Structural changes in three mid-boreal Swedish forest landscapes, 1885-1996

Changes in the structure and composition of 123000 ha of boreal forests in Sweden, were analysed using historical records. These forests had not been commercially logged when the first forest surveys took place in the late 1800s, so the earliest surveys provide unique data on structure of the natural boreal forest. The pre-exploitation forests had many large-diameter living and standing dead trees (Pinus sylvestris L. and Picea abies (L.) Karst.), and were dominated by stands >200 years old. Commercial exploitation in the late 1800s, subsequent intensive forest management and fire protection have generated a forest landscape dominated by relatively young and dense stands, totally different from the pre-exploitation forests. Since the late 1800s, both the number of large trees and the volume of snags have been reduced by about 90%, and the area of old stands has diminished to <1%. These fundamental changes have reduced the number of habitats for many red-listed species considerably. We conclude that the essential characteristics of the natural forest landscape have to be re-created in order to restore and maintain natural biodiversity. (C) 1998 Elsevier Science Ltd. All rights reserved.