Modelled impact of Norway spruce logging residue extraction on biodiversity in Sweden

Logging residues are increasingly being extracted for bioenergy purposes. This study estimates how extraction of fine woody debris (FWD) may affect the overall habitat availability for 577 species of wood-and bark-inhabiting basidiomycetes, beetles, and lichens in Sweden using Norway spruce (Picea abies (L.) Karst.) as their primary substrate. We combined modeling of (i) the amount of various types of woody debris available throughout a forest rotation in managed forests with (ii) a classification of each species' associations with different types of wood. In three different regions, we compared a scenario with no logging residue extraction with three different levels of extraction. Our results suggest that the extraction may cause a 35%-45% reduction in aboveground FWD and a more than 20% decline in the potential amount of substrate for about 50% of the species (affecting basidiomycetes and beetles more than lichens). The intensified forestry during the last century has, however, steadily increased the production of FWD. Furthermore, no red-listed species is primarily associated with logging residues of Norway spruce. Therefore, the current situation in Sweden with extraction of 70% of Norway spruce FWD on 50% of the clearcuts probably constitutes a minor contribution to the regional extinction risks.