Densities of large living and dead trees in old-growth temperate and boreal forests

We recorded and reviewed densities and basal areas of large living and dead trees in old-growth forest in Europe. Recorded densities were similar to those reported from old-growth forests in eastern North America, but lower than in northwestem North America. Based on our results we suggest that, 10-20 living trees per ha with dbh > 70 cm may have been typical values for many central European and south Scandinavian virgin forests. In boreal forests, it was probably common with at least 20 living trees per ha with dbh > 40 cm. Basal areas of living trees in mixed old-growth forests in central Europe and southern Sweden were 34-40 m 2 per ha on dry ground and about 60 m(2) per ha in wet alder-ash-spruce forests. Densities of large trees (dbh > 40 cm) were twice as high in the latter forest type than on dry ground in Bialowieza forest, Poland. Based on our results, we propose the following generalizations to be further tested in other old-growth temperate and boreal forests: 1. Among all standing trunks (including high stumps) about 10% are dead. but this proportion increases for the largest trees. The proportion of standing trees that are dead seem to be independent of total basal areas. Based on this, we suggest that the volume of dead wood is directly proportional to the productivity of old-growth forests. 2. Standing dead trees (snags) are on average larger than downed dead trees. Trees with dbh >40 cm often dominate the basal area and volume of standing dead trees and living trees. 3. About 30% (20-40%) of the basal area and volume of dead trees is standing in old-growth forests. This proportion seems to be independent of total volume of dead wood. Large disturbances by fire, strong winds and insects may temporarily change these proportions considerably in individual stands. (C) 2002 Elsevier Science B.V. All rights reserved.