Environmental and human-related gradients shape the community structure of medium and large terrestrial mammals in a...

Medium- and large-sized terrestrial mammals play key ecological roles in tropical forests; however, the relative importance of environmental filters and anthropogenic disturbances in structuring their assemblages in Amazonian campinarana (white-sand) ecosystems remains poorly understood. In this study, we evaluated the influence of these factors on species composition and habitat use by medium- and large-sized terrestrial mammals, as well as by the frugivore-herbivore guild in Amazonian campinarana ecosystems. We used camera traps and structural equation modelling. We recorded 22 species over 4721 camera-trap days, with assemblages dominated by frugivore-herbivores and by dietary and habitat generalists, such as the common opossum (Didelphis marsupialis). Habitat use by the overall mammal assemblage was higher in areas with lower vegetation height, whereas terrain elevation relative to the nearest drainage (HAND index) had an indirect effect mediated by vegetation structure. In contrast, frugivore-herbivore species showed more selective responses, with higher habitat-use intensity in areas farther from human influence. Mammal assemblages were predominantly influenced by distance to houses, whereas the composition of the frugivore-herbivore guild was associated with distance to houses and tree height. Our results demonstrate that even low levels of human presence are sufficient to structure mammal assemblages, reinforcing the need for spatially explicit management strategies aimed at conserving the functional integrity of these unique and highly sensitive ecosystems.