Diversidade de mamíferos de médio e grande porte em paisagens antropizadas da Caatinga

Abstract

The exploration of natural areas has intensified with the increasing of human population, notably because their needs for food production through agriculture and livestock. This process has caused exotic species introduction and changes in landscape characteristics which, in turn, determine structural changes in medium and large mammal communities. In order to fill the gaps about the consequences of change landscape on Caatinga mamalian fauna, this study aimed to identify the effect of anthropogenic disturbance on the diversity of medium and large mammals communities of Caatinga in two regions with different precipitation regimes and different conservation efforts: Catimbau National Park (CNP), PE, one of the largest conservation units in Caatinga, Pernambuco State, and Cariri (CAR), the driest region in Brazil, including a desertification nucleus of Caatinga. The main hypothesis tested was if the forest loss leads to impoverishment and homogenization of medium and large native mammals communities, favoring exotic species. Remote sensing techniques were used to determine forest coverage in 18 landscapes in CNP and 4 landscapes in CAR and camera traps were used to record medium and large mammals for 24 hours/day over five months in Pernambuco and nine months in Paraíba. Species composition and dominance patterns were described along the disturbance gradient and alpha, beta and gamma patterns of diversity were also estimated for the communities. As expected, the forest loss decreased the alpha diversity of native species and increased exotic species diversity in CNP. This also occurred in CAR, but the reduction of native species diversity as well as increasing of exotic species diversity in the most disturbed landscapes were non-linear. In addition, regional beta diversity was very low in both regions, suggesting that Caatinga is going through a biotic homogenization process. The gamma diversity of native species was also extremely low (8 species in CNP and 10 in CAR), given that 183 species have been recorded in Caatinga. Raising the concerns, about 75% of the records (593 in the PNC and 2808 in the CAR) were of exotic species. In fact, there is a general tendency for communities in the most disturbed landscapes being taxonomically diminished to only two species: Capra hircus (goats) and Cerdocyon thous (foxes), albeit rare species such as Mazama gouazoubira and Herpailurus yagouaroundi may still persist. Overall, the results indicate that both regions harbor novel mammal communities under a pattern of exotic species dominance. This is concerning once exotic species are predominantly herbivorous and can cause a considerable impact on plant biomass, with cascade effects on ecosystem functioning. To reverse this condition and avoid a greater mischaracterization of native mammalian fauna, we suggested that forest restoration actions should be implemented to control hunting and illegal trade, that native species should be reintroduced in locally extinct areas and the development of new models of sustainable livestock.