Jouni Partanen, Risto Häkkinen, Anneli Viherä-Aarnio, Niina Stenvall, Heikki Hänninen. (2026). Short-day treatment in late summer reduces the chilling requirement in Norway spruce seedlings. Silva Fennica vol. 60 no. 2 article id 25053. https://doi.org/10.14214/sf.25053

Keywords: bud burst percentage; days to bud burst; rest; endodormancy release; forcing, quiescence

Highlights: Short-day treatment reduces the chilling requirement and the time to bud burst in Norway spruce seedlings; Forcing photoperiod does not affect the time to bud burst of short-day treated seedlings; In natural outdoor conditions, the short-day treatment advances the bud burst slightly.

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Artificial shortening of photoperiod with short-day (SD) treatment in late summer is a common measure in forest nurseries to advance the growth cessation and increase the frost hardiness of seedlings in the autumn. We conducted an experimental study of the effect of SD treatment (12 h) in the preceding summer and the photoperiod (16 h, 8 h) prevailing in the regrowth test under forcing conditions. The effect of these factors on the chilling requirement in second-year Norway spruce Picea abies (L.) Karst. seedlings was studied. Half of the seedlings were first subjected to a three-week SD treatment between 11 July and 1 August 2005, whereas the other half were used as the control group. The seedlings were first exposed to chilling in natural conditions. Subsequently, samples of the seedlings were transferred at intervals between September and May to a regrowth test in growth-promoting forcing conditions in a greenhouse. Additionally, we observed the bud burst of the seedlings in natural conditions during the next spring. Our main result was that SD treatment reduced the chilling requirement in the seedlings. Long photoperiod (16 h) in the forcing conditions also reduced the chilling requirement. The buds of the SD-treated seedlings burst earlier than those of the control seedlings and generally at almost the same time in both photoperiods. This suggests that the photoperiod prevailing in the forcing conditions has no additional delaying or advancing effect on the bud burst of SD-treated seedlings. In natural outdoor conditions, the SD treatment in the preceding summer advanced the springtime bud burst slightly.

Partanen, Natural Resources Institute Finland (Luke), Production Systems, Juntintie 154, FI-77600 Suonenjoki, Finland https://orcid.org/0009-0007-1782-4283 E-mail: ext.jouni.partanen@luke.fi
Häkkinen, Natural Resources Institute Finland (Luke), Production Systems, P.O. Box 2, FI-00791 Helsinki, Finland https://orcid.org/0009-0007-1687-1045 E-mail: risto.hakkinen@yahoo.com
Viherä-Aarnio, Natural Resources Institute Finland (Luke), Production Systems, P.O. Box 2, FI-00791 Helsinki, Finland https://orcid.org/0000-0002-1777-637X E-mail: annelivihe@outlook.com
Stenvall, Natural Resources Institute Finland (Luke), Production Systems, P.O. Box 2, FI-00791 Helsinki, Finland https://orcid.org/0000-0002-9447-8712 E-mail: niina.stenvall@luke.fi
Hänninen, State Key Laboratory for Development and Utilization of Forest Food Resources, Zhejiang A&F University, 666 Wusu Street, Hangzhou 311300, PR China https://orcid.org/0000-0003-3555-2297 E-mail: hhannin@zafu.edu.cn

article id 25025, category Research article

Mikko T. Niemi, Marjo Palviainen, Annamari Laurén. (2026). Enhanced multi-objective decision support in peatland forestry using Peatland simulator SUSI. Silva Fennica vol. 60 no. 2 article id 25025. https://doi.org/10.14214/sf.25025

Keywords: forest planning; drainage; tree growth; nutrient leaching; trade-offs; ditch depth; greenhouse gas emissions

Highlights: Reaching multidimensional economic and environmental objectives in peatland forest management can be enhanced using process-based ecosystem models; Applying ditch depth of 60 cm in ditch network maintenance improved the trade-off between timber production and soil greenhouse gas emissions compared with the conventional ditch depth of 90 cm; Intensive drainage can reduce tree growth in southern Finland during dry summers.

