Building biodiversity: Vegetated façades as habitats for spider and beetle assemblages

In a context of urban greening, vegetated façades offer a great potential to enhance urban biodiversity. Yet, little is known about the ecological drivers of such man-made ecosystems on assemblages.We assessed four types of façades: three types of vegetated-façades–CP (climbing plant façades), FL (felt layer façades) and SM (substrate module façades)–and concrete bare wall) as a control. On 33 façades located in and around Paris (France), we compared the effects of façade type with the area, the properties of the surrounding landscape on spider and beetle assemblages.The façade type showed major differences in their ecological, their floristic and their management specifications. CP were xerothermophilous habitats similar to cliffs, whereas SM and FL were damp and cool habitats, similar to vegetated waterfalls. These differences in local scale properties influenced more arthropod assemblages than landscape properties, which showed higher species richness and abundance in SM and lower ones in bare walls. Façade types clearly sheltered different beetles’ assemblages in terms of species and traits, including more affine to damp habitat in SM and FL than the other types. Despite the presence of few rare species of Northern France, the assemblages of spiders were dominated by generalist species.Our results show the capacity of vegetated façades to shelter arthropods and argue for their development in cities.