Green corridors in urban landscapes affect the arthropod communities of domestic gardens

Abstract

Ecological corridors are landscape elements that prevent the negative effects of fragmentation. However, their effectiveness has never been clearly validated in urban landscapes.We analysed the role of green corridors in an urban context by comparing metacommunities of arthropods in (i) woodlots considered as sources of species, (ii) woody corridors and domestic gardens that are (iii) connected (CG) or (iv) disconnected to corridors (DG) and taking into account the connectivity of the matrix. We trapped 3 taxa of arthropods – spiders, carabids and staphylinids – because they are sensitive to fragmentation but with different dispersal capabilities. We analysed their species richness, abundance and taxonomic and functional composition.For the 3 taxa, the taxonomic and functional compositions of communities in CG were closer to those of the corridor and the source than those of DG. Woodland species were associated with source, corridor and CG. A lower abundance in DG was revealed for staphylinids and spiders. Lower species richness in DG was observed for staphylinids.The differences between taxa could be explained by the dispersal capabilities of the species and by their various responses to landscape structures. For carabids, processes at a wider scale could be responsible for their rarity in sources and, consequently, in gardens. For spiders, the colonisation from other sources could explain the high species richness found in disconnected gardens.Our results suggest that the role of corridors is crucial for enhancing biodiversity in green spaces such as domestic gardens. Our results clarify the effectiveness of corridors in urban landscapes and have direct implications for the ecological management of cities.