Current issue: 57(2)

Under compilation: 57(3)

Scopus CiteScore 2021: 2.8
Scopus ranking of open access forestry journals: 8^th
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Silva Fennica vol. 57 | 2023

Category: Editorial

article id 23043, category Editorial

Anna Lintunen. (2023). Passion for science. Silva Fennica vol. 57 no. 2 article id 23043. https://doi.org/10.14214/df.23043

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Lintunen, Institute for Atmospheric and Earth System Research / Forest Sciences, University of Helsinki, Viikinkaari 1, Biokeskus 3, 00790 Helsinki, Finland https://orcid.org/0000-0002-1077-0784 E-mail: anna.lintunen@helsinki.fi

article id 23011, category Editorial

Sergio de Miguel. (2023). Artificial intelligence-driven disruption in science production ahead. Silva Fennica vol. 57 no. 1 article id 23011. https://doi.org/10.14214/sf.23011

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de Miguel, University of Lleida, Av. Alcalde Rovira Roure 191, 25198 Lleida, Spain; Joint Research Unit CTFC – AGROTECNIO – CERCA, Ctra de Sant Llorenç de Morunys, km 2, 25280 Solsona, Spain https://orcid.org/0000-0002-9738-0657 E-mail: sergio.demiguel@udl.cat

Category: Research article

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 23019, category Research article

Victor F. Strîmbu, Tron Eid, Terje Gobakken. (2023). A stand level scenario model for the Norwegian forestry – a case study on forest management under climate change. Silva Fennica vol. 57 no. 2 article id 23019. https://doi.org/10.14214/sf.23019

Keywords: forest planning; carbon balance; climate change mitigation; forest stand simulator

Highlights: GAYA 2.0: a new scenario analysis model focusing on forest carbon fluxes; Carbon sequestration potential estimated at regional level; GAYA 2.0 may be used to estimate the costs of obtaining carbon benefits by adapting the forest management.

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Carbon sequestration and income generation are competing objectives in modern forest management. The climate commitments of many countries depend on forests as carbon sinks which must be quantified, monitored, and projected into the future. For projections we need tools to model forest development and perform scenario analyses to assess future carbon sequestration potentials under different management regimes, the expected net present value of such regimes, and possible impacts of climate change. We propose a scenario analysis software tool (GAYA 2.0) that can assist in answering these types of questions using stand level simulations, detailed carbon flow models and an optimizer. This paper has two objectives: (1) to describe GAYA 2.0, and (2) demonstrate its potential in a case study where we analyze the forest carbon balance over a region in Norway based on national forest inventory sample plots. The tool was used to map the optimality front between the carbon benefit and net present value. We observed changes in net present value for different levels of carbon benefit as well as changes in optimal management strategies. We predicted future changes in several forest carbon pools as well as albedo and illustrated the impact of gradual increase in forest productivity (i.e., due to climate warming). Having been updated and modernized from its previous version with increased attention to forest carbon and energy fluxes, GAYA 2.0 is an effective tool that offers multiple opportunities to perform various types of scenario analyses in forest management.

Strîmbu, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, NO-1432 Ås, Norway https://orcid.org/0000-0002-0588-2036 E-mail: victor.strimbu@nmbu.no
Eid, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, NO-1432 Ås, Norway E-mail: tron.eid@nmbu.no
Gobakken, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, NO-1432 Ås, Norway https://orcid.org/0000-0001-5534-049X E-mail: terje.gobakken@nmbu.no

article id 23012, category Research article

Jari Vauhkonen, Juho Matala, Ari Nikula. (2023). Future browsing damage in seedling stands according to projected forest resources and moose population density. Silva Fennica vol. 57 no. 2 article id 23012. https://doi.org/10.14214/sf.23012

Keywords: forest management planning; forest development simulation; forest projection; Markov chain; scenario analysis; transition matrix model

Highlights: Projections of forest resources and seedling stands damaged by moose browsing; Damaged seedling stand area modelled by moose population and forest characteristics; Moose damage predicted by the age class structure of simulated future forests.

