The Effects Of Forest Biomass Harvesting On Biodiversity

Extraction of dead wood as forest fuels will decrease the amounts of dead wood in the landscape. Because dead and decaying wood has been identified as a key factor in explaining why many forest species are threatened (Berg et al. 1994, Esseen et al. 1997), extraction of forest fuels may increase the threat. The wood that is presently in focus for use as forest fuel is mainly logging residues, i.e. twigs, branches and tops, although logging stumps and whole trees might also be used (see below). The logging residues may be defined as belonging to fine woody debris (FWD), in contrast to coarse woody debris (CWD). The limit between fine and coarse wood is here defined at 10 cm diameter. Coarse wood is widely acknowledged as an important habitat for saproxylic (wood living) organisms (Grove 2002), especially for threatened species (Berg et al. 1994), and many studies have therefore been done on saproxylic organisms in coarser dimensioned wood. Finer wood has been much less studied. It has generally been retained in forest operations and is therefore abundant in managed forest landscapes. However, comparative studies show that fine wood hosts a large number of species (Harz & Topp 1999, Kappes & Topp 2004, Kruys & Jonsson 1999, Nittérus et al. 2004, Nordén et al. 2004, Schiegg 2001). There might also be organisms that use the fine wood for shelter on open areas (Gunnarsson et al. 2004). Thus, the extraction of fine woody debris from the forest landscape might reduce the habitat for several organisms.