Fragment configuration or environmental quality? Understanding what really matters for the conservation of native mammals in the Atlantic Forest of Argentina

The fragmentation of natural environments is one of the most important threats to biodiversity and involves changes in landscape configuration and habitat quality. The Atlantic Forest of South America has been highly fragmented, which creates concern for the conservation of its biodiversity. We evaluated the effects of forest loss and fragmentation on the terrestrial mammal assemblage of the Atlantic Forest of Misiones, Argentina. The area still contains large fragments and a forest cover >50%. We evaluated the effect of the configuration of the fragments (area, isolation) and the quality of the environment surrounding them (% of forest, land uses, poaching). We sampled mammal assemblages with camera-traps. We used generalized linear models, with the number of species in smaller forest fragments (49 stations) and the difference in their composition to that of the largest forest fragment (control situation; 53 stations) as response variables. Species richness in the fragments increased with the proportion of forest in their surroundings and decreased with the distance to population sources. The dissimilarity of the assemblages of smaller fragments to those of the largest fragment increased with forest disturbance and by the contrast of the land uses (e.g., annual crops) surrounding the fragments. We modeled and mapped these effects, which can be used as spatially explicit planning tools for the conservation of the mammal assemblage in this landscape. The effect of fragmentation on the mammal assemblage is mediated by both anthropic effects that affect the quality of the environment and by the spatial configuration of fragments in the landscape.