Fewer berries and more pods: losers and winners of chronic disturbance in an Ecuadorian tropical dry forest

Abstract

Although chronic disturbance is widely recognized as a main driver of biodiversity loss in tropical dry forests, their consequences beyond the taxonomic loss perspective (i.e the functional dimension of diversity) still need to be clarified, especially in those plant traits associated with dispersal. Here, we evaluated the effects of chronic disturbance on the functional diversity of a seasonally dry tropical forest, and their potential effects on the frugivores guild. We characterized eight plant traits related to seed dispersal and calculated the community weighted means and functional diversities for trees and the whole woody community. We used generalized linear models to evaluate the effects of the disturbance on these functional estimates in relation with the abundance and diversity of fruits as resources for wildlife. Our results revealed that, the dominance of plants with costly fruiting species was reduced with disturbance. Functional richness and divergence were reduced with the disturbance, mainly in the qualitative traits. Finally, the availability of resources was slightly different between groups of dispersers, observing a general pattern of reduction in the availability and richness of fruits with disturbance. Our results suggest that the changes in species richness and abundance are not random but the result of filtering on traits related to dispersal costs and their subsequent ability to withstand environmental stress. The observed changes in vegetation have a direct effect on the availability of resources for frugivorous species, which in the medium term can affect the woody species persistence and catalyze the woody species loss.