Habitat amount interacting synergistically with cattle intrusion drives pervasive changes in leaf-litter ant assemblages in Amazonian Forest remnants

Deforestation driven by the expansion of cattle ranching activities towards the southern edge of the Amazon Forest transforms the landscape and is a threat to biological diversity. A secondary impact associated with this kind of fragmentation is cattle intrusion in Legal Reserves. To assess the fragmentation effect (habitat amount) and cattle intrusion on forest remnants, we sampled ground-dwelling ants in 24 forest remnants and the matrix adjacent to each remnant, in Meridional Amazon, Brazil. In all, we recorded 3,156 occurrences of ants, comprising 262 species. In addition to the natural characteristics of the areas (leaf-litter weight), the changes resulting from fragmentation (habitat amount) and cattle intrusion act synergistically affecting ground-dwelling ants’ assemblage. This result shows that the pervasive effect of habitat reduction due to forest fragmentation combined with habitat degradation (habitat quality) in the ground-dwelling ants’ assemblage.