We sampled several arthropods (spiders, true bugs, beetles and hymenopterans) from buildings covered by green roofs in 115 sites across northern France. We considered 3 types of green roofs with diverse vegetal structures: muscinal (moss/sedum - M) roofs, herbaceous (moss/sedum and meadow - H) roofs and arbustive (moss/sedum, meadow and shrub - A) roofs.
The species richness and the abundance of most of the taxa were significantly higher on A roofs, which displayed more complex vegetation. Predominantly common species comprised the arthropod communities. However, xero-thermophilic species and species from sandy and rocky habitats were also present because green roofs could serve as habitat analogs of those dry natural habitats. Except for hymenopterans, we did not observe a difference in the functional composition of communities; however, the taxonomic composition of spider communities was significantly affected by the green roof type. The surrounding environment and other local variables exhibited a minor influence on the composition, abundance and richness of the arthropods. We revealed a major role for the vegetal structures in arthropod communities and the ability of green roofs to enhance urban biodiversity.