Habitat permeability drives community metrics, functional traits, and herbivory in neotropical spontaneous urban flora

Abstract

Urbanization is among the main drivers of global biodiversity changes. Urban areas are increasing faster, particularly in global biodiversity hotspots. Therefore, more evidence is needed on how urban gradients drive plant traits and interactions with herbivores in neotropical regions. Here, we investigated how urbanization intensity and habitat permeability affect metrics (species richness, composition and vegetation cover), functional traits, and herbivory of plant communities, focusing on spontaneous native and non-native species in a neotropical city in Brazil. Non-native species represented 64.6 % of the occurrences, and habitat permeability had a stronger influence on plant communities than urbanization intensity. The intensity of urbanization decreased the species richness and increased the specific leaf area in native and non-natives plants. Habitat permeability also affected species composition. Permeable habitats had higher vegetation cover, herbivory, and height of the non-native communities. Life forms as geophyte for non-natives, chamaephyte, and hemicryptophyte for natives, and zoochoric dispersal syndrome were more frequent in permeable habitats. Impermeable habitats had higher frequencies of therophyte life form, and autochoric dispersal syndrome for native species. The higher vegetation cover, the lower direct interference from humans, and the permeability of habitats allowed more different functional traits within plant community and more interactions between plants and herbivores along the urbanization intensity gradient. The permeability of urban habitats, in a medium-sized neotropical city, has greater influence on the variation of the plant community than the intensity of urbanization. This highlights the importance of the presence of permeable areas in supporting plant biodiversity within highly paved urban gradients.