Retrospective gap analysis in a Swedish boreal forest landscape using historical data

The main problem when adapting forest management to mimic natural processes and structures is the lack of detailed knowledge about historical forest conditions. One way to refine these management goals is by local analysis of change in forest conditions over time. The aim of this investigation was to perform a retrospective regional gap analysis by using historical data. Forest surveys and cadastral maps from the 19th and 20th century were compared with a recent forest survey in a 170 km(2) coniferous forest landscape in the middle boreal zone of Sweden. Changes in species composition, age distribution and landscape pattern were analysed at different spatial scales using a GIS. Spatio-temporal analyses were made to compare representative forest types. During the 20th century, dear-cutting has replaced fire as the most important factor influencing the landscape pattern. The old-growth forest is fragmented and the proportion is much lower than in other boreal forest landscapes, Since the 19th century, the landscape has changed from a matrix of forest older than 100 years to a highly fragmented landscape with only small patches of forest older than 100 years. Multi-aged stands have gradually been converted to even-aged stands. The gap analysis indicates: a large deficit of multi-aged pine forest. Restoring this forest type requires large areas where Scots pine is allowed to naturally regenerate from seed trees on burned sites. Some trees need to grow to natural maturity (i.e. 200+ years) and die naturally. The restoration of deciduous forest should be directed towards mixed stands. Currently used models to describe the natural landscape are inadequate to use as basis for ecological landscape planning. We conclude that retrospective gap analysis can be used to refine goal setting in Swedish FSC-certification. (C) 2001 Elsevier Science B.V. All rights reserved.