Fennica vol. 34 no. 1 article id 642. https://doi.org/10.14214/sf.642

Keywords: Norway spruce; logging damage; Butt rot; root rot; clear felling; stump root infection

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Two studies were carried out to examine the effects of clear-felling operations on stump roots of Norway spruce (Picea abies (L.) Karst.). In study I, the number of cases and the degree of damage to stump roots of Norway spruce were investigated on three clear-felled sites in northern and southern Sweden respectively. The cutting was done in winter or spring. A mean of 37% of the stumps had signs of root damage caused by clear-felling operations. Study II was carried out on two sites in southern and two sites in northern Sweden. The trees were clear-felled in June or July. The frequency of natural infection by Heterobasidion annosum (Fr.) Bref. through damaged roots was compared to infection through stump surfaces. The total area of damage on roots was 88% of the stump surface area. On average, 54% of the stumps were infected through the stump surface and 19% through locations of root damage. The root infections, however, were generally small in size as compared to stump surface infections. The study shows that damage to roots at clear-felling may be extensive, but this probably is not of great importance for the efficacy of stump treatment against H. annosum.

Rönnberg, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: jonas.ronnberg@ess.slu.se

article id 652, category Research article

M. J. Youngman, G. D. Kulasiri, I. M. Woodhead, G. D. Buchan. (1999). Use of combined constant rate and diffusion model to simulate kiln-drying of Pinus radiata timber. Silva Fennica vol. 33 no. 4 article id 652. https://doi.org/10.14214/sf.652

Keywords: simulation; timber drying; diffusion; constant drying-rate

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This paper presents the use of a combined constant drying-rate and diffusion model to simulate the drying of Pinus radiata timber under kiln-drying conditions. The constant drying-rate and diffusion coefficients of the model, which control the drying rate of individual pieces of timber, were determined from calibrating the model against the experimental drying curves obtained under the kiln-drying conditions. The experimental drying curves were obtained from the gravimetric measurements of the moisture content of timber during kiln drying. Statistical relationships were developed for the constant drying-rate and the diffusion coefficients of the model as functions of kiln temperature and the dry basis density of timber. To determine the effects of variability of timber, a simulation scheme was developed based on the model, the probability distribution of the density of timber, the equations for the constant drying-rate coefficient and the diffusion coefficient. The model and the associated simulation method provides a simple way to estimate the drying time of a stack of timber using parameters determined from experimental results for the specific timber kiln.

Youngman, Lincoln University, Appl. Management and Computing Division, P.O. Box 84, Canterbury, New Zealand E-mail: mjy@nn.nz
Kulasiri, Lincoln University, Appl. Management and Computing Division, P.O. Box 84, Canterbury, New Zealand E-mail: kulasird@tui.lincoln.ac.nz
Woodhead, Lincoln University, Appl. Management and Computing Division, P.O. Box 84, Canterbury, New Zealand E-mail: imw@nn.nz
Buchan, Lincoln University, Appl. Management and Computing Division, P.O. Box 84, Canterbury, New Zealand E-mail: gdb@nn.nz

article id 651, category Research article

Annika S. Kangas, Jyrki Kangas. (1999). Optimization bias in forest management planning solutions due to errors in forest variables. Silva Fennica vol. 33 no. 4 article id 651. https://doi.org/10.14214/sf.651

Keywords: forest planning; uncertainty; prediction; decision analysis

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The yield of various forest variables is predicted by means of a simulation system to provide information for forest management planning. These predictions contain many kinds of uncertainty, for example, prediction and measurement errors. Inevitably, this has an effect on forest management planning. It is well known that uncertainty in the forest yields causes optimistic bias in the observed values of the objective function. This bias increases with the error variances. The amount of bias, however, also depends on the error structure and the relations between the objective variables. In this paper, the effect of uncertainty in forest yields on optimization is studied by simulation. The effect of two different sources of error, the correlation structure of these errors and relations among the objective variables are considered, as well as the effect of two different optimization approaches. The relations between the objective variables and the error structure had a notable effect on the optimization results.

Kangas, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: annika.kangas@metla.fi
Kangas, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: jk@nn.fi

article id 649, category Research article

Tord Johansson. (1999). Biomass production of Norway spruce (Picea abies (L.) Karst.) growing on abandoned farmland. Silva Fennica vol. 33 no. 4 article id 649. https://doi.org/10.14214/sf.649

Keywords: Norway spruce; biomass production; Picea abies; thinning; LAI; abandoned farmland; basic density

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Biomass production of forests has been studied for at least a century. Tree biomass is used in Sweden both as industrial raw material and an energy source. Few studies dealing with biomass yield from Norway spruce (Picea abies (L.) Karst.) growing on farmland are published. Practical recommendations are sparsely. The aim of this study was to construct dry weight equations for Norway spruce growing on farmland. Dry weight equations for fractions of Norway spruce trees were made. Biomass production was estimated in 32 stands of Norway spruce growing on abandoned farmland. The stands were located in Sweden at latitudes ranging from 58° to 64° N, and their total age varied from 17 to 54 years. A modified ‘mean tree technique’ was used to estimate biomass production; i.e. the tallest tree was chosen for sampling. The actual mean total dry weight above stump level for the 32 stands was 116 ton ha–1, with a range of 6.0 to 237.4 ton d.w. ha–1. When previous thinning removals were included, the mean biomass value was 127 ton ha–1 (6.0–262.8). In addition to estimating conventional dry weights of trees and tree components, basic density, specific leaf area, total surface area and leaf area index, among other measures, were estimated. Norway spruce biomass yields on plots subjected to different thinning were compared. The total harvested biomass was 75–120 ton d.w. ha–1 in heavy thinnings from below. Stands were thinned four to five times, with the first thinning at 23–27 years and the last at 51–64 years. The harvested biomass obtained in the first thinning was 18–38 ton d.w. ha–1. Total biomass production was 178–305 ton d.w. ha–1. Stands thinned from above supplied 71–130 ton d.w. ha–1 in total and 17–42 ton d.w. ha–1 in the first thinning. The total biomass supply was 221–304 ton d.w. ha–1. Unthinned stands produced a total of 155–245 ton d.w. ha–1.

Johansson, Swedish University of Agricultural Sciences, Department of Forest Management and Products, P.O. Box 7060, S-750 07 Uppsala, Sweden E-mail: tord.johansson@sh.slu.se

article id 648, category Research article

Sauli Härkönen. (1999). Forest damage caused by the Canadian beaver (Castor canadensis) in South Savo, Finland. Silva Fennica vol. 33 no. 4 article id 648. https://doi.org/10.14214/sf.648

Keywords: Canadian beaver; Castor canadensis; forest damage; prevention of damage; type of damage

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The increasing Canadian beaver (Castor canadensis) population has caused forest damage in Finland. However, the occurrence, extent and importance of the damage have not been comprehensively studied. The field inspection was carried out in all of the beaver damage areas (n = 50) in the Anttola, Juva and Pieksämäki game management units in summer 1998. The characteristics of the damage areas, types of damage and the severity of the damage were examined. The size of the damage areas averaged 2.2 ha. The damage areas occurred on peatland forest more (p < 0.05) than expected. The dominant tree species were commercially valuable trees such as Scots pine (Pinus sylvestris) (33%), Norway spruce (Picea abies) (18%) and birches (Betula spp.) (47%). Birch occurred as dominant tree species more (p < 0.05) than expected. The proportion of older forest development classes was considerable. The most important type of damage was flooding (50%) caused by the damming activity of beavers. The trees were dead or dying in 18% of the damage areas. It was estimated that the ecosystem engineering performed by beavers was of no importance in 28% of the damage areas. Prevention of beaver damage has been carried out in 80% of the damage areas. In the study area, beaver numbers have steadily increased, although the number of beavers taken by hunting and the allowed hunting harvest have sharply increased. It is suggested that the methods used to prevent beaver damage should be improved and a compensation system should be provided by the state for the most damaged areas. Beavers can cause damage to commercial forestry, and this should be taken into account more effectively in the management plans made by the game management districts.

Härkönen, South Savo Game Management District, P.O. Box 14, FIN-51901 Juva, Finland E-mail: sauli.harkonen@riistanhoitopiirico.inet.fi

article id 647, category Research article

Tapio Linkosalo. (1999). Regularities and patterns in the spring phenology of some boreal trees. Silva Fennica vol. 33 no. 4 article id 647. https://doi.org/10.14214/sf.647

Keywords: Populus tremula; Pinus sylvestris; flowering; Alnus glutinosa; bud burst; Alnus incana; phenological regulation; phenological time series; Betula sp.

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Phenological time series of flowering and bud burst of Populus tremula (L.) and Betula sp., and the flowering of Pinus sylvestris (L.), Alnus glutinosa (L.) and Alnus incana (L.) were constructed from data collected in Finland during the period 1896–1955. The resulting combined time series were examined with two aims in mind: first, to determine the phenological regularities between different species and, second, to detect patterns of spring advancement over a geographically large area. The results indicate that the geographical pattern of spring advancement is rather uniform from year to year, and between different species. Furthermore, the mechanisms regulating the timing of phenological events in different species seem to function in a similar way, suggesting an unanimous optimal response to climatic conditions.

Linkosalo, University of Helsinki, Department of Forest Ecology, Unioninkatu 40 B, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: tapio.linkosalo@helsinki.fi

article id 658, category Research article

Muru Juurola, Pekka Ollonqvist, Heikki Pajuoja, Mikko Toropainen. (1999). Outcomes of forest improvement work in Finland. Silva Fennica vol. 33 no. 3 article id 658. https://doi.org/10.14214/sf.658

Keywords: forest policy; forest improvement work; subsidies; input-output method; allowable cut

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This paper discusses public subsidies aimed at intensifying timber production as an initial part of an evaluation of the profitability of forest investment subsidies in Finland. In many countries there are very few proper ex post evaluations of the forest policy instruments in economic terms. The scarcity of timber among users and their attempts to construct new forest policy are discussed first. The increments in annual growth and growing stock as well as its valuation are then evaluated. The final gross utility increments due to forestry investments are measured through their importance in the forest industry products. The direct and indirect changes in GDP are calculated by using the input-output method.

Juurola, The Finnish Forest Research Institute, Helsinki Research Centre, Unioninkatu 40 A, FIN-00170 Helsinki, Finland E-mail: mj@nn.fi
Ollonqvist, The Finnish Forest Research Institute, Helsinki Research Centre, Unioninkatu 40 A, FIN-00170 Helsinki, Finland E-mail: po@nn.fi
Pajuoja, The Finnish Forest Research Institute, Helsinki Research Centre, Unioninkatu 40 A, FIN-00170 Helsinki, Finland E-mail: heikki.pajuoja@metla.fi
Toropainen, The Finnish Forest Research Institute, Helsinki Research Centre, Unioninkatu 40 A, FIN-00170 Helsinki, Finland E-mail: mt@nn.fi

article id 656, category Research article

Klaus Silfverberg, Markus Hartman. (1999). Effects of different phosphorus fertilisers on the nutrient status and growth of Scots pine stands on drained peatlands. Silva Fennica vol. 33 no. 3 article id 656. https://doi.org/10.14214/sf.656

Keywords: needles; Scots pine; stand growth; drainage; phosphorus; peat; fertilisation

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The aim of the study was to compare the effects of phosphorus fertilisers of different solubility and different phosphorus doses. The material was collected from 8 field experiments situated on drained peatlands in southern and central Finland (60°–65°N). The sites were drained, oligotrophic pine fens and pine bogs, which had been fertilised between 1961 and 1977 with different combinations of N, K and P. In 1991–94 stand measurements and foliar and peat sampling were carried out on 162 sample plots. Apatite, rock phosphate and superphosphate affected basal area growth to a rather similar extent. However, apatite slightly surpassed superphosphate and rock phosphate at the end of the study period in two hollow-rich S. fuscum bogs. Higher doses of phosphorus did not significantly increase the basal area growth. The foliar phosphorus concentrations clearly reflected the effect of the P fertilisation. Especially on the pine bogs basic fertilisation with 66 kg P/ha maintained the needle phosphorus concentrations at a satisfactory level for more than 25 years after fertilisation. The amount of phosphorus in the 0–20 cm peat layer was not significantly increased either by basic fertilisation or refertilisation. The phosphorus reserves in the peat in the individual experiments were between 88 and 327 kg/ha. There was a strong correlation between the amounts of phosphorus and iron in the peat. Large amounts of iron in peat may reduce the solubility and availability of phosphorus. According to the foliar phosphorus concentrations in the basic-fertilised plots, the need for refertilisation seems to be unnecessary during the 25-year postfertilisation period at least. None of the basic fertilisation treatments seriously retarded the basal area growth compared to the refertilised treatments. There seems to be a greater shortage of potassium than of phosphorus, because the foliar potassium concentrations and the amounts of potassium in the 0–20 cm peat layer were very low in several of the experiments.

Silfverberg, The Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: klaus.silfverberg@metla.fi
Hartman, The Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: mh@nn.fi

article id 665, category Research article

Kari Kangas. (1999). Trade of main wild berries in Finland. Silva Fennica vol. 33 no. 2 article id 665. https://doi.org/10.14214/sf.665

Keywords: imports; bilberry; non-wood forest products; trade; lingonberry; exports

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The price trends and markets of the main wild berries, bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.), were analysed in this study, which covered both domestic use of berries, imports and exports. The periods considered were for bilberries from 1988 to 1997 and for lingonberries from 1979 to 1994. The results indicated that both exports and imports have increased and domestic berries have lost their market share to imports in domestic use. One possible explanation for this trend was found in price development. Both export and import prices have decreased, but export price has still been higher than the import price. Simultaneously the domestic price has decreased the fastest. The formation of the price of lingonberries paid to the pickers in the organised domestic markets was studied with a regression model. The results indicated that domestic price was negatively dependent on the amounts of lingonberries demanded in the domestic markets and positively dependent on the export price. Correlation analysis gave evidence on the same kind of relations concerning bilberries.

Kangas, University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: kari.kangas@forest.joensuu.fi

article id 664, category Research article

Anssi Niskanen. (1999). The financial and economic profitability of field afforestation in Finland. Silva Fennica vol. 33 no. 2 article id 664. https://doi.org/10.14214/sf.664

Keywords: plantation; efficiency; cost-benefit-analysis; net-present-value

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The aim of the study was to assess the rate of return on invested capital and soil expectation value in field afforestation from the financial (business economic) and economic (national economic) point of views in Finland using 1996 cost and price data. Risks for renewal planting and negative growth impacts of reduction in plantation density were explicitly included in the profitability assessments. Results indicated that due to the subsidies and favorable regulations for obtaining them in 1996, field afforestation was financially profitable for farmers regardless of what species was used for planting. From the national economic point of view, investments in field afforestation provided only substantial return on invested capital, being highest after risk adjustments in Norway spruce (Picea abies) plantations.

Niskanen, European Forest Institute, Torikatu 34, FIN-80101 Joensuu, Finland E-mail: anssi.niskanen@efi.fi

article id 661, category Research article

Eira-Maija Savonen, Anna Saarsalmi. (1999). Effects of clone and fertilization on the seed and foliar chemical composition of Scots pine (Pinus sylvestris) grafts. Silva Fennica vol. 33 no. 2 article id 661. https://doi.org/10.14214/sf.661

Keywords: needles; Scots pine; nutrient concentration; seeds; seed orchards

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Effects of clone and fertilization on the seed and foliar nutrient concentrations of Scots pine grafts were investigated in a seed orchard in southern Finland. The seed and foliar samples for chemical analyses were collected during winters 1985–86 and 1988–89 from 39 grafts per clone fertilized in spring 1986. There were 6 clones and 13 treatments for each clone with three replications. The treatments consisted of N, P, K in various combinations, micronutrients, wood ash and grass control. Macro- (N, P, K, Ca, Mg) and micronutrients (Cu, Zn, B) were analysed. There were statistically significant differences between the clones in seed nutrient concentrations. The variation of the K, Mg, Ca, Zn and Cu concentrations between the two study years was considerably larger in the seeds than in the needles. The concentrations of these elements in the seeds were low in the year of an abundant seed crop in spite of fertilization. This had, however, no negative effects on germination of seeds. The proportions of crude fat and crude protein were high in both years (34% and 35% in 1985 ; 33% and 38% in 1988). Fertilization had only minor or no effect at all on the seed chemical composition in the orchard with a satisfactory nutrient status of the soil. Also on the foliar nutrient concentrations the effect of the clone was stronger than that of fertilization. Grafts with large needles produced heavy seeds, which had more storage proteins than the lighter seeds.

Savonen, The Finnish Forest Research Institute, Parkano Research Station, Kaironiementie 54, FIN-39700 Parkano, Finland E-mail: eira-maija.savonen@metla.fi
Saarsalmi, The Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: as@nn.fi

article id 670, category Research article

Jouni Vettenranta. (1999). Distance-dependent models for predicting the development of mixed coniferous forests in Finland. Silva Fennica vol. 33 no. 1 article id 670. https://doi.org/10.14214/sf.670

Keywords: Norway spruce; Scots pine; competition; growth models; Monte Carlo simulation; crown models

Abstract | View details | Full text in PDF | Author Info

Distance-dependent growth models and crown models, based on extensive material, were built for Scots pine and Norway spruce growing in a mixed forest. The crown ratio was also used as a predictor in a diameter growth model to better describe the thinning reaction. The effect of crown ratio on the growth dynamics was studied in simulation examples. Monte Carlo simulation was used to correct the bias caused by nonlinear transformations of predictors and response. After thinnings the crown ratio as a predictor was found to be a clear growth-retarding factor. The growth retarding effect was stronger among pines with thinnings from below, whereas the estimated yield of spruces over rotation was slightly greater when the crown ratio was included than without it. With each type of thinning the effect of crown ratio on pine growth was almost the same, but the growth of spruces was clearly delayed when the stand was thinned from above. Simulation examples also showed that it is profitable to raise the proportion of spruces during rotation, since spruces maintain the growth more vigorous at older ages. The total yield during 90 years rotation was about 20% higher if the stand was transformed into a pure spruce stand instead of pine.

Vettenranta, Kivirinnanpolku 4, FIN-40950 Muurame, Finland E-mail: vettenr@cc.joensuu.fi

article id 669, category Research article

Simo Poso, Guangxing Wang, Sakari Tuominen. (1999). Weighting alternative estimates when using multi-source auxiliary data for forest inventory. Silva Fennica vol. 33 no. 1 article id 669. https://doi.org/10.14214/sf.669

Keywords: remote sensing; two-phase sampling; forest inventory methods

Abstract | View details | Full text in PDF | Author Info

Five auxiliary data sources (Landsat TM, IRS-IC, digitized aerial photographs, visual photo-interpretation and old forest compartment information) applying three study areas and three estimators, two-phase sampling with stratification, the k nearest neighbors and regression estimator, were examined. Auxiliary data were given for a high number of sample plots, which are here called first phase sample plots. The plots were distributed using a systematic grid over the study areas. Some of the plots were then measured in the field for the necessary ground truth. Each auxiliary data source in combination with field sample information was applied to produce a specific estimator for five forest stand characteristics: mean diameter, mean height, age, basal area, and volume of the growing stock. When five auxiliary data sources were used, each stand characteristic and each first phase sample plot were supplied with five alternative estimates with three alternative estimators. Mean square errors were then calculated for each alternative estimator using the cross validation method. The final estimates were produced by weighting alternative estimates inversely according to the mean square errors related to the corresponding estimator. The result was better than the final estimate of any of the single estimators. The improvement over the best single estimate, as measured in mean square error, was 16.9% on average for all five forest stand characteristics. The improvement was fairly equal for all five forest stand characteristics. Only minor differences among the accuracies of the three alternative estimators were recorded.

Poso, Department of Forest Resource Management, P.O. Box 24 (Unioninkatu 40 B), FIN-00014 University of Helsinki, Finland E-mail: simo.poso@helsinki.fi
Wang, Department of Forest Resource Management, P.O. Box 24 (Unioninkatu 40 B), FIN-00014 University of Helsinki, Finland E-mail: gw@nn.fi
Tuominen, Department of Forest Resource Management, P.O. Box 24 (Unioninkatu 40 B), FIN-00014 University of Helsinki, Finland E-mail: st@nn.fi

article id 667, category Research article

Timo Kärki. (1999). Predicting the value of grey alder (Alnus incana) logs based on external quality. Silva Fennica vol. 33 no. 1 article id 667. https://doi.org/10.14214/sf.667

Keywords: alder; log quality; sawn timber quality; log value

Abstract | View details | Full text in PDF | Author Info

The quality of grey alder logs (Alnus incana) was studied by sawing sample logs from two different forests in November 1995–February 1996. For grading of grey alder logs and sawn timber the proposed system of Keinänen and Tahvanainen (1995) plus the reject -grade was used. In general, grey alder logs have knots from the base to the top. All types of knots appear, and the length of the knot-free section is small at the base. In small-dimensioned logs there are fewer knots than in larger logs. Especially in large top logs, there were many more fresh knots than in other types of logs. Evidently, in different types of logs the different grades of sawn timber are located in comparable sections along the length. It also seems that the worse the grade class was, the longer was also the length of the class. The most common reasons for decreasing grade were dry knots and discoloration.

Kärki, University of Joensuu, Faculty of Forestry, P.O. BOX 111, FIN-80101 Joensuu, Finland E-mail: timo.karki@forest.joensuu.fi

article id 666, category Research article

Rolf Pape. (1999). Influence of thinning on spiral grain in Norway spruce grown on highly productive sites in southern Sweden. Silva Fennica vol. 33 no. 1 article id 666. https://doi.org/10.14214/sf.666

Keywords: Norway spruce; thinning; grain angle; ring width; growth rate; spiral grain

Abstract | View details | Full text in PDF | Author Info

Grain spirality was investigated in eight stands of Norway spruce (Picea abies (L.) Karst.) subjected to different thinning regimes. The dominating general pattern of spiral grain found in this study was typical for conifers, with a maximum of left-handed spirality close to the pith, which decreased towards the bark and sometimes changed to right-handed spiral grain in the outer growth rings. However, there was a large amount of between-tree variation in spiral grain. The effect of thinning on grain spirality was investigated by relating annual ring width to spiral grain, since thinning affects growth rate. A positive correlation between ring width and grain angle was found, but a considerable number of trees showed no or a negative correlation. A statistically significant effect of ring width was only found in five of the eight stands. Heavy thinnings, removing 60% of the basal area of a stand, considerably increased spiral grain, whereas the effects of light thinnings were inconsistent. These results support the findings of earlier studies indicating that spiral grain formation is under considerable genetic control, while its expression can be changed by silvicultural methods which affect growth rate.

Pape, Swedish University of Agricultural Sciences, Department of Forest Yield Research, P.O. Box 7061, S-750 07 Uppsala, Sweden E-mail: rolf.pape@sprod.slu.se

article id 676, category Research article

Erik Sundström. (1998). Afforestation of low-productive peatlands in Sweden – a tree species comparison. Silva Fennica vol. 32 no. 4 article id 676. https://doi.org/10.14214/sf.676

Keywords: Pinus sylvestris; fertilization; Picea abies; afforestation; drainage; tree species; climate; Pinus contorta; broadcast fertilization; spot fertilization

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In 1970, five low-productive treeless peatlands in Sweden, ranging from latitudes 56°N to 67°N, were drained and fertilized for afforestation. The aim of the study was to determine the effect of four ditch spacings, varying from 7.5 to 60 m, and five NPK-fertilizer combinations, on the survival and growth of planted Scots pine (Pinus sylvestris), lodgepole pine (Pinus contorta), Norway spruce (Picea abies), and silver birch (Betula pendula) seedlings. The assessments were carried out 18–22 years after planting. Neither silver birch, nor Norway spruce was regarded suitable for the site type. The mortality of silver birch was almost complete, and Norway spruce did not grow well in any of the study areas, however, better than Scots pine in the north. Lodgepole pine had better height and diameter growth but also higher mortality rates than Scots pine. In the two northernmost experimental areas no response to fertilization was found. In the other three areas, the response to fertilization did not differ between species. Phosphorus was the most effective of the added fertilizer elements, whereas nitrogen showed no positive effect. Broadcast fertilizer application, with three times higher amount of fertilizer per ha gave the same growth response as spot application.

