Response of avian and mammal seed dispersal networks to human-induced forest edges in a sub-humid tropical forest

Abstract

Species-rich ecosystems as tropical forests are extremely vulnerable to anthropogenic destruction. Most tropical plant species rely on animals to disperse their seeds. However, patterns of mutualistic interactions have rarely been explored, and seed dispersal networks are still poorly studied in Africa. Here, we examine how forest edges’ (FE) seed dispersal networks differ from the mature forest (MF) at a West African sub-humid tropical forest within the National Park of Cantanhez (Guinea-Bissau). Additionally, we explore species’ roles within the network. MF had higher fruit availability, more frugivore visitors, and plant–frugivore interactions. Network structure was quite similar between habitats, showing signs of redundancy, and some robustness to species’ extinction. FE was more nested, modular, and specialized, whereas MF had higher connectance, interaction evenness, and robustness to extinction. Most species were generalists, but large-bodied frugivores prevailed at MF. FE showed a higher vulnerability, mostly to the loss of trees. Trees are key, keeping the structure of both networks. Large-bodied frugivores and fruiting-tree species that work as network connectors should thus be the focus of active conservation management in these forests. Only viable populations of these species will ensure a good performance of the seed dispersal network, promoting the natural regeneration of the ecosystem.