Effect of habitat and landscape fragmentation on the medium and large mammalian communities in the southeastearn Atlantic Forest in Minas Gerais

Abstract

The habitat amount and fragmentation of landscapes in the Brazilian Atlantic Forest contribute to population size declines and species extinction, especially for forest specialists. We describe the composition of medium and high mammals’ community in the southeastern Atlantic Forest of Minas Gerais and analyzing how mammal assemblages respond to landscape and different landscape variables. Specifically: (1) describe the diversity, abundance, and naïve occupancy of the mammal community, (2) compared the α, relative abundance and naïve occupancy of the mammal assemblages between seasonal and ombrophilous forest, (3) determine how the habitat amount, core area, patch size, area of the focal fragment, structural and functional connectivity, influences the richness of native, specialist, generalist, and exotic mammalian communities, and (4) know the beta-diversity across the all fragments and seasonal and ombrophilous forests. Additionally, (5) we present a short communication with the first record of bush dog (Speothos venaticus) in the Minas Gerais Atlantic Forest, and (6) we produce the video “Selfies in the Atlantic Forest” to disseminate the results obtained in this thesis. We conducted this research between January 2019 to March 2020 in 22 fragments in the southeastern Brazilian Atlantic Forest, in 15 municipalities of Minas Gerais and one of Rio de Janeiro. We identified a gamma diversity of 33 species, principally of the orders Carnivora and Artiodactyla. Alpha diversity and evenness profiles were not different between seasonal and ombrophilous forests, and the relative abundance only differed for Leopardus wiedii. The naïve occupancy did not reach completeness (naïve≠1), ranging between 5% – 68%, and the species Eira barbara and Didelphis aurita had the highest values. The differences between the two types of vegetation were given by the β-diversity, corresponds practically to the species turnover between forests. Therefore, we must conserve native forest remnants, seasonal and ombrophilous, to ensure the persistence of native mammals, mainly the most threatened species. The inference multi-model confirms the species-area hypothesis only to specialist species, their richness responds positively at the scale of 3000 m. The exotic species responds negatively at the scale 1000 m, and the generalist and native species did not respond significantly to percentage the habitat amount. However, when contrasting the effect of habitat amount with the other metrics of landscape, we found the functional connectivity is the most parsimonious model, for native and specialist species, indicating a possible threshold to ensure their occurrence. Additionally, we found a high beta diversity and species substitution between sites (90% and 85% respectively), and low species nesting (4%). In conclusion, we found that each group of mammals responds differently to the landscape metrics at a large spatial scale, therefore, to detect the effect of landscape metrics requires considering species groups, like native, specialist, generalist, and exotic species. These results highlight the importance of promoting functional connectivity between forest fragments and increasing the -stepping stones- to favor the conservation of a greater number of species and reduce the extinction of specialist species in the Brazilian Atlantic Forest of Minas Gerais.