Sundström, Swedish University of Agricultural Sciences, Dept. of Silviculture, S-901 83 Umeå, Sweden E-mail: erik.sundstrom@ssko.slu.se

article id 675, category Research article

Per Linder, Peter Jonsson, Mats Niklasson. (1998). Tree mortality after prescribed burning in an old-growth Scots pine forest in northern Sweden. Silva Fennica vol. 32 no. 4 article id 675. https://doi.org/10.14214/sf.675

Keywords: forest management; coarse woody debris; tree mortality; nature conservation; forest fire; dead trees

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Tree mortality and input of dead trees were studied after a prescribed burning in a forest reserve in northern Sweden. The stand was a multi-layered old-growth forest. The overstorey was dominated by Scots pine (Pinus sylvestris L.) and the understorey consisted of mixed Scots pine and Norway spruce (Picea abies L. Karst.). Ground vegetation was dominated by ericaceous dwarf-shrubs and feathermosses. The stand has been affected by six forest fires during the last 500 years. The prescribed burning was a low intensity surface fire that scorched almost 90% of the ground. Tree mortality for smaller pines and spruces (DBH < 10 cm) was over 80% in the burned parts of the reserve. For larger pines, 10–50 cm DBH, mortality showed a decreasing trend with increasing diameter, from 14% in class 10–20 cm DBH to 1.4% in class 40–50 cm DBH. However, pines with DBH ≥ 50 cm had a significantly higher mortality, 20%, since a high proportion of them had open fire scars containing cavities, caused by fungi and insects, which enabled the fire to burn inside the trunks and hollow them out. The fire-induced mortality resulted in a 21 m3 ha–1 input of dead trees, of which 12 m3 ha–1 consisted of trees with DBH ≥ 30 cm. An increased mortality among larger trees after low-intensity fires has not previously been described in Fennoscandian boreal forests, probably owing to a lack of recent fires in old-growth stands. However, since large pines with open fire scars were once a common feature in the natural boreal forest, we suggest that this type of tree mortality should be mimicked in forestry practices aiming to maintain and restore natural forest biodiversity.

Linder, Department of Forest Vegetation Ecology, SLU, S-901 83 Umeå, Sweden E-mail: pl@nn.se
Jonsson, Department of Forest Vegetation Ecology, SLU, S-901 83 Umeå, Sweden E-mail: pj@nn.se
Niklasson, Southern Swedish Forest Research Centre, SLU, Box 49, S-230 53 Alnarp, Sweden E-mail: mn@nn.se

article id 673, category Research article

Lauri Palva, Eero Garam, Sari Palmroth, Raimo Sepponen, Pertti Hari. (1998). Utilizing a multipoint measuring system of photosynthetically active radiation in photosynthetic studies within canopies. Silva Fennica vol. 32 no. 4 article id 673. https://doi.org/10.14214/sf.673

Keywords: carbon dioxide; instrumentation; measurement; photosynthetically active radiation

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A novel multipoint measuring system of photosynthetically active radiation (PAR) has been constructed and operated within a Scots pine canopy. A regular grid of 800 measuring points has been incorporated into a cuvette to observe the spatial and temporal distribution of PAR incident on the needles of a twig along with simultaneous measurements of the CO2 exchange in order to determine the dependence of photosynthesis on PAR. It was shown that large errors can result if the photosynthetic rate is estimated using the mean value of PAR instead of the instantaneous values of PAR detected at given points in the region of the needles. The results demonstrate that the obtained regression between the CO2 exchange rate estimated using the multipoint PAR measuring system and the measured CO2 exchange rate is as good within a canopy as in unshaded conditions.

Palva, Helsinki University of Technology, Applied Electronics Laboratory, P.O. Box 3000, FIN-02015 HUT, Finland E-mail: lauri.palva@hut.fi
Garam, Helsinki University of Technology, Applied Electronics Laboratory, P.O. Box 3000, FIN-02015 HUT, Finland E-mail: eg@nn.fi
Palmroth, University of Helsinki, Dept. of Forest Ecology, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: sp@nn.fi
Sepponen, Helsinki University of Technology, Applied Electronics Laboratory, P.O. Box 3000, FIN-02015 HUT, Finland E-mail: rs@nn.fi
Hari, University of Helsinki, Dept. of Forest Ecology, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail: ph@nn.fi

article id 681, category Research article

Virpi Palomäki, Alpo Hassinen, Matti Lemettinen, Timo Oksanen, Heljä-Sisko Helmisaari, Jarmo Holopainen, Seppo Kellomäki, Toini Holopainen. (1998). Open-top chamber fumigation system for exposure of field grown Pinus sylvestris to elevated carbon dioxide and ozone concentration. Silva Fennica vol. 32 no. 3 article id 681. https://doi.org/10.14214/sf.681

Keywords: Pinus sylvestris; CO2; open-top chamber; O3

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An open-top chamber fumigation system was built in a young Scots pine stand to study the effects of realistic elevated ozone (O3) and carbon dioxide (CO2) concentrations and their combination on trees in natural conditions. Doubled CO2 concentration compared to present ambient concentration, and O3 concentration between 40 ppb and 70 ppb in the first study year (1994) and doubled O3 concentration in years 1995 and 1996 were the target concentrations in the chambers. The O3 concentration in the chambers was successfully maintained close to the target concentration and differences between chambers were small. The mean CO2 concentration in the CO2 treatment was ca. 100 ppm below the target, but was maintained at this level throughout the growing season. Two degrees higher mean air temperature and slightly lower light intensity compared to open air were measured in the chambers. The operation of the fumigation system was satisfactory during the three study years and repeatability of the gas treatments can be regarded good in this low cost exposure system.

Palomäki, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland E-mail: virpi.palomaki@uku.fi
Hassinen, Mekrijärvi Research Station, FIN-82900 Ilomantsi, Finland E-mail: ah@nn.fi
Lemettinen, Mekrijärvi Research Station, FIN-82900 Ilomantsi, Finland E-mail: ml@nn.fi
Oksanen, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland E-mail: to@nn.fi
Helmisaari, Finnish Forest Research Institute, Department of Forest Ecology, P.O.Box 18, FIN-01301 Vantaa, Finland E-mail: hsh@nn.fi
Holopainen, Agricultural Research Centre, FIN-31600 Jokioinen, Finland E-mail: jh@nn.fi
Kellomäki, University of Joensuu, Faculty of Forestry, P.O.Box 111, FIN-80101 Joensuu, Finland E-mail: sk@nn.fi
Holopainen, University of Kuopio, Department of Ecology and Environmental Science, P.O.Box 1627, FIN-70211 Kuopio, Finland E-mail: th@nn.fi

article id 692, category Research article

Eero Mattila. (1998). Use of satellite and field information in a forest damage survey of eastern Finnish Lapland in 1993. Silva Fennica vol. 32 no. 2 article id 692. https://doi.org/10.14214/sf.692

Keywords: National Forest Inventory; remote sensing; forest damage survey

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The study area consists of the Finnish part of a Landsat 5 TM image from 1990. Three independent field samples were measured during 1991–93 in the study area. The first sample was used to compile training areas for supervised maximum likelihood classification of the image. Classification accuracy was studied in the second sample. The spectral separability of the forest strata usable in practical forestry was poor. The extent of the damage area was estimated by the principle of stratified sampling. The estimate included considerable bias because the field sample had not been objectively selected from the image classes. The third field sample was measured as part of the National Forest Inventory of Finland. It is wholly objective, and about ten times larger than the two earlier field samples. The poor spectral separability of the forest strata was confirmed by the NFI sample. However, this sample could be used in stratified sampling with little or no bias in the estimation of the damage area estimate. 14 different damage types were separated according to specific damaging agent. A thematic map was produced which presents the spatial distribution of two damage-rich image classes. The study area comprises 18 300 sq.km, of which 38% were damaged. At first sight it would appear that the proportion of damaged forest has tripled in ten years. However, this is not the case because now special attention was paid to forest health in the field work. Despite this, it is possible that some damage caused by unfavourable climatic phenomena in the ’80s was still perceptible in 1993. No damage caused directly by air pollution has yet been verified in the study area.

Mattila, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: eero.mattila@metla.fi

article id 691, category Research article

Jacek Oleksyn, Mark G. Tjoelker, Peter B. Reich. (1998). Adaptation to changing environment in Scots pine populations across a latitudinal gradient. Silva Fennica vol. 32 no. 2 article id 691. https://doi.org/10.14214/sf.691

Keywords: Pinus sylvestris; climate change; provenance; growth; temperature; photoperiod

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In several growth chamber and field experiments we examined the growth response of Scots pine (Pinus sylvestris L.) populations from a wide latitudinal range to temperature and photoperiod. The duration of the shoot elongation period of one-year-old seedlings was affected by temperature and photoperiod. In contrasting temperatures, 23/20 °C, 20/17 °C, and 17/14 °C (day/night), shoot elongation period for all populations was shortest in the high and longest in the low temperature treatments. The northern populations from 61–57°N ceased height growth earlier than the other populations in the southern 50°N photoperiod. The order of growth cessation among populations at 50°N in the chamber experiment and at 52°N in the field experiment was similar and related to observed population differences in terminal leader growth and total tree height. Since the length of growing season is under strong environmentally-mediated genetic control in Scots pine, potential climatic changes such as increasing temperature will probably alter the length and timing of growth in aboveground tree parts, but likely in the opposite direction (a shorter growing season) than has been often hypothesized (a longer growing season). Tree-ring analyses of a provenance experiment established in 1912 indicate that the main climatic factors that limited ring-width growth in Scots pine were air temperatures in the winter months of December through March. Low winter temperatures were followed by the formation of narrow rings over the next summer. Based on responses to temperature, Scots pine populations from the continuous European range can be divided in several geographic groups along a latitudinal gradient. Our results suggest that in developing new models to predict the response of Scots pine to changing environmental conditions, it is necessary to include intraspecific differentiation in acclimation and adaptation to environmental factors.

Oleksyn, Polish Academy of Sciences, Institute of Dendrology, Parkowa 5, PL-62-035 Kórnik, Poland; University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: oleks001@gold.tc.umn.edu
Tjoelker, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: mgt@nn.us
Reich, University of Minnesota, Department of Forest Resources, 1530 Cleveland Ave. N., St. Paul, MN 55108, USA E-mail: pbr@nn.us

article id 689, category Research article

Erik W. Andersson, Kostas A. Spanos, Timothy J. Mullin, Dag Lindgren. (1998). Phenotypic selection compared to restricted combined index selection for many generations. Silva Fennica vol. 32 no. 2 article id 689. https://doi.org/10.14214/sf.689

Keywords: genetic diversity; heritability; status number; phenotypic selection; index selection

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A breeding population has been subjected to repeated selection and crossing by simulation. Unrestricted phenotypic selection and restricted combined index selection were compared at the same effective number for five generations. Results show that phenotypic selection often achieves the gain and diversity possible to achieve by combined index selection but the relative efficiency is different for different family sizes and heritabilities. When phenotypic selection was compared with restricted combined index method at low heritabilities, both methods performed almost equally in terms of gain at the same effective number in small family sizes, although in large families, phenotypic selection was less efficient. At high heritabilities phenotypic selection was as efficient as combined index selection. Phenotypic selection was more efficient in conserving additive variance than combined index selection over five generations compared at the same gain and effective number. The introduction of a dominance component to the total variance had little effect. An increased breeding population size by a factor of ten resulted in an increased additive gain by app. 15%. The conclusion is that even though combined index selection is superior in identifying and extracting the potential for breeding achievements, it is generally not performing better than mass selection when compared at the same effective population size in small families.

Andersson, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83, Umeå, Sweden E-mail: erik.andersson@genfys.slu.se
Spanos, N.AG.RE.F.-Forest Research Institute, 57006 Vassilika, Thessaloniki, Greece E-mail: kas@nn.gr
Mullin, Genesis Forest Science Canada Inc., C.P. 64 Succursale Haute-Ville, Québec, QC G1R 4M8 Canada E-mail: tjm@nn.ca
Lindgren, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83, Umeå, Sweden E-mail: dl@nn.se

article id 701, category Research article

Antrei Lausti, Markku Penttinen. (1998). The analysis of return and its components of non-industrial private forest ownership by forestry board districts in Finland. Silva Fennica vol. 32 no. 1 article id 701. https://doi.org/10.14214/sf.701

Keywords: non-industrial private forests; risk; return; portfolio management; forestry board district; performance evaluation

Abstract | View details | Full text in PDF | Author Info

Non-industrial private forest ownership returns and risks in Finland are both estimated and disaggregated to local Forestry Board Districts (FBD) level. Additionally, the FBD level return is divided into price change, felling and change in the growing stock components, which are compared with the inflation rate. The results are based on a complete count of the stumpage prices, silvicultural costs and state subsidies as well as the National Forest Inventory (NFI) data. The influence of taxation is discussed as well. Although this database is excellent for economic studies as well, the estimation methodology is vitiated by a host of problems, the resolution of which is the major contribution of this study. The study period is 1972–1996. The results show that there have been fairly large differences in forest ownership returns and prices depending on the Forestry Board District. Results show that the price change component has been larger in Northern Forestry Board Districts, as much as 0.9% above the inflation rate in Lapland FBD, than in Southern Forestry Board Districts, 1.5% less than the inflation rate in southern Helsinki FBD. The net increase, however, has been larger in Southern Forestry Board Districts than in Northern Forestry Board Districts. Using the average net increment in Finland as a comparison base, the net increment in South Karelia exceeded it by 0.6%, but fell below it by 1.8% in Northeastern Finland. Finally, the return over the whole period is compared to the return on private housing and inflation in the case of North Savo. In all, the estimation methodology developed also serves as spin-off product development for the Forest Statistics Information Service (FSIS).

Lausti, Helsinki School of Economics and Business Administration, Centre for Doctoral Programme, Runeberginkatu 15 A, FIN-00100 Helsinki, Finland E-mail: al@nn.fi
Penttinen, Finnish Forest Research Institute, Helsinki Research Centre, Unioninkatu 40 A, FIN-00170 Helsinki, Finland E-mail: markku.penttinen@metla.fi

article id 23057, category Climate resilient and sustainable forest management – Review article

Ane Christensen Tange, Hanne K. Sjølie, Gunnar Austrheim. (2024). Effectiveness of conservation measures to support biodiversity in boreal timber-production forests. Silva Fennica vol. 58 no. 2 article id 23057. https://doi.org/10.14214/sf.23057

Keywords: forestry; sustainable forest management; dead wood enhancement; forest certification; green tree retention; riparian buffer zone

Highlights: A systematic review of in-situ conservation measures displays that forest biodiversity levels are largely maintained upon harvest with conservation measures compared to unlogged forest; The type of control impacts the frequency of positive, not significant and negative observations; The relatively few significant results restrain distinct conclusions on the effectiveness of the assessed conservation measures to support biodiversity.

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Large parts of the boreal forest ecosystems have been greatly affected by human use, and the current timber-oriented forest management practice that dominates boreal forests is proven to cause biodiversity and ecosystem services declines. These negative effects are mitigated in various ways, including in-situ measures implemented upon harvest. The measures comprise trade-offs between economic and ecological aims; thus, requiring solid knowledge of their effectiveness. However, comprehensive literature review of the effectiveness of such measures is scarce. We aim to fill part of this void by reviewing the scientific literature that have gauged effects of four in-situ conservation measures: green tree retention (GTR), patch retention (PR), dead wood retention (DW) and riparian buffer zones (RB). Two outcomes were considered, species richness and species abundance across taxa.

From a total of 3012 initial papers, 48 met our inclusion criteria that generated 238 unique results. Results were grouped according to control. 178 studies used mature, unlogged forest as control. Out of those, 68% of the findings were not significant, i.e., suggesting no significant impact of harvest with biodiversity measures on species richness and species abundance compared to no harvest. Eighteen percent of the observations showed negative effects and 14% of the observations showed positive effects compared to no harvest. Sixty studies used harvest with no measures as control, of which 45% showed significant positive effects, meaning that compared to harvest with no measures, harvest with conservation measures has positively effects on species richness and abundance. However, 43% of the studies found no significant effect of the implemented conservation measures compared to harvest with no measures taken.

The relatively few significant results reported restrain distinct conclusions on the effectiveness of the assessed conservation measures, but some degree of conservation measure is likely to have positive effects on biodiversity in timber-production forest. However, the scientific basis does not allow for pointing to threshold levels. Higher transparency of study design and statistical results would allow us to include more studies. There is a clear need for more research of effectiveness of common conservation measures in timber-production forests in order to strengthen the knowledge basis. In particular, there are few studies that employ harvest without any conservation measure as control. This is pivotal knowledge for forest managers as well as for policymakers for preserving biodiversity and the ecosystems in forest.

Tange, Inland Norway University of Applied Sciences, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Department of Forestry and Wildlife Management, Evenstad, Norway; Glommen Mjøsen Skog SA, Elverum, Norway https://orcid.org/0009-0001-3145-8159 E-mail: ane.tange@inn.no
Sjølie, Inland Norway University of Applied Sciences, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Department of Forestry and Wildlife Management, Evenstad, Norway https://orcid.org/0000-0001-8099-3521 E-mail: hanne.sjolie@inn.no
Austrheim, University Museum Norwegian University of Science and Technology, Department of Natural History, Trondheim, Norway https://orcid.org/0000-0002-3909-6666 E-mail: gunnar.austrheim@ntnu.no

article id 24021, category Review article

Eva Ring, Märtha Wallgren, Erland Mårald, Per Westerfelt, Line Djupström, Aron Davidsson, Johan Sonesson. (2024). Forest roads in Sweden – infrastructure with multiple uses and diverse impacts. Silva Fennica vol. 58 no. 4 article id 24021. https://doi.org/10.14214/sf.24021

Keywords: insects; forestry; recreation; reindeer; water; plants; wildlife

Highlights: The extensive network of forest roads in Sweden facilitates both forestry transportation and other activities including recreation, berry-picking, hunting, tourism, and firefighting; The multiple uses of roads can lead to conflicts when the interests between stakeholders and forest owners collide; Despite its extent, research into the social, ecological, and environmental consequences of Sweden’s forest road network is limited.

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Since the 1950s, more than 200 000 km of roads have been built in Sweden’s forests, making them easily accessible and open to multiple uses. The aim of this study was to review the impacts of forest roads in Sweden from a broad perspective encompassing social, ecological, and environmental factors. The Swedish case is interesting because it has an extensive network of permanent forest roads which were built primarily for forestry-related transportation but are currently used by many other stakeholders for many different purposes. Forest roads not only facilitate transportation of wood, machinery, personnel, and equipment into and out of the forest but also enable emergency response to wildfires and support berry and mushroom picking, hunting, recreation, tourism, and access to second homes. The roads increase the opportunities for members of the public to experience forests in various ways. Conflicts arise when different interests collide, for example when the interests of the forest owner clash with those of commercial berry-picking companies, tourism entrepreneurs, or reindeer (Rangifer tarandus L.) herding. Forest roads may have ecological impacts such as barrier and disturbance effects, fragmentation or loss of habitats, altering fauna movement patterns, and changing the composition of plant and insect species. The environmental impacts of forest roads relate to, among other things, hydrology, water quality, and erosion. Predicted changes in the climate are likely to place new demands on Swedish forest roads but, despite their extent, this review shows that there is only a small amount of rather fragmented research on their social, ecological, and environmental consequences. Overall, few studies appear to cover both social and ecological/environmental factors and their interactions, either in Sweden or elsewhere. This review provides examples of such interactions in the case of Sweden, and suggests that more research into these and the specific social, ecological, and environmental factors involved is warranted.

Ring, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-8962-9811 E-mail: eva.ring@skogforsk.se
Wallgren, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden; Swedish University of Agricultural Sciences, Department of Wildlife, Fish, and Environmental Studies, 907 36 Umeå, Sweden https://orcid.org/0000-0002-3172-4496 E-mail: martha.wallgren@skogforsk.se
Mårald, Umeå University, Department of Historical. Philosophical and Religious Studies, 901 87 Umeå, Sweden https://orcid.org/0000-0002-2291-9910 E-mail: erland.marald@umu.se
Westerfelt, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0003-2040-8305 E-mail: per.westerfelt@skogforsk.se
Djupström, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden; Swedish University of Agricultural Sciences, Department of Wildlife, Fish, and Environmental Studies, 907 36 Umeå, Sweden https://orcid.org/0000-0003-4536-7765 E-mail: line.djupstrom@skogforsk.se
Davidsson, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0009-0007-2736-8656 E-mail: Aron.davidsson@skogforsk.se
Sonesson, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-2018-7496 E-mail: Johan.sonesson@skogforsk.se

article id 23056, category Review article

Eva Ring, Ulf Sikström. (2024). Environmental impact of mechanical site preparation on mineral soils in Sweden and Finland — a review. Silva Fennica vol. 58 no. 1 article id 23056. https://doi.org/10.14214/sf.23056

Keywords: carbon; nitrogen; soil disturbance; vegetation; water; chemistry; greenhouse gas

Highlights: Mechanical site preparation is carried out on large areas, but limited research on its environmental impact has been undertaken; It affects nitrogen and carbon cycling over the first few years, and has a minor initial impact on CO₂, CH₄ and N₂O fluxes; It increases tree carbon stores and possibly ecosystem carbon stores; Reducing its soil disturbance intensity is warranted.

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Mechanical site preparation (MSP) is deliberate soil disturbance which is undertaken to improve the conditions for forest regeneration. Disc trenching and mounding are the dominant MSP practices currently used in Sweden and Finland. In this paper, the impacts of MSP on the soil, water quality, greenhouse gas (GHG) emissions and ground vegetation of mineral soil sites in Sweden and Finland are reviewed. The practices considered are patch scarification, mounding, inverting, disc trenching, and ploughing, which together represent a wide range of soil disturbance intensity. The environmental effects of MSP in this region have not been studied extensively. The environmental impact of MSP derives from the process of creating microsites which involves horizontal and/or vertical redistribution of soil and soil mixing. This typically affects decomposition, element circulation and leaching, vegetation coverage and uptake of nutrients and water, and possibly erosion and sediment exports. Following disc trenching or mounding the effects on GHG emissions appear to be minor over the first two years. For a few years after disc trenching concentrations in soil water collected below ridges are higher than that below furrows for some elements (e.g., NO₃^-, NH₄⁺, Mg²⁺, and total or dissolved organic C). The physical and chemical effects of ploughing remain detectable for several decades. There is little evidence about how the effects of forestry activities in upland areas on soil-water chemistry are transferred to adjacent surface water bodies, including what role streamside discharge areas play. MSP increases the tree biomass C store and may increase the total ecosystem C store. The impact of MSP on the cover and abundance of ground vegetation species depends on the composition of the original plant community, MSP intensity, and the establishment rate of different species. Species cover generally seems to decline for late succession understory species, while pioneer and ruderal species can benefit from the microsites created. Areas containing lichens which are used for reindeer forage require special consideration. More research is needed on the environmental effects of MSP, particularly regarding its long-term effects. Further efforts should be made to develop efficient site-preparation practices which better balance the disturbance intensity with what is needed for successful regeneration.

Ring, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83, Uppsala, Sweden https://orcid.org/0000-0002-8962-9811 E-mail: eva.ring@skogforsk.se
Sikström, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83, Uppsala, Sweden E-mail: ulf.sikstrom@skogforsk.se

article id 10609, category Review article

Jaakko Jussila, Emil Nagy, Katja Lähtinen, Elias Hurmekoski, Liina Häyrinen, Cecilia Mark-Herbert, Anders Roos, Ritva Toivonen, Anne Toppinen. (2022). Wooden multi-storey construction market development – systematic literature review within a global scope with insights on the Nordic region. Silva Fennica vol. 56 no. 1 article id 10609. https://doi.org/10.14214/sf.10609

Keywords: sustainability; construction industry; consumer; forest-wood value chain; municipality; urbanization

Highlights: Enabling factors for WMC market diffusion include benefits from cost-efficiency gains from prefabrication and industrialization and perceived sustainability benefits; Inexperience of using wood, and path dependencies to use concrete and steel in multi-storey building are the key barriers for mainstreaming WMC market development; More research is needed on the development in the wood construction value-chains to challenge the dominant concrete-based construction regime in the housing markets.

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Climate change sets high pressures on the construction industry to decrease greenhouse gas emissions. Due to the carbon storage properties and potential to use renewable resources efficiently, wooden multi-storey construction (WMC) is an interesting alternative for the construction industry to enhance sustainable development combined with the aesthetic and well-being benefits of wood perceived among many consumers. For forest industry firms, industrial wood construction is a possibility to seek for business opportunities and bring socio-economic benefits for local economies. Despite positive drivers, WMC still remains a niche even in the forest-rich countries.The purpose of our study is to add understanding on the WMC market development by conducting a systematic literature analysis on international peer-reviewed studies from the past 20 years. Our special focus is on the role of WMC in the housing markets studied from the perspectives of the demand, supply and local governance factors. As specific aims, we 1) synthesize the key barriers and enabling factors for the WMC market growth; 2) identify the actors addressed in the existing studies connected to the WMC market development, and 3) summarize research methods and analytical approaches used in the previous studies. As a systematic method to make literature searches in Web of Science and Scopus for years 2000–2020, we employed PRISMA guidelines. By using pre-determined keywords, our searches resulted in a sample of 696 articles, of which 42 full articles were after selection procedure included in-depth content analysis. Our results showed cost-efficiency gains from industrialized prefabrication and perceived sustainability benefits by consumers and architects enabled a WMC market diffusion. The lack of experiences on the WMC, and path dependencies to use concrete and steel continue to be key barriers for increased WMC. Although our research scope was the global WMC market development, most of the literature concerned the Nordic region. The key actors covered in the literature were businesses (e.g., contractors, manufacturers and architects) involved in the wood construction value-chains, while residents and actors in the local governance were seldomly addressed. Currently, case studies, the use of qualitative data sets and focus on the Nordic region dominate the literature. This hinders the generalizability of findings in different regional contexts. In the future, more research is needed on how sustainability-driven wood construction value-chains are successfully shaping up in different geographical regions, and how they could challenge the dominant concrete-based construction regime.

