Current issue: 58(2)

Under compilation: 58(3)

Scopus CiteScore 2021: 2.8
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Silva Fennica vol. 58 no. 1 | 2024

Category : Editorial

article id 24016, category Editorial

Pekka Nygren. (2024). Advancing the Everyone’s Right to Forest Science: opening research data and computational codes in Silva Fennica. Silva Fennica vol. 58 no. 1 article id 24016. https://doi.org/10.14214/sf.24016

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Nygren, Finnish Society of Forest Science, Viikinkaari 6, FI-00790 Helsinki, Finland https://orcid.org/0000-0002-3730-9840 E-mail: pekka.nygren@metsatiede.org

Category : Research article

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 23062, category Research article

Tobias Semberg, Anders Nilsson, Rolf Björheden, Linnea Hansson. (2024). Real-time target point identification and automated log grasping by a forwarder, using a single stereo camera for both object detection and boom-tip control. Silva Fennica vol. 58 no. 1 article id 23062. https://doi.org/10.14214/sf.23062

Keywords: vector analysis; forwarder; forest operations; loading; boom automation; object detection; stereo camera

Highlights: Simple target-point detection in real time using only a stereo camera; Sturdiness ensured through the simple feedback system based on the same camera; Automated boom-tip control and log grasping successfully tested on full-sized forwarder; A step toward semi-automation (operator support) or autonomous forwarding.

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The forest industry is constantly striving to increase productivity and cut costs, and many research and innovation projects are currently focusing on semi-automated or autonomous systems. A key element, with several possible solutions, is automated log grasping, where researchers and manufacturers are looking for efficient and sturdy ways to solve the task in real-time forwarding operations. This study presents a simple method for automated log grasping using only a single stereo camera for object detection (log and grapple) and a simple controller moving the boom, with feedback from the camera as boom-tip control. The accuracy, precision, and repeatability of the method was tested on a full-scale forwarder. Boom movements were examined from two different start positions in relation to the target position, with the log placed at three different angles. The overall log-grasping success was also evaluated. The tests were performed in a full-scale, real-time operation, without hand-eye calibration or other sensor data from the machine. The method was precise, with high repeatability, but the grasping point showed a minor systematic offset, depending on log angle. However, the deviation in accuracy was too small to affect the success rate. In practice, the most difficult log angles can be avoided by moving the machine slightly. The log grasping method may become part of an autonomous forwarding system or could provide operator support in semi-automated systems.

Semberg, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden E-mail: tobias.semberg@skogforsk.se
Nilsson, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden E-mail: anders.nilsson@skogforsk.se
Björheden, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-4158-102X E-mail: rolf.bjorheden@skogforsk.se
Hansson, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-9788-1734 E-mail: linnea.hansson@skogforsk.se

article id 23058, category Research article

Johanna Jetsonen, Annamari Laurén, Heli Peltola, Olli Muhonen, Juha Nevalainen, Veli-Pekka Ikonen, Antti Kilpeläinen, Eeva-Stiina Tuittila, Elisa Männistö, Nicola Kokkonen, Marjo Palviainen. (2024). Effects of nitrogen fertilization on the ground vegetation cover and soil chemical properties in Scots pine and Norway spruce stands. Silva Fennica vol. 58 no. 1 article id 23058. https://doi.org/10.14214/sf.23058

Keywords: boreal forest; competition index; forest fertilization; upland forests; vegetation cover

Highlights: Nitrogen (N) fertilization decreased the total cover of ground vegetation; N fertilization decreased the cover of mosses and dwarf shrubs and increased the cover of herbaceous plants; N concentration of the mor humus layer increased with the N fertilization; The magnitude of these changes depended on the intensity of the N fertilization.

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The aim of this study was to investigate the short-term effects of nitrogen (N) fertilization intensity on the ground vegetation cover and soil chemical properties in two Scots pine (Pinus sylvestris L.) and two Norway spruce (Picea abies (L.) Karst.) dominated stands on upland forest sites in Eastern Finland. The fertilizer was applied using a helicopter in the spruce stands and a forwarder in the pine stands. The distribution and the amount of fertilizer was measured with funnel traps. Cover of each species of ground vegetation was estimated before fertilization and 3–4 years after it in pine and 2–3 years after it in spruce stands. Further, the cover observations were aggregated by plant types. Based on measurements, we analyzed the effects of the funnel-trap-observed amount of N fertilizer on the cover and plant type composition of ground vegetation and soil N and C concentration. In addition, we analyzed the impacts of competition caused by trees on the ground vegetation cover based on competition indices. N fertilization increased the cover of herbaceous plants and decreased the cover of mosses and dwarf shrubs, and the total cover of ground vegetation. Further, it increased the N concentration of the mor humus layer. The magnitude of the changes increased with the intensity of the N fertilization. The competition caused by trees did not affect the cover of ground vegetation.

