Habitat characteristics structuring bee communities in a forest-shrubland ecotone

Abstract

The relationship between bee community composition and habitat characteristics at local scales may inform management decisions and conservation strategies for species of conservation concern. Ecotones are transition zones between two adjacent habitats that can potentially support abundant and diverse bee communities by providing complementary habitat characteristics within the foraging distance of most bee species. In a forest-shrubland ecotone, we evaluated the relationships between multiple habitat characteristics and the taxonomic and functional diversity of bee communities. Early in the growing season, floral abundance was positively associated with bee abundance but negatively associated with bee richness and functional diversity, indicating that large floral displays increase specialization of common bee species. The abundance of trees within the ecotone was positively associated with coarse woody debris (CWD), and in turn CWD had a positive association with bee richness and functional diversity early in the growing season and positive association with functional richness later in the growing season. Ecological processes within the ecotone that convert trees into CWD may provide resources for aboveground cavity nesting bee species. Late in the growing season soil composition was associated with bee functional diversity. The functional richness of bee communities also had a positive association with the specialization of bee-flower interaction networks, indicating that bee communities with more functional groups contain more specialist bee species. Studies that disentangle the effects of specific habitat characteristics on bee community composition will help identify management strategies that are consistent with bee conservation in ecotone environments.