Data from: Rainforest fragmentation decreases the robustness of plant-frugivore interaction networks

Tropical rainforests are biodiversity hotspots that provide a variety of
ecosystem functions and services. Seed dispersal by fruit-eating birds is
an important ecosystem process in the regeneration of tropical
rainforests, which is increasingly threatened by widespread deforestation.
In particular, the expansion of agricultural land often leads to forest
fragmentation, which can have a negative impact on the interactions
between plants and frugivores and thus on seed dispersal. However, little
is known about how forest fragmentation affects the structure and
robustness of plant-frugivore interaction networks. Here, we examined the
effects of forest fragmentation on species richness of frugivorous birds
interacting with focal tree species, and the structure and robustness of
plant-frugivore interaction networks in the tropical lowland forests of
northern Costa Rica. Species richness of frugivorous birds at the forest
edges increased with fragment size and forest cover in the surrounding
landscape, as well as with local fruit availability. Modularity and
robustness of plant-frugivore networks increased with enhanced fragment
size and forest cover, while network specialization (H2´) increased only
with greater forest cover. Additionally, the three common tanager species
(Ramphocelus passerinii, Thraupis palmarum, and Thraupis episcopus) were
identified as key bird species for network functioning by promoting
among-module and within-module connectivity. Conservation measures should
therefore not only focus on threatened specialist species, but more on the
key species that enhance network structure and consequently increase the
robustness of these trophic interaction networks. Ultimately, our study
demonstrates that tropical forest fragmentation simplifies network
structure, making these interactions more vulnerable to anthropogenic
disturbances.