Quelques facteurs de la biodiversité végétale dans les prairies humides des corridors fluviaux

Abstract

Summary This paper examines the main ecological variables, constraints and perturbations, which control species richness in the communities and community diversity in the river—marginal wetlands of the Shannon (Eire) and the Torridge (Devon, U.K.). Conducted in the framework of a multidisciplinary research programme of the EC (Functional Analysis of European Wetland Ecosystems, FAEWE), this study concluded that hydrodynamics, linked with topography, controls community diversity. Above—ground plant biomass linked, with availability of nitrogen and phosphorus, control the degree of species richness. The maximum species diversity is found in moist oligotrophic grasslands, extensively grazed or mown annually. This corresponds with intermediate levels of disturbance and stress (sensu Connell and Grime).