Jussila, University of Helsinki, Department of Forest Sciences, P.O. Box 4, FI-00014 University of Helsinki, Finland E-mail: jaakko@jussila.fi
Nagy, Swedish University of Agricultural Sciences, Department of Forest Economics, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: emil.nagy@slu.se
Lähtinen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: katja.lahtinen@luke.fi
Hurmekoski, University of Helsinki, Department of Forest Sciences, P.O. Box 4, FI-00014 University of Helsinki, Finland E-mail: elias.hurmekoski@helsinki.fi
Häyrinen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: liina.hayrinen@luke.fi
Mark-Herbert, Swedish University of Agricultural Sciences, Department of Forest Economics, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: cecilia.mark-herbert@slu.se
Roos, Swedish University of Agricultural Sciences, Department of Forest Economics, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: anders.roos@slu.se
Toivonen, University of Helsinki, Department of Forest Sciences, P.O. Box 4, FI-00014 University of Helsinki, Finland E-mail: ritva.toivonen@helsinki.fi
Toppinen, University of Helsinki, Department of Forest Sciences, P.O. Box 4, FI-00014 University of Helsinki, Finland E-mail: anne.toppinen@helsinki.fi

article id 10516, category Review article

Faujiah N. Ritonga, Jacob N. Ngatia, Run X. Song, Umar Farooq, Sonia Somadona, Andi T. Lestari, Su Chen. (2021). Abiotic stresses induced physiological, biochemical, and molecular changes in Betula platyphylla: a review. Silva Fennica vol. 55 no. 3 article id 10516. https://doi.org/10.14214/sf.10516

Keywords: antioxidant; cis-acting elements; gene; ROS production; transcription factor

Highlights: Abiotic stress influence Betula platyphylla growth, development, and yield production by impairing physiological, biochemical, and molecular functions; Overexpression or RNAi line of transcription factors enhance the abiotic stress tolerance of B. platyphylla; MYB and AP2/ERF are the most frequently transcription factor family that has been explored over the last two decades in B. platyphylla under abiotic stress.

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Abiotic stress is one of the major factors in reducing plant growth, development, and yield production by interfering with various physiological, biochemical, and molecular functions. In particular, abiotic stress such as salt, low temperature, heat, drought, UV-radiation, elevated CO2, ozone, and heavy metals stress is the most frequent study in Betula platyphylla Sukaczev. Betula platyphylla is one of the most valuable tree species in East Asia facing abiotic stress during its life cycle. Using transgenic plants is a powerful tool to increase the B. platyphylla abiotic stress tolerance. Generally, abiotic stress reduces leaves water content, plant height, fresh and dry weight, and enhances shed leaves as well. In the physiological aspect, salt, heavy metal, and osmotic stress disturbs seed germination, stomatal conductance, chlorophyll content, and photosynthesis. In the biochemical aspect, salt, drought, cold, heat, osmotic, UV-B radiation, and heavy metal stress increases the ROS production of B. platyphylla cells, resulting in the enhancement of enzymatic antioxidant (SOD and POD) and non-enzymatic antioxidant (proline and AsA) to reduce the ROS accumulation. Meanwhile, B. platyphylla upregulates various genes, as well as proteins to participate in abiotic stress tolerance. Based on recent studies, several transcription factors contribute to increasing abiotic stress tolerance in B. platyphylla, including BplMYB46, BpMYB102, BpERF13, BpERF2, BpHOX2, BpHMG6, BpHSP9, BpUVR8, BpBZR1, BplERD15, and BpNACs. These transcription factors bind to different cis-acting elements to upregulate abiotic stress-related genes, resulting in the enhancement of salt, drought, cold, heat, osmotic, UV-B radiation, and heavy metal tolerance. These genes along with phytohormones mitigate the abiotic stress. This review also highlights the candidate genes from another Betulacea family member that might be contributing to increasing B. platyphylla abiotic stress tolerance.

Ritonga, State Key Laboratory of Tree Genetics and Breeding, Forestry College, Northeast Forestry University, Harbin 150040, China E-mail: ritongafaujiah@ymail.com
Ngatia, College of Wildlife and Protected Areas, Northeast Forestry University, Harbin 150040, China E-mail: jacob.ngatia3@gmail.com
Song, State Key Laboratory of Tree Genetics and Breeding, Forestry College, Northeast Forestry University, Harbin 150040, China E-mail: 13359850710@163.com
Farooq, College of Life Science, Northeast Forestry University, Harbin 150040, China E-mail: uf@nn.ch
Somadona, College of Agriculture, Riau University, Pekanbaru 28293, Indonesia E-mail: sonia_hut@yahoo.co.id
Lestari, Forestry Major, College of Agriculture, Mataram University, Mataram 83125, Indonesia E-mail: atlestari@unram.ac.id
Chen, State Key Laboratory of Tree Genetics and Breeding, Forestry College, Northeast Forestry University, Harbin 150040, China E-mail: chensu@nefu.edu.cn

article id 10381, category Review article

Carl F. Salk. (2020). Interpreting common garden studies to understand cueing mechanisms of spring leafing phenology in temperate and boreal tree species. Silva Fennica vol. 54 no. 5 article id 10381. https://doi.org/10.14214/sf.10381

Keywords: photoperiod; bud break; budburst; chilling; elevation gradients; latitudinal gradients; leaf flush; reciprocal transplant experiments; xylem anatomy

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Trees are particularly susceptible to climate change due to their long lives and slow dispersal. However, trees can adjust the timing of their growing season in response to weather conditions without evolutionary change or long-distance migration. This makes understanding phenological cueing mechanisms a critical task to forecast climate change impacts on forests. Because of slow data accumulation, unconventional and repurposed information is valuable in the study of phenology. Here, I develop and use a framework to interpret what phenological patterns among provenances of a species in a common garden reveal about their leafing cues, and potential climate change responses. Species whose high elevation/latitude provenances leaf first likely have little chilling requirement, or for latitude gradients only, a critical photoperiod cue met relatively early in the season. Species with low latitude/elevation origins leafing first have stronger controls against premature leafing; I argue that these species are likely less phenologically flexible in responding to climate change. Among published studies, the low to high order is predominant among frost-sensitive ring-porous species. Narrow-xylemed species show nearly all possible patterns, sometimes with strong contrasts even within genera for both conifers and angiosperms. Some also show complex patterns, indicating multiple mechanisms at work, and a few are largely undifferentiated across broad latitude gradients, suggesting phenotypic plasticity to a warmer climate. These results provide valuable evidence on which temperate and boreal tree species are most likely to adjust in place to climate change, and provide a framework for interpreting historic or newly-planted common garden studies of phenology.

Salk, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, P.O. Box 49, SE- 230 53 Alnarp, Sweden; Faculty of International Studies, Utsunomiya University, 350 Minemachi, Utsunomiya-shi, Tochigi 321-8505 Japan; Institute for Globally Distributed Open Research and Education (IGDORE) E-mail: carl.salk@slu.se

article id 10172, category Review article

Ulf Sikström, Karin Hjelm, Kjersti Holt Hanssen, Timo Saksa, Kristina Wallertz. (2020). Influence of mechanical site preparation on regeneration success of planted conifers in clearcuts in Fennoscandia – a review. Silva Fennica vol. 54 no. 2 article id 10172. https://doi.org/10.14214/sf.10172

Keywords: natural regeneration; regeneration chain; seedling growth; coniferous seedlings; disturbed soil surface; seedling survival

Highlights: Mechanical site preparation (MSP) increases seedling survival rates by 15–20%; Survival rates of 80–90% ca. 10 years after MSP and planting conifers are possible; MSP can increase tree height 10–15 years after planting by 10–25%; The increase in growth rate associated with MSP may be temporary, but the height enhancement probably persists.

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In the Nordic countries Finland, Norway and Sweden, the most common regeneration method is planting after clearcutting and, often, mechanical site preparation (MSP). The main focus of this study is to review quantitative effects that have been reported for the five main MSP methods in terms of survival and growth of manually planted coniferous seedlings of Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.) and lodgepole pine (Pinus contorta var. latifolia Engelm.) in clearcuts in these three countries. Meta analyses are used to compare the effects of MSP methods to control areas where there was no MSP and identify any relationships with temperature sum and number of years after planting. In addition, the area of disturbed soil surface and the emergence of naturally regenerated seedlings are evaluated. The MSP methods considered are patch scarification, disc trenching, mounding, soil inversion and ploughing. Studies performed at sites with predominately mineral soils (with an organic topsoil no thicker than 0.30 m), in boreal, nemo-boreal and nemoral vegetation zones in the three Fenno-Scandinavian countries are included in the review. Data from 26 experimental and five survey studies in total were compiled and evaluated. The results show that survival rates of planted conifers at sites where seedlings are not strongly affected by pine weevil (Hylobius abietis L.) are generally 80–90% after MSP, and 15–20 percent units higher than after planting in non-prepared sites. The experimental data indicated that soil inversion and potentially ploughing (few studies) give marginally greater rates than the other methods in this respect. The effects of MSP on survival seem to be independent of the temperature sum. Below 800 degree days, however, the reported survival rates are more variable. MSP generally results in trees 10–25% taller 10–15 years after planting compared to no MSP. The strength of the growth effect appears to be inversely related to the temperature sum. The compiled data may assist in the design, evaluation and comparison of possible regeneration chains, i.e. analyses of the efficiency and cost-effectiveness of multiple combinations of reforestation measures.

Sikström, Skogforsk, Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: ulf.sikstrom@skogforsk.se
Hjelm, Skogforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden E-mail: karin.hjelm@skogforsk.se
Holt Hanssen, Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, NO-1431 Ås, Norway E-mail: kjersti.hanssen@nibio.no
Saksa, Natural Resources Institute Finland (Luke), Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: timo.saksa@luke.fi
Wallertz, Swedish University of Agricultural Sciences (SLU), Asa Forest Research Station, SE-360 30 Lammhult, Sweden E-mail: kristina.wallertz@slu.se

article id 9984, category Review article

Christoph Kogler, Peter Rauch. (2018). Discrete event simulation of multimodal and unimodal transportation in the wood supply chain: a literature review. Silva Fennica vol. 52 no. 4 article id 9984. https://doi.org/10.14214/sf.9984

Keywords: logistics; supply chain management; forest products industry; decision support systems; validation and verification of simulation models; resilient risk management

Highlights: Focus on discrete event simulation, wood supply chain and multimodal transport; Analyses of 12 review articles and a core of 32 research papers, complemented by 48 related ones; Research focus from unimodal to multimodal transport to build efficient, resilient, green and socially sustainable supply chains; Development of robust risk management considering supply risks, demand risks and external risks is needed.

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This review systematically analyses and classifies research and review papers focusing on discrete event simulation applied to wood transport, and therefore illustrates the development of the research area from 1997 until 2017. Discrete event simulation allows complex supply chain models to be mapped in a straightforward manner to study supply chain dynamics, test alternative strategies, communicate findings and facilitate understanding of various stakeholders. The presented analyses confirm that discrete event simulation is well-suited for analyzing interconnected wood supply chain transportation issues on an operational and tactical level. Transport is the connective link between interrelated system components of the forest products industry. Therefore, a survey on transport logistics allows to analyze the significance of entire supply chain management considerations to improve the overall performance and not only one part in isolation. Thus far, research focuses mainly on biomass, unimodal truck transport and terminal operations. Common shortcomings identified include rough explanations of simulation models and sparse details provided about the verification and validation processes. Research gaps exist concerning simulations of entire, resilient and multimodal wood supply chains as well as supply and demand risks. Further studies should expand upon the few initial attempts to combine various simulation methods with optimization.

Kogler, Institute of Production and Logistics, Department of Economics and Social Sciences, University of Natural Resources and Life Sciences, Vienna, Feistmantelstrasse 4, A-1180 Vienna, Austria https://orcid.org/0000-0001-8811-152X E-mail: christoph.kogler@boku.ac.at
Rauch, Institute of Production and Logistics, Department of Economics and Social Sciences, University of Natural Resources and Life Sciences, Vienna, Feistmantelstrasse 4, A-1180 Vienna, Austria http://orcid.org/0000-0002-5812-4415 E-mail: peter.rauch@boku.ac.at

article id 1660, category Review article

Lars Rytter, Morten Ingerslev, Antti Kilpeläinen, Piritta Torssonen, Dagnija Lazdina, Magnus Löf, Palle Madsen, Peeter Muiste, Lars-Göran Stener. (2016). Increased forest biomass production in the Nordic and Baltic countries – a review on current and future opportunities. Silva Fennica vol. 50 no. 5 article id 1660. https://doi.org/10.14214/sf.1660

Keywords: fertilization; tree breeding; tree species; coppice; cultivation areas; growth increment; nurse crops

Highlights: Annual growth is 287 million m³ in the forests of the Nordic and Baltic countries; Growth can be increased by new tree species, tree breeding, high-productive management systems, fertilization and afforestation of abandoned agricultural land; We predict a forest growth increment of 50–100% is possible at the stand scale; 65% of annual growth is harvested today.

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The Nordic and Baltic countries are in the frontline of replacing fossil fuel with renewables. An important question is how forest management of the productive parts of this region can support a sustainable development of our societies in reaching low or carbon neutral conditions by 2050. This may involve a 70% increased consumption of biomass and waste to meet the goals. The present review concludes that a 50–100% increase of forest growth at the stand scale, relative to today’s common level of forest productivity, is a realistic estimate within a stand rotation (~70 years). Change of tree species, including the use of non-native species, tree breeding, introduction of high-productive systems with the opportunity to use nurse crops, fertilization and afforestation are powerful elements in an implementation and utilization of the potential. The productive forests of the Nordic and Baltic countries cover in total 63 million hectares, which corresponds to an average 51% land cover. The annual growth is 287 million m³ and the annual average harvest is 189 million m³ (65% of the growth). A short-term increase of wood-based bioenergy by utilizing more of the growth is estimated to be between 236 and 416 TWh depending on legislative and operational restrictions. Balanced priorities of forest functions and management aims such as nature conservation, biodiversity, recreation, game management, ground water protection etc. all need consideration. We believe that these aims may be combined at the landscape level in ways that do not conflict with the goals of reaching higher forest productivity and biomass production.

Rytter, The Forestry Research Institute of Sweden (Skogforsk), Ekebo 2250, SE-26890 Svalöv, Sweden E-mail: lars.rytter@skogforsk.se
Ingerslev, Copenhagen University, Department of Geosciences and Natural Resource Management, Rolighedsvej 23, DK-1958, Frederiksberg C, Denmark E-mail: moi@ign.ku.dk
Kilpeläinen, Finnish Environment Institute, Joensuu Office, P.O. Box 111, FI-80101 Joensuu, Finland; University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: antti.kilpelainen@ymparisto.fi
Torssonen, University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: Piritta.Torssonen@uef.fi
Lazdina, Latvian State Forest Research Institute “Silava”, 111 Riga str, Salaspils, LV 2169 Latvia E-mail: Dagnija.Lazdina@silava.lv
Löf, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, Box 49 SE-230 53 Alnarp, Sweden E-mail: magnus.lof@slu.se
Madsen, Copenhagen University, Department of Geosciences and Natural Resource Management, Rolighedsvej 23, DK-1958, Frederiksberg C, Denmark E-mail: pam@ign.ku.dk
Muiste, Estonian University of Life Sciences, Institute of Forestry and Rural Engineering, Dept. Forest Industry, Kreutzwaldi 5, Tartu 51014, Estonia E-mail: Peeter.Muiste@emu.ee
Stener, The Forestry Research Institute of Sweden (Skogforsk), Ekebo 2250, SE-26890 Svalöv, Sweden E-mail: Lars-Goran.Stener@skogforsk.se

article id 1008, category Review article

Janusz Szmyt. (2014). Spatial statistics in ecological analysis: from indices to functions. Silva Fennica vol. 48 no. 1 article id 1008. https://doi.org/10.14214/sf.1008

Keywords: spatial analyses; spatial indices; spatial functions; spatial ecology

Highlights: Spatial statistics provides a quantitative description of natural variables distributed in space and time; The objectives of spatial analysis are to detect spatial patterns and to confirm if a pattern found is significant; Spatially explicit indices and functions may be applied depending on the information collected from the field; Development of the specific software supports spatial analyses.

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This paper presents a review of the most common methods in ecological studies aimed at spatial analysis of population structures (horizontal and vertical), based on point process statistics. Methods based on simple spatially explicit indices as well as more sophisticated methods relying on functions are described in a comprehensible manner. Simple indices revealing the information on spatial structure at the scale of the nearest neighbor can be easily implemented in practical forestry. On the other hand, spatial functions, based on much more detailed data, describe the spatial structure in terms of the spatial relationships between the natural processes and population structures and because of this complexity they are rarely used in forest practice. Including both methods in a single paper is also valuable from the potential reader’s point of view saving their time for searching and choosing the appropriate method to make their spatial analysis. This paper can also serve as an initial guide for young researchers or those who are going to start their studies on spatial aspects of bio-systems. Avoiding the statistical and mathematical details makes this paper understandable for readers who are not statisticians or mathematicians. Readers will find many references related to each method described here, allowing them to find solutions to different problems observed in practice. This paper ends with a list of the most common specific software packages available to support spatial analysis.

Szmyt, Department of Silviculture, Faculty of Forestry, Poznań University of Life Sciences, ul. Wojska Polskiego 69, 60-625 Poznań, Poland E-mail: jszmyt@up.poznan.pl

article id 446, category Review article

Guntis Brumelis, Bengt Gunnar Jonsson, Jari Kouki, Timo Kuuluvainen, Ekaterina Shorohova. (2011). Forest naturalness in northern Europe: perspectives on processes, structures and species diversity. Silva Fennica vol. 45 no. 5 article id 446. https://doi.org/10.14214/sf.446

Keywords: disturbances; dead wood; natural forest; biological diversity

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Saving the remaining natural forests in northern Europe has been one of the main goals to halt the ongoing decline of forest biodiversity. To facilitate the recognition, mapping and efficient conservation of natural forests, there is an urgent need for a general formulation, based on ecological patterns and processes, of the concept of “forest naturalness”. However, complexity, structural idiosyncracy and dynamical features of unmanaged forest ecosystems at various spatio-temporal scales pose major challenges for such a formulation. The definitions hitherto used for the concept of forest naturalness can be fruitfully grouped into three dimensions: 1) structure-based concepts of natural forest, 2) species-based concepts of natural forest and 3) process-based concepts of natural forest. We propose that explicit and simultaneous consideration of all these three dimensions of naturalness can better cope with the natural variability of forest states and also aid in developing strategies for forest conservation and management in different situations. To become operational, criteria and indicators of forest naturalness need to integrate the three dimensions by combining species (e.g. red-listed-, indicator- and umbrella species) with stand and landscape level structural features that are indicative of disturbance and succession processes.

Brumelis, Faculty of Biology, University of Latvia, Kronvalda bulv. 4, Riga, LV-1586, Latvia; E-mail: guntis.brumelis@lu.lv
Jonsson, Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, Sundsvall, Sweden E-mail: bgj@nn.se
Kouki, School of Forest Sciences, University of Eastern Finland, Joensuu, Joensuu E-mail: jk@nn.fi
Kuuluvainen, Department of Forest Sciences, University of Helsinki, Finland E-mail: tk@nn.fi
Shorohova, Saint-Petersburg State Forest Academy, Saint-Petersburg, Russia & Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland E-mail: es@nn.ru

article id 73, category Review article

Timo Kuuluvainen, Tuomas Aakala. (2011). Natural forest dynamics in boreal Fennoscandia: a review and classification. Silva Fennica vol. 45 no. 5 article id 73. https://doi.org/10.14214/sf.73

Keywords: disturbance; age structure; stand replacement; cohort; gap; patch; natural disturbance emulation

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The aim here was to review and summarize the findings of scientific studies concerning the types of forest dynamics which occur in natural forests (i.e. forests with negligible human impact) of boreal Fennoscandia. We conducted a systematic search for relevant studies from selected reference databases, using search terms describing the location, structure and processes, and degree of naturalness of the forest. The studies resulting from these searches were supplemented with other known works that were not indexed in the databases. This procedure yielded a total of 43 studies. The studies were grouped into four types of forest dynamics according to the information presented on the characteristics of the native disturbance-succession cycle: 1) even-aged stand dynamics driven by stand-replacing disturbances, 2) cohort dynamics driven by partial disturbances, 3) patch dynamics driven by tree mortality at intermediate scales (> 200 m²) and 4) gap dynamics driven by tree mortality at fine scales (< 200 m²). All four dynamic types were reported from both spruce and pine dominated forests, but their commonness differed. Gap dynamics was most commonly reported in spruce forests, and cohort dynamics in pine forests. The studies reviewed provide the best obtainable overall picture of scientific findings concerning the characteristics and variability of the unmanaged boreal forest dynamics in Fennoscandia. The results demonstrate that the unmanaged Fennoscandian forests are characterized by more diverse and complex dynamics than has traditionally been acknowledged.

Kuuluvainen, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: timo.kuuluvainen@helsinki.fi
Aakala, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ta@nn.fi

article id 38, category Review article

Matieu Henry, Nicolas Picard, Carlo Trotta, Raphaël J. Manlay, Riccardo Valentini, Martial Bernoux, Laurent Saint-André. (2011). Estimating tree biomass of sub-Saharan African forests: a review of available allometric equations. Silva Fennica vol. 45 no. 3B article id 38. https://doi.org/10.14214/sf.38

Keywords: aboveground biomass; databases; inventories; models; Tier method; wood specific gravity

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In response to the growing interest in estimating carbon stocks in forests, available allometric equations have been compiled for sub-Saharan Africa. Tree, sprout and stand volume and biomass equations were reviewed. The 850 equations and 125 related references were incorporated into an open-access database on the Carboafrica website (http://www.carboafrica.net). The collected information provides a basic tool for the estimation of biomass and carbon stocks and other purposes, such as bioenergy and fodder supply assessment. A Tier-method approach was developed to illustrate the possible use of the equations. Current available biomass expansion factors that are used to convert a volume to the total aboveground biomass appear to be limited; incomplete species-specific allometric equations are preferred to generalised equations. The analysis of the database highlighted important gaps in available tools to assess forest carbon stocks and changes in these stocks. A quality control assessment revealed that 22% of the equations were misreported and recommendations were proposed to guide further research. Further statistical analyses, such as the Bayesian approach, would help to produce more accurate biomass estimates.

Henry, IRD, UMR Eco&Sols, Montpellier SupAgro, 2 place Viala, 34060 Montpellier, France; Di.S.A.F.Ri, Università degli Studi della Tuscia, Viterbo, Italy; and AgroParisTech-ENGREF, GEEFT, Montpellier, France E-mail: henry@unitus.it
Picard, CIRAD, Montpellier, France E-mail: np@nn.fr
Trotta, Di.S.A.F.Ri, Università degli Studi della Tuscia, Viterbo, Italy E-mail: ct@nn.it
Manlay, IRD, UMR Eco&Sols, Montpellier SupAgro, 2 place Viala, 34060 Montpellier, France; and AgroParisTech-ENGREF, GEEFT, Montpellier, France E-mail: rjm@nn.fr
Valentini, Di.S.A.F.Ri, Università degli Studi della Tuscia, Viterbo, Italy E-mail: rv@nn.it
Bernoux, IRD, UMR Eco&Sols, Montpellier SupAgro, 2 place Viala, 34060 Montpellier, France E-mail: mb@nn.fr
Saint-André, CIRAD, Montpellier, France; and INRA, UR1138, Biogeochimie des Ecosystèmes Forestiers, Champenoux, France E-mail: lsa@nn.fr

article id 36, category Review article

Tuomo Wallenius. (2011). Major decline in fires in coniferous forests – reconstructing the phenomenon and seeking for the cause. Silva Fennica vol. 45 no. 1 article id 36. https://doi.org/10.14214/sf.36

Keywords: human influence; fire-history; fire suppression; forest dynamics; Pinus

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Steep decline in forest fires about a century ago occurred in coniferous forests over large areas in North America and Fennoscandia. This poorly understood phenomenon has been explained by different factors in different regions. The objective of this study is to evaluate the validity of the four most commonly suggested causes of the decrease in forest fires: fire fighting, over-grazing, climate change and human influence. I compiled the available dendrochronological data and estimated the annually burned proportions of Pinus-dominated forests in four subcontinental regions during the past 500 years. These data were compared to the development of fire suppression, grazing pressure, climate and human livelihoods. The annually burned proportions declined over 90% in all studied regions. In three out of the four regions fires decreased decades before fire suppression began. Available drought data are annually well correlated with fires but could not explain the decrease of the level in annually burned areas. A rapid increase in the number of livestock occurred at the same time with the decrease in fires in the Western US but not in Fennoscandia. Hence, fire suppression in Central Fennoscandia and over-grazing in the Western US may have locally contributed to the reduction of burned areas. More general explanation is offered by human influence hypothesis: the majority of the past forest fires were probably caused by humans and the decrease in the annually burned areas was because of a decrease in human caused fires. This is in accordance with the old written records and forest fire statistics. The decrease in annually burned areas, both in Fennoscandia and the United States coincides with an economic and cultural transition from traditional livelihoods that are associated with high fire use to modern agriculture and forestry.

