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Silva Fennica vol. 57 no. 2 | 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

Category: Research article

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

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.

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

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