Effects of suburbanization on forest bee diversity

Land-use change is a dominant factor driving species distributions, abundances, and diversity. Although there is increasing evidence that urbanization can affect the abundance and diversity of native species, less work has focused on the effects of urbanization on mutualist species, such as pollinators. Native bees are of particular interest because of their importance in conferring a critical ecosystem service and concerns over possible region-wide declines in native bee diversity. We investigated the effects of one form of urbanization, suburban development, on the abundance and diversity of bees in and around the Raleigh/Durham area of North Carolina. We established five paired sites in naturally occurring forest (forested) and suburban forest (suburban) and sampled for bees using a combination of bee bowls and hand-netting from March through July of 2008 and 2009. We found significantly higher bee abundance in suburban sites in both years, double that of forested sites. Observed species richness was greater in suburban sites, though only significantly so in 2008. There were no significant differences in diversity or evenness estimates between suburban and forested sites in either year. These results suggest that suburban developments have the potential to harbor more native bees than natural forests and underscore the need for more research within urban habitats. Further investigation into the mechanisms driving these results will lead to a better understanding of the impacts of urbanization on pollinator communities. Future research should focus on how such impacts subsequently affect the ecology of forest plant-pollinator interactions.