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. Green roof and ground-level habitats supported pollinators and natural enemies, while ground-level had greater mean pollinator and natural enemy richness and Shannon diversity. Green roofs intentionally designed for biodiversity using native plants for habitat did not differ from those designed for stormwater management and energy reduction using non-native plants in insect community metrics used in this study. These findings suggest that urban greenspaces continue to provide valuable habitat while connectivity and structure play a role in shaping urban insect communities.