TIME SCALE FOR FOREST REGROWTH : ABANDONED GRAZING AND AGRICULTURAL AREAS IN SOUTHERN NORWAY

The purpose of the paper is to demonstrate how rapidly abandoned agricultural and grazing land becomes naturally forested. The study was carried out in The Romerike Landscape Protection Area in southern Norway. The area is a ravine landscape in a southern boreal vegetation region used for agricultural production and grazing of domestic animals for several hundred years. When agriculture was mechanized and single-product specialization was introduced about 1950, the area was gradually abandoned as agricultural land and lay open for regrowth as a forest ecosystem. The open areas, previously used for grazing, decreased by close to 50%, with an increase in areas covered by shrubs and forest, mainly grey alder. Succession rate of regrowth depended upon distance to forest edge and vegetation type with slower regrowth in wet areas at the bottom of the ravines compared to the dryer areas. The consequences of changes in land use are less diverse communities and a reduction in the length of ecotones between, e.g. forest and open land. The regrowth with forest could reduce the diversity of flora and fauna in the long term.