2. The principles of nature-oriented forest management
Most of the untouched boreal forests have been naturally
regenerated through large catastrophes. Storm and fire will
open the landscape, result in a huge amount of dead or dying
trees and let the pioneer tree species to germinate. Only a
few areas, mainly moist forests, have remained as refugia
outside forest fires (Lehtonen, 1997). The aim of modern
nature-oriented forest management is to mimic the natural
dynamics of northern boreal forests. It means removal
mainly of small trees by thinning in mid-rotation stands and
removal of most of the trees by final cutting for
regeneration. The survival of insects and fungi, which are
dependent on dead wood, will be favoured by leaving dead
trees and a small part of living trees in the forest in all phases
of the rotation period (Siitonen et al., 2000). Most of the
insects living in dead and rotten wood can survive in single
trees on clearcut areas, because they are adapted to largescale catastrophes. Burning of the logging residues and the
undervegetation will make the survival of coal-dependent
insects possible, while natural fires are nowadays prevented
by fire control (Ahnlund and Lindhe, 1992).