Prescribed burns most effective in dry conditions
Prescribed forest burning is often conducted in spring when the ground is moist, but a new PhD thesis from the Swedish University of Agricultural Sciences (SLU) shows they are most beneficial for biodiversity during dry conditions.
Many species, including beetles and fungi, depend on fire-created dead wood, and some are entirely fire-dependent.
Doctoral student Ellinor Ramberg studied over 50 burns in Sweden and Finland, analyzing wood-inhabiting fungi, beetles, dead wood, and tree regeneration. Her findings show that burnings in dry weather produce more dead wood and better regeneration of deciduous trees. For some species groups such as wood-inhabiting fungi benefits only appear after several years—up to 16 years post-burn.
Burning spruce-rich forests creates especially large amounts of dead wood, as spruce trees are highly fire-sensitive. Still, a mix of forest types is important to support diverse species. Ramberg also found that proximity to protected forests boosts species richness in burned areas, while landscapes dominated by clearcuts reduce it.
Although safety is crucial, Ramberg suggests that burning later in the season, when conditions are drier, may improve burn outcomes.
Contact
Ellinor Ramberg
ellinor.ramberg@slu.se