Management scale drives bee and forb biodiversity patterns in suburban green spaces

Land management can occur at very small scales, such as in individual home gardens, and at very large scales, such as at the municipal scale or beyond. The scale of management can affect environmental heterogeneity and thus can affect biodiversity at alpha, beta, and gamma scales. Urban areas provide a unique opportunity to evaluate the effects of large- versus small-scale land management on different scales of biodiversity. We surveyed floral resources and bees in residential backyards and powerline corridors in the Chicago suburbs, with yards representing small-scale management and powerline corridors representing large-scale management. We calculated alpha diversity, beta diversity, and gamma diversity for both floral and bee species. We also determined absolute nestedness for corridors and neighborhoods to gain further insight into effects of management on species composition. We found that beta diversity for both floral resources and bees was highest in response to small-scale yard management and its creation of heterogeneous landscapes, while alpha and gamma diversity patterns were less clear. We also found that the floral resource and bee communities demonstrated absolute nestedness in both powerline corridors and residential neighborhoods, respectively. Our results indicate that taxa may respond to the effects of management scale differently owing to variation in their mobility or resource requirements. Our study results demonstrate that suburban residential areas may be prime targets for biodiversity conservation due to their environmental heterogeneity.