Wallenius, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland E-mail: tuomo.wallenius@metla.fi

article id 147, category Review article

Arja Lilja, Marja Poteri, Raija-Liisa Petäistö, Risto Rikala, Timo Kurkela, Risto Kasanen. (2010). Fungal diseases in forest nurseries in Finland. Silva Fennica vol. 44 no. 3 article id 147. https://doi.org/10.14214/sf.147

Keywords: damping-off; grey mold; root dieback; needle casts; snowblights; scleroderris canker; Sirococcus; pine twisting rust; stem lesions and top dying; leaf lesions; Venturia; powdery mildews

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Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and silver birch (Betula pendula) are the major tree species grown in Finnish forest nurseries where 99% of the seedlings are grown in containers first in plastic-covered greenhouses and later outdoors. The main diseases on conifer seedlings are Scleroderris canker (Gremmeniella abietina), Sirococcus blight and cankers (Sirococcus conigenum), snow blights (Herpotrichia juniperi and Phacidium infestans) and needle casts (Lophodermium seditiosum and Meria laricis). Also grey mould (Botrytis cinerea) and birch rust (Melampsoridium betulinum) are among the diseases to be controlled with fungicides. During last years Scleroderris canker has been a problem on Norway spruce, which has been since 2000 the most common species produced in Finnish nurseries. Root die-back (uninucleate Rhizoctonia sp.) on container-grown spruce and pine was a problem in the 1990s. Today the disease has become less common in modern nurseries due to improvements in hygiene and cultivation practice. Since 1991 stem lesions and top dying caused by Phytophthora cactorum has been a problem on birch. The ongoing climate change has already had effect on rusts and powdery mildews as well as other fungi infecting leaves. All diseases, which gain high precipitation and warm and long autumns. For same reasons winter stored seedlings need sprayings against grey mold. Fungal infections are also possible during short-day (SD) treatment, that is necessary for summer and autumn plantings and a beneficial step prior freezing temperatures outside or in freezer storage. Growers are encouraged to use cultural and integrated pest management techniques such as better nursery hygiene, including removing plant debris in nursery growing areas and hot water washing of containers plus removal of diseased, spore-producing seedlings and trees around the nursery.

Lilja, Finnish Forest Research Institute, Vantaa, Finland E-mail: arja.lilja@metla.fi
Poteri, Finnish Forest Research Institute, Suonenjoki, Finland E-mail: mp@nn.fi
Petäistö, Finnish Forest Research Institute, Suonenjoki, Finland E-mail: rlp@nn.fi
Rikala, Finnish Forest Research Institute, Suonenjoki, Finland E-mail: rr@nn.fi
Kurkela, Finnish Forest Research Institute, Vantaa, Finland E-mail: tk@nn.fi
Kasanen, University of Helsinki, Department of Forest Sciences, Helsinki, Finland E-mail: rk@nn.fi

article id 249, category Review article

Rimvydas Vasaitis, Jan Stenlid, Iben M. Thomsen, Pia Barklund, Anders Dahlberg. (2008). Stump removal to control root rot in forest stands. A literature study. Silva Fennica vol. 42 no. 3 article id 249. https://doi.org/10.14214/sf.249

Keywords: biofuel; stand growth; Armillaria; forest disturbance; Heterobasidion; Phellinus weirii

Abstract | View details | Full text in PDF | Author Info

Tree stumps are expected to be increasingly used for energy production in Fennoscandia, thus environmental consequences of stump removal from forest land must be assessed. Aim of this work was to compile available data on the efficacy of stump removal in eradication of root rot fungi (Heterobasidion, Armillaria, and Phellinus), and to review its potential impacts on establishment and productivity of next forest generation. Site disturbance and some technical and economical aspects are discussed, and needs for future research outlined in northern European context. The review demonstrates that stump removal from clear-felled forest areas in most cases results in, a) reduction of root rot in the next forest generation, b) improved seedling establishment, and c) increased tree growth and stand productivity. Observed disturbances caused to a site by stumping operations are normally acceptable. The available data strongly suggests that possibly many (if achievable, all) rot-containing stumps must be removed during harvesting of stumps. Provided equal availability, the priority should be given for stump removal from root rot-infested forest areas, instead of healthy ones. As most studies were done in North America and Britain, several questions must be yet answered under Fennoscandian conditions: a) if and to which extent the conventional stump removal for biofuel on clear-felled sites could reduce the occurrence of Heterobasidion and Armillaria in the next forest generation, b) what impact is it likely to have on survival of replanted tree seedlings, and c) what consequences will there be for growth and productivity of next forest generation.

Vasaitis, Department of Forest Mycology & Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-75007 Uppsala, Sweden E-mail: rimvys.vasaitis@mykopat.slu.se
Stenlid, Department of Forest Mycology & Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-75007 Uppsala, Sweden E-mail: js@nn.se
Thomsen, Forest & Landscape, University of Copenhagen, Hoersholm Kongevej 11, DK-2970 Hoersholm, Denmark E-mail: imt@nn.dk
Barklund, Department of Forest Mycology & Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-75007 Uppsala, Sweden E-mail: pb@nn.se
Dahlberg, Swedish Species Information Centre, Swedish University of Agricultural Sciences, P.O. Box 7007, SE-75007 Uppsala, Sweden E-mail: ad@nn.se

article id 312, category Review article

Katja Lähtinen. (2007). Linking resource-based view with business economics of woodworking industry: earlier findings and future insights. Silva Fennica vol. 41 no. 1 article id 312. https://doi.org/10.14214/sf.312

Keywords: strategy; competitiveness; enterprises; resources; woodworking firms

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The business environment and sources of competitiveness in the woodworking industry have changed notably since the 1990s. Wood products are traded globally, and with the increase of trade, abundant forest resources are no longer the main source of sustainable competitiveness. Competition within the woodworking industry is increasing both between European and non-European enterprises, as well as within the EU. Capability to create value-added, making rational strategic choices, and creative usage of intangible and tangible resources have been emphasized as crucial for sustaining woodworking industry competitiveness in higher cost-level countries. Resource-based view (RBV) defines the availability of intangible assets, capabilities and tangible resources, and their heterogeneous combination to form the basis for company success. The objective of this review is to examine the possibilities to employ the RBV to the study of the woodworking industry by combining existing empirical results of the factors of companies’ competitiveness with assessment of the RBV. In the existing literature, strategies implemented in woodworking companies have been approached rather widely, while the role of intangible and tangible resources in building firm-level success has received less focus. In addition, a significant gap exists in linking firms’ financial accounting information with empirical data on their resource-usage and business strategies. In future studies, more information of the effects of these strategic elements on the actual business success of the firms would be needed.

Lähtinen, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: katja.lahtinen@metla.fi

article id 390, category Review article

Bengt Gunnar Jonsson, Nicholas Kruys, Thomas Ranius. (2005). Ecology of species living on dead wood – lessons for dead wood management. Silva Fennica vol. 39 no. 2 article id 390. https://doi.org/10.14214/sf.390

Keywords: forest management; saproxylic species; coarse woody debris; woodland key habitats; landscape planning; Fennoscandian forests; epixylic species

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Dead wood has been identified as a crucial component for forest biodiversity. Recent research has improved our understanding of habitat relations for many species associated with dead wood. However, the consequences for forest management are yet to be explored. In this review we build upon the growing volume of studies on dead wood dependent species, the dynamics of dead wood and ecological theory in order to identify the challenges for forest management at the landscape level. The review has a Fennoscandian focus, but the problems and challenges are similar in many forest ecosystems. We argue that it is necessary to 1) counteract the current shortage in availability of dead wood, 2) concentrate planning at the landscape level in order to minimize isolation and reduce edge effects, 3) create a variety of dead wood types, and 4) utilise available quantitative analytical tools. This calls for new approaches to management that to a large extent includes available knowledge, and to find platforms for planning forested landscapes with diverse holdings.

Jonsson, Mid Sweden University, Dept of Natural Sciences, SE-851 70 Sundsvall, Sweden E-mail: bengt-gunnar.jonsson@miun.se
Kruys, SLU, Dept of Forest Resource Management and Geomatics, SE-901 83 Umeå, Sweden E-mail: nk@nn.se
Ranius, SLU, Dept of Entomology, SE-750 07 Uppsala, Sweden E-mail: tr@nn.se

article id 489, category Review article

Ralph J. Alig. (2003). U.S. landowner behavior, land use and land cover changes, and climate change mitigation. Silva Fennica vol. 37 no. 4 article id 489. https://doi.org/10.14214/sf.489

Keywords: adaptation; carbon sequestration; forest sector; mitigation

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Landowner behavior is a major determinant of land use and land cover changes, an important consideration for policy analysts concerned with global change. Study of landowner behavior aids in designing more effective incentives for inducing land use and land cover changes to help mitigate climate change by reducing net greenhouse gas emissions. Afforestation, deforestation, reforestation, and timber harvest are the most frequent land management practices that influence forest carbon stocks and flux. Research studies provide estimates of how private landowners respond to market signals and government programs and how they alter land management. For example, landowners have tended to retain subsidized afforested stands well beyond program life in the United States, suggesting that similar programs for climate change mitigation could result in high rates of retention. At the same time, policy makers need to be aware that unintended consequences of policies can lead to significantly different outcomes than envisioned, including leakage possibilities.

Alig, USDA Forest Service, Forestry Sciences Lab, 3200 SW Jefferson Way, Corvallis, Oregon 97331, USA E-mail: ralig@fs.fed.us

article id 546, category Review article

Teijo Palander, Mari Toivonen, Sanna Laukkanen. (2002). GroupWare and group decision support systems for wood procurement organisation. A review. Silva Fennica vol. 36 no. 2 article id 546. https://doi.org/10.14214/sf.546

Keywords: collaboration; teamwork-based organisation; group decision-making; communication

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Many kinds of decision support systems (DSSs) have been suggested for use of wood procurement organisations, but few meet the real needs of team managers in group decision-making process. Therefore, it has been concluded that the important features of group decision support systems (GDSSs) should be developed for teamwork-based organisations. Electronic meeting systems (EMSs), Computer-aided Visualisations (CAVs) and heuristics as well as other numerical approaches as combined with optimisation seem to be some of the most promising elements of GroupWare, because decisions are made in distributed groups and they deal with human behaviour. Relations between GDSSs and spontaneous decision conferencing (SDC) for modern organisations are also discussed, and suggestions for future research of management approaches are also given.

Palander, University of Joensuu, Faculty of Forestry, Box 111, FIN-80101 Joensuu, Finland E-mail: teijo.palander@forest.joensuu.fi
Toivonen, University of Joensuu, Faculty of Forestry, Box 111, FIN-80101 Joensuu, Finland E-mail: mt@nn.fi
Laukkanen, University of Joensuu, Faculty of Forestry, Box 111, FIN-80101 Joensuu, Finland E-mail: sl@nn.fi

article id 553, category Review article

Yves Bergeron, Alain Leduc, Brian D. Harvey, Sylvie Gauthier. (2002). Natural fire regime: a guide for sustainable management of the Canadian boreal forest. Silva Fennica vol. 36 no. 1 article id 553. https://doi.org/10.14214/sf.553

Keywords: biodiversity; natural disturbance; landscape patterns; coarse filter; harvest pattern; volume retention; historic variability; even-age management

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The combination of certain features of fire disturbance, notably fire frequency, size and severity, may be used to characterize the disturbance regime in any region of the boreal forest. As some consequences of fire resemble the effects of industrial forest harvesting, conventional forest management is often considered as a disturbance that has effects similar to those of natural disturbances. Although the analogy between forest management and fire disturbance in boreal ecosystems has some merit, it is important to recognise that it also has its limitations. Short fire cycles generally described for boreal ecosystems do not appear to be universal; rather, important spatial and temporal variations have been observed in Canada. These variations in the fire cycle have an important influence on forest composition and structure at the landscape and regional levels. Size and severity of fires also show a large range of variability. In regions where the natural matrix of the boreal forest remains relatively intact, maintenance of this natural variability should be targeted by forest managers concerned with biodiversity conservation. Current forest management tends to reduce this variability: for example, fully regulated, even-aged management will tend to truncate the natural forest age distribution and eliminate over-mature and old-growth forests from the landscape. We suggest that the development of strategic-level forest management planning approaches and silvicultural techniques designed to maintain a spectrum of forest compositions and structures at different scales in the landscape is one avenue to maintain this variability. Although we use the boreal forest of Quebec for our examples, it is possible to apply the approach to those portions of the boreal forest where the fire regime favours the development of even-aged stands in burns.

Bergeron, NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, C.P. 8888, Succursale Centre-ville, Montréal, Québec, Canada H3C 3P8 E-mail: bergeron.yves@uqam.ca
Leduc, NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, C.P. 8888, Succursale Centre-ville, Montréal, Québec, Canada H3C 3P8 E-mail: al@nn.ca
Harvey, NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, C.P. 8888, Succursale Centre-ville, Montréal, Québec, Canada H3C 3P8 E-mail: bdh@nn.ca
Gauthier, NSERC-UQAT-UQAM Industrial Chair in Sustainable Forest Management, C.P. 8888, Succursale Centre-ville, Montréal, Québec, Canada H3C 3P8 E-mail: sg@nn.ca

article id 551, category Review article

Anders Dahlberg. (2002). Effects of fire on ectomycorrhizal fungi in Fennoscandian boreal forests. Silva Fennica vol. 36 no. 1 article id 551. https://doi.org/10.14214/sf.551

Keywords: boreal forests; ectomycorrhizal fungi; fire; population; community

Abstract | View details | Full text in PDF | Author Info

Fire, the primary natural disturbance factor in Fennoscandian boreal forests, is considered to have exerted major selection pressure on most boreal forest organisms. However, recent studies show that few ectomycorrhizal (EM) fungi appear to have evolved post-fire adaptations, no succession of EM fungi following fire is apparent after low intensity fires, and only two EM fungal taxa exclusively fruit at post-fire conditions. In this paper I review the present knowledge of effects of forest fire on EM fungal communities in Fennscandian boreal forests, put into perspective by a comparison from other parts of the world. Characteristically, these boreal forests consist of less than a handful of tree species, e.g. Scots pine and Norway spruce, while the below ground communities of EM fungi is impressively species rich with presently more than 700 known taxa. Commonly, forest fires in Fennoscandia have been of low intensity, with a considerable portion of the trees surviving and the organic humus layer partly escaping combustion. Hence, EM fungi appear to largely have evolved under conditions characterised by a more or less continuous presence of their hosts. In fact, the composition of EM fungi within a forest appear be more variable due to spatial variation than due to wildfire. However, in areas with high intensity burns and high tree mortality, most EM fungi may locally be killed. Thus, the legacy of EM fungi following wildfire depends on the survival of trees, which determine the potential for mycorrhizal growth, and the combustion and heating of the organic soil, which directly correlate to mortality of mycorrhizas. The questions if and to what degree fires may be of significance for yet unidentified spatiotemporal dynamics of EM fungal populations and communities are discussed. Recent experiments indicate a few EM fungi are favoured by high intensity burn conditions whereas others disappear. The consequences of wildfires in temperate conifer forests differ considerably from those in boreal forests. Wildfires in temperate conifer forests are typically high intensity stand-replacing fires that cause a total combustion of organic layers. Subsequently, pre-fire EM fungal communities are largely eradicated and a succession of post-fire EM fungi is initiated.

Dahlberg, Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, SE-750 07 Uppsala, Sweden E-mail: anders.dahlberg@artdata.slu.se

article id 549, category Review article

Andrei Gromtsev. (2002). Natural disturbance dynamics in the boreal forests of European Russia: a review. Silva Fennica vol. 36 no. 1 article id 549. https://doi.org/10.14214/sf.549

Keywords: boreal forests; disturbance dynamics; European Russia; fires; windthrow

Abstract | View details | Full text in PDF | Author Info

In the European part of the Russian boreal zone the dynamics of pristine forests (taiga) has been studied by several generations of researchers. Many studies have examined the patterns and role of fire, windthrow, insect outbreaks and other natural disturbances. An attempt is made to provide a brief review of these studies. The reviewed studies show that lightning strikes were the only natural source of fires in taiga. The frequency of fires varied in various types of pristine landscape from 1–2 per century to 1–2 per millennium. Fires maintained a dynamic equilibrium between compositionally different forest communities or their certain ratio and areal occurrence. Fires favored the regeneration and recovery of pine forests and prevented the replacement of shade-intolerant species (e.g. pine) by shade-tolerant ones (e.g. spruce). Taiga forests generally displayed a mosaic pattern that varied from pioneer plant communities, growing in open burns, to climax communities that were extremely seldom affected by fire. The reviewed studies suggest that fires were a powerful ecological factor in pristine taiga, being largely responsible for the structure and spontaneous dynamics of forest communities. Windfalls were also common in pristine taiga landscapes and they regulated spontaneous dynamics in a gap-mosaic regime, which is most characteristic of spruce forests.

Gromtsev, Forest Research Institute, Karelian Research Centre of the Russian Academy of Sciences, P.O. Box 185610, Petrozavodsk, Pushkin st. 11, Russia E-mail: gromtsev@karelia.ru

article id 24061, category Complex remote sensing-assisted forest surveys - Research article

Zsofia Koma, Johannes Breidenbach. (2025). Large-scale validation of forest attribute maps across different spatial resolutions. Silva Fennica vol. 59 no. 2 article id 24061. https://doi.org/10.14214/sf.24061

Keywords: airborne laser scanning; National Forest Inventory; forest resource mapping; resolution dependence

Highlights: The study assesses stand-level uncertainty of biomass, volume, basal area, and Lorey’s height estimates resulting from the prediction of maps across varying spatial resolutions (1–30 m); The changes of RMSE and bias across the different spatial resolutions were generally small (< 5%) for additive forest attributes such as biomass, volume, and basal area; The changes of RMSE and bias were also small for Lorey’s height as a non-additive forest attribute if the resolution difference was less than 2 times of the native resolution; The models fitted at the resolution of the NFI plot size can be used to produce forest attribute maps at 10 m resolution without concerning increases in uncertainty at stand-level.

Abstract | Full text in HTML | Full text in PDF | Author Info

Fine-scale, spatially explicit forest attribute maps are essential for guiding forest management and policy decisions. Such maps, based on the combination of National Forest Inventory (NFI) and remote sensing datasets, have a long tradition in the Nordic countries. Harmonizing the pixel size among national forest attribute maps would considerably improve the utility of the maps for users. However, the maps are often aligned with the NFI plot size, and the influence of creating these maps at different spatial resolutions (i.e. pixel sizes) is little studied. We assess the stand-level uncertainty (RMSE) of biomass, volume, basal area, and Lorey’s height estimates resulting from the aggregation of maps across varying spatial resolutions. Models fit at 16 m native resolution using more than 14 000 NFI plots were applied for predictions at pixels sizes (side lengths) of 1, 5, 10, 16, and 30 m. For independent validation, we used more than 600 field plots – that cover a total area of 24 ha and were clustered within 65 stands across Norway. For all attributes, the lowest RMSEs, ranging from 6.86% for Lorey’s height to 13.86% for volume, were observed for predictions at pixel sizes of 5 m to 16 m. The RMSE changes across resolutions were generally small (< 5%) for biomass, volume, and basal area. For Lorey’s height, changing the spatial resolution resulted in large RMSEs of up to 25%. Overall, our findings suggest that the main forest attributes can be mapped at a finer resolutions without complex adjustments.

Koma, Norwegian Institute for Bioeconomy Research (NIBIO), Division of Forest and Forest Resources, Department National Forest Inventory, Høgskoleveien 7, 1433 Ås, Norway https://orcid.org/0000-0002-0003-8258 E-mail: zsofia.koma@nibio.no
Breidenbach, Norwegian Institute for Bioeconomy Research (NIBIO), Division of Forest and Forest Resources, Department National Forest Inventory, Høgskoleveien 7, 1433 Ås, Norway https://orcid.org/0000-0002-3137-7236 E-mail: johannes.breidenbach@nibio.no

article id 24062, category Research note

Jussi Manner, Hagos Lundström. (2025). The effect of boom-tip control on harvester time consumption in Picea abies dominated final-felling stands: case study. Silva Fennica vol. 59 no. 1 article id 24062. https://doi.org/10.14214/sf.24062

Keywords: productivity; automation; cut-to-length logging; crane work; Intelligent Boom Control (IBC); Levels of Automation (LoA); operator assistance system

Highlights: Two experienced harvester operators (A and B) participated in the study; Operator A reduced time consumption by 10% with boom-tip control, while operator B neither saved nor lost time; Operator A’s time savings occurred exclusively during the work element felling-processing; Variation in the results between the operators emphasizes the need for further research involving a larger pool of operators.

Abstract | Full text in HTML | Full text in PDF | Author Info

Crane work accounts for the majority of a harvester’s productive working time. Boom-tip control assists operators by coordinating end-effector movements, offering the potential to improve productivity. With boom-tip control, the operator steers the boom-tip directly rather than controlling individual crane joints. Despite being commercially available for several years, research on boom-tip control’s impact on harvester work – particularly compared to forwarder work – is limited. Therefore, this study analysed the effect of boom-tip control on harvester time consumption (s m^-3) in final-felling stands, involving two experienced operators (A and B) driving a John Deere 1470G harvester. John Deere’s boom-tip control system, Intelligent Boom Control (IBC), was compared to a conventional boom-control system. Data were analysed separately for each operator. While operator A saved time using IBC, no statistically significant difference between IBC and the conventional boom-control system was observed for operator B. For operator A, IBC reduced total time consumption (s m^-3) by approximately 10%. The results indicate a need for further research, involving multiple machine manufacturers, operators, and work environments such as thinning and final-felling stands. Moreover, future studies should preferably utilise automated data recording to generate large follow-up datasets on harvester work.

Manner, Skogforsk, Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-4982-3855 E-mail: jussi.manner@skogforsk.se
Lundström, Skogforsk, Uppsala Science Park, 751 83 Uppsala, Sweden E-mail: hagos.lundstrom@skogforsk.se

article id 24039, category Research note

Jussi Manner, Hagos Lundström. (2024). The effect of forked trees on harvester time consumption in a Pinus contorta final-felling stand. Silva Fennica vol. 58 no. 4 article id 24039. https://doi.org/10.14214/sf.24039

Keywords: productivity; stem quality; stem defect; lodgepole pine; cut-to-length logging; double stem; forking

Highlights: For forked trees, codominant stems double harvester time consumption per tree, while double crowns have only minor impacts on harvester time consumption; Forked trees should be removed during thinning when they can still be time-efficiently multi-tree handled; Dealing with forked trees at a later rotation age, when they are too large for multi-tree handling, becomes excessively time-consuming.

Abstract | Full text in HTML | Full text in PDF | Author Info

The consensus on the factors affecting harvester productivity is generally widely acknowledged in the discipline. However, research results regarding the effect of forking on productivity are diverse. Some studies show that harvester productivity is halved when harvesting double stems compared to single-stem trees, while other studies indicate that forking does not necessarily decrease harvester productivity. These differences in study results can depend on what is considered forking. In our study, the forking occurred above the breast-height level. We defined codominant stems as forked trees too large to be multi-tree handled. In contrast, we defined double crowns as forked trees that could be multi-tree handled. The objective of our study was to analyse how the presence of codominant stems and/or double crowns affects harvester time consumption. The study was conducted in Sweden in 2022, involving two operators and two large harvesters. The 45-year-old Pinus contorta Douglas ex Loudon-dominated stand was clearcut during the study. We found that the presence of codominant stems doubles harvester time consumption per tree, while double crowns had only a minor impact on harvester time consumption. Additionally, total time consumption increased linearly with increasing diameter at breast height. Based on these findings, we recommend that forked trees be removed already during thinning when they can still be time-efficiently multi-tree handled. Dealing with forked trees later during the rotation cycle, when they are too large for multi-tree handling, is excessively time-consuming.

Manner, Skogforsk, Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-4982-3855 E-mail: jussi.manner@skogforsk.se
Lundström, Skogforsk, Uppsala Science Park, 751 83 Uppsala, Sweden E-mail: hagos.lundstrom@skogforsk.se

article id 23064, category Research note

Henrik Lindberg, Tuomas Aakala, Ilkka Vanha-Majamaa. (2024). Ignition probability and fuel consumption of boreal ground vegetation fuels – an experimental study in Finland. Silva Fennica vol. 58 no. 3 article id 23064. https://doi.org/10.14214/sf.23064

Keywords: forest fires; ground vegetation; prescribed burning; flammability; fuel moisture content; mass loss rate

Highlights: Ignition probability and mass loss rates clearly differed in experimental burnings among four common circumboreal moss and lichen species; Cladonia rangiferina was the most flammable, Dicranum spp. the least flammable and Pleurozium schreberi and Hylocomium splendens intermediate.

