Large Protected Areas Safeguard Mammalian Functional Diversity in Human-Modified Landscapes

Abstract

Habitat loss and fragmentation are pervasive processes driving the disappearance of populations and species in the Neotropical region. Since species loss may translate into functional loss, assessing changes in the composition of assemblages’ functional traits might improve our understanding of the ecological roles played by species and ecosystem functioning. Here, we investigate how landscape structure and composition impact the functional diversity of terrestrial mammals in 18 forest patches composing eight protected areas in Southern Brazil. We used functional diversity (FD) based on dietary, physical, and behavioral traits and species vulnerability to extinction. We determined which landscape variables (patch size, proportions of forest and sugarcane, and patch isolation) most influenced mammal FD values by using a both-direction stepwise model selection from a linear global model. Finally, we evaluated the role of trophic guilds in explaining the variation in the FD values using a Principal Component Analysis. Between 2012 and 2017, using camera traps, we recorded 26 native medium- and large-sized mammals throughout the protected areas, of which 6 are regionally threatened, and 5 domestic/exotic species. Richness among the forest patches varied from 4 to 24 species (9.05 ± 5.83), while the FD values varied from 1.29 to 6.59 (2.62 ± 1.51). FD variation was best explained by patch size, which exhibited a strong positive correlation (adjusted R2 = 0.55, slope = 0.67, p < 0.001). Insectivores and frugivores presented the highest correlation with patch size, explaining most of the variation in the FD values. Our findings strengthen the paramount role of large protected areas in maintaining mammal diversity and their ecological functions in human-modified landscapes.