Frugivores and seed removal at Tetragastris altissima (Burseraceae) in a fragmented forested landscape of French Guiana

Abstract

We aimed at (1) determining how community-wide disruptions affect visitation by frugivores at trees and (2) estimating the impact of visitation shifts on seed fate following fruit consumption, especially seed removal. We compared the seed fate of a frugivore-dispersed tree species (Tetragastris altissima, Burseraceae) in four forested islands with that for a mainland continuous forest at Saint-Eugène, French Guiana. Tetragastris trees attracted opportunistic frugivore species available in the area, the most productive trees attracting more consumer species. Only primates, which are more susceptible to forest disturbances than birds and have low abilities to cross a non-forested matrix, were more frequent at Tetragastris on the mainland than on islands. Only opportunistic frugivorous primate species acting as low-efficiency seed dispersers were recorded. As a result, seed removal was equally low among habitats (nearly 26%), high percentages of seeds dropping below tree crowns. The scarcity of large-bodied specialist frugivorous primates throughout the landscape probably explained this low removal. Our results underline how difficult it is to generalize the cascading effects of disruptions in a frugivore community on tree seed fate, these effects likely varying according to the tree species and animal community involved.