Abstract | Full text in HTML | Full text in PDF | Author Info

In boreal forests fires often ignite and spread within the dominant moss and lichen cover of the ground layer vegetation, which thus greatly influences fire hazard. We used an experimental set-up in greenhouse conditions to study the differences in how (1) fuel moisture and (2) wind velocity influence the ignition probability and fuel consumption among four common circumboreal ground vegetation fuels, Pleurozium schreberi (Willd. ex Brid.) Mitt., Hylocomium splendens Schimp., Dicranum spp. and Cladonia rangiferina (L.) F. H. Wigg. Our results show that the reindeer lichen C. rangiferina was clearly the most flammable species, with high ignition probability even at high moisture contents and low wind velocities. Of the mosses, Dicranum was the least flammable, with low ignition probability and mass loss at low wind velocities regardless of moisture content. P. schreberi and H. splendens behaved somewhat similarly with wind velocities quickly increasing the initially low ignition probability and mass loss observed in the absence of wind. However, especially for mass loss, among-species differences tended to disappear with stronger winds. The observed differences can be explained by the different structures and growth forms of the studied species and open a potential avenue for improving forest fire risk predictions.

Lindberg, Häme University of Applied Sciences, School of Bioeconomy, Visamäentie 35 A, P.O. Box 230, FI-13100 Hämeenlinna, Finland https://orcid.org/0000-0001-9045-2673 E-mail: henrik.lindberg@hamk.fi
Aakala, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-0160-6410 E-mail: tuomas.aakala@uef.fi
Vanha-Majamaa, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: ilkka.vanha-majamaa@luke.fi

article id 23017, category Research note

Yrjö Nuutinen, Jari Miina. (2023). Effect of boom corridor and selective thinning on the post-treatment growth of young Scots pine and birch stands. Silva Fennica vol. 57 no. 2 article id 23017. https://doi.org/10.14214/sf.23017

Keywords: geometrical thinning; systematic thinning; thinning reaction

Highlights: During the 4–5-year post-treatment period, boom corridor thinning did not result in growth and yield losses compared to selective thinning; Within the boom corridor and selective thinning treatments, the increment of trees at the edge of strip roads or corridors was higher than at those trees located in the middle of strip roads and/or corridors.

Abstract | Full text in HTML | Full text in PDF | Author Info

Boom corridor thinning (BCT) is a harvester’s working method, primarily suitable for dense, unmanaged young stands. The method was first studied in Sweden in the early 2000s. In Finland, the idea has been further developed and studied for Finnish forests. The advantage is in the corridor, where the harvester head can move more swiftly, and there is no need to identify trees to grow as much as when using the traditional selective thinning (Sel) method. Moreover, the method can be conducted without cost-intensive pre-clearing of undergrowth, creating post-stands with higher biodiversity. This study is the sequel to a previous study in which experiments on BCT and Sel were established in 2017–2018. The experiments were remeasured 4–5 years after their establishment, and the effect of BCT treatments of Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth) on the post-treatment growth and growth reaction of individual trees within the treatments was compared to traditional Sel. During the post-treatment period, BCT did not result in growth or yield losses compared to Sel. Within the treatments, the increment of trees at the edge of strip roads or corridors was higher than that of trees located in the middle of strip roads and/or corridors. A longer post-treatment period needs to be studied to analyse the effect of BCT on the total yield and especially the yield of saw logs during the rest of the rotation period.

Nuutinen, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6 B, FI-80100 Joensuu, Finland https://orcid.org/0000-0003-3360-4444 E-mail: yrjo.nuutinen@luke.fi
Miina, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6 B, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-8639-4383 E-mail: jari.miina@luke.fi

article id 10765, category Research note

Girmantė Jurkšienė, Virgilijus Baliuckas, Donatas Naugžemys, Donatas Žvingila. (2022). Chloroplast DNA polymorphism and morphometric characteristics of Carpinus betulus in the Lithuania forests. Silva Fennica vol. 56 no. 3 article id 10765. https://doi.org/10.14214/sf.10765

Keywords: polymorphism; european hornbeam; intergenic spacer; involucres; migration refugia

Highlights: A 24 bp deletion was found in the chloroplast DNA region of two populations in the southeastern part of Lithuania; Morphometric differences in hornbeam involucre between the study populations were significant; The existence of two haplotypes of the chloroplast DNA region supports the hypothesis of two migration refugia in Carpinus betulus populations.

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The European hornbeam (Carpinus betulus L.) is a medium-sized deciduous tree that spreads northeast of the middle of Lithuania. Carpinus betulus L. is a native tree in Poland, and its branch is migrated by two Pleistocene refugia. We hypothesised that its branches had spread to Lithuania. In this study, we selected 10 populations of hornbeam that were chosen from their distribution location. We sequenced the chloroplast intergenic spacer psbA-trnH of 70 individuals. We found 24 bp deletion in chloroplast DNA (cpDNA) individuals of two populations in the southeastern part of Lithuania. In the seven forest populations, we examined the morphological variability of hornbeam seed involucres and nuts variations of 30 morphometric characteristics. Initial genetic population studies were conducted over a wider area; when differences were detected, morphological studies were conducted in the contact zone. Morphometric differences between the study populations were significant. The existence of two haplotypes of cpDNA supports the hypothesis of two migration refugia in C. betulus populations. This study contributes to significant novel knowledge about the morphological and cpDNA variability of European hornbeam populations in Lithuania and Europe.

Jurkšienė, Institute of forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1 Girionys, LT-53101 Kaunas, Lithuania https://orcid.org/0000-0001-8210-6711 E-mail: girmante.jurksiene@lammc.lt
Baliuckas, Institute of forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepų str. 1 Girionys, LT-53101 Kaunas, Lithuania; Faculty of Forest Sciences and Ecology, Agriculture Academy, Vytautas Magnus University, K. Donelaičio g. 58, LT-44248 Kaunas, Lithuania E-mail: virgilijus.baliuckas@lammc.lt
Naugžemys, Botanical Garden of Vilnius University, Vilnius University, Kairėnų Str. 43, Vilnius 10239, Lithuania https://orcid.org/0000-0001-6744-5360 E-mail: genetikas@gmail.com
Žvingila, Department of Botany and Genetics, Institute of Biosciences, Life Sciences Center, Vilnius University, Saulėtekio Av. 7, LT-10257 Vilnius, Lithuania https://orcid.org/0000-0001-7826-1815 E-mail: donatas.zvingila@gf.vu.lt

article id 10561, category Research note

Urszula Zajączkowska, Piotr Dąbrowski, Waldemar Kowalczuk, Grzegorz Tarwacki. (2022). Leaf photosynthetic capacity, trunk wood structure and stem xylem sap flow in 700-years old Quercus robur L.: a pilot study upon oak ‘Bartek’, a natural monument in Poland. Silva Fennica vol. 56 no. 3 article id 10561. https://doi.org/10.14214/sf.10561

Keywords: photosynthetic capacity; ‘Bartek’ oak; tree stem tomography; xylem sap flow

Highlights: Photosynthetic and hydraulic capacity of a 700-year-old Quercus robur is comparable to reference values from the literature measured in younger oak trees.

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Physiological studies of long-lived trees are particularly important at this time, especially in light of the need for trees to adapt to global climate change. The results of the present studies were obtained on an approximately 700-year-old Quercus robur L. – the ‘Bartek’ oak. The tree has to adapt to changing climatic conditions, starting from the transition between the Medieval Warm Period and the Little Ice Age, up to the present time of rapid global climate change. Tomograph imaging showed decay of the tree trunk interior and revealed that undamaged wood forms a thin layer around the trunk perimeter. Two series of experiments were carried out to assess the physiological state of the tree. The first concerned measurements related to photosynthetic capacity: chlorophyll a fluorescence, gas exchange (CO₂ assimilation, transpiration), stomatal conductance and leaf water potential. The second series concerned xylem sap flow velocity and anatomical studies of stem wood. Photosynthetic capacity was within the limits reported for young healthy trees. The diurnal pattern of velocity of xylem sap flow was also typical for young vigorous trees and flow velocity correlated positively with solar radiation and negatively with air relative humidity. Anatomical observations of the outermost wood showed relatively narrow annuals rings with large diameter earlywood vessels. The results indicate that the veteran tree does not show signs of water stress probably due to a good balance of water flow and that leaf area of the canopy needs only the current ring of wood to feed transpiration of the canopy.

Zajączkowska, Department of Forest Botany, Warsaw University of Life Sciences - SGGW, 159 Nowoursynowska Street, 02-776 Warsaw, Poland https://orcid.org/0000-0002-7119-7547 E-mail: urszula_zajaczkowska@sggw.edu.pl
Dąbrowski, Department of Environmental Development Warsaw University of Life Sciences - SGGW, Warsaw, Poland https://orcid.org/0000-0002-2867-8839 E-mail: piotr_dabrowski@sggw.edu.pl
Kowalczuk, Ekosystem Waldemar Kowalczuk Tomasz Kowalczuk, Otwock, Poland E-mail: ekosystem@ekosystem.waw.pl
Tarwacki, Forest Protection Department, Forest Research Institute, Sękocin Las, Poland https://orcid.org/0000-0001-5979-7788 E-mail: G.Tarwacki@ibles.waw.pl

article id 10683, category Research note

Aarne Hovi, Petr Lukeš, Lucie Homolová, Jussi Juola, Miina Rautiainen. (2022). Small geographical variability observed in Norway spruce needle spectra across Europe. Silva Fennica vol. 56 no. 2 article id 10683. https://doi.org/10.14214/sf.10683

Keywords: albedo; remote sensing; reflectance; transmittance; land surface modeling; leaf optical properties; radiative transfer modeling

Highlights: Spectra of Norway spruce needles were collected from three sites in Europe (49°–62°N); The same acquisition and processing parameters were applied throughout the campaign; Geographical variability in the needle spectra was small; Comparison of the spectra of coniferous needles and broadleaved tree foliage is also presented.

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Foliage spectra form an important input to physically-based forest reflectance models. However, little is known about geographical variability of coniferous needle spectra. In this research note, we present an assessment of the geographical variability of Norway spruce (Picea abies (L.) H. Karst.) needle albedo, reflectance, and transmittance spectra across three study sites covering latitudes of 49–62°N in Europe. All spectra were measured and processed using exactly the same methodology and parameters, which guarantees reliable conclusions about geographical variability. Small geographical variability in Norway spruce needle spectra was observed, when compared to variability observed between previous measurement campaigns (employing slightly varying measurement and processing parameters), or to variability between plant functional types (broadleaved vs. coniferous). Our results suggest that variability of needle spectra is not a major factor introducing geographical variability to forest reflectance. The results also highlight the importance of harmonizing measurement protocols when collecting needle spectral libraries. Furthermore, the data collected for this study can be useful in studies where accurate information on spectral differences between broadleaved and coniferous tree foliage is needed.

Hovi, Aalto University, School of Engineering, Department of Built Environment, P.O. Box 14100, FI-00760 Aalto, Finland https://orcid.org/0000-0002-4384-5279 E-mail: aarne.hovi@aalto.fi
Lukeš, Global Change Research Institute of the Czech Academy of Sciences, Bělidla 986/4a, 603 00 Brno, Czech Republic https://orcid.org/0000-0002-3707-6557 E-mail: lukes.p@czechglobe.cz
Homolová, Global Change Research Institute of the Czech Academy of Sciences, Bělidla 986/4a, 603 00 Brno, Czech Republic https://orcid.org/0000-0001-7455-2834 E-mail: homolova.l@czechglobe.cz
Juola, Aalto University, School of Engineering, Department of Built Environment, P.O. Box 14100, FI-00760 Aalto, Finland https://orcid.org/0000-0002-6050-7247 E-mail: jussi.juola@aalto.fi
Rautiainen, Aalto University, School of Engineering, Department of Built Environment, P.O. Box 14100, FI-00760 Aalto, Finland; Aalto University, School of Electrical Engineering, Department of Electronics and Nanoengineering, P.O. Box 15500, FI-00760 Aalto, Finland https://orcid.org/0000-0002-6568-3258 E-mail: miina.a.rautiainen@aalto.fi

article id 10600, category Research note

Nea Kuusinen, Aarne Hovi, Miina Rautiainen. (2021). Contribution of woody elements to tree level reflectance in boreal forests. Silva Fennica vol. 55 no. 5 article id 10600. https://doi.org/10.14214/sf.10600

Keywords: reflectance model; bark; hyperspectral; spectral mixture analysis

Highlights: Contribution of woody elements to reflectance of boreal tree species was estimated using spectral mixture analysis and airborne hyperspectral data; Mean woody element contribution varied between 0.14–0.19 (Scots pine), 0.12–0.20 (birches) and 0.09–0.10 (Norway spruce).

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Spectral mixture analysis was used to estimate the contribution of woody elements to tree level reflectance from airborne hyperspectral data in boreal forest stands in Finland. Knowledge of the contribution of woody elements to tree or forest reflectance is important in the context of lea area index (LAI) estimation and, e.g., in the estimation of defoliation due to insect outbreaks, from remote sensing data. Field measurements from four Scots pine (Pinus sylvestris L.), five Norway spruce (Picea abies (L.) Karst.) and four birch (Betula pendula Roth and Betula pubescens Ehrh.) dominated plots, spectral measurements of needles, leaves, bark, and forest floor, airborne hyperspectral as well as airborne laser scanning data were used together with a physically-based forest reflectance model. We compared the results based on simple linear combinations of measured bark and needle/leaf spectra to those obtained by accounting for multiple scattering of radiation within the canopy using a physically-based forest reflectance model. The contribution of forest floor to reflectance was additionally considered. The resulted mean woody element contribution estimates varied from 0.140 to 0.186 for Scots pine, from 0.116 to 0.196 for birches and from 0.090 to 0.095 for Norway spruce, depending on the model used. The contribution of woody elements to tree reflectance had a weak connection to plot level forest variables.

Kuusinen, Department of Built Environment, School of Engineering, Aalto University, P.O. Box 14100, FI-00076 Aalto, Finland E-mail: nea.kuusinen@aalto.fi
Hovi, Department of Built Environment, School of Engineering, Aalto University, P.O. Box 14100, FI-00076 Aalto, Finland E-mail: aarne.hovi@aalto.fi
Rautiainen, Department of Built Environment, School of Engineering, Aalto University, P.O. Box 14100, FI-00076 Aalto, Finland; Department of Electronics and Nanoengineering, School of Electrical Engineering, Aalto University, P.O. Box 15500, FI-00076 Aalto, Finland https://orcid.org/0000-0002-6568-3258 E-mail: miina.a.rautiainen@aalto.fi

article id 10557, category Research note

Mikko T. Niemi. (2021). Improvements to stream extraction and soil wetness mapping within a forested catchment by increasing airborne LiDAR data density – a case study in Parkano, western Finland. Silva Fennica vol. 55 no. 5 article id 10557. https://doi.org/10.14214/sf.10557

Keywords: remote sensing; interpolation; laser scanning; digital elevation model conditioning; overland flow routing; soil drainage; wetness index

Highlights: Overland flow routing can be improved with high-density airborne LiDAR data; Kriging and inverse-distance weighting outperformed triangulated irregular networks in DEM interpolation; A hybrid breaching-filling workflow performed well for DEM conditioning in the Finnish landscape; Enhanced stream extraction and soil wetness mapping contribute to multi-purpose precision forestry.

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The pulse density of airborne Light Detection and Ranging (LiDAR) is increasing due to technical developments. The trade-offs between pulse density, inventory costs, and forest attribute measurement accuracy are extensively studied, but the possibilities of high-density airborne LiDAR in stream extraction and soil wetness mapping are unknown. This study aimed to refine the best practices for generating a hydrologically conditioned digital elevation model (DEM) from an airborne LiDAR -derived 3D point cloud. Depressionless DEMs were processed using a stepwise breaching-filling method, and the performance of overland flow routing was studied in relation to a pulse density, an interpolation method, and a raster cell size. The study area was situated on a densely ditched forestry site in Parkano municipality, for which LiDAR data with a pulse density of 5 m^–2 were available. Stream networks and a topographic wetness index (TWI) were derived from altogether 12 DEM versions. The topological database of Finland was used as a ground reference in comparison, in addition to 40 selected main flow routes within the catchment. The results show improved performance of overland flow modeling due to increased data density. In addition, commonly used triangulated irregular networks were clearly outperformed by universal kriging and inverse-distance weighting in DEM interpolation. However, the TWI proved to be more sensitive to pulse density than an interpolation method. Improved overland flow routing contributes to enhanced forest resource planning at detailed spatial scales.

Niemi, Department of Forest Sciences, University of Helsinki, FI-00014 University of Helsinki, Finland E-mail: mikko.t.niemi@helsinki.fi

article id 10491, category Research note

Atte Komonen, Ilkka Puumala, Gergely Várkonyi, Reijo Penttilä. (2021). Wood-decaying fungi in old-growth boreal forest fragments: extinctions and colonizations over 20 years. Silva Fennica vol. 55 no. 1 article id 10491. https://doi.org/10.14214/sf.10491

Keywords: polypores; fragmentation; extinction debt; habitat loss; spruce forest

Highlights: Rare fungi can persist for decades in isolated old-growth forest fragments; The remaining old-growth forest fragments should be urgently protected, even if they are isolated from larger expanses of natural biotopes.

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According to ecology theory, isolated habitat fragments cannot maintain populations of specialized species. Yet, empirical evidence based on monitoring of the same fragments over time is still limited. We studied the colonization–extinction dynamics of eight wood-decaying fungal species in 16 old-growth forest fragments (<14 ha) over a 20-year period (1997–2017). We observed 19 extinctions and 5 colonizations; yet, the distribution of extinctions and colonizations did not differ from the one expected by chance for any of the species. Twenty-six percent of the extinctions took place in two natural fragments amid large forest–peatland complexes. Phellinus nigrolimitatus (Romell) Bourdot and Galzin decreased and Phellinus ferrugineofuscus (P. Karst.) Bourdot increased in abundance (number of logs occupied). The volume of living spruce trees in the forest fragments correlated positively with the number of logs inhabited in five of the study species. Because fragment characteristics did not affect species turnover, it seems that stochastic processes governed colonizations and extinctions. Although the least abundant species in 1997 had declined, and the most abundant species had become more abundant, it appears that specialized wood-decaying fungi can persist for decades in isolated old-growth forest fragments, if suitable dead wood is continuously available.

Komonen, University of Jyväskylä, Department of Biological and Environmental Science, School of Resource Wisdom, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: atte.komonen@jyu.fi
Puumala, University of Jyväskylä, Department of Biological and Environmental Science, School of Resource Wisdom, P.O. Box 35, FI-40014 University of Jyväskylä, Finland E-mail: ilkka.puumala1@outlook.com
Várkonyi, Finnish Environment Institute, Friendship Park Research Centre, Lentiirantie 342 B, FI-88900 Kuhmo, Finland E-mail: gergely.varkonyi@ymparisto.fi
Penttilä, Natural Resources Institute Finland, Natural resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: reijo.penttila@luke.fi

article id 10263, category Research note

Paul N. Katjutin, Natalia I. Stavrova, Vadim V. Gorshkov, Andrew Yu. Lyanguzov, Irina Ju. Bakkal, Sergey A. Mikhailov. (2020). Radial growth of trees differing in their vitality in the middle-aged Scots pine forests in the Kola peninsula. Silva Fennica vol. 54 no. 3 article id 10263. https://doi.org/10.14214/sf.10263

Keywords: Pinus sylvestris; northern taiga; radial increment; basal area increment

Highlights: Unmanaged middle-aged boreal Scots pine forests in the Kola peninsula are characterised by the prevalence of moderately and strongly weakened trees (65–70%); Radial increment and basal area increment differ greatly (70–75% and 85–90%, respectively) between Scots pine trees differing in their vitality; The trends of annual ring width in Scots pine trees aged from 15–35 to 65–85 years in green moss and green moss-lichen type pine forests are similar; the dynamics of basal area increment differs substantially in relation to forest site type.

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The research was carried out in unmanaged middle-aged (75–85 years) Northern taiga Scots pine (Pinus sylvestris L.) forests in the Kola peninsula. It was established that forests of green moss-lichen and green moss site types are characterised by a predominance (65–70% by stand volume) of moderately and strongly weakened trees. Trees of differing vitality have significant differences in annual increment. Healthy trees had a radial increment (RI) 70–75% greater than that of dying trees, and a basal area increment (BAI) 85–90% greater. The dynamics of the RI and BAI of Scots pine trees for the 70-year period (from 1945 to 2015) is different. The RI of all individuals in the communities studied decreases consistently. The decrease is expressed more strongly in green moss Scots pine forests (80–95% from 1945 to 2015) compared to green moss-lichen forests (60–80%); it manifests itself more in strongly weakened and dying individuals (75–95%) than in healthy and moderately weakened ones (60–80%). Annual basal area increment in green moss Scots pine forests increases by 45–65% from stand establishment until the trees are 25 to 35 years old and subsequently decreases by 50–80% to 70–80 years of age. In green moss-lichen pine forests the BAI of Scots pine remains rather stable in healthy and moderately weakened trees and decreases in strongly weakened and dying individuals by 45% and 75–80%, respectively throughout the studied period.

Katjutin, Komarov Botanical Institute of the Russian Academy of Sciences, Professora Popova str. 2, 197376, Saint-Petersburg, Russia E-mail: paurussia@binran.ru
Stavrova, Komarov Botanical Institute of the Russian Academy of Sciences, Professora Popova str. 2, 197376, Saint-Petersburg, Russia E-mail: nstavrova@binran.ru
Gorshkov, Komarov Botanical Institute of the Russian Academy of Sciences, Professora Popova str. 2, 197376, Saint-Petersburg, Russia; Saint-Petersburg State Forest Technical University, letter U, 5, Institutsky per., 194021, Saint-Petersburg, Russia E-mail: vgorshkov@binran.ru
Lyanguzov, Saint-Petersburg State University, 7/9 Universitetskaya Emb., 199034, Saint-Petersburg, Russia E-mail: andrewlyanguzov@gmail.com
Bakkal, Komarov Botanical Institute of the Russian Academy of Sciences, Professora Popova str. 2, 197376, Saint-Petersburg, Russia E-mail: bakkal@binran.ru
Mikhailov, Komarov Botanical Institute of the Russian Academy of Sciences, Professora Popova str. 2, 197376, Saint-Petersburg, Russia E-mail: smikhailov@binran.ru

article id 10195, category Research note

Tiina Laine, Leena Hamberg, Veli-Matti Saarinen, Timo Saksa. (2019). The efficacy of Chondrostereum purpureum against sprouting of deciduous species after mechanized pre-commercial thinning. Silva Fennica vol. 53 no. 3 article id 10195. https://doi.org/10.14214/sf.10195

Keywords: vegetation management; silviculture; mechanization; Chondrostereum purpureum; fungal treatment; stump sprouts

Highlights: Fungal treatments increased stump mortality compared to the control (cutting only); The fungal treatment did not decrease the number of sprouts per stump; Application during mechanized pre-commercial thinning did not yield as high stump mortalities as in earlier treatments performed manually.

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The use of a white-rot fungus, Chondrostereum purpureum (Pers. Ex Fr.) Pouzar, as a biocontrol agent against sprouting has been studied with good results. The aim of the study was to investigate the efficacy of two pre-commercial thinning machines, Tehojätkä and Mense, to spread an inoculum of C. purpureum as a biocontrol agent on freshly cut birch (Betula pendula Roth and B. pubescens Ehrh.), European aspen (Populus tremula L.), rowan (Sorbus aucuparia L.), and goat willow (Salix caprea L.) stumps (the fungal treatment) and compare that to the control (cutting only, done by Tehojätkä). Efficacy was investigated in terms of stump mortality and the number of sprouts per stump. This study was conducted in one stand and sprouting was investigated for three years after treatment. The fungal treatment resulted in higher mortality of stumps (34.0% for Tehojätkä and 41.5% for Mense after three years), compared to the control (13.4%). However, the fungal treatment did not decrease the number of sprouts per stump compared to the control. The low occurrence of basidiomata indicates that the accuracy of the spreading mechanism was not satisfactory, causing low mortality figures for the fungal treatment compared to previous studies. In the future, this mechanized method may provide a promising alternative in sprout control if the spreading mechanisms, the accuracy of the treatment, and consequently the efficacy could be improved.