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An important modifier of forests and forestry practices is browsing by cervids. As high populations of moose (Alces alces L.) cause extensive forest damage in the Fennoscandian boreal forests, models should be able to predict the susceptibility of projected forest structures to browse damage. We augmented the European Forestry Dynamics Model (EFDM) for the area of seedling stands damaged by moose. The augmented model was tested in projecting both forest resources and moose damage for 18 million hectares of forest land in Finland, based on input data from the National Forest Inventory (NFI). Modeling the area of seedling stands damaged as a function of moose population density, forest characteristics, and region-specific interactions of these variables was found to work realistically for 30 years, predicting that the area of seedling stands damaged by moose would increase by up to a third from the last NFI observation. Our work lays the groundwork for modeling consequential, large-scale ecological and socio-economic effects of moose browsing.

Vauhkonen, 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 Helsingin yliopisto, Finland E-mail: jari.vauhkonen@uef.fi
Matala, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6 B, FI-80100 Joensuu, Finland 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 22028, category Research article

Eelis Halme, Matti Mõttus. (2023). Improved parametrisation of a physically-based forest reflectance model for retrieval of boreal forest structural properties. Silva Fennica vol. 57 no. 2 article id 22028. https://doi.org/10.14214/sf.22028

Keywords: forest structure; Sentinel-2; reflectance; hyperspectral; tree distribution

Highlights: Spatial distribution of trees is a key driver for forest reflectance; Knowledge of the ratio of branch to leaf area improves forest reflectance simulation substantially; Different optical properties of the two leaf sides have a notable effect on forest reflectance.

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Physically-based reflectance models offer a robust and transferable method to assess biophysical characteristics of vegetation in remote sensing. Forests exhibit explicit structure at many scales, from shoots and branches to landscape patches, and hence present a specific challenge to vegetation reflectance modellers. To relate forest reflectance with its structure, the complexity must be parametrised leading to an increase in the number of reflectance model inputs. The parametrisations link reflectance simulations to measurable forest variables, but at the same time rely on abstractions (e.g. a geometric surface forming a tree crown) and physically-based simplifications that are difficult to quantify robustly. As high-quality data on basic forest structure (e.g. tree height and stand density) and optical properties (e.g. leaf and forest floor reflectance) are becoming increasingly available, we used the well-validated forest reflectance and transmittance model FRT to investigate the effect of the values of the “uncertain” input parameters on the accuracy of modelled forest reflectance. With the state-of-the-art structural and spectral forest information, and Sentinel-2 Multispectral Instrument imagery, we identified that the input parameters influencing the most the modelled reflectance, given that the basic forestry variables are set to their true values and leaf mass is determined from reliable allometric models, are the regularity of the tree distribution and the amount of woody elements. When these parameters were set to their new adjusted values, the model performance improved considerably, reaching in the near infrared spectral region (740–950 nm) nearly zero bias, a relative RMSE of 13% and a correlation coefficient of 0.81. In the visible part of the spectrum, the model performance was not as consistent indicating room for improvement.

Halme, VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT Espoo, Finland https://orcid.org/0000-0002-7517-6663 E-mail: eelis.halme@vtt.fi
Mõttus, VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT Espoo, Finland https://orcid.org/0000-0002-2745-1966 E-mail: matti.mottus@vtt.fi

article id 22027, category Research article

Timo Saksa, Jari Miina, Olli Luukkonen. (2023). Uprooting as a pre-commercial thinning operation in young Norway spruce stands. Silva Fennica vol. 57 no. 2 article id 22027. https://doi.org/10.14214/sf.22027

Keywords: Picea abies; simulation; precommercial thinning; mechanical young stand management

Highlights: The number of competing birches varied considerably according to the operating conditions; The main factors reducing the quality of uprooting were early operation timing, soil moisture and site fertility; With careful selection of the timing and conditions for uprooting, the quality obtained by uprooting can be improved.

