Today forest management practices apply methods that
are assumed to have a positive impact on forest biodiversity
and ecological sustainability. Mixed stands and broadleaved
tree species are favoured, retention trees and untouched
small keybiotopes are left in regeneration areas, and
compartments are delineated according to landscape. This
new silvicultural orientation was launched into the practice
quickly and, in fact, without a sound scientific evidence of
its actual impact on either forest biodiversity or on growth
and yield of forests (Annila, 1998). Although research on
forest biodiversity markedly expanded in the 1990s, most of
the research activities concentrated on questions concerning
the occurrence of single species. So far, there are only few
studies that extensively assess the biodiversity aspects, and
which take into account simultaneously both the ecological
and socio-economical impacts of silvicultural measures
(Siitonen, 2001).