Vegetation productivity and diversity of acid grasslands in Northern Greece as influenced by winter rainfall and limiting nutrients

摘要

The effects of fertilisation on productivity of individual species and total vegetation and on vegetation diversity were examined in a lowland and an upland grassland developed on acid soils in Northern Greece. Lime and potassium, that were applied only in the lowland grassland, did not affect plant growth. Fertilisation with nitrogen and phosphorus markedly increased vegetation productivity and changed species composition. Nitrogen, especially in combination with P, favoured the early growing grasses in the lowland grassland, the dominant grass species Agrostis capillaris in the upland one and reduced the number of species and the Shannon diversity index in both sites. Phosphorus applied alone favoured mostly the legume species. The relationship between community productivity and diversity was significantly negative in most cases. Effects of N and P on diversity index could be explained by their effects on aboveground biomass. They were more pronounced when winter rainfall was adequate in the lowland grassland and were moderated when vegetation in the upland grassland has been clipped and removed in the previous year.