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Uprooting, as a mechanical pre-commercial thinning operation (PCT), removes competitive, undesired trees with roots to prevent or reduce the need for a second PCT. The state of 66 young Norway spruce (Picea abies (L.) H. Karst.) stands was explored 3–5 years after uprooting to assess the quality of uprooting in terms of the number of competing birches (Betula spp.) and the probability of freely growing crop tree spruce (no competing trees taller than 2/3 of the crop tree’s height). In the uprooted spruce stands, the number of birches was, on average, about 3800 stems ha⁻¹, and in every fifth stand, it was less than 2000 stems ha⁻¹. The number of birches increased with increasing site wetness (TWI), site fertility and thickness of the humus layer. In 80% of the stands, there were at least 1000 freely growing spruces ha⁻¹, which is approximately the stem number to be left growing after first thinning in a spruce stand. If the height of crop tree spruces was 125 cm at uprooting, the probability of freely growing stems varied from 0.6 to 0.8 in typical cases. According to simulations at the first thinning stage, in most stands, birch was less than 10% taller than spruce, and the volume of birches was low enough that, in the future, spruce and birch would grow in the same crown layer as a mixed spruce–birch stand. The results showed that uprooting can serve as the only PCT operation in a planted spruce stand. The quality obtained by uprooting can be improved with careful selection of timing and conditions for uprooting; the optimal uprooting time is when crop tree spruces have reached about breast height.

Saksa, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, 77600 Suonenjoki, Finland https://orcid.org/0000-0002-1776-2357 E-mail: ext.timo.saksa@luke.fi
Miina, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6 B, 80100 Joensuu, Finland https://orcid.org/0000-0002-8639-4383 E-mail: jari.miina@luke.fi
Luukkonen, Metsäsydän Oy, Junninmäentie 53, 52200 Puumala, Finland E-mail: olli.p.j.luukkonen@gmail.com

article id 22026, category Research article

Annika Kangas, Mari Myllymäki, Lauri Mehtätalo. (2023). Understanding uncertainty in forest resources maps. Silva Fennica vol. 57 no. 2 article id 22026. https://doi.org/10.14214/sf.22026

Keywords: autocorrelation; ensemble modelling; kriging; quantile; random forest; sequential Gaussian simulation

Highlights: Forest resources maps without uncertainty assessment may lead to false impression of precision; Suitable tools for visualization of map products are lacking; Kriging method provided accurate uncertainty assessment for pixel-level predictions; Quantile random forest algorithm slightly underestimated the pixel-level uncertainties; With simulation it is possible to assess the uncertainty also for landscape-level characteristics.

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Maps of forest resources and other ecosystem services are needed for decision making at different levels. However, such maps are typically presented without addressing the uncertainties. Thus, the users of the maps have vague or no understanding of the uncertainties and can easily make wrong conclusions. Attempts to visualize the uncertainties are also rare, even though the visualization would be highly likely to improve understanding. One complication is that it has been difficult to address the predictions and their uncertainties simultaneously. In this article, the methods for addressing the map uncertainty and visualize them are first reviewed. Then, the methods are tested using laser scanning data with simulated response variable values to illustrate their possibilities. Analytical kriging approach captured the uncertainty of predictions at pixel level in our test case, where the estimated models had similar log-linear shape than the true model. Ensemble modelling with random forest led to slight underestimation of the uncertainties. Simulation is needed when uncertainty estimates are required for landscape level features more complicated than small areas.

Kangas, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6, 80101 Joensuu, Finland https://orcid.org/0000-0002-8637-5668 E-mail: annika.kangas@luke.fi
Myllymäki, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Latokartanonkaari 9, FI-00790 Helsinki, Finland https://orcid.org/0000-0002-2713-7088 E-mail: mari.myllymaki@luke.fi
Mehtätalo, Natural Resources Institute Finland (Luke), Bioeconomy and environment, Yliopistokatu 6, 80101 Joensuu, Finland https://orcid.org/0000-0002-8128-0598 E-mail: lauri.mehtatalo@luke.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.

