Auswirkungen der Deichmahd auf Vegetation und Arthropoden

River dike grasslands provide habitats for plants and arthropods, while habitat quality strongly depends on vegetation management. Mowing and hay collection cause considerable mortality, while species groups may respond differently, depending on their position within the vegetation, and their trophic level. On dikes at River Inn in Southern Bavaria, we investigated the short-term effects of mowing regimes, fallow strips and hay handling on plant and arthropod diversity within a three-year field experiment. We applied different cutting times (early-June vs. late-September), fallow strips (top vs. middle of the slope) and hay handling techniques (raking vs. suction). To understand the response of arthropods from different trophic levels and strata, we collected carabids and spiders in pitfall traps, and true bugs and cicadas in sweep nets. The results indicate positive effects of early mowing on cicada abundance, while true bugs, carabids and spiders benefitted from late mowing. Fallow strips promoted all species groups, while hay handling had no significant effect. The short-term effects on plant and flower richness and abundance were minor. We conclude that spatio-temporal variation in mowing dates would benefit many species groups.