Management in relation to disturbance in the boreal forest

Disturbances and the consequent habitat heterogeneity are natural features of the boreal forest. Natural disturbances occurring at the level of popula tions, communities and ecosystems (meters to kilometers and years to hundre ds of years), that is, at the 'meso-scale' may provide useful guidelines fo r forest management. This approach is based on the assumption that species are adapted to the disturbance regime of the forest-type that they occupy. However, natural disturbance and human-caused disturbance, such as clear-cu tting, may differ substantially in their ecological effects. Potential diff erences occur on several scales. On the stand scale, removal or destruction of important habitat structures, such as coarse woody debris, during tradi tional clear-cutting may affect species. On the landscape scale, fragmentat ion may cause local extinctions and hamper the recolonization of maturing s ites by old-growth specialists. The effect of these differences on boreal b iota needs to be assessed. On the stand scale, the degree of recovery (resi lience) of populations and communities after human-caused disturbance versu s natural disturbance, that is, the succession process, could be a useful c riterion when developing new forestry methods. On the landscape scale, it i s important to maintain enough patches of suitable habitat for the old-grow th species in order to prevent local extinctions and to promote recolonizat ions. Natural landscapes could be used as a reference here. In conclusion, although possibilities of matching forestry with maintenance of taiga biota through development of harvesting methods that mimic natural disturbance s eem reasonably good, there is an urgent need to establish criteria for the assessment of the success or failure of such methods. The resilience of for est ecosystems as reflected in population changes of surrogate taxa after d isturbance could be used to guide management. (C) 1999 Elsevier Science B.V . All rights reserved.