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Boreal peatland forests have been extensively drained to increase timber production, but the maintenance of shallowed ditches has been questioned due to increased greenhouse gas (GHG) emissions and negative impacts on water quality. Ditch network maintenance (DNM) lowers water table, which typically increases tree growth, but also increases rate of peat decomposition and consequently CO₂ emissions. Multi-objective forest planning balances between the conflicting economic gains and adverse environmental impacts. We used a process-based Peatland simulator SUSI to simulate three management scenarios for 20 forest stands, covering the variety of growing conditions in Finland. We studied how DNM with a reduced ditch depth (60 cm) and a conventional ditch depth (90 cm) affected stand growth, GHG balance, and nitrogen and phosphorus export. Over a 20-year simulation period, annual volume growth response was on average 0.8 m³ ha^-1 when ditch depth was changed from 30 cm to 60 cm and 1.0 m³ ha^-1 when ditch depth was changed from 30 cm to 90 cm. In southern Finland, DNM decreased stand growth in fertile sites. Soil GHG emissions increased on average by 49% and 119% in 60 cm and 90 cm ditch depths, respectively, compared to 30 cm ditch depth. The cost of reducing GHG emissions ranged from 0–22 € per ton of CO₂ in our study sites and scenarios. Our results support the idea that omitting DNM or reducing ditch depth may lead to acceptable compromises, as the marginal cost of soil GHG emissions considerably increases with increasing ditch depth.

Niemi, Department of Forest Sciences, University of Helsinki, 00014 Helsinki, Finland; School of Forest Sciences, University of Eastern Finland, 80101 Joensuu, Finland https://orcid.org/0000-0003-0461-3667 E-mail: mikko.t.niemi@helsinki.fi
Palviainen, Department of Forest Sciences, University of Helsinki, 00014 Helsinki, Finland https://orcid.org/0000-0001-9963-4748 E-mail: marjo.palviainen@helsinki.fi
Laurén, Department of Forest Sciences, University of Helsinki, 00014 Helsinki, Finland https://orcid.org/0000-0002-6835-9568 E-mail: annamari.lauren@helsinki.fi

Category : Sustainable and Eco-Friendly Harvesting Operations - Research article

article id 25047, category Sustainable and Eco-Friendly Harvesting Operations - Research article

Thomas Kronholm, Erik Anerud, Dan Bergström. (2026). Swedish energy plants’ practices and development needs for storage, handling, monitoring and inventory of biofuels. Silva Fennica vol. 60 no. 2 article id 25047. https://doi.org/10.14214/sf.25047

Keywords: biomass; forest fuels; bioenergy; chips; CHP; fuel yard; heating plant

Highlights: Minimizing storage time is the most common measure taken to avoid storage losses; Few cover fuel stacks despite it being considered effective in reducing storage losses; Monitoring fuel quantity and fire risks during storage is often done through subjective methods; The greatest development needs are perceived to be in techniques and methods for inventorying stocks and fuel qualities.

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

Better understanding of the energy plants´ biofuel management and storage strategies, and technologies used for monitoring and forecasting fuel requirements and fuel quality at the energy plants, would facilitate possibilities to direct research and development efforts to promote increase of their efficiency and sustainability in the Swedish energy system. The objectives were therefore to 1) survey Swedish energy plants’ use of current practices for handling, storage, monitoring and inventory of solid biofuels at their feed-in terminals and industry fuel yards and 2) analyse how their current storage management actions taken match with their perceived effectiveness of actions and development needs and theory. The survey shows for example that most fuel transport occurs via truck, and supply contracts commonly span one to two years. While 43% of companies perform their own quality measurements upon delivery, a substantial 37% of respondents were unable to estimate their average annual storage losses. Subjective estimation is the most prevalent method for determining fuel quantity and fire risk during storage. Minimizing storage time was identified as the most effective measure to reduce storage losses. However, we found major gaps between theory and practice. Many energy plants demonstrate a foundational understanding of fuel logistics, but there are significant opportunities for enhancing efficiency and sustainability, by for example: implementing more robust systems for tracking and quantifying storage losses; exploring and integrating advanced technologies for inventory management. Thus, a more data-driven and technologically integrated approach to forest fuel management is crucial for Swedish energy plants to further enhance their resource efficiency, reduce climate impact, and ensure a predictable and cost-effective supply of bioenergy.

Kronholm, Department of Forest Bioeconomy and Technology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden https://orcid.org/0000-0002-7066-0667 E-mail: thomas.kronholm@slu.se
Anerud, Department of Forest Bioeconomy and Technology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden https://orcid.org/0000-0002-4751-2439 E-mail: erik.anerud1@gmail.com
Bergström, Department of Forest Bioeconomy and Technology, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden https://orcid.org/0000-0002-5729-683X E-mail: dan.bergstrom@slu.se

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