Laine, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: tiina.laine@luke.fi
Hamberg, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: leena.hamberg@luke.fi
Saarinen, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: mulinvuori@gmail.com
Saksa, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: timo.saksa@luke.fi

article id 9986, category Research note

Ninni Saarinen, Joanne C. White, Michael A. Wulder, Annika Kangas, Sakari Tuominen, Ville Kankare, Markus Holopainen, Juha Hyyppä, Mikko Vastaranta. (2018). Landsat archive holdings for Finland: opportunities for forest monitoring. Silva Fennica vol. 52 no. 3 article id 9986. https://doi.org/10.14214/sf.9986

Keywords: National Forest Inventory; satellite; Landsat time series

Highlights: The 45-year Landsat archive contained 30 076 images for Finland by December 31, 2017; 16.3% of these were acquired within ±30 days of August 1 (northern hemisphere summer), have <70% cloud cover, and a 30 m spatial resolution; Using time series analyses, these data provide unique information that complements other datasets available for forest monitoring and assessment in Finland.

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There is growing interest in the use of Landsat data to enable forest monitoring over large areas. Free and open data access combined with high performance computing have enabled new approaches to Landsat data analysis that use the best observation for any given pixel to generate an annual, cloud-free, gap-free, surface reflectance image composite. Finland has a long history of incorporating Landsat data into its National Forest Inventory to produce forest information in the form of thematic maps and small area statistics on a variety of forest attributes. Herein we explore the spatial and temporal characteristics of the Landsat archive in the context of forest monitoring in Finland. The United States Geological Survey Landsat archive holds a total of 30 076 images (1972–2017) for 66 scenes (each 185 km by 185 km in size) representing the terrestrial area of Finland, of which 93.6% were acquired since 1984 with a spatial resolution of 30 m. Approximately 16.3% of the archived images have desired compositing characteristics (acquired within August 1 ±30 days, <70% cloud cover, 30 m spatial resolution). Data from the Landsat archive can augment forest monitoring efforts in Finland, provide new information for science and applications, and enable retrospective, systematic analyses to characterize the development of Finnish forests over the past three decades. The capacity to monitor trends based upon this multi-decadal record with the addition of new measurements is of benefit to multisource inventories and offers nationally comprehensive spatially-explicit datasets for a wide range of stakeholders and applications.

Saarinen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland; School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-2730-8892 E-mail: ninni.saarinen@helsinki.fi
White, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland; Canadian Forest Service, (Pacific Forestry Center), Natural Resources Canada, 506 West Burnside Road, Victoria, BC, V8Z 1M5, Canada http://orcid.org/0000-0003-4674-0373 E-mail: joanne.white@canada.ca
Wulder, Canadian Forest Service, (Pacific Forestry Center), Natural Resources Canada, 506 West Burnside Road, Victoria, BC, V8Z 1M5, Canada https://orcid.org/0000-0002-6942-1896 E-mail: mike.wulder@canada.ca
Kangas, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: annika.kangas@luke.fi
Tuominen, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: sakari.tuominen@luke.fi
Kankare, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ville.kankare@helsinki.fi
Holopainen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: markus.holopainen@helsinki.fi
Hyyppä, Department of Remote Sensing and Photogrammetry, Finnish Geospatial Research Institute, National Land Survey of Finland, Geodeetinrinne 2, FI-02431 Masala, Finland E-mail: juha.hyyppa@nls.fi
Vastaranta, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0001-6552-9122 E-mail: mikko.vastaranta@uef.fi

article id 9901, category Research note

Ilze Matisone, Roberts Matisons, Māris Laiviņš, Tālis Gaitnieks. (2018). Statistics of ash dieback in Latvia. Silva Fennica vol. 52 no. 1 article id 9901. https://doi.org/10.14214/sf.9901

Keywords: mortality rate; National Forest Inventory; Fraxinus excelsior; permanent sampling plots

Highlights: Dynamics of ash dieback during 2005–2015 were summarized; The area of ash dominated stands decreased twofold; The number of mature ash trees and their standing volume decreased by 53.1 and 69.9%, compared to 2005, respectively; The mortality of trees was higher during the first part of the survey, the decrease of standing volume culminated later.

Abstract | Full text in HTML | Full text in PDF | Author Info

Dieback of the common ash (Fraxinus excelsior L.) has been spreading throughout Europe since the 1990s, causing severe ecological and economical consequences; however, detailed statistics on its dynamics have been published rarely. This paper presents the dynamics of mature ash-dominated stands in Latvia for the period 2005–2015. Data from the national forest inventory and a permanent sampling plot network were summarised. According to the official statistics, the dieback has caused a twofold decrease in area of the ash stands (from 21 891 to 13 011 ha, which respectively comprised ca. 0.8 to ca. 0.4% of the total forest area). The official statistics on standing volume appeared biased, as they did not account for increased mortality. According to the permanent sampling plots, standing volume and stand density have been affected even more, having decreased by 53.1 and 69.9%, respectively, compared to 2005 (the stand density and standing volume of ash in 2015 was 77 individuals ha^–1 and 151 m³ ha^–1, respectively). The mortality of the trees has not been stable. Stand density decreased faster during 2005–2009 compared to 2010–2015, with mortality rates of 9.6 and 8.2% year^–1, respectively. In contrast, the decrease in standing volume in 2005–2009 was slower than in 2010–2015 (mortality rates were 4.7 and 7.7% year^–1, respectively) because trees with smaller dimensions were more susceptible to the dieback. Nevertheless, the observed mortality rates clearly indicate negative prospects for ash stands in Latvia.

Matisone, Latvian State Forest Research Institute (LSFRI) Silava, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: ilze.matisone@silava.lv
Matisons, Latvian State Forest Research Institute (LSFRI) Silava, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
Laiviņš, Latvian State Forest Research Institute (LSFRI) Silava, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: maris.laivins@silava.lv
Gaitnieks, Latvian State Forest Research Institute (LSFRI) Silava, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: talis.gaitnieks@silava.lv

article id 9899, category Research note

Linda Robalte, Diāna Jansone, Didzis Elferts, Roberts Matisons, Āris Jansons. (2018). Bilberry ramet dimensions in relation to stand age in oligotrophic conditions in Latvia. Silva Fennica vol. 52 no. 1 article id 9899. https://doi.org/10.14214/sf.9899

Keywords: structural diversity; Vaccinium myrtillus; dwarf shrubs; projective cover; hemiboreal forests

Highlights: Bilberry ramet dimensions (age, diameter, height) and their structural diversity, as well as cover, increased with stand age; Active rejuvenation of ramets was observed in younger stands; The oldest bilberry ramets (>10 years of age) occurred in stands older than 70 years.

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Dwarf shrub layer is an important component of boreal and hemiboreal forest ecosystems that has received little attention, particularly regarding its structural diversity, which, however, could serve as an additional proxy for habitat quality. Dimensions of bilberry (Vaccinium myrtillus L.) ramets were assessed in two sites in Latvia covered by dry oligotrophic Scots pine (Pinus sylvestris L.) stands 10–230 years of age. In total, 20 sampling plots (10×10 m) with 156 subplots (1×1 m) were sampled and 630 bilberry ramets analysed. The dimensions of ramets (age, diameter, and height) and cover of bilberry increased with stand age. The age of the studied ramets ranged 2–13 years; 5–6 years-old ramets were most frequent in all stands. The skewness of the distribution of the ramet dimensions shifted with stand age, leaning towards the higher values. Lower structural diversity of ramets was observed in stands 50–100 years of age. The highest diversity of ramet age structure occurred in stands younger than 150 years, whereas the oldest and largest ramets mostly occurred in the older stands (>150 years). Considering structural diversity of ramets, recovery of bilberry after stand-replacing disturbance (e.g. clearcut) was a continuous process, similarly to that observed in tree layer.

Robalte, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia E-mail: robalte.l@gmail.com
Jansone, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia; University of Latvia, Faculty of Biology, Jelgavas Str. 1, LV 1004, Riga, Latvia E-mail: diana.jansone13@gmail.com
Elferts, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia; University of Latvia, Faculty of Biology, Jelgavas Str. 1, LV 1004, Riga, Latvia E-mail: didzis.elferts@lu.lv
Matisons, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia E-mail: roberts.matisons@silava.lv
Jansons, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia E-mail: aris.jansons@silava.lv

article id 7818, category Research note

Roberts Matisons, Guntars Šņepsts, Līga Puriņa, Jānis Donis, Āris Jansons. (2018). Dominant height growth of European beech at the northeasternmost stands in Europe. Silva Fennica vol. 52 no. 1 article id 7818. https://doi.org/10.14214/sf.7818

Keywords: site index; Fagus sylvatica; generalized algebraic difference approach; height models

Highlights: The dominant height growth of the introduced European beech was modelled using the generalised algebraic difference approach; The Chapman-Richards and Sloboda models showed the best fit to the data; Height growth of the second generation trees exceeded the first generation trees; In the western part of Latvia, height growth of beech exceeded that in southern Sweden.

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The height growth of trees influences the productivity of stands and the competitiveness of species, shaping the range of their distribution. Dominant height growth was assessed for European beech (Fagus sylvatica L.), growing outside of its natural distribution range in the western part of Latvia. In 10 neighbouring experimental stands, 20 dominant trees were felled for stem analysis. Height growth was modelled using the generalised algebraic difference approach, applying several non-linear equations and mixed procedures. The Chapman-Richards and Sloboda models showed the best fit to the data. Height growth of the second generation (younger) trees exceeded that of the first generation, and followed curve for a higher site index, suggesting sufficient adaptation and improving conditions. Height growth of the studied beech exceeded predictions for beech in southern Sweden, which is considered to be the northern limit of the species range, yet the growth pattern differed. In Latvia, slower height growth was estimated for site indices < 32 m (in 100 years) during the first 60 years, yet larger maximal height was predicted, suggesting a longer establishment period. Nevertheless, the improving height growth indicated increasing potential for the application of the species in commercial forestry, and an expansion of the species within the region even during the 21th century.

Matisons, Latvian State Forest Research Institute “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
Šņepsts, Latvian State Forest Research Institute “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 E-mail: guntars.snepsts@silava.lv
Puriņa, Latvian State Forest Research Institute “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 E-mail: liga.purina@silava.lv
Donis, Latvian State Forest Research Institute “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 E-mail: janis.donis@silava.lv
Jansons, Latvian State Forest Research Institute “Silava”, Rīgas str. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv

article id 7798, category Research note

Jānis Liepiņš, Jānis Ivanovs, Andis Lazdiņš, Jurģis Jansons, Kaspars Liepiņš. (2017). Mapping of basic density within European aspen stems in Latvia. Silva Fennica vol. 51 no. 5 article id 7798. https://doi.org/10.14214/sf.7798

Keywords: Populus tremula; wood quality; wood density; bark density; density variations

Highlights: Stem bark is significantly denser than wood and does not follow the same variation patterns along the stem; The main trend in radial variation of wood density was the increase from pith to bark; There is a weak relationship between mean basic density and commonly measured stand and tree parameters.

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The objective of this study was to investigate basic density and its within-stem variation by studying 84 European aspen stems from 28 forest stands in Latvia. The studied forest stands covered all age classes from young stands to matured forests in representative growth conditions of European aspen. The densities of 2722 wood and 1022 bark specimens were measured from the sampled trees. Only the knot-free wood specimens without obvious wood defects were chosen for analyses. A map of basic density summarizing its radial and axial variations was constructed to show species-specific, within-stem variability and the relationships between density and tree and stand variables were examined. Stem wood and bark of the European aspen show different patterns of basic density variation along the tree stem. Wood density increases from pith to bark up to certain dimensions and shows a slight decrease afterwards. The weighted basic density of bark (446 ± 39.6 kg m^–3) was higher than stem wood density (393 ± 30.4 kg m^–3). Our results suggest that wood and bark density measurements obtained at breast height can be used for reliable estimation of the densities of whole-tree stem components, while tree parameters such as diameter at breast height (DBH), tree height and social status or stand parameters, including number of trees, basal area and age, are weak predictors in this context.

Liepiņš, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia E-mail: janis.liepins@silava.lv
Ivanovs, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia E-mail: janis.ivanovs@silava.lv
Lazdiņš, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia E-mail: andis.lazdins@silava.lv
Jansons, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia E-mail: jurgis.jansons@silava.lv
Liepiņš, Latvian State Forest Research Institute “Silava”, 111 Rigas Str., LV 2169, Salaspils, Latvia E-mail: kaspars.liepins@silava.lv

article id 1717, category Research note

Jussi Manner, Olle Gelin, Anders Mörk, Martin Englund. (2017). Forwarder crane’s boom tip control system and beginner-level operators. Silva Fennica vol. 51 no. 2 article id 1717. https://doi.org/10.14214/sf.1717

Keywords: productivity; automation; cut-to-length logging; haulage; crane work; extraction; learning curve

Highlights: Boom tip control (BTC) allows the operator to control boom tip movements directly, instead of controlling each movement separately to achieve the desired boom tip movement; BTC eased boom control, so beginner-level operators using BTC achieved higher productivity than beginner-level operators using a conventional (reference) system; There were no significant differences in the slopes of learning curves between the systems.

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The forwarder loads processed wood and transports it to a landing. Productivity of forwarding could be improved by increasing driving speed, but difficult forest terrain limits this. According to current literature, crane work is the most time-consuming work element of forwarding, so improving crane work productivity is essential for improving forwarding productivity. One way to do this is through automation of recurrent boom movement patterns, or alternatively automation can be used to ease crane work. When using conventional boom control (CBC), the operator manually controls each of the independent boom joint movements and combines them to achieve a desired boom tip movement, but boom tip control (BTC) allows the operator to control boom tip movements directly. The objective of the present study was to examine whether BTC facilitates crane work and affects the slopes of learning curves for beginner-level forwarder operators. The study was carried out using a standardised test routine to evaluate effects of two fixed factors, system (levels: CBC, BTC) and point of time (four levels), on five dependent variables. Four of the five dependent variables measured ease of boom control and the fifth measured crane work productivity. The results showed that there were no significant differences in the slopes of learning curves between the systems but the BTC did increase crane work productivity and made boom control easier.

Manner, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden http://orcid.org/0000-0002-4982-3855 E-mail: jussi.manner@skogforsk.se
Gelin, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: olle.gelin@skogforsk.se
Mörk, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: anders.mork@skogforsk.se
Englund, The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: martin.englund@skogforsk.se

article id 1674, category Research note

Nevenka Ćelepirović, Monika Karija Vlahović, Aikaterini Dounavi, Mladen Ivanković. (2016). Optimizations of high throughput multiplex polymerase chain reaction with simple sequence repeat markers for genotyping of common walnut populations (Juglans regia L.). Silva Fennica vol. 50 no. 5 article id 1674. https://doi.org/10.14214/sf.1674

Keywords: SSR markers; nuclear microsatellites; Juglans regia L.; multiplex PCR

Highlights: We combined eleven SSR markers in one multiplex PCR to make faster and cost effective amplification of the common walnut DNA from Croatia; Genetic variation of common walnut from Croatia was moderate at analyzed SSR loci; The resultant multiplex PCR could be used for genotyping of common walnut populations.

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Multiplex polymerase chain reaction (PCR) allows amplification of two or more pair of primers in parallel for amplification of multiple target sequences in a single reaction tube. In this study, we combined existing simple sequence repeat (SSR) markers (nuclear microsatellites) in the novel combination of multiplex PCR to study the population genetics of common walnut from Croatia. From twenty one tested SSR markers, eleven produced satisfactory results in one multiplex PCR. Population genetic results achieved from 15 samples of Croatian common walnut showed moderate genetic variability (average value: He 0.473; Ho 0.568). Our multiplex PCR allowed cost effective work concerning chemicals, plastic ware, device, and working time producing optimal results. The optimized multiplex PCR represented the best combination of eleven SSR primers for genotyping common walnut in a single PCR reaction.

Ćelepirović, Division of Genetics, Forest Tree Breeding and Seed Science, Croatian Forest Research Institute, Jastrebarsko, Croatia E-mail: celepirovic.nevenka@gmail.com
Karija Vlahović, DNA Laboratory, Department of Forensic Medicine&Criminology, School of Medicine, University of Zagreb, Zagreb, Croatia E-mail: monika.karija.vlahovic@mef.hr
Dounavi, Department of Forest Protection, Forest Research Insitute of Baden-Württemberg, Wonnhaldesttr. 4, 79100 Freiburg, Germany E-mail: aikaterini.dounavi@forst.bwl.de
Ivanković, Division of Genetics, Forest Tree Breeding and Seed Science, Croatian Forest Research Institute, Jastrebarsko, Croatia E-mail: mladeni@sumins.hr

article id 1656, category Research note

Līga Puriņa, Roberts Matisons, Āris Jansons, Silva Šēnhofa. (2016). Survival of European beech in the central part of Latvia 33 years since the plantation. Silva Fennica vol. 50 no. 4 article id 1656. https://doi.org/10.14214/sf.1656

Keywords: Fagus sylvatica; introduction experiment; sapling mortality; northeasternmost beech trial

Highlights: Beech saplings growing in the central part of Latvia had ca. 80% survival during the recent three decades; The dimensions of saplings varied greatly likely due to canopy conditions; Some beech self-regeneration was observed; Mainly saplings had narrow crowns; The distribution of sapling dimensions had the reverse-J shape, suggesting successful development of beech.

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The projections of vegetation zones suggest increasing growth potential of European beech (Fagus sylvatica L.) in Northern Europe. Such changes usually are most apparent in the marginal populations. In this study, survival of young beech growing in an experimental plantation under canopy of a mixed coniferous stand in the central part of Latvia was assessed after 33 years since the establishment. The planting material originated from an older experimental stand in the western part of Latvia. Although, at present, the studied plantation could be considered as the northeasternmost beech stand in Europe, a good survival was observed – ca. 80% of the seedlings have survived, despite several cold spells of ca. –30 °C that occurred during the recent three decades. Additionally, some self-regeneration i.e. branch sprouting was observed. The saplings were rather low, as their mean height was ca. 4 m. Still, some individuals, which were growing under canopy openings, reached considerable dimensions; their height and stem diameter exceeded 10 m and 9 cm, respectively. The distribution of sapling dimensions had the reverse-J shape that is typical for shade tolerant species, indicating normal development of the beech regrowth. The crowns of saplings were narrow and the stems were spindly, suggesting that trees with a good stem quality might be bred. Hence, our results suggest that environmental conditions in the central part of Latvia have been satisfactory for beech, thus encouraging establishment of more extensive trials within the region.

Puriņa, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: liga.purina@silava.lv
Matisons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
Jansons, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv
Šēnhofa, LSFRI “Silava”, Rigas str. 111, Salaspils, Latvia, LV2169 E-mail: silva.senhofa@silava.lv

article id 1518, category Research note

Francesco Chianucci. (2015). A note on estimating canopy cover from digital cover and hemispherical photography. Silva Fennica vol. 50 no. 1 article id 1518. https://doi.org/10.14214/sf.1518

Keywords: forest canopy; foliage cover; crown cover; fisheye photography; cover photography

Highlights: Comparison of fisheye (DHP) and cover (DCP) photography for estimating canopy cover; Digital photographic estimates validated against artificial images with known cover; Accuracy of cover estimates from DHP is influenced by mean gap size and actual cover; Accuracy of cover estimates from DCP is not influenced by mean gap size and actual cover.

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Fast and accurate estimates of canopy cover are central for a wide range of forestry studies. As direct measurements are impractical, indirect optical methods have often been used in forestry to estimate canopy cover. In this paper the accuracy of canopy cover estimates from two widely used canopy photographic methods, hemispherical photography (DHP) and cover photography (DCP) was evaluated. Canopy cover was approximated in DHP as the complement of gap fraction data at narrow viewing zenith angle range (0°–15°), which was comparable with that of DCP. The methodology was tested using artificial images with known canopy cover; this allowed exploring the influence of actual canopy cover and mean gap size on canopy cover estimation from photography. DCP provided robust estimates of canopy cover, whose accuracy was not influenced by variation in actual canopy cover and mean gap size, based on comparison with artificial images; by contrast, the accuracy of cover estimates from DHP was influenced by both actual canopy cover and mean gap size, because of the lower ability of DHP to detect small gaps within crown. The results were replicated in both DHP and DCP images collected in real forest canopies. Finally, the influence of canopy cover on foliage clumping index and leaf area index was evaluated using a theoretical gap fraction model. The main findings indicate that DCP can overcome the limits of indirect techniques for obtaining unbiased and precise estimates of canopy cover, which are comparable to those obtainable from direct, more labour-intensive techniques, being therefore highly suitable for routine monitoring and inventory purposes.

Chianucci, Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria – Forestry Research Centre, viale Santa Margherita 80, 52100 Arezzo, Italy http://orcid.org/0000-0002-5688-2060 E-mail: fchianucci@gmail.com

article id 1443, category Research note

Jouni Partanen, Risto Häkkinen, Heikki Hänninen. (2015). Significance of the root connection on the dormancy release and vegetative bud burst of Norway spruce (Picea abies) seedlings in relation to accumulated chilling. Silva Fennica vol. 50 no. 1 article id 1443. https://doi.org/10.14214/sf.1443

Keywords: phenology; bud burst percentage; days to bud burst; dormancy release; forcing

Highlights: Cutting the root connection slightly increased the number of days to bud burst of Norway spruce seedlings under warm conditions but it had no consistent effect on bud burst percentage; Our results obtained with seedlings suggest that using detached tree material in dormancy release experiments may slightly affect the results but it will evidently not lead to drastically erroneous conclusions.

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The effect of cutting the root connection by detaching the shoot from the root system on dormancy release and vegetative bud burst was examined in 2-year-old seedlings of Norway spruce (Picea abies [L.] Karst.). Seedlings were transferred at 1–4 week intervals between October and January from outdoor conditions to experimental forcing in a heated greenhouse. Before forcing, half of the seedlings were cut above ground line, and the detached shoots were forced with their cut ends placed in water. The intact seedlings were forced with their root system remaining intact in the pots. Vegetative bud burst was observed visually. Cutting the root connection slightly increased days to bud burst in the forcing conditions, however, no consistent effect on bud burst percentage was found. Our preliminary seedling data suggest that using detached tree material in dormancy release experiments may have a small effect on bud burst date but it will evidently not lead to drastically erroneous conclusions. Further studies, using different seed lots, are needed to assess the effect of detaching on the dormancy release and bud burst, especially in adult trees.

Partanen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: jouni.partanen@luke.fi
Häkkinen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: risto.hakkinen@luke.fi
Hänninen, University of Helsinki, Department of Biosciences, Viikki Plant Science Centre (ViPS), P.O. Box 65, FI-00014 University of Helsinki, Finland E-mail: heikki.hanninen@helsinki.fi

article id 1415, category Research note

Zorica Šarac, Tanja Dodoš, Nemanja Rajčević, Srdjan Bojović, Petar Marin, Jelena Aleksić. (2015). Genetic patterns in Pinus nigra from the central Balkans inferred from plastid and mitochondrial data. Silva Fennica vol. 49 no. 5 article id 1415. https://doi.org/10.14214/sf.1415

Keywords: genetic differentiation; genetic diversity; the Balkans; European black pine; chloroplast microsatellites; mitochondrial nad7 intron 1; haplotype network

Highlights: Seven populations of Pinus nigra from the central Balkans, representing four infraspecific taxa, were analyzed with chloroplast microsatellites and a mitochondrial locus; Molecular data failed to support infraspecific circumscriptions; Levels of genetic diversities/differentiation at both genomes were in the range of those reported in western Mediterranean populations of P. nigra; Iberian/African and Balkans’ populations share one mtDNA polymorphism and differ in three mutations.

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Pinus nigra J.F. Arnold, European black pine, is a typical component of Mediterranean and sub-Mediterranean coniferous forests with highly fragmentary distribution. Western Mediterranean populations of this species have been studied genetically to date, while eastern populations from the central Balkans, which are larger and more abundant, are still genetically understudied. We analyzed seven populations of P. nigra representing all infraspecific taxa recognized within the central Balkans (subspecies nigra with varieties nigra and gocensis Đorđević; and subspecies pallasiana (Lamb.) Holmboe with varieties pallasiana and banatica (Endl.) Georgescu et Ionescu), with three chloroplast microsatellites (cpDNA SSRs) and one mitochondrial (mtDNA) locus. Although our molecular data failed to support circumscription of studied infraspecific taxa, we found that genetic patterns at both genomes are in accordance with those found previously in westward populations of this species, that is – exceptionally high levels of genetic diversity (H_T = 0.949) and low genetic differentiation (G_ST = 0.024) at the cpDNA level, and moderate levels of genetic diversity (H_T = 0.357) and genetic differentiation (G_ST = 0.358) at the mtDNA level. Based on genealogical relations of mtDNA types currently present in Balkans’ and Iberian/African populations, we inferred that the ancestral gene pool of P. nigra already harbored polymorphism at position 328 prior to the divergence to two lineages currently present in westward and eastward parts of the species range distribution. Subsequent occurrence of three mutations, which distinguish these two lineages, suggests their long-term isolation.

