SD23: Cedar glade bee communities and their interactions with endemic flowering plants

Bees are a group of obligate flower-feeding insects, and their diversity and abundance depend on the distribution of their host plants. For this reason, it is important to study the interactions between rare and endemic plants in threatened ecosystems and the bees that rely on them. Cedar glades are limestone rock outcroppings that provide insular habitat to a variety of endemic plant species, occurring only in a small region of central Tennessee. Surveys of wild bees in these systems are historically scarce. In 2023, we collected flower-visiting bees and wasps in replicated monthly surveys from April to September at three cedar glades. We demonstrate that this system maintains a high extant diversity of native bees despite ongoing development in the surrounding landscape, and we uncovered a complex assemblage of species interactions between bees and plants occurring throughout the flowering season. We collected 1,360 specimens representing more than 129 species, including 11 state records for Tennessee, disjunct populations of the Colletes robertsonii specializing on the endemic Dalea gattingeri, and numerous other rare bee species. These bees were captured while foraging on 77 different species of flowering plants. We found that the interaction networks between insects and plants were asymmetrical in the cedar glades - specialists tended to interact with generalists. Our research uses cedar glades as a model system for understanding complex ecological interactions and highlights the importance of these natural areas as biodiversity reservoirs in highly fragmented, human-modified landscapes.