STRUCTURAL-CHANGES IN 3 MID-BOREAL SWEDISH FOREST LANDSCAPES, 1885-1996

Changes in the structure and composition of 123000 ha of boreal forest s 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 str ucture 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 year s old. Commercial exploitation in the late 1800s, subsequent intensive forest management and fire protection have generated a forest landsca pe dominated by relatively young and dense stands, totally different f rom the pre-exploitation forests. Since the late 1800s, both the numbe r 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 speci es considerably. We conclude that the essential characteristics of the natural forest landscape have to be re-created in order to restore an d maintain natural biodiversity. (C) 1998 Elsevier Science Ltd. All ri ghts reserved.