Prescribed burning, when combined with tree retention, can effectively support natural regeneration in managed boreal forests, new research shows. The study demonstrates that post-fire seedling establishment remains strong across key commercial species, Scots pine and birch, suggesting that integrating these practices may help reconcile biodiversity goals with sustainable forest management.

In a landscape-scale experiment, the researchers found that natural tree regeneration (i.e. not artificially seeded or planted) met or exceeded commercial standards after prescribed burning and clear-cutting with moderate levels of green tree retention. Pioneer species that establish after disturbance, including Scots pine and silver birch, flourished after burning, while Norway spruce, a species that grows later in forest development, did better on unburned areas where it remained after harvesting. Compared to these harvested areas, natural regeneration was smaller and sparser in protected areas that were burned for restoration with no harvesting. In protected areas, a new generation of young trees may regenerate more slowly and lead to a more diverse age structure of trees after fires.

The researchers examined the quality and amount of natural tree regeneration 11 years after prescribed burning and tree retention treatments in a replicated large-scale experiment. A total of 24 sites ranging in size from three to five hectares were distributed across the landscape in the Ilomantsi and Lieksa regions of Eastern Finland. Half of these were burned in the summer of 2001, while the other half remained unburned. Each site was either clear-cut, harvested with retention (10 m³/ha or 50 m³/ha), or left uncut. On each site, a systematic grid of plots was established where the density, height, diameter, health, and species of each tree was recorded, to investigate how trees regenerate after harvesting and burning.

The study suggests that current forest management practices on dry upland Scots pine sites could be updated to better meet biodiversity objectives, while still achieving commercially acceptable regeneration. New practices include retaining higher amounts of mature trees during harvesting, prescribed burning after harvesting, and reducing site preparation that disturbs the soil. The higher costs of burning and decreased harvesting volume due to retention trees can be partially offset by relying on natural regeneration and eliminating the need to scarify the soil to improve regeneration. The overarching aim of these practices is to counteract the negative effects of clear-cutting and to increase biodiversity and improve habitats for threatened species in the intensively managed Fennoscandian boreal forest.

Research article:
Nicola Kokkonen, Jari Kouki. Natural tree regeneration 11 years after prescribed burning with tree retention in the Fennoscandian boreal forest. Forest Ecology and Management, Volume 612, 2026. https://doi.org/10.1016/j.foreco.2026.123765