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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 10764, category Research article

Sabiha Acer, Zeynel Arslangündoğdu, Asko Lehtijärvi. (2023). The occurrence and pathogenicity of fungi associated with Orthotomicus erosus on Pinus brutia in the Southern Marmara, Türkiye. Silva Fennica vol. 57 no. 2 article id 10764. https://doi.org/10.14214/sf.10764

Keywords: Ophiostoma; pathogenicity; Graphilbum; Leptographium; Mediterranean pine beetle; Turkish pine; Southern Marmara

Highlights: Three ophiostomatoid fungi species are recorded, associated with Orthotomicus erosus on Pinus brutia for the first time in Türkiye; Ceratocystis ips has the highest frequency. The association between Leptographium wingfieldiiand Orthotomicus erosus occurred with high frequency; While all three fungal species are severely pathogenic for pines in some regions, they are weak pathogens for Turkish pine in Türkiye.

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Fungal pathogens associated with bark beetles constitute one of the most significant problems to forest health. The Turkish pine (Pinus brutia Ten.) is a native species in the forests of Türkiye and occurs in the Mediterranean-type climate. The Southern Marmara is a natural occurrence area of Turkish pine in the Marmara Region. In the present study, trap logs were set up in pure Pinus brutia forests to investigate fungi associated with Orthotomicus erosus (Wollaston) (Mediterranean pine beetle) throughout Southern Marmara. Orthotomicus erosus adults, larvae, and their galleries were sampled and individually cultured on a 1% CSMA (cycloheximide–streptomycin malt agar) medium. Three ophiostomatoid fungi were identified using morphological characteristics and molecular genetic analyses: Ceratocystis (syn. Ophiostoma) ips (Rumbold) C. Moreau, Graphilbum sp. H.P. Upadhyay & W.B. Kendr., and Leptographium wingfieldii M. Morelet. All three species were new in records of the fungal flora of Türkiye. The most dominant of these species, Ceratocystis ips was isolated 69%. Unexpectedly, L. wingfieldii had a high-frequency association with O. erosus (27%). The pathogenicity tests showed that all three species could cause lesions on branches of Turkish pine but were non-pathogenic or weak pathogenic.

Acer, Istanbul University-Cerrahpaşa, Department of Forest Entomology and Protection, Faculty of Forestry, 34473, Istanbul, Türkiye E-mail: sacer@iuc.edu.tr
Arslangündoğdu, Istanbul University-Cerrahpaşa, Department of Forest Entomology and Protection, Faculty of Forestry, 34473, Istanbul, Türkiye E-mail: zeynel@iuc.edu.tr
Lehtijärvi, Isparta University of Applied Sciences, Sütçüler Prof. Dr. Hasan Gürbüz Vocational School, 32950, Isparta, Türkiye E-mail: askolehtijarvi@isparta.edu.tr

article id 23001, category Research article

Eirik Ogner Jåstad, Niels Oliver Nagel, Junhui Hu, Per Kristian Rørstad. (2023). The location and capacity-dependent price impacts of biofuel production and its effect on the forest industry. Silva Fennica vol. 57 no. 1 article id 23001. https://doi.org/10.14214/sf.23001

Keywords: partial equilibrium model; biofuel location policy; biomass supply; forest-based biofuel; nordic forest sector

Highlights: Large biofuel units prefer regions close to transportation facilities; Forest owners are the main winners if large-scale biofuel production is established; The first production units reduce export, hence should be located at an exporting hub; Biofuel production will reduce the Norwegian export of roundwood to Sweden; Biofuel production increases the local demand and pulpwood prices.

