Species composition and above ground phytomass in chalk grassland with different management

During the last decades chalk grasslands lost their agricultural importance in the greater part of their distribution area in W Europe. Due to their botanical richness a number of chalk grassland sites were established as Nature Reserve. As a consequence of the semi-natural character of these grasslands an appropriate management is necessary to maintain or to re-create this vegetation including a great number of rare and endangered species.This paper deals with the results of three different management practices, viz. mowing in autumn, sheep grazing and abandoning, of a medium term (8–11 yr) permanent plot experiment. Sheep grazing was considered the best management since it resulted in the highest number of species, phanerogams as well as bryophytes, and the highest number of characteristic chalk grassland species. Abandoning resulted in a decrease in species number and a dominance of a few species only.The changes in species number are related to the above ground biomass. Under the canopy in the abandoned plot light intensity and the Red/Far-red ratio are very low, which partly explains the decrease in species number as such conditions are not favourable to seedling emergence and survival.Plant nomenclature follows Heukels & Van Ooststroom (1975) for phanerogams, Margadant & During (1976) and van der Wijk et al. (1969) for bryophytes, and Westhoff & den Held (1969) for syntaxa.Presented at the Symposium on Vegetation Dynamics, organized by the International Society for Vegetation Science at Montpellier, 15–20 September 1980. I am grateful to Dr. H. J. During for useful comments.