Silva Fennica vol. 59 | 2025

The carbon substitution and storage effects related to Norwegian forests and the forest sector were compared under three potential roundwood harvest scenarios: maintaining harvests at 2021 levels, increasing harvests by 20% due to policies aimed at maximizing economic benefits from the forest sector, and reducing harvests by 20% due to biodiversity concerns. For harvested wood products, both the current product structure and hypothetical alternatives were considered. The carbon stock development in forests was projected using a forestry simulation tool for Norway. Many uncertainties in carbon storage, substitution parameters, and data have been addressed using Monte Carlo simulations. Shifting a portion of pulpwood use to produce wood-based insulation materials and textile fibres was found to increase the climate benefits from the Norwegian forest sector. In contrast, the shift to bioethanol production had only a marginal effect compared to the current production structure. The analysis spanned the next two decades, which is a period relevant to the investment and operational lifespan of industrial facilities. The results suggest that during this time, smarter use of harvested roundwood for HWPs with high carbon substitution benefits can be an effective means of climate change mitigation. However, in the long term, enhancing forest carbon sinks by reducing harvests may be more beneficial for the climate, provided that global efforts to reduce emissions from energy production are successful and lead to a decrease in emissions associated with the production of various materials.

• Kallio, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O.Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0002-5393-761X E-mail: maarit.kallio@nmbu.no
• Strîmbu, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O.Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0002-0588-2036 E-mail: victor.strimbu@nmbu.no
• Gobakken, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O.Box 5003, NO-1432 Ås, Norway E-mail: helle.ross.gobakken@nmbu.no
• Gobakken, Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, P.O.Box 5003, NO-1432 Ås, Norway https://orcid.org/0000-0001-5534-049X E-mail: terje.gobakken@nmbu.no

The poor cost-effectiveness of mechanized planting (MECP) is the main reason for the low mechanization rate of planting. In this study, we investigated the productivity of the mechanized excavator-based planting of Norway spruce (Picea abies [L.] H. Karst.) seedlings based on data collected by the Risutec Asta documentation system. We also compared the costs of a MECP chain with two different manual planting (MAP) chains, where mounding was carried out by a crawler excavator (EXC) or a continuously advancing mounder (CONT). The MECP of seedlings was carried out using an EXC equipped with a Risutec PM-160 planting device. Generally, the nine study sites in western Finland contained few surface obstacles (e.g., the logging residues had mainly been harvested), which made the conditions very suitable for MECP. The average production time taken by the MECP was 9 h ha^–1. The operating hour (G₁₅-h) productivity averaged 215 seedlings G₁₅-h⁻¹, with the mean planting time being 13.8 s seedling⁻¹. Loading 160 seedlings into the seedling cassette took approximately 10 min (3.8 s seedling⁻¹). Overall, the cost of the MECP was about 3% lower than for the EXC + MAP. However, when productivity was set at <210 seedlings G₁₅-h⁻¹, the cost of the MECP was higher than that of the EXC + MAP. Based on our findings, the most cost-efficient planting chain was CONT + MAP. However, based on our results, the required level of productivity can be achieved if the sites are suitable for MECP and the machine operators are skilled.

• Kemppainen, School of Forest Sciences, University of Eastern Finland (UEF), P.O. Box 111, FI-80101 Joensuu, Finland; Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland https://orcid.org/0009-0000-6184-8812 E-mail: kalle.kemppainen@uef.fi
• Kärhä, School of Forest Sciences, University of Eastern Finland (UEF), P.O. Box 111, FI-80101 Joensuu, Finland E-mail: kalle.karha@uef.fi
• Laitila, Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0003-4431-3319 E-mail: juha.laitila@luke.fi
• Sairanen, School of Forest Sciences, University of Eastern Finland (UEF), P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0009-0008-8632-3797 E-mail: anttsair@student.uef.fi
• Kankaanhuhta, Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0001-5785-5972 E-mail: ville.kankaanhuhta@luke.fi
• Viiri, UPM-Kymmene Plc, UPM Forest, Peltokatu 26 C 4, FI-33100 Tampere, Finland https://orcid.org/0000-0003-3952-9481 E-mail: heli.viiri@upm.com
• Peltola, School of Forest Sciences, University of Eastern Finland (UEF), P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-1384-9153 E-mail: heli.peltola@uef.fi

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

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

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

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

In this paper, we present a new methodology that directly extracts the geometry of woody features (wood and bark) and foliage from 3D data originating from terrestrial laser scans. Our goal was to enhance the precision of radiative transfer models for modelling tree shading by using highly resolved 3D tree models. The approach was tested on a single apple tree (Malus domestica (Suckow) Borkh.) in a peri-urban setting and was validated by utilising an open-source radiative transfer model and comparing the simulation output with in-situ measurements of photosynthetically active radiation (PAR) as well as simulations utilizing turbid voxels of 0.2 m and 1 m edge length. The in-situ measurements of 60 PAR sensors showed a correlation coefficient (r) of 0.92 with the simulated light intensities for the reconstructed polygons which was higher than for the voxel-based approaches (0.2 m:  r = 0.85, 1 m: r = 0.73). We were able to demonstrate that our approach effectively simulates light extinction through the canopy. This innovative method has the potential to easily provide detailed insights into high resolution radiation patterns within forests, which are connected to multiple ecosystem functions like species and habitat diversity.

• Frey, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany https://orcid.org/0000-0001-7895-702X E-mail: julian.frey@wwd.uni-freiburg.de
• Schindler, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany https://orcid.org/0000-0003-2972-1920 E-mail: zoe.schindler@wwd.uni-freiburg.de
• McClatchy, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany E-mail: patrickjmcclatchy@gmail.com
• Morhart, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany https://orcid.org/0000-0003-1874-5011 E-mail: christopher.morhart@wwd.uni-freiburg.de
• Larysch, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany https://orcid.org/0000-0002-1191-5770 E-mail: elena.larysch@wwd.uni-freiburg.de
• Seifert, Chair of Forest Growth and Dendroecology, University of Freiburg, Freiburg im Breisgau, Tennenbacher Str. 4, 79106 Freiburg, Germany; Department of Forest and Wood Science, Stellenbosch University, Private Bag X1, Matieland, 7602, Stellenbosch, South Africa https://orcid.org/0000-0002-9611-6272 E-mail: thomas.seifert@wwd.uni-freiburg.de

• Yrttimaa, School of Forest Sciences, University of Eastern Finland, FI-80101 Joensuu, Finland https://orcid.org/0000-0003-2648-523X E-mail: tuomas.yrttimaa@uef.fi
• Liikonen, School of Forest Sciences, University of Eastern Finland, FI-80101 Joensuu, Finland E-mail: lauriliik@uef.fi
• Erkkilä, School of Forest Sciences, University of Eastern Finland, FI-80101 Joensuu, Finland E-mail: aapo.erkkila@uef.fi
• Vastaranta, School of Forest Sciences, University of Eastern Finland, FI-80101 Joensuu, Finland https://orcid.org/0000-0001-6552-9122 E-mail: mikko.vastaranta@uef.fi