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 the 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 tended to be lower in yards compared to the powerline
corridors. 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
variations 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.