Arthropod diversity and ecological processes on green roofs in a semi-rural area of Argentina: Similarity to neighbor ground habitats and landscape effects

Green roofs could mitigate the negative effects of urbanization by providing habitats for arthropods. However, more studies are necessary to understand if these new ecosystems can harbor similar numbers of species and levels of ecological processes than habitats at the ground-level. In 15 houses of 1-2 floors with extensive green roofs from a semi-rural area in Cordoba (central Argentina), we analyzed the species richness and abundance of arthropods on green roofs and their neighboring ground-level habitats and evaluated the influence of landscape composition (proportion of buildings, grasslands, and streets). We focus on feeding groups (herbivores, predators, omnivores, detritivores, parasitoids, and pollinators) and two ecological processes (herbivory and predation). Moreover, we tested two factors that may drive the communities on ground-level habitats and green roofs: habitat area and plant species richness. Species richness and abundance of arthropods (total and by feeding groups), and predation rates were significantly higher in ground-level habitats than on green roofs. Nevertheless, arthropod diversity on living roofs was striking, with almost 400 species from different feeding groups. Street cover in the landscape negatively affected total richness and several feeding groups. On ground-level habitats, herbivory increased with street cover and predation with grassland cover. The main factor driving arthropods in both green roofs and ground-level habitats was habitat area, whereas plant richness had a positive effect only in predators, detritivores, and omnivores. Our results reinforce the role of green roofs as habitat for arthropod species in semi-rural areas of Latin-American countries, where the evidence was so far lacking.