Increasing densities of leaf-cutting ants (Atta spp.) with proximity to the edge in a Brazilian Atlantic forest.

摘要

A survey of Atta sp. was conducted in Coimbra, the single largest remnant of the Atlantic forest of northeast Brazil to (1) evaluate whether the abundance of colonies changes with distance to the forest edge, (2) estimate the depth of edge influence, and (3) analyse whether A. sexdens and A. cephalotes, two co-occurring Atta species, respond differentially to edges. A total of 80 Atta colonies were identified, 43 belonging to A. cephalotes and 37 to A. sexdens. Although, both species similarly increased along the edge, the magnitude of the edge effect was species-specific, as indicated by a significant interaction term between species and distance. This study demonstrated for the first time a profound edge effect on the colony density of A. cephalotes and A. sexdens. Results indicated that populations of these species strongly benefit from the presence or creation of forest edges, and thus add to the list of disturbed habitats (e.g., secondary forests, plantations, pastures, roads, forest isolates) facilitating the spread of these dominant herbivores..