Šarac, University of Niš, Faculty of Sciences and Mathematics, Department of Biology and Ecology, Višegradska 33, 18000 Niš, Serbia E-mail: saraczorica@gmail.com
Dodoš, University of Belgrade, Faculty of Biology, Institute of Botany and Botanical Garden “Jevremovac”, Studentski trg 16, 11000 Belgrade, Serbia E-mail: tanjadodos@bio.bg.ac.rs
Rajčević, University of Belgrade, Faculty of Biology, Institute of Botany and Botanical Garden “Jevremovac”, Studentski trg 16, 11000 Belgrade, Serbia E-mail: nemanja@bio.bg.ac.rs
Bojović, University of Belgrade, Institute for Biological Research “Siniša Stanković”, Boulevard Despota Stefana 142, 11060 Belgrade, Serbia E-mail: bojovic@ibiss.bg.ac.rs
Marin, University of Belgrade, Faculty of Biology, Institute of Botany and Botanical Garden “Jevremovac”, Studentski trg 16, 11000 Belgrade, Serbia E-mail: pdmarin@bio.bg.ac.rs
Aleksić, University of Belgrade, Institute of Molecular Genetics and Genetic Engineering, Vojvode Stepe 444a, P.O. Box 23, 11000 Belgrade, Serbia E-mail: aleksic_jelena@yahoo.com.au

article id 1320, category Research note

Abbot Okotie Oghenekaro, Geoffrey Daniel, Fred O Asiegbu. (2015). The saprotrophic wood-degrading abilities of Rigidoporus microporus. Silva Fennica vol. 49 no. 4 article id 1320. https://doi.org/10.14214/sf.1320

Keywords: simultaneous decay; wood degradation; white rot; delignification

Highlights: Rigidoporus microporus isolates displayed varying saprotrophic capabilities on wood blocks of Rubber tree (Hevea brasiliensis); Percentage mass loss of (Hevea brasiliensis) wood blocks caused by the pathogenic Rigidoporus microporus was significantly higher than that observed with the endophytic isolate; The endophytic isolate has very poor saprotrophic ability on Hevea brasiliensis wood blocks.

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Saprotrophic wood-decaying abilities of Rigidoporus microporus (Polyporales, Basidiomycota) syn. Rigidoporus lignosus and the structural alterations induced in wood blocks of Hevea brasiliensis Muell. Arg were studied. Mass loss of wood blocks was analyzed after 3 and 6 months respectively and the patterns of decay by pathogenic and endophytic isolates of this fungus were investigated using light microscopy. Effects of temperature on growth of the isolates on malt extract agar were also investigated. The R. microporus isolated from a non-H. brasiliensis host caused the highest percentage mass loss (27.2% after 6 months), followed by isolates ED310 (21.1%) and M13 (15.7%), both collected from diseased H. brasiliensis plantations. The isolate initially identified as an endophyte showed very low saprotrophic wood decay capability (4.3% after 6 months). The optimal temperature for growth of the isolates was 30 °C; except for the endophytic isolate which showed highest growth at 25 °C. Wood samples degraded by the R. microporus isolates showed simultaneous attack of wood cell walls, typical of white rot fungi. Results of the study indicate variability in the wood degrading abilities of the isolates and the potential differences in their physiology are discussed. Our findings further support the need for a taxonomical revision of the Rigidoporus genus.

Oghenekaro, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: abbot.oghenekaro@helsinki.fi
Daniel, Department of Forest Products/Wood Science, Swedish University of Agricultural Sciences, P.O. Box 7008, SE-75007 Uppsala, Sweden E-mail: geoffrey.daniel@slu.se
Asiegbu, Department of Forest Sciences, University of Helsinki, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: fred.asiegbu@helsinki.fi

article id 1255, category Research note

Āris Jansons, Roberts Matisons, Līga Puriņa, Una Neimane, Jānis Jansons. (2015). Relationships between climatic variables and tree-ring width of European beech and European larch growing outside of their natural distribution area. Silva Fennica vol. 49 no. 1 article id 1255. https://doi.org/10.14214/sf.1255

Keywords: Fagus sylvatica; introduced species; wood increment; climatic limitation; Latvia; Larix decidua

Highlights: In western Latvia, variation of tree-ring width of European beech and European larch within stands was similar; Dry summers and cold winters caused common event years in tree-rings; Moisture availability at the end of summer was apparently the main limiting factor for tree-ring width; Winter and spring temperature did not have significant and lasting effect on variation of tree-ring width.

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Relationships between climatic variables and tree-ring width (TRW) of dominant European larch (Larix decidua Mill.) and European beech (Fagus sylvatica L.) trees growing outside of their natural distribution area in western Latvia were studied. Chronologies of TRW, which covered the periods 1949–2012 and 1911–2012, were produced for beech and larch, respectively. Common signatures in TRW between both species were observed, but their amplitude differed. Correlation analysis showed that variation of TRW of both species was affected by drought related climatic variables. Tree-ring width of beech was affected by temperature in the previous July and August and the effect of spring and autumn temperature was observed. Since the 1980s, the effect of July precipitation has become significant. Summer precipitation was significant for larch in the mid-part of the previous century; however, temperature in the previous September has become a limiting factor since 1970s. The limiting effect of winter and spring temperature apparently lost its significance around the 1950s.

Jansons, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 E-mail: aris.jansons@silava.lv
Matisons, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 E-mail: robism@inbox.lv
Puriņa, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 E-mail: liga.purina@silava.lv
Neimane, LSFRI „SILAVA”, Rigas Str. 111, Salaspils, Latvia, LV2169 E-mail: una.neimane@silava.lv
Jansons, Forest Competence Centre, Dzerbenes str. 27, Riga, Latvia, LV1006 E-mail: janis.jansons@mnkc.lv

article id 1145, category Research note

Juha Siitonen. (2014). Ips acuminatus kills pines in southern Finland. Silva Fennica vol. 48 no. 4 article id 1145. https://doi.org/10.14214/sf.1145

Keywords: tree mortality; Scots pine; Ips acuminatus; Phaenops cyanea; drought

Highlights: Recently dead pines colonized by Ips acuminatus were frequently found in southern Finland, in a region where the species was thought to be absent; Colonized trees were typically large (average DBH 30 cm), located at open spots in pine-dominated stands, often forming groups of several trees; The damages may be a consequence of dry and hot summers during the 2000s.

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Recently dead Scots pines (Pinus sylvestris L.) apparently killed by Ips acuminatus (Gyllenhal) were observed in Sipoo, southern Finland, in summer 2013. This record was unexpected and in contradiction with what is currently known about the distribution and aggressiveness of the species in Finland. The aim of this study was to survey a larger area in Uusimaa region, to find out whether I. acuminatus occurs frequently in recently dead pines, and whether inhabited trees share some common tree- or site-level characteristics. Galleries of I. acuminatus were found in most of the studied trees. A total of 96 inhabited trees were found in 21 separate sites. Colonized pines were typically large (average DBH 30 ± 9 cm) trees located in relatively open pine-dominated heathland stands at half-open, sun-exposed spots. The whole upper part of the trunk with thin bark was usually occupied. Galleries of Tomicus piniperda L. or T. minor Hartig occurred only in few cases in the same trees, indicating that the trees had died later in the summer. Galleries of the jewel beetle Phaenops cyanea F. were found in 13 trees. Trees colonized by I. acuminatus often occurred as small groups, with generally 1–12 trees (average 3 trees), but in one exceptional group there were no less than 35 trees. It is possible that the hot and dry summers during the 2000s have increased the susceptibility of pines to insect damage, and have contributed to a population growth of I. acuminatus.

Siitonen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: juha.siitonen@metla.fi

article id 1126, category Research note

Rebecka Mc Carthy, Per Magnus Ekö, Lars Rytter. (2014). Reliability of stump sprouting as a regeneration method for poplars: clonal behavior in survival, sprout straightness and growth. Silva Fennica vol. 48 no. 3 article id 1126. https://doi.org/10.14214/sf.1126

Keywords: Populus spp.; coppice regeneration; vegetative regeneration; short-rotation forestry

Highlights: Clonal differences were found in stump sprout survival; Clonal differences occurred in sprout straightness; It is uncertain if the ability to produce a high number of stump sprouts is beneficial.

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The interest in poplars (Populus spp.) has increased globally as a result of the current incentive to expand the use of biomass for energy. So far, knowledge about poplar stump sprouting is generally poor. The objective of this study was to investigate poplar stump sprouting as regeneration method in harvested plantations. A 19-year-old poplar clonal test, including 23 different clones, on former arable land was harvested in the winter. After one year, stumps were assessed for sprout survival, sprout straightness, number of sprouts, sprout height and basal diameter. Differences between clones were found for survival and sprout straightness. Clonal differences were also found in mean size of sprouts (basal diameter and height). However, no differences were found between clones when comparing size of the tallest sprout or number of sprouts produced on stumps. This study indicates that stump sprouts from various poplar clones differ in survival, sprout straightness and mean growth, which should be taken into account when planning for the next tree generation. The study needs to be complemented with other studies to better assess sprouting characteristics for different clones.

Mc Carthy, Forestry Research Institute of Sweden, Skogforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden & Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: rebecka.mccarthy@skogforsk.se
Ekö, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: Per.Magnus.Eko@slu.se
Rytter, Forestry Research Institute of Sweden, Skogforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden E-mail: lars.rytter@skogforsk.se

article id 1026, category Research note

Leif Nutto, Ricardo A. Malinovski, Martin Brunsmeier, Felipe Schumacher Sant’Anna. (2013). Ergonomic aspects and productivity of different pruning tools for a first pruning lift of Eucalyptus grandis Hill ex Maiden. Silva Fennica vol. 47 no. 4 article id 1026. https://doi.org/10.14214/sf.1026

Keywords: forest management; wood quality; work science; handsaw; shear

Highlights: Pruning of hardwoods coming from forest plantations is becoming more and more important in Brazil to replace scarce wood from tropical forests; Evaluating productivity of different pruning tools is essential for the economic output of plantations managed for high quality wood; Pruning activities of forest workers can be classified as “hard” or “very hard work”. Depending on the tools used physical long-term damages may be prevented.

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For the substitution of wood from tropical rainforests pruning of Eucalyptus for producing valuable hardwoods in short rotation plantations has become important. Existing tools and ergonomic aspects of pruning were not yet well analysed under these conditions. The objective of the study is to evaluate the productivity and ergonomics of three different pruning tools in a pruning lift up to 3 m in height. The trees used in the study came from an 18-month-old clonal Eucalyptus grandis stand planted in a 5.0 x 2.8 m spacing. Two manual pruning tools and an electric shear were tested for productivity by using time studies. Ergonomic aspects were evaluated by two test persons using pulse meter equipment. The highest productivity could be shown for the electric shear (236 trees per working day), followed by the manual shear (196 trees/day) and the handsaw (180 trees/day). The heartbeat rate of the two test persons ranged from a level of “very hard work” for the manual tools to “middle hard” and “hard work” for the electric shear. The workload level to achieve the productivity currently reached in practice using purely manual tools is extremely high, exceeding the permanent working capacity of the operators and leading to physical degradation on the long run.

Nutto, Department for Forestry, Federal University of Paraná, Av. Pref. Lothário Meissner, 632, Curitiba, PR, Brazil E-mail: lnutto.ufpr@gmail.com
Malinovski, Department for Forestry, Laboratory of Forest Operations, Federal University of Paraná, Av. Prefeito Lothario Meissner, 900, Curitiba, PR, Brazil E-mail: ricardo@colheitademadeira.com.br
Brunsmeier, Chair of Forest Utilization, University of Freiburg, Werthmannstraße 6, 79085 Freiburg, Germany E-mail: martin.brunsmeier@fobawi.uni-freiburg.de
Schumacher Sant’Anna, Department for Forestry, Laboratory of Forest Operations, Federal University of Paraná, Av. Prefeito Lothario Meissner, 900, Curitiba, PR, Brazil E-mail: felipe@colheitademadeira.com.br

article id 974, category Research note

Kristina Ahnlund Ulvcrona, Lars Karlsson, Ingegerd Backlund, Urban Bergsten. (2013). Comparison of silvicultural regimes of lodgepole pine (Pinus contorta) in Sweden 5 years after precommercial thinning. Silva Fennica vol. 47 no. 3 article id 974. https://doi.org/10.14214/sf.974

Keywords: direct seeding; forest production; corridor thinning; biomass harvest; PCT

Highlights: Management regimes can serve different purposes such as biomass production, pulp and timber production or a combination of those; 30 tons biomass or 38–45 m³ stem volume ha^–1 could be derived by schematic corridor thinning (70%) at year 20; Producing large amounts of biomass early in the rotation period does not exclude a conversion into pulp and timber production.

Abstract | Full text in HTML | Full text in PDF | Author Info

Early effects (stem volume, mean diameter at breast height weighted against basal area (Dgv) (Dgv), biomass and damage frequency) of different silvicultural regimes 18-19 years after direct seeding of lodgepole pine in northern Sweden were analysed. A Conventional regime, (i) precommercial thinning (PCT) to 2200 stems ha^-1, was compared to: (ii) High biomass production (15 300 stems ha^-1, no PCT) with and without corridor thinning at year 20, (iii) production of Large dimension trees (PCT to 1700 stems ha^-1), (iv), Combined high biomass production and production of conventional round wood (PCT to 4500 stems ha^-1). PCT was done 15 yrs after direct seeding for all PCT treatments. Local biomass functions showed that the regimes aiming at High biomass production displayed ca 144-157% more biomass and 134-143% more stem volume than the Conventional and Large dimension regimes (ca 21 tons and 31 m³ ha^-1). Dgv for the 1000 (9.2 cm) and 2000 (8.3 cm) largest trees ha^-1 appeared unaffected by regime. By schematic corridor thinning (70% of the total area) at year 20 in the High biomass regime, 27-32 tons of biomass ha^-1 and 38-45 m³ ha^-1 could be derived while still having a Dgv of the 1000 largest trees ha^-1 of about 8 cm. Therefore, this study indicates that it is possible to produce and harvest large amounts of biomass and stem volume early in the rotation period without excluding later pulp and timber production. This initial regime comparison should be continued over time.

Ahnlund Ulvcrona, SLU, Forest Biomaterials and Technology, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: kristina.ulvcrona@slu.se
Karlsson, SLU, Forest Biomaterials and Technology, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: lars.karlsson@slu.se
Backlund, SLU, Forest Biomaterials and Technology, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: ingegerd.backlund@slu.se
Bergsten, SLU, Forest Biomaterials and Technology, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: urban.bergsten@slu.se

article id 442, category Research note

Emil Modig, Bo Magnusson, Erik Valinger, Jonas Cedergren, Lars Lundqvist. (2012). Damage to residual stand caused by mechanized selection harvest in uneven-aged Picea abies dominated stands. Silva Fennica vol. 46 no. 2 article id 442. https://doi.org/10.14214/sf.442

Keywords: selection cutting; logging damage; continuous cover management; residual stand; logging methods

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Permanent field plots were established in two uneven-aged Norway spruce (Picea abies (L.) Karst) dominated stands in west-central Sweden. The objective was to quantify level and type of damage caused by harvesting and to quantify the difference between two treatments: T20) only skid road harvest (20 m distance between ca. 4 m wide roads), and T40) skid road harvest (40 m distance between ca. 4 m wide roads) combined with thinning between the roads. In T40, the goal was to harvest approximately the same standing volume as in T20. After harvest, two circular sample plots (radius 18 m, i.e. 1018 m₂) were established at random locations within each treated area. All mechanical damage on the stem caused by harvest was measured and registered, including bark stripping larger than 15 cm₂, stem broken or split, and tearing of branches causing damage on the stem. About 70–90 per cent of the damaged trees were smaller than 15 cm dbh. Very few trees larger than 25 cm dbh were damaged. In T20, more than 50 per cent of the damaged trees were located less than 5 m from the skid road, compared to less than 25 per cent for T40, in which more than 50 per cent of the damaged trees were located 5–10 m from the skid road. Creating only half the number of skid roads caused no more damage, and was probably more profitable because mean stem volume was about 1.5 times larger than in T20.

Modig, Statens fastighetsverk, Jokkmokk, Sweden E-mail: em@nn.se
Magnusson, Skogsstyrelsen, Bräcke, Sweden E-mail: bm@nn.se
Valinger, Deparment of Forest Ecology and Management, SLU, SE-901 83 Umeå, Sweden E-mail: ev@nn.se
Cedergren, Mariehamn, Åland E-mail: jc@nn.se
Lundqvist, Deparment of Forest Ecology and Management, SLU, SE-901 83 Umeå, Sweden E-mail: lars.lundqvist@slu.se

article id 61, category Research note

Janine Schweier, Gero Becker. (2012). Harvesting of short rotation coppice – harvesting trials with a cut and storage system in Germany. Silva Fennica vol. 46 no. 2 article id 61. https://doi.org/10.14214/sf.61

Keywords: productivity; harvest operations; marginal sites; SRC; Stemster MK III

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Short rotation coppice (SRC) harvesting techniques are available in Germany, but broad experience and knowledge about machine performance and the related effective costs of harvesting operations are still missing. This information is crucial, as harvesting costs strongly influence the economic performance of the overall supply chain. Therefore, it was the aim of this study to collect and analyze productivity data of different harvesting systems for SRC. The combined cut and chip system on the one hand and the cut and storage system on the other hand were studied by literature review. Several studies analyze the combined cut and chip systems and the reported machine productivities showed great variations. The average was 30 green tons per scheduled machine hour (gt smh^–1). Few studies are analysing the cut and storage system. They report that machines still are under development and that further research is needed. Therefore, time studies of harvesting operations using the cut and storage system were carried out. Five trials were performed with the harvesting machine “Stemster MK III” developed by Nordic Biomass. The share of productive working time was 85% and the average productivity was 21 gt smh^–1. These results were compared with values from the literature. Resulting harvesting costs were calculated per oven dry ton (euros odt^–1). The advantages and disadvantages of both harvesting systems are highlighted.

Schweier, Albert-Ludwigs-University Freiburg, Institute of Forest Utilisation and Work Science, Freiburg, Germany E-mail: janine.schweier@fobawi.uni-freiburg.de
Becker, Albert-Ludwigs-University Freiburg, Institute of Forest Utilisation and Work Science, Freiburg, Germany E-mail: gb@nn.de

article id 71, category Research note

Jaana Luoranen, Heli Viiri. (2012). Soil preparation reduces pine weevil (Hylobius abietis L.) damage on both peatland and mineral soil sites one year after planting. Silva Fennica vol. 46 no. 1 article id 71. https://doi.org/10.14214/sf.71

Keywords: mineral soil; peatland; pine weevil; soil preparation; vole

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We studied pine weevil (Hylobius abietis (L.)) feeding damage to Norway spruce and Scots pine seedlings planted in regeneration areas located on peatlands or on mineral soil sites in Southern and Central Finland. The survey included two planting years and a total of 60 regeneration areas (40 areas on peatlands and 20 on mineral soil sites). Some sites classified as peatland were as transformed or transforming drained peatlands that also contained mineral soil on a prepared surface. The soil preparation method, type of surface material around a seedling, pine weevil, vole-induced or other damage and the health of each seedling were observed in systematically selected circular sample plots. There was slightly more pine weevil damage on peatland than on mineral soil sites. More seedlings were damaged on unprepared peat and humus than on a prepared surface. Seedlings surrounded by a prepared surface had a slightly greater risk of being gnawed by pine weevil when planted on prepared peat compared to planting on prepared mineral soil. Vole damage was observed only in one region during one year. Mounded areas had slightly less vole damage than patched areas. In order to reduce damage caused by pine weevils and voles, it is important to scarify the regeneration area properly before insecticide-treated seedlings are planted. Mounding and patching are recommended so that seedlings can be planted in mineral soil whenever possible, even in the case of peatlands.

Luoranen, Finnish Forest Research Institute, Suonenjoki Unit, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: jaana.luoranen@metla.fi
Viiri, Finnish Forest Research Institute, Joensuu Unit, Joensuu, Finland E-mail: hv@nn.fi

article id 37, category Research note

D. N. Avtzis, F. A. Aravanopoulos. (2011). Host tree and insect genetic diversity on the borderline of natural distribution: a case study of Picea abies and Pityogenes chalcographus (Coleoptera, Scolytinae) in Greece. Silva Fennica vol. 45 no. 1 article id 37. https://doi.org/10.14214/sf.37

Keywords: bark beetles; genetic bases; marginal populations; northern Greece; Norway spruce

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Picea abies (L.) Karst. and Pityogenes chalcographus constitute a commonly observed host tree–insect association in Eurasia, with the natural distribution of the bark beetle overlapping that of Norway spruce. The southernmost borderline of their distributions occurs in the Elatia forest (Mt. Rodopi, Greece), where these interacting organisms may experience severe conditions due to the effects of climate change. In order to assess the dynamics of this host tree–insect association, the genetic diversity of both organisms was studied. In contrast to previous studies, the assessment of molecular diversity was based on the same mitochondrial gene (Cytochrome Oxidase One) sequence for both host and pest. This analysis revealed a remarkably higher genetic diversity of P. chalcographus compared to that of P. abies, something that renders the insect capable not only of adapting to novel environmental conditions, but even of shifting to other host species. On the contrary, P. abies presented a narrow genetic base, a potential drawback at the southern-most region of the species natural distribution. Synthesizing the preliminary outcome for both organisms, it appears that P. chalcographus exhibits an evolutionary advantage over P. abies, something that should be considered when planning conservation strategies for the relict forest of Elatia.

Avtzis, Aristotle University of Thessaloniki, Laboratory of Forest Genetics and Tree Breeding, Thessaloniki, Greece E-mail: dimitrios.avtzis@gmail.com
Aravanopoulos, Aristotle University of Thessaloniki, Laboratory of Forest Genetics and Tree Breeding, Thessaloniki, Greece E-mail: FAA@nn.fi

article id 136, category Research note

Tomasz D. Mazgajski, Michal Zmihorski, Katarzyna Abramowicz. (2010). Forest habitat loss and fragmentation in Central Poland during the last 100 years. Silva Fennica vol. 44 no. 4 article id 136. https://doi.org/10.14214/sf.136

Keywords: afforestation; fragmentation; landscape history; forest continuity; deforestation; ancient forest

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The process of habitat fragmentation consists of two components – habitat loss and fragmentation per se. Both are thought to be among the most important threats to biodiversity. However, the biological consequences of this process such as species occurrence, abundance, or genetic structure of population are driven by current, as well as previous, landscape configurations. Therefore, historical analyses of habitat distribution are of great importance in explaining the current species distribution. In our analysis, we describe the forest fragmentation process for an area of 178 km² in the northern part of Mazowsze region of central Poland. Topographical maps from the years 1890, 1957 and 1989 were used. Over the 100-year period, forest coverage in this area changed from 17% to 5.6%, the number of patches increased from 19 to 42, while the area of the forest interior decreased from 1933 ha to 371 ha. The two components of fragmentation were clearly separated in time. Habitat loss occurred mainly during the first period (1890–1957) and fragmentation per se in the second (1957–1989). Moreover, we recorded that only 47.7% of all the currently (in 1989) afforested areas constitute sites where forests previously occurred (in 1890 and 1957). For forest dwelling organisms characterized by low dispersal abilities, the effective forest coverage seems to be a half of the real forest area in the studied landscape. New afforestations should be planned especially to increase those patches which contain ancient forest, where various plants and animals sensitive to fragmentation may have survived.

Mazgajski, Polish Academy of Sciences, Museum & Institute of Zoology, Wilcza 64, PL 00-679 Warsaw, Poland E-mail: mazgaj@miiz.waw.pl
Zmihorski, Polish Academy of Sciences, Museum & Institute of Zoology, Wilcza 64, PL 00-679 Warsaw, Poland E-mail: mz@nn.pl
Abramowicz, Department of Ecology, University of Warsaw, Banacha 2, PL 02-097 Warsaw, Poland E-mail: ka@nn.pl

article id 470, category Research note

Paula Jylhä, Juha Laitila. (2007). Energy wood and pulpwood harvesting from young stands using a prototype whole-tree bundler. Silva Fennica vol. 41 no. 4 article id 470. https://doi.org/10.14214/sf.470

Keywords: productivity; energy wood; pulpwood; bundling; integrated harvesting; Fixteri

Abstract | View details | Full text in PDF | Author Info

The productivity of cutting and bundling whole trees using the first prototype of a bundle-harvester comprised of a harwarder as the base machine, an accumulating felling head, and a compacting device was studied in three young stands in order to facilitate the further development of the concept. In addition, the removal and its composition were studied as a means of laying the foundations for developing methods for work rating and measurement on delivery. Bundling enables in-depth integration of pulpwood and energy wood procurement. Both energy wood (crown biomass) and pulpwood can be incorporated into the same bundles, and the subsequent separation of these fractions takes place at the debarking phase at the pulpmill. Bundle-harvesting productivities were relatively low (2.8–3.7 m³/E₀-h) when compared to current harvesting technology. Improving working techniques, machine structure, and components showed great potential for increasing the efficiency of the concept. The bundles were dimensionally uniform. Their solid volume varied between 0.350 m³ and 0.513 m³, depending on the bundle assortment and stand properties. Integrating energy wood harvesting with pulpwood harvesting increased removal even by 59 per cent.

