Bee communities in restored prairies are structured by landscape and management,not local floral resources

Restored habitats require long-term management to maintain biodiversity and ensure ecosystem functions. Management strategies are often developed for plant communities, including through seeding and disturbance management, but these actions are taken with a focus on plant dynamics and with little knowledge of the effects on non-plant organisms. Wild bees are often expected to respond to such management actions via their effects on local floral resource availability, but management may also affect bees by altering survival and nesting independently of plant community responses. Working in restoration plantings within a large, actively managed tallgrass prairie preserve, we separated the effects of management and landscape context on bee community abundance and richness from the effects of these covariates on bees mediated through the abundance and richness of the local flowering plant community. We found that bees responded primarily to disturbance management (via bison) and the amount of prairie and forest habitat in the landscape, indicating that across landscapes with relatively abundant flowers and nest-sites, these landscape-level resources are more important than local floral resources for structuring bee communities. In contrast, floral communities responded to restoration age and prescribed burning. Because bees respond to different factors and at a different landscape scale than local plant communities, we conclude that management designed for plants is not sufficient for pollinators. Landscape level restoration may therefore require targeted habitat design and management to successfully restore functionally important animals.