Impact of inundation regime and meadow management on wild bee communities and bee-flower networks in the Donau-Auen National Park.

Wild bee communities on flood-prone meadows were compared with those on rarely inundated sites in the National Park Donau-Auen. Flower-visiting bees ere sampled on 32 meadows between April and August 2016. Counter to expectation, flooding regime had no significant impact on observed individual numbers. Rather, bee species richness was higher on regularly flooded meadows. As a potential driver of this pattern, an increased beta diversity among annually flooded meadows was identified. Additionally, three network metrics erived from a bipartite plant-bee interaction matrix were analyzed. None of the network indices was affected by flooding regime. We conclude that extreme floods may have a devastating effect on wild bee populations, but communities quickly recover. This resilience surely depends on recolonization from the surrounding landscape. Hence it is important to consider biodiversity on a landscape scale beyond the limits of the nature reserve.