Human activity causes abrupt changes in resource availability across the landscape. In order to persist in human-altered landscapes organisms need to adapt to these changes and shift their habitat use accordingly. Little is known about the mechanism by which whole communities adapt to these changes and persist in human-altered landscapes. We hypothesize that complementary habitat use is a mechanism through which native species persist in human-altered landscapes. Specifically, we studied wild bee communities in agro-natural landscapes and explored their community-level patterns of habitat and resource use over space and time. The study was conducted in the Eastern USA in 6 agro-natural landscapes. Within each landscape a block of the three main bee habitat types in the region was established – natural habitat (deciduous woods), agriculture fields and abandoned (old) fields. Within each habitat we established a 1 hectare plot and sampled bees and floral resources from spring to fall.
Results/Conclusions
Each of the three habitats exhibited a unique seasonal pattern in amount and diversity of floral resources, and together they created phenological complementarity in foraging resources available for bees across the agro-natural landscape. Individual bee species as well as the bee community as a whole responded to these spatio-temporal patterns in floral availability and exhibited a parallel pattern of complementary habitat use. The majority of wild bees, including all the main crop visitors, used chiefly the agriculture fields and old fields in a complementarily manner, while the natural habitat supported very limited number of bees, mostly not crop visitors. Hence, for maintaining crop pollination, old fields are an important feature in arable landscapes. Our study provides a detailed examination of the mechanism that enables bees to persist in highly dynamic agro-natural landscapes, and points to the need for a broad cross-habitat perspective in managing these landscapes.