Land-use impact on plant communities in semi-natural sub-alpine grasslands of Budalen, central Norway

Sub-alpine, semi-natural grasslands induced by mountain summer farming in Budalen, central Norway, can be divided into two main habitats: small enclosures at each summer farm site, and the pastures surrounding them. Enclosures are exposed to different land-use regimes including grazing, mowing, fertilisation and soil disturbance. Pastures have never been fertilised or ploughed and the current grazing pressure is moderate. All investigated pastures are former haymaking areas. Higher conservation values of pastures compared to enclosures is reflected both in patterns of species richness and the occurrence of vulnerable species. Higher species richness in pastures is related to lower nutrient levels, lower loss of ignition in the soil, and higher levels of pH. Vulnerable species are concentrated in species-rich pastures, and have tow local abundance and regional distribution. Enclosures reflect a complexity in land-use, were the effects of mowing, fertilising and ploughing on plant community patterns could not be separated. Tree and shrub species are common in both habitats, and indicate a successional invasion of woody species. Maintenance of land-uses that have created semi-natural grasslands in the long term perspective (grazing, cutting of trees and shrubs, and mowing) is necessary to prevent forest succession, and a prerequisite for future conservation of sub-alpine, semi-natural grasslands. (C) 1998 Elsevier Science Ltd. All rights reserved.