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Forest-based biofuel stands out as a promising solution to avoid fossil emissions in parts of the transport sector. Biofuel production will need large amounts of forest biomass, collected from a large area. Roundwood is costly to transport compared with other goods. Therefore, the location of forest-based biofuel production is a crucial part of an investment decision. This study analyses the optimal location of biofuel plants in Norway and the implications for the traditional forest sector in the Nordic countries. We test different numbers of production units, different sizes of the units, and various raw materials. The study applies a partial equilibrium model that covers the Norwegian and Nordic forest sectors, with 356 regions in Norway. The results indicate that small biofuel plants have the potential to turn exporting regions into importing regions. Larger biofuel plants are suitable for areas with large harvest activity today or regions with access to harbour or timber terminals along railways. We find that forest owners close to a biofuel plant will profit the most from biofuel production. Policymakers and investors should take into account that different locations and production capacities have different impacts on the forest sectors.

Jåstad, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0002-1089-0284 E-mail: eirik.jastad@nmbu.no
Nagel, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0002-3171-0262 E-mail: niels.oliver.nagel@nmbu.no
Hu, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0003-0001-5993 E-mail: junhui.hu@nmbu.no
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

article id 22019, category Research article

Aleksi Nirhamo, Juha Pykälä, Kimmo Jääskeläinen, Jari Kouki. (2023). Habitat associations of red-listed epiphytic lichens in Finland. Silva Fennica vol. 57 no. 1 article id 22019. https://doi.org/10.14214/sf.22019

Keywords: boreal forests; deciduous trees; biodiversity; conservation; threatened species

Highlights: We analyzed the habitat associations of 231 nationally red-listed epiphytic lichen species in Finland; Their habitat associations were varying, but deciduous trees, old forests and trees, and microclimates with intermediate or high light availability and humidity were particularly important; The maintenance of the habitats of many red-listed epiphytic lichens is difficult if not impossible to combine with intensive forest management.

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

The Finnish red list shows that the epiphytic lichen flora of Finnish forests is highly threatened and declining steeply. Red lists provide limited information on the habitat associations of threatened species, which could be relevant in informing management and conservation measures. We used documented empirical data and expert assessments to determine for each red-listed (IUCN categories Near Threatened, NT; Vulnerable, VU; Endangered, EN; Critically Endangered, CR; Regionally Extinct, RE) epiphytic lichen species of Finland the following key habitat associations: host tree species, substrate type, habitat type, geographical distribution, preferred microclimate, and minimum required forest and tree age. The most important host tree species were Picea abies (L.) H. Karst. and Populus tremula L. Other tree species of high importance included Sorbus aucuparia L. and Salix caprea L. One fourth of red-listed epiphytic lichens were primarily lignicolous. Most species required old-growth forests (required by 41% of species) or old trees (52%), but many species required only mature forests (36%) or trees (35%). The microclimatic preferences of most red-listed epiphytic lichens consisted of high or intermediate light availability and humidity. Most species whose status had deteriorated were dependent on deciduous trees. The continuous availability of old deciduous trees (especially Populus, Salix and Sorbus) requires special attention in both managed and protected forests. Red-listed epiphytic lichens would be aided by increased forest protection or transitioning to less intensive management regimes.

Nirhamo, School of Forest Sciences, University of Eastern Finland, Joensuu, Finland https://orcid.org/0000-0002-1487-533X E-mail: aleksi.nirhamo@uef.fi
Pykälä, Finnish Environment Institute, Helsinki, Finland https://orcid.org/0000-0002-7566-9310 E-mail: juha.pykala@syke.fi
Jääskeläinen, Kuopio Museum of Natural History, Kuopio, Finland E-mail: jaaskimmo@gmail.com
Kouki, School of Forest Sciences, University of Eastern Finland, Joensuu, Finland https://orcid.org/0000-0003-2624-8592 E-mail: jari.kouki@uef.fi

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.

