Partitioning of Bee Diversity at a Small Spatial Scale in an Urban Arboretum

Global pollinator declines have stimulated efforts to better understand local pollinator diversity. Urban greenspaces, such as parks and gardens, have the potential to serve as refuges for pollinators within urban landscapes. In this study, we surveyed bees within the University of Alabama (UA) Arboretum, a mixed-use park of roughly 24 ha, and the contiguous UA Harry Pritchett Running Park, a former golf course of roughly 57 ha, within the city of Tuscaloosa, AL. To investigate how heterogeneity within this small greenspace influences bee community structure, we distributed sample sites across 3 habitats, each with unique total area, land-use characteristics, vegetation, and management intensity. We combined morphological identification with molecular approaches for specimen identification using cytochrome c oxidase subunit I sequences to create a specimen + DNA barcode reference collection. Overall, we collected 386 bees and 42 species. Diversity was partitioned across habitats, suggesting that the community was structured by variation in landscape characteristics. Our results suggest ways in which urban pollinator refuges may be managed to enhance species diversity, such as by retention of unmowed areas and planting permanent gardens supporting diverse floral resources. Importantly, this survey sets a baseline for developing broader monitoring programs within the largely unstudied region of central Alabama.