Local and landscape drivers of bee taxonomic and functional trait diversity within vacant lots

Cleveland, Ohio is a post-industrial legacy city with an over 50% decline of its peak population. As a result, an overabundance of abandoned homes have been torn down creating vacant land. Over 27,000 vacant lots are managed with monthly mowing, creating a mosaic of bee forage in the urban spontaneous vegetation. Further, vacant lots have been targeted for greening initiatives such as urban agriculture or pocket-prairies of native plants. These greenspaces support over 30% of known Ohio bee species. Towards developing a city-wide strategy for bee conservation, we aimed to determine how different approaches to greening influenced the functional richness of bees within a patch. To understand this, we compiled five years of bee collections from vacant lots, urban farms, and pocket-prairies. For each species we determined the body length, lecty, nesting type, and sociality. Next, we created null models of Cleveland’s urban species pool to compare how bees assorted in each habitat compared to random chance. We discovered that many functional traits responded similarly regardless of greening initiative. However, soil nesting, wood nesting, and specialist bees varied in their response to greening initiatives with fewer species found in pocket-prairies than expected by chance. Our findings illustrate that a low-cost vacant land management strategy of monthly mowing is as or even more valuable as bee habitat when compared to higher-cost farms or pocket-prairies. Our findings further illustrate the importance of these minimally managed greenspaces as forage and advocate for their incorporation as part of bee conservation plans for legacy cities.