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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 10767, category Research article

Semo Mogeia, Alberto A. Manhiça, Andrade F. Egas. (2023). Wood ash content variation in Eucalyptus grandis clones in Mozambique. Silva Fennica vol. 57 no. 1 article id 10767. https://doi.org/10.14214/sf.10767

Keywords: sapwood; heartwood; base-top; bioenergy quality; woody fuel

Highlights: Eucalyptus grandis heartwood produces better fuel than sapwood, if assuming ash content as energy quality parameter; Younger individuals have higher ash content in sapwood, and older individuals in the heartwood; There was not significant stem end variation of ash content in heartwood and sapwood.

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The sustainability of native forests in Sub-Saharan Africa depends on the diversification of sources to generate bioenergy, and Eucalyptus spp. wood has been highlighted. However, the determination of energy quality parameters has been a challenge to enable plantation wood to generate energy. The research assessed the ash content of radial and longitudinal samples of Eucalyptus grandis (Hill) clone with different ages and growth sites. Samples were collected in three pre-established plots in the center of Mozambique. Five trees were cut down in each plot and six discs were removed from each tree. Grinded samples with <0.5 mm particle size were generated from the heartwood and sapwood of each disk to determine the ash content. Wood from 7-year-olds had a higher ash content compared to 9-year-olds. The two sample plots differed from each other in terms of wood ash content. Heartwood samples had smaller ash content than sapwood samples. In general, the ash content of the intermediate positions was lower than those from the base and top of the stem, for both radial sections. No conclusive differences were found between samples from the base and the top of the trees, indicating that the material from the top of the trees can also be used as wood fuel. Ash content can be a considerable parameter to assess the quality of the wood of Eucalyptus spp. as a fuel.

Mogeia, Universidade Lúrio, Faculdade de Ciências Agrárias, Departamento de Silvicultura e Maneio [Lurio University, Faculty of Agricultural Sciences, Department of Forestry and Management], Campus de Wanaango, EN733, Km 42, Unango, Niassa, Mozambique E-mail: smogeia@unilurio.ac.mz
Manhiça, Centro de Investigação Florestal, [Forestry Research Center], Marracuene, EN1, Maputo província, Mozambique E-mail: albertomanhica@gmail.com
Egas, Universidade Eduardo Mondlane, Faculdade de Agronomia e Engenharia Florestal, Departamento de Florestas, [Eduardo Mondlane University, Faculty of Agronomy and Forestry Engineering, Department of Forests], Av. Julius Nyerere, Maputo cidade, Mozambique E-mail: aegas8@gmail.com

article id 10752, category Research article

Oiva Hiltunen, Ville Hallikainen, Teijo Palander. (2023). Analysing the groundwater level and its determinants in a drained peatland forest: a case study in South Lapland, Finland. Silva Fennica vol. 57 no. 1 article id 10752. https://doi.org/10.14214/sf.10752

Keywords: peatland; groundwater level; load-bearing capacity; subsoil

Highlights: Mineral subsoils under a peat layer (less than 1 m) affect the groundwater level; During average precipitation, silty subsoil often makes groundwater level remain too high for timber haulage; If the subsoil is sandy and the peat layer is thin, the groundwater level gets lower; The amount of stand evapotranspiration alone is not enough to keep the groundwater level low enough.

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In southern Lapland, 70% of drained peatland forests have a peat layer thickness of less than one metre. On these sites, the question is how the subsoil under the peat affects groundwater level and thus timber harvesting. The aim of this study was to investigate the effect of the peat layer (<1 m) and subsoil on the groundwater level and its variation during the growing season (non-frost) by modelling the factors affecting water level. In sandy soils, the groundwater level rose by 20 cm when the peat layer thickness increased from 20 to 70 cm. In silty soils the effect of the peat thickness on groundwater remained minor. When the subsoil was sand or coarser, the groundwater level was usually deeper than when it was silty or finer. The effect of stand volume (m^–3 ha^–1) on the groundwater level was rather weak albeit significant. The model explained a significant part of the groundwater surface variation, with a marginal coefficient of determination (R²) of 68%. It seems that the rutting of roads could be avoided in late summer if the precipitation is remarkably lower during that period, or if the subsoil is sandy with thin peat layer on top of it. Because the groundwater level affects the load-bearing capacity of timber-harvesting machinery, it is important to study this issue in more detail in the future.

