Fill two needs with one deed: Redes multicamadas aves-plantas e a manutenção da ornitofauna em ambientes urbanos

Abstract

The constant advance of urbanization and human expansion in recent decades has led to significant habitat loss and fragmentation, altering the structure of ecosystems. Two important ecosystem functions that can suffer from anthropogenic impacts are pollination and seed dispersal. These interactions are relevant to the diversification, reproduction and maintenance of the plants and animals involved, as well as the structuring and functioning of ecosystems, and it is known that their diversity declines with changes in land use, including urbanization. With this in mind, we analyzed bird-plant interactions by building multi-layered networks in Ilha Solteira and Campinas, two cities in São Paulo, Brazil. We divided the networks for each city into resource networks (fruit and flower) and the effectiveness of the interactions in the two resources (legitimate and illegitimate), totalling three networks per city. The resource networks proved to be not strongly modular, confirming a trend of the generalization of interactions in urban environments, but which has never before been explored in a multi-layered network. They were contrasting networks in terms of the potential functions performed by birds, since Ilha Solteira had a higher rate of legitimate interactions in seed dispersal (57.4%) and illegitimate interactions in pollination (58.9%), while the opposite occurred in the Campinas networks, with 51.8% and 74.2%, respectively. We found no significant relationships between the role of the species and the origin of the plants, indicating mixed interactions between birds and native and non-native plants. We also noticed a contrasting relationship between the centrality and mass of the birds, where smaller birds were more important in their roles in a small urban natural area (Campinas), while larger birds were more central to the structure of the networks in a mostly urban environment (Ilha Solteira). Finally, we identified key plant species in the localities, such as Bombax ceiba (non-native), Inga laurina and Handroanthus vellosoi, both natives (Ilha Solteira); and B. ceiba, Spathodea campanulata and Roystonea oleracea, all non-natives (Campinas), capable of providing both flower and fruit resources for birds in the region, making them interesting for urban planning based on bird conservation, and the possible replacement of non-native trees with natives of similar importance in structuring interactions.