Jetsonen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Finland 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 E-mail: heli.peltola@uef.fi
Muhonen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0009-0007-4051-8567 E-mail: olli.muhonen@forestvital.com
Nevalainen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0009-0000-2972-4385 E-mail: juha.hs.nevalainen@gmail.com
Ikonen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-1732-2922 E-mail: veli-pekka.ikonen@uef.fi
Kilpeläinen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-4299-0578 E-mail: antti.kilpelainen@uef.fi
Tuittila, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland E-mail: eeva-stiina.tuittila@uef.fi
Männistö, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-3869-6739 E-mail: elisa.mannisto@uef.fi
Kokkonen, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland https://orcid.org/0000-0003-0197-2672 E-mail: nicola.kokkonen@uef.fi
Palviainen, Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Finland E-mail: marjo.palviainen@helsinki.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.

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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 22017, category Research article

Andis Lazdiņš, Ainārs Lupiķis, Kaspars Polmanis, Arta Bārdule, Aldis Butlers, Santa Kalēja. (2024). Carbon stock changes of drained nutrient-rich organic forest soils in Latvia. Silva Fennica vol. 58 no. 1 article id 22017. https://doi.org/10.14214/sf.22017

Keywords: drainage; hemiboreal forests; organic soil; peat compaction; peatland forests; subsidence of the peat layer

Highlights: In moderate nutrient-rich forest site type (Myrtillosa turf. mel.), a significant subsidence of peat layer after drainage is associated with compaction rather than decomposition of peat; In nutrient-rich forest site type (Oxalidosa turf. mel.), a contribution of soil C stock losses to subsidence of the peat layer is significant; In moderate nutrient-rich forest site type (Myrtillosa turf. mel.), type of dominant tree species has higher impact on changes in soil C stock after drainage than in nutrient-rich forest site type (Oxalidosa turf. mel.); Distribution of different forest site types involving soil nutrient status has to be taken into account when CO₂ emissions from drained organic soil in forest land are estimated at national level.

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Impact of drainage of organic soils in forest land on soil carbon (C) stock changes is of high interest not only to accurately estimate soil C stock changes, but also to provide scientifically based recommendations for forest land management in context of climate change mitigation. To improve knowledge about long-term impact of drainage on nutrient-rich organic soils in hemiboreal forests in Latvia, 50 research sites representing drained conditions (Oxalidosa turf. mel. (Kp) and Myrtillosa turf. mel. (Ks) forest site types) and undrained conditions as control areas (Caricoso-phragmitosa, Dryopterioso-caricosa and Filipendulosa forest site types) were selected. Soil C stock changes after drainage was evaluated by comparing current C stock in drained organic soils to theoretical C stock before drainage considering impact of soil subsidence. During the 53-years period after drainage, the peat subsidence was higher in nutrient-rich Kp forest site type compared to moderate nutrient-rich Ks forest site type (peat subsided by 37.0 ± 4.8 and 23.3 ± 4.8 cm, respectively). In nutrient-rich Kp forest site type, soil C stock decreased by 4.98 ± 1.58 Mg C ha^-1 yr^-1 after drainage, while no statistically significant changes in soil C stock (0.19 ± 1.31 Mg C ha^-1 yr^-1) were observed in moderate nutrient-rich soils in Ks forest site type. Thus, in Ks forest site type, the main driver of the peat subsidence was the physical compaction, while in Kp forest site type contribution of organic matter decomposition and consequent soil C losses to subsidence of the peat was significant.

