Woodland regeneration in a coastal heathland area in central Norway

摘要

The open coastal heulhlands in Norway have changed character in recent decades, mainly because traditional practices such as burning, cutting and grazing have been abandoned or reduced. In a project aimed at increasing our knowledge of woodland regeneration in oceanic boreal heathlands. an area on the island of Kalvaya in the archipelago of Vikna on the extreme outer coast of central Norway has been studied. Kalvoya has calcareous bedrock; rich heath, rich fens and low-herb woodland cover 20% of the island. Large parts are paludified, and wet heath and mire vegetation cover 60%. The island has not been inhabited, but it was used for summer farming in the latter part of the 19th century and later for stock grazing. The woodland and scrub were mapped using aerial photographs from 1961 and 1981 and by fieldwork in 2001. Vegetation changes were analyzed using GIS techniques. Woodland and scrub increased from 3.0% in 1961, to 4.3% in 1981. to 11.6% in 2001. Betula pubescens is the commonest woody species. The oldest trees are 150 to 175 years old, growing in the most heavily wooded area, far away from the summer farm. In addition to human impact (summer farm, grazing pressure), the geology, terrain (degree of exposure), and climatic factors are important for woodland colonisation and distribution.