Role of midwestern USA forests in supporting habitat specialist and generalist bee populations

Temperate forests in eastern and midwestern USA are dominated by deciduous tree species that leaf out in spring, leaving heavily shaded understory habitats in the summer that provide few resources for bees. Before leaf-out in these forests, a flush of spring ephemeral flowers, as well as flowering trees and shrubs provide resources for bee populations. Bee species that specialize on these early flowers are mostly solitary species that do not persist into the summer season. Other bee species may use these early forest resources in spring but require complementary habitats to support their populations in the fall. We report on the association between forested landscapes and bee abundance in Ohio, USA from a large state-wide survey. We tested two hypotheses: 1) the abundance bees previously identified as forest specialists increases with forested landcover but species identified as habitat generalists do not, and 2) species richness of bees increases with forest cover by incorporating forest specialist and generalist species. Preliminary results show a positive association between forest cover and bee abundance per sampling event, bee species richness, and the abundance of forest specialists. Contrary to expectations, however, forest specialist and habitat generalist species showed similar patterns of abundance across a range of forest covers. Many of the forest specialist species had low relative abundances in the bee community, which might contribute to their weak response to forest cover. Land use history and life history factors may also contribute to the response of bee species to forest cover.