Habitat corridors connect fragmented habitats to allow the movement of individuals between otherwise isolated ecological communities. Corridors have been shown to increase species richness in habitat patches, however, few studies have examined the influence of corridors on the abundance and spatial distributions of species in fragmented landscapes. Further, it remains unknown whether connectivity affects species’ number and quality of offspring. To look at the effects of corridors on communities, we studied wood-nesting Hymenoptera (wasps and bees) living in habitat patches across replicated experimental landscapes. Each experimental landscape was composed of a center patch of longleaf pine savanna habitat surrounded by four equally sized (1 ha) habitat fragments, one of which was connected to the center by a 150 m corridor. To collect wood-nesting wasps and bees, we used a passive method called trapnesting in which empty nesting resources (trapnests) were left in each habitat patch for a growing season to allow occupation by cavity-nesting Hymenoptera. We used two trapnest materials, wood and bamboo, and at the end of the growing season counted the total number of nests created per patch. Following removal of trapnests from the field, we allowed Hymenopteran individuals to emerge, to identify and measure all specimens.
Results/Conclusions
The most common groups that nested in the bamboo trapnests included mud wasps, ichneumonid wasps, and leaf-cutter bees (Megachile sp.). Hymenopterans constructed 243 nests total across all bamboo trapnests and 510 nests total across all wood trapnests. Species composition differed significantly between the two trap types (F=28.55, p=0.001), indicating that using two trapnest materials greatly increased representation of the total Hymenopteran community. However, we did not find any evidence that increased connectivity due to habitat corridors affected the morphospecies composition of wood-nesting Hymenoptera (F=1.53, p=0.185). In addition, habitat corridors did not significantly affect the abundance of Hymenoptera in either the bamboo trapnests (χ2=0.37, p=0.832) or wood trapnests (χ2=0.15, p=0.698). We have not yet analyzed differences in Hymenopteran body size and body condition between connected and unconnected patches. Our results indicate that connectivity does not affect wood-nesting Hymenopteran communities.