Negative effects of urbanization on terrestrial arthropod communities: A meta‐analysis

Abstract

Aim: Urbanization is one of the most significant anthropogenic alterations of the surface of the Earth and constitutes a major threat to biodiversity at the global level. Arthropods are a very diverse group of organisms, with many species that provide essential ecosystem services. However, their response to urbanization is still unclear. Here, we describe the first meta‐analysis to evaluate the overall effects of urbanization on terrestrial arthropod communities and driving factors related to cities, arthropods and methods. Location: Global. Time period: 1979–2019. Major taxa studied: Arthropods. Methods: We compiled a dataset of 162 publications that have evaluated the effects of urbanization along rural–urban gradients, which yielded 196 observations for diversity and 148 for abundance of arthropods. Moderator variables related to cities (climatic region, size, age, air pollution level and vegetation cover), arthropods (taxonomic and functional group and mobility level) and methods (study duration and type of gradient) were considered. We analysed the data through a hierarchical meta‐analysis that allowed us to take into account the dependence of multiple effect sizes obtained from one study. Results: Overall, urbanization had a negative effect on the diversity and abundance of terrestrial arthropods. The magnitude of the changes in diversity and abundance along the urban gradient depended on the arthropod taxonomic group. Coleoptera and Lepidoptera were the most affected groups, suggesting that not all species respond in the same way to urbanization. In addition, the age of the cities had a slightly negative influence, but only on abundance. Main conclusions: Our results indicate that terrestrial arthropod communities are less diverse and abundant in more urbanized landscapes. Considering the current biodiversity crisis and the fact that urbanization is one of the most extreme forms of global environmental change, the evidence presented here could be useful to support and direct new conservation efforts in urban habitats.