Insect pollinator and natural enemy communities in green roof and ground-level urban habitats

Abstract

Urban greenspaces, including green roofs and ground-level urban habitats provide habitat for insect communities in cities. However, beneficial insect communities likely differ between human-managed habitats because of varying provision of resources and connectivity in these greenspaces. This study examined the insect communities in four extensive green roofs and three non-adjacent, similarly structured, managed ground-level habitats. We detected a high degree of overlap in insect taxa but found moderate differences in overall insect community composition between the green roof and ground-level habitats. While there was no difference in Shannon diversity between green roofs and ground-level habitats, the ground-level habitat had greater insect taxa richness. Although, both green roof and ground-level habitats supported pollinators and natural enemies, ground-level had greater mean pollinator and natural enemy richness and Shannon diversity. Unexpectedly, green roofs intentionally designed using native plants for habitat did not differ from those that used non-native plants in insect community metrics used in this study. These findings suggest that connectivity and structure might play an outsized role in shaping urban insect communities.