Kalle Kemppainen, Jari Miina, Eetu Tarvainen, Ville Kankaanhuhta, Juha Laitila, Heli Peltola, Markus Strandström, Kalle Kärhä. (2026). Quality of drill-based site preparation and early performance of Norway spruce and Scots pine seedlings planted in different seasons. Silva Fennica vol. 60 no. 3 article id 26011. https://doi.org/10.14214/sf.26011

Keywords: forest regeneration; seedling survival; manual planting; mechanical soil preparation

Highlights: A drill-based device for mechanical site preparation significantly reduces soil exposure; The drill created mostly good (61%) or satisfactory (34%) planting spots for conifer seedlings; Two years after planting, Norway spruce seedlings performed better than Scots pine seedlings.

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

Mechanical site preparation (MSP) is essential for successful forest regeneration. However, excessively exposed soil may harm the environment and increase the total costs of seedling stand management. A drill-based MSP device (drill), designed to reduce soil exposure, was recently tested in Finland. This study investigated the quality of drill-based MSP and the early performance of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) seedlings planted in different seasons on five mineral soil stands. The findings showed that the mean area of the drilling spots (0.18 m²) was about 20% of that reported for mounding. The drill mostly resulted in good (61%) or satisfactory (34%) planting spot quality (e.g., good spots were covered with mineral soil). Ground and soil obstacles, such as roots, stones, stumps, and logging residues, negatively affected planting spot quality. About 13% of the planting spots did not have a pure mineral soil cover, which is required to mitigate pine weevil (Hylobius abietis L.) damage. Most seedlings were still alive one year after planting, but the proportion of healthy seedlings was 71% for Norway spruce and 48% for Scots pine two years after planting. Overall, drill-based MSP may be most feasible for drier sites with less competitive ground vegetation. However, the productivity and costs, the performance of the planted seedlings, and other potential benefits of drill-based MSP should be further tested under varying operating conditions and compared with those of conventional MSP methods.

Kemppainen, School of Forest Sciences, University of Eastern Finland, Yliopistokatu 7, FI-80100 Joensuu, Finland; Natural Resources Institute Finland, Yliopistokatu 6, FI-80100 Joensuu, Finland https://orcid.org/0009-0000-6184-8812 E-mail: kalle.kemppainen@uef.fi
Miina, Natural Resources Institute Finland, Yliopistokatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-8639-4383 E-mail: jari.miina@luke.fi
Tarvainen, School of Forest Sciences, University of Eastern Finland, Yliopistokatu 7, FI-80100 Joensuu, Finland E-mail: eetu.tarvainen@harvestia.fi
Kankaanhuhta, Natural Resources Institute Finland, Yliopistokatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0001-5785-5972 E-mail: ville.kankaanhuhta@luke.fi
Laitila, Natural Resources Institute Finland, Yliopistokatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0003-4431-3319 E-mail: juha.laitila@luke.fi
Peltola, Natural Resources Institute Finland, Yliopistokatu 6, FI-80100 Joensuu, Finland https://orcid.org/0000-0003-1384-9153 E-mail: heli.peltola@uef.fi
Strandström, Metsäteho Oy, Vernissakatu 1, FI-01300 Vantaa, Finland https://orcid.org/0009-0004-0868-3042 E-mail: markus.strandstrom@metsateho.fi
Kärhä, School of Forest Sciences, University of Eastern Finland, Yliopistokatu 7, FI-80100 Joensuu, Finland https://orcid.org/0000-0002-8455-2974 E-mail: kalle.karha@uef.fi

article id 26005, category Research article

Therese Strömvall Nyberg, Mikolaj Lula, Hammed Adekunle, Urban Nilsson, Göran Örlander, Emma Holmström. (2026). Forest development and financial outcomes under shelterwood and clearcut regimes in mixed stands. Silva Fennica vol. 60 no. 3 article id 26005. https://doi.org/10.14214/sf.26005

Keywords: Pinus sylvestris; Picea abies; land expectation value; combination method; Drettinge method

Highlights: Shelterwood and mixed species regeneration can be a viable strategy under suitable conditions; Active management and timely overstory removal in shelterwood systems are important for financial revenue and stand development; Clearcuts consistently yielded higher financial returns than shelterwood.

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

We assessed long-term outcomes of a regeneration experiment comparing clearcutting and shelterwood treatments, each with and without mechanical site preparation (MSP). The experiment was established in the early 1990s across Sweden and combined natural regeneration of Scots pine (Pinus sylvestris L.) with planting of Norway spruce (Picea abies (L.) H. Karst.; 2500 seedlings ha^–1). The first assessment showed Norway spruce dominance on southern sites and potential for mixed stands in central and northern regions. In 2022–2023, sites were re-measured to assess stand structure and productivity at mid-rotation, and the measured data were then used to parameterize Heureka decision support system (DSS) for simulations to final harvest. Southern sites developed into Norway spruce-dominated stands, with higher volume in clearcut than shelterwood treatments. Central and northern sites developed into mixed species stands, with higher volumes in shelterwood treatments in central Sweden. In northern Sweden, retained shelterwood negatively affected understory growth, highlighting the importance of active management while using shelterwood. Despite these regional differences, land expectation value (LEV) was consistently higher for clearcut treatments. Even in central Sweden, higher volumes in shelterwood treatments did not compensate for the additional costs associated with shelterwood cuttings. Our results show that establishing mixed species stands through shelterwood and planting can be viable depending on site conditions, but likely results in lower revenue than clearcutting.

Strömvall Nyberg, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, 234 56 Alnarp, Sweden https://orcid.org/0009-0007-0280-6023 E-mail: therese.stromvall@slu.se
Lula, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, 234 56 Alnarp, Sweden E-mail: mikolaj.lula@slu.se
Adekunle, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, 234 56 Alnarp, Sweden E-mail: hammedadekunle43@yahoo.com
Nilsson, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, 234 56 Alnarp, Sweden E-mail: urban.nilsson@slu.se
Örlander, Department of Forestry and Wood Technology, Linnaeus University, 351 95 Växjö, Sweden E-mail: goran.orlander@outlook.com
Holmström, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, 234 56 Alnarp, Sweden https://orcid.org/0000-0003-2025-1942 E-mail: emma.holmstrom@slu.se

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