Abstract (eng)
A widely discussed practice in conservation is the use of extensive grazing and mowing to enhance biodiversity in European cultivated landscapes. Flood protection embankments in riverine landscapes have become important refugia for grassland communities, but also highly dependent on regular management. Grasshoppers (Orthoptera) are the most important herbivores in European grasslands. Here, they were used as model organisms to assess effects of the management measures grazing and mowing. The study sites in the Danube Floodplain National Park (eastern Austria) include both mown meadows and meadows that have only recently been grazed by sheep. Changes in abundance, species richness, assemblage composition and the impact on individual species on the flood protection embankment were assessed. Species composition differed greatly between grazed and mown sections of the studied dyke. Several species differed substantially in abundance between treatments, showing an increased abundance of Orthoptera in the mowing treatment. Especially species listed as Least Concern showed significantly higher abundances in the mown meadows. However, a significantly greater species diversity was recorded in the grazing treatment. The gradual grazing management was less invasive than the mowing regime and provided a wide array of different vegetation structures during the season. Therefore, it is advised to continue grazing or, alternatively, to mow at a lower scale to allow migration to undisturbed patches.