Cities are growing rapidly, thereby expected to cause a large-scale biotic homogenization and reducing ecosystem resilience. Evidence for the homogenization hypothesis is mostly derived from plants and birds, whereas arthropods have so far been neglected. Further, not much is known on how urbanization alters ecosystem resilience. Here, we tested the homogenization hypothesis with three insect indicator groups. Further, we hypothesized that ecosystem resilience, calculated based on response traits of the three insect indicator groups, is lower in urban compared to rural areas. The indicator groups were bugs, beetles, and leafhoppers, which were caught on standardized birch trees in a total of six Swiss cities and six intensively managed agricultural areas nearby.
Results/Conclusions
Species turnover between cities was reduced for most indicator groups compared to species turnover between rural areas, suggesting that urbanization leads to a large scale biotic homogenization. Further, the analyses of response traits of the indicator groups suggest that in the urban ecosystem the arthropod communities are less resilient to disturbances compared to rural communities. Overall, the results show that urbanization has a negative large-scale impact on the diversity of native species, and that ecosystem resilience is reduced in cities compared to rural areas. Specific measures in cities targeted at increasing the persistence of species which are typical for the respective biogeographic region and vary in their response traits could help to stop the loss of biodiversity and ecosystem resilience.