Hiltunen, Lapland University of Applied Sciences, Jokiväylä 11, FI-96300 Rovaniemi, Finland E-mail: oivah@student.uef.fi
Hallikainen, Natural Resources Institute Finland, Ounasjoentie 6, FI-96300 Rovaniemi, Finland E-mail: ville.hallikainen@luke.fi
Palander, The University of Eastern Finland, Faculty of Science, Forestry and Technology, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0002-9284-5443 E-mail: teijo.s.palander@uef.fi

article id 10648, category Research article

Antti-Jussi Lindroos, Hannu Ilvesniemi. (2023). Weathering rates of Ca and Mg related to granitic and gabbro mineralogy in boreal forest soils and the effect of mechanical soil disturbance on weathering release. Silva Fennica vol. 57 no. 1 article id 10648. https://doi.org/10.14214/sf.10648

Keywords: ploughing; base cations; rotation period; mineral soil weathering

Highlights: Weathering rates were higher in the gabbro than the granitic areas; Weathering was an important Ca and Mg source to forest trees, and it increased after mechanical soil disturbance.

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This study’s aim was to calculate the weathering rates of Ca and Mg for five boreal forest soils in southern Finland on granitic and gabbro containing bedrock. The effect of mineralogy on the total concentrations of Ca and Mg in soil and weathering rates was evaluated. The aim was also to estimate the effect of mechanical soil disturbance related to ploughing on the weathering in the gabbro area. The total concentrations of SiO₂, CaO, MgO, and Zr were determined by XRF, and weathering rates of Ca and Mg were determined based on the changes in the CaO, MgO, and Zr concentrations. The weathering rates of Ca+Mg varied 5–38 mmol_c m^–2 year^–1 in the E+B/BC horizons among the plots. Soil disturbance related to ploughing increased the weathering of Ca and Mg largely in the disturbed part of the topmost mineral soil as indicated by the decreasing concentrations of Ca and Mg after mechanical soil disturbance. The weathering input of Ca in the undisturbed soil did not fully replace the Ca output in final whole-tree cutting. The weathering input of Mg in the undisturbed soil was sufficient to replace the lost Mg in stemwood harvesting but not on all the plots the lost Mg in whole-tree harvesting. Weathering rates were higher in the gabbro than the granitic areas.

Lindroos, Natural Resources Institute Finland (Luke), Natural resources, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: antti.lindroos@luke.fi
Ilvesniemi, Natural Resources Institute Finland (Luke), Production systems, Latokartanonkaari 9, FI-00790 Helsinki, Finland E-mail: hannu.ilvesniemi@luke.fi

Category: Review article

article id 22018, category Review article

Felipe de Miguel-Díez, Thomas Purfürst, Mauricio Acuna, Eduardo Tolosana-Esteban, Tobias Cremer. (2023). Estimation of conversion factors for wood stacks in landings and their influencing parameters: a comprehensive literature review for America and Europe. Silva Fennica vol. 57 no. 1 article id 22018. https://doi.org/10.14214/sf.22018

Keywords: log properties; roundwood measurement; roundwood purchase; stack properties; wood supply chain

Highlights: Midpoint diameter, stacking quality, crookedness, log length, delimbing quality and bark thickness strongly influence the conversion factors; In Europe and America, a total of 48 methods were developed to estimate the conversion factors of wood stacks; The conversion factors should be estimated for each wood assortment and tree species.

