PUB - Publikationen an der Universität Bielefeld

The gravimetric soil water content of four different successional stages of inland dune vegetation revealed pronounced seasonal changes and particularly a major drought period in the late summer. In order to analyze the effect of these seasonal water changes on the competitive interactions of two dominant species (Carex arenaria and Deschampsia flexuosa) in one of these stages root development was compared under experimentally manipulated water conditions in a minirhizotron experiment. Under well-watered conditions, the root growth of C. arenaria and D. flexuosa was not influenced by competition, but was significantly reduced for C. arenaria at low water availability. Accordingly, the relative yield based on total biomass was significantly lower under water shortage than under well-watered conditions for C. arenaria, indicating higher interspecific competition compared to intraspecific competitive interactions. These results indicate (i) that soil water status is an important factor for belowground competitive interactions and (ii) that seasonal changes in soil water content may have a pronounced effect on the outcome of competition and, in consequence, on the structure of the respective plant communities.