Lazdiņš, Latvian State Forest Research Institute ‘Silava’ (LSFRI Silava), Rigas str. 111, Salaspils, LV-2169, Latvia https://orcid.org/0000-0002-7169-2011 E-mail: andis.lazdins@silava.lv
Lupiķis, Latvian State Forest Research Institute ‘Silava’ (LSFRI Silava), Rigas str. 111, Salaspils, LV-2169, Latvia E-mail: ainars.lupikis@inbox.lv
Polmanis, Latvian State Forest Research Institute ‘Silava’ (LSFRI Silava), Rigas str. 111, Salaspils, LV-2169, Latvia https://orcid.org/0000-0003-2579-353X E-mail: kaspars.polmanis@silava.lv
Bārdule, Latvian State Forest Research Institute ‘Silava’ (LSFRI Silava), Rigas str. 111, Salaspils, LV-2169, Latvia https://orcid.org/0000-0003-0961-5119 E-mail: arta.bardule@silava.lv
Butlers, Latvian State Forest Research Institute ‘Silava’ (LSFRI Silava), Rigas str. 111, Salaspils, LV-2169, Latvia https://orcid.org/0000-0003-3118-1716 E-mail: aldis.butlers@silava.lv
Kalēja, Latvian State Forest Research Institute ‘Silava’ (LSFRI Silava), Rigas str. 111, Salaspils, LV-2169, Latvia E-mail: santa.kaleja@silava.lv

Category : Review article

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

Category : Research note

article id 23071, category Research note

Mattias Finndin, Per Milberg. (2024). The population development of small trees and shrubs after 100 years of free succession of a wooded meadow in southern Sweden. Silva Fennica vol. 58 no. 1 article id 23071. https://doi.org/10.14214/sf.23071

Keywords: conservation; land-use change; nemoral forest; plants; regrowth; wooded grassland

Highlights: Using a unique map of trees and shrubs from 1937, we estimated the mortality of woody species typical of wooded meadows after management ceased in 1923; Both population size and canopy cover of the studied species had decreased during the past 86 years; On the other hand, several tree and shrub specimens endured for a century, pointing to the slow changes involved as well as the potential for restoration.

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

Wooded meadows are characterised by traditional-historic human use. Deliberate selection of species, pollarding and haymaking has created a complex and biodiverse habitat where small trees and shrubs were prevalent. This study set out to document what happens to such trees and shrubs during succession to forest, the normal fate when wooded meadows are abandoned but also when other open to semi-open patches revert to forest. The study was conducted at a site in southern Sweden where traditional management was abandoned by 1923 when the area was protected for research and allowed to follow natural succession. The current study is a follow-up of a 1937-inventory of small trees and shrubs. The results show a decrease in both population size and canopy cover in the selected species during the past 86 years. Hence, we can expect a loss of these species when wooded meadow are abandoned and left to developed into forests. On the other hand, several tree and shrub specimens endured for a century, pointing to the slow changes involved as well as the potential for restoration.

Finndin, IFM Biology, Conservation Ecology Group, Linköping University, 581 83 Linköping, Sweden https://orcid.org/0009-0003-7620-7104 E-mail: mattef123@gmail.com
Milberg, IFM Biology, Conservation Ecology Group, Linköping University, 581 83 Linköping, Sweden https://orcid.org/0000-0001-6128-1051 E-mail: permi@ifm.liu.se

Category : Discussion article

article id 24004, category Discussion article

Jussi Manner. (2024). Automatic work-element detection: the missing piece in developing intelligent coaching systems for cut-to-length logging machinery. Silva Fennica vol. 58 no. 1 article id 24004. https://doi.org/10.14214/sf.24004

Keywords: forwarder; harvester; work method; operator effect; assistance system; instructor; trainer

Highlights: Next-generation logging systems will crucially impact the future demand for automatic data gathering and work guidance; Artificial intelligence emerges as a gamechanger, prompting re-evaluation of traditional approaches to automatically gather data, especially for forwarders; Industry-wide, interdisciplinary discussions are vital for charting alternative future paths for automatic data gathering and work guidance.

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

The productivity of cut-to-length machine operators exhibits a significant disparity, with the most productive individuals demonstrating twice the efficiency of their less productive counterparts. This discrepancy is largely attributed to variations in work methods. While supervised training has proven effective in streamlining work methods and enhancing productivity, the availability of forest-machine instructors for supervision is limited. Intelligent coaching systems (ICS) are periodically proposed to address this constraint. ICS are computer-based aids that offer machine operators real-time feedback on their work and guide them on how to rationalize their work. The successful implementation of ICS initially requires the development of systems for automatic work-element detection (AWED). Therefore, this article explores the history, current status, and technological possibilities of AWED. Additionally, key features of ICS are briefly reviewed. Lastly, a broader, interdisciplinary discussion is initiated on how to strategically allocate limited research resources. Questions surrounding the feasible ambition level for ICS and AWED are raised, prompting considerations for the next steps in research and development.

Manner, Skogforsk, Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-4982-3855 E-mail: jussi.manner@skogforsk.se

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