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In commercial transaction of stacked roundwood, the estimation of the stack net volume plays a key role. One generalized method to determine the net volume is using conversion factors that relate the gross and net volumes. In this literature review the developed methods to estimate the conversion factors as well as their influencing parameters were analyzed based on 153 references from America and Europe. According to the results, 48 different methods (including their variants) for estimating the conversion factors were developed. The newest methods enabled their accurate determination inexpensively, e.g., photo-optical methods or 3D simulation models. The analyzed references revealed that 30 parameters influence the conversion factors. Based on this comprehensive review, each stakeholder involved in the roundwood supply chain can know which method is used for estimating the conversion factors in the analyzed territories and which influencing parameters should be considered when purchasing roundwood in order to accurately assess the solid wood content in the stacks.

de Miguel-Díez, Eberswalde University for Sustainable Development, Department of Forest Utilization and Timber Markets, Eberswalde, Germany; University of Freiburg, Chair of Forest Operations, Freiburg, Germany https://orcid.org/0000-0002-3800-7449 E-mail: felipe.diez@hnee.de
Purfürst, University of Freiburg, Chair of Forest Operations, Freiburg, Germany https://orcid.org/0000-0001-9661-0193 E-mail: thomas.purfuerst@foresteng.uni-freiburg.de
Acuna, University of the Sunshine Coast, Forest Research Institute, Sunshine Coast, Queensland, Australia E-mail: macuna@usc.edu.au
Tolosana-Esteban, Universidad Politécnica de Madrid, E.T.S.I. Montes, Forestal y del Medio Natural, Madrid, Spain https://orcid.org/0000-0003-2561-0342 E-mail: eduardo.tolosana@upm.es
Cremer, Eberswalde University for Sustainable Development, Department of Forest Utilization and Timber Markets, Eberswalde, Germany https://orcid.org/0000-0001-7866-944X E-mail: Tobias.Cremer@hnee.de

article id 10709, category Review article

Pavel Škvor, Martin Jankovský, Pavel Natov, Jiří Dvořák. (2023). Evaluation of stress loading for logging truck drivers by monitoring changes in muscle tension during a work shift. Silva Fennica vol. 57 no. 1 article id 10709. https://doi.org/10.14214/sf.10709

Keywords: timber transportation; biofeedback; driver; electromyography; physical load

Highlights: This study compared the workload of drivers when driving different types of vehicles; The combination of a truck and trailer exposes the driver to a significantly greater workload than trucks without trailers; The workload of drivers varied during a work shift i.e. drivers experienced significantly more workload in the middle of their work shifts.

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Our research aimed to quantify and evaluate the stress loading of drivers by monitoring the loading of the radial extensor muscle at the wrist joint (musculus extensor carpi radialis) when they drove different types of timber trucks. We monitored changes in the electric potential of skeletal muscles with electromyographic measurements and measurements of changes of heart rate using the Biofeedback 2000 ^x-pert device. The drivers were observed throughout their work shifts during normal operation of logging trucks and logging trucks with trailers. As a reference, muscle load was measured when driving a passenger car. We evaluated the normality of the measured data and obtained descriptive statistics from the individual measurements. The differences in stress load associated with driving the different types of vehicles increased whilst driving on lower-class roads. Results showed a high stress load for drivers of loaded vehicles when driving on narrow roads. It was more challenging to control a loaded logging truck with a trailer than driving a logging truck, with the difference in muscular loading reaching 22.5%. Driving a logging truck with a trailer produced 46.5% more muscle loading compared to driving a loaded passenger car. For preventive health and safety reasons, it would be reasonable to alternate between drivers when operating various vehicles, thus minimizing the development of possible health issues.

Škvor, Department of Forestry Technologies and Construction, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6 - Suchdol, Czech Republic https://orcid.org/0000-0001-7540-4761 E-mail: skvorp@fld.czu.cz
Jankovský, Department of Forestry Technologies and Construction, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6 - Suchdol, Czech Republic E-mail: jankovskym@fld.czu.cz
Natov, Department of Forestry Technologies and Construction, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6 - Suchdol, Czech Republic E-mail: natov@fld.czu.cz
Dvořák, Department of Forestry Technologies and Construction, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6 - Suchdol, Czech Republic https://orcid.org/0000-0002-5986-8002 E-mail: dvorakj@fld.czu.cz

Category: Research note

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.

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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

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