Urban pollinator communities are structured by local-scale garden features, not landscape context

Abstract Context Understanding the drivers of urban pollinator communities is relevant to both biodiversity conservation and sustainable agriculture, particularly in urban community gardens. However, much interest has been placed on bee communities, focused on bee species alpha diversity and which large-scale factors predict their occurrence and abundance. Objectives In this study we build on previous urban bee work by investigating how a suite of specific local-scale garden features and landscape context influence the composition of the entire arthropod flower visiting community in urban agroecosystems. Methods We conducted pollinator observations in 33 gardens across two large German cities, Berlin & Munich, over two years. We then tested the influence of local-scale and landscape-scale factors on pollinator community composition, and beta diversity. Results Across the two cities, local-scale garden features predominantly influenced pollinator communities in urban community gardens, more so than landscape context. Features such as vegetation height, floral and woody plant richness and bare soil cover significantly influenced pollinator community composition—leading to a dominance of preferable taxa such as bees, butterflies and hoverflies, while garden size and urbanization did not. Beta diversity of pollinator communities did not decrease along an urbanization gradient indicating no urban homogenization impact on the full pollinator community. Conclusions Decisions made at the local garden scale can significantly influence pollinator communities and their floral resources. As we found that garden features can support beneficial taxa that provide important ecosystem services in urban agroecosystems, gardeners and practitioners can focus on implementing these features to support pollinators and therefore garden productivity.