Differential response of plant and insect pollinator communities to fragmentation in coastal dune slacks

Abstract Habitat destruction and fragmentation are one of the main drivers of pollinator decline and biodiversity loss in general. However, the exact effects of habitat fragmentation on pollinator communities are still poorly understood, and it remains unclear which patch characteristics are most important in driving pollinator diversity and community composition. In this study, we inventoried plant and insect diversity in a total of 19 fragmented dune slacks in Belgium. Specifically, we assessed the effects of dune slack area and connectivity on plant and pollinator diversity and community composition. Additionally, we investigated to what extent plant diversity had an impact on insect pollinator communities. The results indicated that species richness of both plants and insects was significantly related to patch area, whereas patch connectivity only had a significant effect on plant diversity. Nestedness analyses showed that plant communities of small dune slacks were a subset of the communities of large patches, but no such patterns were found for insect communities. Turnover in pollinator communities was high and significantly related to the distance separating dune slacks. Overall, our results highlight the importance of large patches for sustaining both plant and pollinator communities. Additionally, enhancing connectivity has the potential to promote plant diversity and consequently benefit pollinator species.