Considering vertical space reveals hidden links and increased modularity of plant-frugivore networks

However, how vertical stratification of fruit sources and animal feeding niches affect the structure and functioning of frugivory networks has not previously been well studied. We used infrared cameras under trees and direct observations on trees to extensively sample the whole frugivory networks in a subtropical forest in Southwest China.

We analyzed the structure of on-the-tree, under-the-tree, space-free aggregated (where links lacked vertical spatial information), and space-based aggregated frugivory networks (where links included vertical spatial information). We uncovered vertical differentiation in frugivore composition (dissimilarity > 0.7) and less than 5% overlap of links occurring both under and on trees. Network analyses revealed high complementarity between the under- and on-the-tree frugivory networks.