Associate Professor University of Texas Austin, Texas
Human-dominated habitats are expanding in size and number due to human population growth, thus it is essential to deepen our understanding of how local and landscape-level habitat composition impacts important mutualistic relationships in the face of these continued global changes. Green spaces within urban areas, such as parks, wildlife refuges, grasslands, and community gardens can be particularly beneficial for bees, but it depends on how they are maintained over time. We conducted a study to examine how changes in local environmental variables of green spaces and the surrounding landscape composition within a rapidly developing city over a 7-year period affect bee abundance, richness, and evenness, including comparisons between groups with different nesting strategies and body sizes. We found lower abundances of the overall bee community, below-ground nesting bees, and small-bodied bees in 2020 compared to 2013. We also found fewer species of below-ground nesting bees, small-bodied bees, and large-bodied bees in 2020 compared to 2013. These findings were mainly driven by local-level changes in percent bare ground and percent live vegetation and landscape-level changes in percent developed habitat across years. Our results indicate that changes in nesting and food resources for bees can alter bee diversity, thus green spaces should be managed in ways that improve nesting habitat and floral abundance to ensure that urbanizing areas can support pollinators.