Bison create heterogeneous habitat that benefits wild bees: A decade of research in restored tallgrass prairie

Restored habitats require long-term management to maintain biodiversity and ecosystem function, but management strategies are often developed primarily to support plant communities with little knowledge of how management actions affect non-plant taxa. Wild bees are essential for the long-term resilience of restored ecosystems because of the pollination services they provide. Over a decade of research at The Nachusa Grasslands (Illinois), we have investigated how wild bee communities respond to management actions, in particular, bison grazing, an historic ecosystem driver of tallgrass prairie that is used for restoration management today. Our work suggests that bison affect wild bee communities through structural disturbance, perhaps by impacting nest site availability, rather than through effects on flowering plant communities. We show that bee abundance, but not species richness, decreases with the presence of bison and that bee nesting groups (ground-nesting, stem-/hole-nesting, and cavity-nesting) differ in their response to bison. We document a diverse community of Hymenoptera and their associated nest parasites nesting in bison wallows, a rare microhabitat in restored tallgrass prairies. Our results show that the spatiotemporal habitat variation created by bison helps to support the high diversity and abundance of wild bees observed in restored tallgrass prairies.