| Urban and suburban development is a dominant factor driving ecological processes at local and regional scales and its impacts on biodiversity and ecosystem services are alarming. Pollinators, especially bees, and the ecosystem services they provide are of particular concern, given their importance for both the conservation of native plants and their value to global food production. However, bees might benefit from moderate levels of development, depending on how they alter the availability of foraging and nesting resources. How such changes in bee communities and other floral interactors affect native plants persisting in urban and suburban areas is less studied. To determine how one type of low-intensity human development, suburbanization, affects bee communities, pollination, and the mechanisms involved, I characterized the bee communities of suburban and natural forests in the Raleigh-Durham area of North Carolina, and used a series of experiments and observations to explore factors driving bee communities and their pollination services to native plants. Overall, suburban forests more bees than natural forests. Moreover, suburban bee richness and composition was similar to those in natural forests. Bee abundance and richness were both positively associated with local floral diversity and the amount of open habitats in the surrounding landscape. Hand-pollination experiments using three native flowering plants suggested that increased bee abundance associated with suburban developments did not translate into increased pollination services. Finally, a manipulative field experiment demonstrated that floral herbivory, which is generally more prevalent in suburban areas, can indirectly effect plant reproduction through altered pollinator behavior and subsequently pollen export. Taken together, these results suggest that while suburban areas can hold conservation value for bees, increased bee abundance in suburban areas does not translate into increased pollination services to native plants. Furthermore, plant interactions with other floral consumers can modify the outcome of plant-pollinator interactions, and have sex-specific effects on plant reproduction. |