Jylhä, Finnish Forest Research Institute, Kannus Research Unit, P.O. Box 44, FI-69101 Kannus, Finland E-mail: paula.jylha@metla.fi
Laitila, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jl@nn.fi

article id 379, category Research note

Daniel Ligné, Lars Eliasson, Tomas Nordfjell. (2005). Time consumption and damage to the remaining stock in mechanised and motor manual pre-commercial thinning. Silva Fennica vol. 39 no. 3 article id 379. https://doi.org/10.14214/sf.379

Keywords: birch; Scots pine; cleaning; time study; brush saw; Husqvarna; Vimek

Abstract | View details | Full text in PDF | Author Info

Selective pre-commercial thinning (PCT) is usually carried out by workers with a brush saw in order to increase the growth of the potential crop trees (main stems) through removal of competing trees. In the last decade relative PCT costs have increased, partly because stands are denser and have higher trees when treated, which has led to new interest for mechanised PCT. The objective was to compare mechanised and motor manual PCT regarding productivity and damage to remaining main stems. Time consumption for, and damage after, mechanised and motor manual PCT were studied on 50 plots per treatment in mixed pine birch stands with an initial stand density exceeding 4500 stems ha–1. In the present study productivity was influenced by stand density, stand height and the quota between height and diameter. Irrespectively of these factors, mechanised PCT was 0.74 hours ha–1 slower than motor manual PCT. Motor manual PCT of the average stand (average height 3.69 m, 10 816 stems ha–1) took 5.06 effective hours. In average 2475 and 2805 main stems ha–1 were left after the mechanised and motor manual treatments, respectively, whereof 1.3 and 2.1% were damaged by the treatments. The results show that efficiency in motor manual PCT has increased in dense and tall stands compared to older studies. Motor manual PCT was more time effective than mechanised PCT, and thereby also even more cost-effective. However, the potential for technical and methodological development of mechanised PCT is probably larger than for motor manual PCT.

Ligné, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: dl@nn.se
Eliasson, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: lars.eliasson@norraskogsagarna.se
Nordfjell, Swedish University of Agricultural Sciences, Department of Silviculture, SE-901 83 Umeå, Sweden E-mail: tn@nn.se

article id 403, category Research note

Timo Saksa, Juha Heiskanen, Jari Miina, Jaakko Tuomola, Taneli Kolström. (2005). Multilevel modelling of height growth in young Norway spruce plantations in southern Finland. Silva Fennica vol. 39 no. 1 article id 403. https://doi.org/10.14214/sf.403

Keywords: Norway spruce; Picea abies; height growth; mounding; disc trenching; container seedlings; intra-level correlation; variance-component model

Abstract | View details | Full text in PDF | Author Info

Height development of Norway spruce (Picea abies (L.) Karst.) transplants was studied on 22 sites prepared by disc trenching or mounding. At the age of 4–9 years the plantations were surveyed using a multistage sampling design. For every planted spruce on a plot, the past annual height increments were measured as far into the past as possible. Multilevel mixed linear modelling was used to analyse the variation in growth at different levels (year, stand, cluster, plot, tree) and the effects of climatic and site characteristics on height growth. The within-plantation variation in height growth was higher on mounded sites than on disc-trenched sites. The mean temperature and the precipitation sum of the summer months affected height growth positively. Soil characteristics measured from undisturbed soil did not explain the height growth of seedlings on mounded sites, whereas on disc-trenched sites, the depth of the organic layer and the soil temperature had a positive effect and the depth of the eluvial horizon a negative effect. The modelling approach used proved to be a useful method for examining the sources of variation in development of young plantations.

Saksa, The Finnish Forest Institute, Suonenjoki Research Station, FI-77600 Suonenjoki, Finland E-mail: ts@nn.fi
Heiskanen, The Finnish Forest Institute, Suonenjoki Research Station, FI-77600 Suonenjoki, Finland E-mail: jh@nn.fi
Miina, The Finnish Forest Institute, Joensuu Research Centre, P. O. Box 68, FI-80101 Joensuu, Finland E-mail: jm@nn.fi
Tuomola, The University of Joensuu, Mekrijärvi Research Station, FI-82900 Ilomantsi, Finland E-mail: jt@nn.fi
Kolström, The University of Joensuu, Mekrijärvi Research Station, FI-82900 Ilomantsi, Finland E-mail: tk@nn.fi

article id 517, category Research note

Matti Huotari, Mareena Jaskari, Erkki Annila, Vilho Lantto. (2003). Responses of olfactory receptor neurons of the large pine weevil to a possible deterrent Neutroil® and two other chemicals. Silva Fennica vol. 37 no. 1 article id 517. https://doi.org/10.14214/sf.517

Keywords: olfactory receptor neuron; attractant; repellent; Hylobius abietis; action potential; silent period; electroantennogram

Abstract | View details | Full text in PDF | Author Info

Electrophysiological responses of olfactory receptor neurons were measured from the antennal sensilla of large pine weevils (Hylobius abietis L.) at 1 s exposure to Neutroil®-hexane mixture odour as a possible deterrent chemical and, for comparison, to α-pinene, α-pinene-ethanol mixture, and ethanol odours, respectively. Neutroil® is a commercial chemical pulp-mill product which has been studied earlier as a deterrent for large pine weevils with preliminary feed tests. In addition, ethanol, hexane and clean carrier air responses were measured. Odour pulses and clean air, as a zero reference value, were directed at a fixed insect antenna in order to induce olfactory responses. Simultaneous olfactory responses, i.e. Hylobius electroantennograms (EAG) and action potential responses, were recorded and these responses of Hylobius olfactory receptor neurons (ORN), such as action potential rates, silent periods and EAG responses, were analyzed for all simultaneous recordings. The exposures to α-pinene, α-pinene-ethanol mixture, pure ethanol and hexane caused an increase of the action potential rate (up to 70 pulses per second) in the ORNs sensitive to these odours, while the Neutroil®-hexane mixture exposures caused either silent periods with a duration between 0.6 and 1.1 s for 1 s exposure pulses or they had no response at all in the ORNs sensitive to the other odours. Thus, the possible deterrence may be caused by inhibition of some pinene-alcohol ORNs.

Huotari, University of Oulu, P.O. Box 4500, FIN-90014 University of Oulu, Finland E-mail: matti.huotari@oulu.fi
Jaskari, University of Oulu, P.O. Box 4500, FIN-90014 University of Oulu, Finland E-mail: mj@nn.fi
Annila, Finnish Forest Research Institute, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: ea@nn.fi
Lantto, University of Oulu, P.O. Box 4500, FIN-90014 University of Oulu, Finland E-mail: vl@nn.fi

article id 569, category Research note

Heikki Kauhanen. (2002). Occurrence of fires in the eastern Saariselkä area, north-west Russia. Silva Fennica vol. 36 no. 1 article id 569. https://doi.org/10.14214/sf.569

Keywords: fire; anthropogenic fire; burn; Russia; satellite image; vegetation mosaic

Abstract | View details | Full text in PDF | Author Info

The occurrence of fires was studied in the eastern Saariselkä area, North-West Russia, by using satellite images and topographical maps. In total, more than 330 burned areas were pinpointed in the study area of 4770 km2. Old burns were concentrated in the eastern part of the study area, but young burns were more common in the west. Sites affected by fires in the more recent past were much smaller than those burnt over earlier. The abundance of burns along rivers and the border surveillance road provided evidence of human impact. The most significant changes in the landscape were found in the eastern part of the study area, where spruce forests had been replaced by birch woodlands.

Kauhanen, Finnish Forest Research Institute, Kolari Research Station, Muoniontie 21 A, FIN-95900 Kolari, Finland E-mail: heikki.kauhanen@metla.fi

article id 624, category Research note

Hashim Ali El Atta. (2000). Effect of diet and seed pretreatment on the biology of Bruchidius uberatus (Coleoptera, Bruchidae). Silva Fennica vol. 34 no. 4 article id 624. https://doi.org/10.14214/sf.624

Keywords: Bruchidius uberatus; Bruchidae; Acacia nilotica; seed borer biology

Abstract | View details | Full text in PDF | Author Info

Diet significantly (P < 0.0001) affected fecundity of Bruchidius uberatus Fahraeus. Provision of 1% sugar solution increased fecundity from 15 eggs/female to 47. Furthermore, sugar solution prolonged significantly the oviposition period of B. uberatus from one week to two weeks. Diet also significantly (P < 0.0001) increased adult longevity. Mean adult longevity recorded was 3, 7 and 13 days in control, water and sugar treatments, respectively. Seed pretreatment had a highly significant impact on the various developmental stages of B. uberatus. Maximum egg hatchability occurred in non-husked Acacia nilotica (L.) Willd. ex Del. seeds (83%), moderate in de-husked seeds (74%) and least in seeds presoaked in concentrated sulphuric acid (42%). The frequency of larvae that developed successfully into pupae was greatest in non-husked seeds (72%), nevertheless in de-husked and acid pretreated seeds, absolutely no larvae developed into pupae and hence the adult stage was not reached in these two treatments. Thus, de-husking and acid pretreatment of A. nilotica seeds is highly recommended.

El Atta, University of Khartoum, Faculty of Forestry, Department of Forest Conservation and Protection, Shambat, Sudan E-mail: hashimelatta@yahoo.com

article id 659, category Research note

Anneli Viherä-Aarnio, Pirkko Velling. (1999). Growth and stem quality of mature birches in a combined species and progeny trial. Silva Fennica vol. 33 no. 3 article id 659. https://doi.org/10.14214/sf.659

Keywords: stem quality; growth; Betula pendula Roth; Betula pubescens Ehrh.; Betula papyrifera Marsh.; progeny; timber production

Abstract | View details | Full text in PDF | Author Info

The growth and stem quality of silver birch (Betula pendula), downy birch (B. pubescens) and paper birch (B. papyrifera) were compared in a 32-year-old field trial in southern Finland. The material consisted of different unselected stand origins and progenies of phenotypically selected plus trees of silver and downy birch from southern Finland and differing stand origins of paper birch from the North-West Territories, Canada. Growth, yield and a number of stem quality traits, including taper, sweep, stem defects, heights of different crown limits and length of the veneer timber part of the stem were measured or observed. The native Finnish silver and downy birches were superior to paper birch in terms of both yield and stem quality, silver birch being the best. Progenies of silver birch plus trees were better than the stand origin, indicating that the former are able to reach high quality veneer log size in a shorter time than unselected material. The cultivation of paper birch can not be considered viable in Finland.

Viherä-Aarnio, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: anneli.vihera-aarnio@metla.fi
Velling, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: pv@nn.fi

article id 679, category Research note

Hans-Örjan Nohrstedt, Gunnar Börjesson. (1998). Respiration in a forest soil 27 years after fertilization with different doses of urea. Silva Fennica vol. 32 no. 4 article id 679. https://doi.org/10.14214/sf.679

Keywords: mineral soil; Pinus sylvestris L.; carbon mineralization; humus; podzol

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A number of previous studies have shown that N fertilization often reduces respiration in forest soils. However, the durability of this effect has not been fully explored. In this study, the response of soil respiration to a single fertilization with urea, applied 27 years earlier, was examined in a field experiment located in a stand of Pinus sylvestris in central Sweden. The doses that had been added were 120, 240 and 600 kg N ha–1. Samples were taken from the humus layer and the upper 7.5 cm of the mineral soil. Sieved samples were incubated in the laboratory. No effect of the previous fertilization on soil respiration was found, thus indicating that the reduction shown in earlier studies is not persistent. There was a tendency that the highest N dose had caused a higher N concentration and a lower C/N-ratio in the humus layer and a higher C concentration in the mineral soil.

Nohrstedt, The Forestry Research Institute of Sweden, Uppsala Science Park, S-751 83 Uppsala, Sweden E-mail: hans-orjan.nohrstedt@skogforsk.se
Börjesson, Department of Microbiology, Swedish University of Agricultural Sciences, P.O. Box 7025, S-750 07 Uppsala, Sweden E-mail: gb@nn.se

article id 26001, category Discussion article

Hanne K. Sjølie, Brett J. Butler, Francisco X. Aguilar, Isabella Hallberg-Sramek, Veera Tahvanainen, Anniina Kietäväinen, Matti Maltamo, Silvia M. Korth, Dohun Kim, Lucas Nahuel Lopez, Ane C. Tange, Lisa Ockier. (2026). A call for improving forest socioeconomic data with inspiration from national forest inventories. Silva Fennica vol. 60 no. 1 article id 26001. https://doi.org/10.14214/sf.26001

Keywords: biophysical information; data integration; forest ownership survey; forest product survey

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National forest inventories have long and strong traditions in many countries and they can offer a wealth of information about the biophysical aspects of forests such as tree growth, carbon fluxes and biodiversity. However, these are in most cases not paralleled by data representing the socioeconomic dimensions of forests. Integration of socioeconomic and biophysical data has the potential to better unveil interactions between human and natural resources and can therefore better support policy. Climate change has multiple impacts on forest resources. Policies to support sustainable forestry, the bioeconomy, and climate change mitigation and adaptation are constantly developing. At the same time, forest owners’ attitudes and forest markets are evolving. More data is needed to advance the understanding of the links between the human and biophysical factors and the relationship between these factors and the complex objectives of forests. We compared the national forest inventories, national forest owner surveys, and national forest product surveys across Argentina, Finland, Norway, Sweden and the USA. The national forest inventories in all selected countries are built on solid methodological grounds and have strong institutional support and funding. However, the consistency of methods, frequency of implementation, and institutional support for forest owner and forest product surveys are in many cases lacking. There is also a lack of integration between biophysical and socioeconomic data. The USA was the only studied country with integrated biophysical and socioeconomic data. We suggest that this approach reflects the needs of data integration and can serve as a reference for other countries.

Sjølie, Department of Forestry and Wildlife Management, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, University of Inland Norway, Elverum, Norway https://orcid.org/0000-0001-8099-3521 E-mail: hanne.sjolie@inn.no
Butler, USDA Forest Service, Northern Research Station, Amherst, MA, USA https://orcid.org/0000-0002-2465-7993 E-mail: –
Aguilar, Department of Forest Economics, Swedish University of Agricultural Sciences, Umeå, Sweden https://orcid.org/0000-0003-0226-4467 E-mail: francisco.aguilar@slu.se
Hallberg-Sramek, Department of Forest Resource Management, Swedish University of Agricultural Science, Umeå, Sweden https://orcid.org/0000-0002-9645-9208 E-mail: isabella.hallberg.sramek@slu.se
Tahvanainen, School of Forest Sciences, University of Eastern Finland, Joensuu, Finland https://orcid.org/0009-0004-4527-992X E-mail: –
Kietäväinen, Department of Forest Economics, Swedish University of Agricultural Sciences, Umeå, Sweden https://orcid.org/0009-0001-9435-1519 E-mail: anniina.kietavainen@slu.se
Maltamo, School of Forest Sciences, University of Eastern Finland, Joensuu, Finland https://orcid.org/0000-0002-9904-3371 E-mail: matti.maltamo@uef.fi
Korth, Universidad Nacional de Misiones, Posadas, Misiones, Argentina https://orcid.org/0009-0007-3261-8234 E-mail: –
Kim, Department of Forest Economics, Swedish University of Agricultural Sciences, Umeå, Sweden https://orcid.org/0000-0002-1919-3346 E-mail: dohun.kim@slu.se
Lopez, Department of Forestry and Wildlife Management, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, University of Inland Norway, Elverum, Norway https://orcid.org/0009-0006-6860-3408 E-mail: lucas.lopez@inn.no
Tange, Department of Forestry and Wildlife Management, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, University of Inland Norway, Elverum, Norway; Glommen-Mjøsen Skog SA, Elverum, Norway https://orcid.org/0009-0001-3145-8159 E-mail: –
Ockier, Universidad Nacional de Misiones, Posadas, Misiones, Argentina E-mail: lisa@ockier.de

article id 25031, category Discussion article

Simon Lebel Desrosiers, Nicolas Bélanger, Evelyne Thiffault, Nelson Thiffault. (2025). Climate change and transformation in forest fire regimes: an opportunity for the implementation of assisted migration of tree species in the Canadian boreal forest? Silva Fennica vol. 59 no. 2 article id 25031. https://doi.org/10.14214/sf.25031

Keywords: fire severity; site suitability; post-fire regeneration; climate change adaptation; forest resilience; reforestation strategies; tree migration

Highlights: Increasing fire activity is reshaping post-disturbance landscapes in boreal forests; Post-fire sites offer new opportunities for introducing climate-resilient tree species; Fire can improve or impair site conditions for forest regeneration; Assisted migration of tree species may enhance reforestation success after severe wildfires; Research on post-fire regeneration of introduced species remains critically limited.

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Climate change is intensifying fire regimes in boreal forests, leading to ecological disruption and raising concerns about forest resilience and post-disturbance recovery. Altered fire dynamics creates novel opportunities for implementing adaptive silviculture for climate change, including assisted migration, the intentional movement and establishment of tree species or tree populations outside their current range of distribution to better match anticipated future climates. Here, we examine how the increasing frequency, severity, and spatial extent of Canadian boreal wildfires can serve as strategic windows for introducing climate-resilient tree species and genotypes. We review how fire influences the availability and suitability of post-fire sites for assisted migration, highlighting how fire-induced changes in soil abiotic and biotic properties may facilitate or hinder the establishment of relocated tree species. While fire can simplify site preparation, reduce biotic competition, and temporarily enhance soil nutrient availability, it may also degrade soil structure by consuming or altering soil organic matter and increasing soil susceptibility to erosion and disrupt essential mycorrhizal associations. We argue that assisted migration of tree species can be a proactive silvicultural tool when used in areas with regeneration failure or where future climate conditions are likely to exceed the tolerance limits of native species. Whilst scientific evidence remains limited on the regeneration success of migrated species and genotypes in post-fire environments, we argue for an integrated adaptation strategy that combines natural regeneration with targeted assisted migration interventions, guided by local site conditions, genetic considerations, and policy support, to build resilient boreal forests under changing disturbance regimes.

Lebel Desrosiers, Laboratoire sur la science des données, Université du Québec (TÉLUQ), 5800, rue Saint-Denis, bureau 1105, Montréal, Québec H2S 3L5, Canada https://orcid.org/0009-0007-1592-8505 E-mail: simon.lebeldesrosiers@teluq.ca
Bélanger, Laboratoire sur la science des données, Université du Québec (TÉLUQ), 5800, rue Saint-Denis, bureau 1105, Montréal, Québec H2S 3L5, Canada E-mail: nicolas.belanger@teluq.ca
Thiffault, Centre de recherche sur les matériaux renouvelables, Université Laval, 2425 De la Terrasse St, Québec, Québec G1V 0A6, Canada https://orcid.org/0000-0001-9586-3834 E-mail: evelyne.thiffault@sbf.ulaval.ca
Thiffault, Service canadien des forêts, Ressources naturelles Canada, 1055, rue Du P.E.P.S., C.P. 10380, Québec, Québec G1V 4C7, Canada https://orcid.org/0000-0003-2017-6890 E-mail: nelson.thiffault@canada.ca

article id 10350, category Discussion article

Maja Peteh. (2020). A synthesis of the characteristics of current national, regional and international forestry journals. Silva Fennica vol. 54 no. 3 article id 10350. https://doi.org/10.14214/sf.10350

Keywords: forestry; geographical coverage; journal title list; scientific publishing

Highlights: Currently, 451 forestry-related journals are published worldwide (41.7% in Europe, 37.3% in Asia) in 32 different languages (47.9% in English only); 6 categories have been defined for the geographical coverage of a journal (55.5% of which have been defined as national and 18.2% as international); The journals could increase their visibility and value by improving their websites and submitting relevant information to international indexing databases.

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One of the main objectives of the International Union of Forest Research Organization’s WP 9.01.06 (Forest Science Publishing) is to clarify the range of forestry-related journals in the context of the overall objective of supporting authors and readers to deepen their knowledge of forestry. This study extended an earlier list of forestry journals using the ISSN database and the CAB abstracts. The study included 451 journal titles, each categorized by ISSN, publisher, language of publication, website, and geographical coverage (i.e. national, regional, international, or three mixed intermediate categories), as well as information on indexing in Web of Science, Scopus, DOAJ, and SherpaRomeo. The included journals are published in 61 countries and in 32 different languages. Those categorized as international are mostly published in English. 21.7% of the journals are indexed in Web of Science and 34.1% in Scopus. 95.6% of the titles are published online or in the print+online publishing model, but only 57.0% of the titles are published in Open Access, of which only 33.7% are indexed in DOAJ.

Peteh, University of Ljubljana, Biotechnical Faculty, Večna pot 83, Ljubljana 1000, Slovenia; Slovenian Forestry Institute, Večna pot 2, Ljubljana 1000, Slovenia https://orcid.org/0000-0002-9636-1155 E-mail: maja.peteh@gozdis.si

article id 270, category Discussion article

Seppo Rouvinen, Jari Kouki. (2008). The natural northern European boreal forests: unifying the concepts, terminologies, and their application. Silva Fennica vol. 42 no. 1 article id 270. https://doi.org/10.14214/sf.270

Keywords: human influence; biodiversity; natural ecosystems; natural forests; protection; terminology

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Recent emphasis on conserving the biodiversity has stressed the value of natural ecosystems in saving the species from extinction. In the Fennoscandian region the conifer-dominated boreal forests form the largest single ecosystem. The forests have been under varying intensity of human influence for decades or centuries. Recent attempts have tried to seek the last remaining natural forests to be included in the protection programmes. However, due to long and widespread human influence, finding and defining the natural forests has proven to be extremely difficult, not only because they are so rare but also because the concept of natural forest is vague. These difficulties are partly seen through the diverse terminology used. We first review the varying terminology as seen in recent studies. Secondly, we propose the basis for defining the natural forest and show some intriguing and challenging difficulties are involved in the concept. These difficulties are at least partly related to inherent strong and long-term dynamic component in boreal forest ecosystems that is manifested over several temporal and spatial scales. Finally, we outline a more general terminology with associated indicators and measurements that might be used in the classification and terminology. Conceptual clarification is necessary, for example, to compile ecologically justified and representative global, national and regional forest statistics. Many currently applied definitions of “forest” and “natural” that are applied in the context of forest statistics overlook ecologically important components of natural forests, and thus provide quite misleading or inadequate data of existing diversity patterns in these ecosystems.

Rouvinen, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: sr@nn.fi
Kouki, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: jari.kouki@joensuu.fi

article id 573, category Discussion article

Matti Koivula, Jari Niemelä. (2002). Boreal carabid beetles (Coleoptera, Carabidae) in managed spruce forests – a summary of Finnish case studies. Silva Fennica vol. 36 no. 1 article id 573. https://doi.org/10.14214/sf.573

Keywords: management; logging; succession; boreal; forestry; landscape; Carabidae; clear-cutting; edge; retention felling

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Koivula, Department of Ecology and Systematics, Division of Population Biology, P.O. Box 65, FIN-00014 University of Helsinki, Finland E-mail: matti.koivula@helsinki.fi
Niemelä, Department of Ecology and Systematics, Division of Population Biology, P.O. Box 65, FIN-00014 University of Helsinki, Finland E-mail: jn@nn.fi

article id 475, category Commentary

Petteri Muukkonen, Raisa Mäkipää. (2006). Biomass equations for European trees: addendum. Silva Fennica vol. 40 no. 4 article id 475. https://doi.org/10.14214/sf.475

Keywords: aboveground biomass; allometry; biomass functions; belowground biomass; dbh; tree diameter; tree height

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A review of stem volume and biomass equations for tree species growing in Europe (Zianis et al. 2005) resulted in suggestions for additional equations. The numbers of original equations, compiled from scientific articles were 607 for biomass and 230 for stem volume. On the basis of the suggestions and an updated literature search, some new equations were published after our review, but more equations were also available from earlier literature. In this addendum, an additional 188 biomass equations and 8 volume equations are presented. One new tree species (Pinus cembra) is included in the list of volume equations. Biomass equations for twelve new tree species are presented: Abies alba, Carbinus betulus, Larix decidua, P. cembra, P. nigra, Quercus robur, Salix caprea, S. ‘Aquatica’, S. dasyclados, S. phylicifolias, S. triandra and S. accuparia. The tree-level equations predict stem volume, whole tree biomass or biomass of certain components (e.g., foliage, roots, total above-ground) as a function of diameter or diameter and height of a tree. Biomass and volume equations with other independent variables have also been widely developed but they are excluded from this addendum because the variables selected may reflect locally valid dependencies that cannot be generalized to other geographical regions. Most of the equations presented here are developed for Sweden, Finland and Norway in northern Europe, for Austria in central Europe and for Italy in southern Europe. There are also few equations from Poland and Belgium. Most of the equations deal with above-ground components such as stem, branches and foliage, but some new equations are also available for root biomass. Zianis et al. (2005) and this addendum can be used together as guides to the original publications of these equations. Our updated database of the biomass and volume equations is available also from the website www.metla.fi/hanke/3306/tietokanta.htm.

Muukkonen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: petteri.muukkonen@metla.fi
Mäkipää, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: raisa.makipaa@metla.fi

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Category : Review article

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Category : Research note

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