Planting native wildflowers improves vacant land as bee habitat in a post-industrial city

As people leave post-industrial cities, abandoned homes are demolished and
transformed into vacant lots. These greenspaces have been demonstrated to
provide habitat for urban wildlife and supply ecosystem services to
communities. In the post-industrial city of Cleveland, Ohio, U.S.A.,
approximately 37% of the state’s bee fauna has been collected within
vacant lots. Our goal was to determine if planting native wildflowers
(“pocket prairies”) on vacant land would improve these sites as bee
habitat. We hypothesized that pocket prairies would support a greater
proportion of the regional bee species pool, represented by Metropark
grassland bee communities in the suburban landscape, compared to unaltered
vacant lots. Using pan traps and hand vacuums, we sampled bees in each
treatment from June to September 2019. We collected 1,087 bees
representing 24 genera and 81 species. Bees visited over 30 floral
species, including native wildflowers and urban spontaneous vegetation.
Metropark grasslands supported a higher bee species richness and diversity
than urban pocket prairies. Both Metropark grasslands and pocket prairies
supported a higher bee abundance, diversity, and species richness than
urban vacant lots. Synthesis and Applications: Despite the substantially
smaller extent of the pocket prairies, these habitats supported a similar
bee abundance to the Metropark grasslands. Bees foraged on intentionally
planted wildflowers and non-native spontaneous vegetation, highlighting
the importance of managing both components in urban greenspaces. Our
results suggest that greening vacant land can improve post-industrial
cities as bee habitat.