Small mammals respond to extreme habitat fragmentation in the Brazilian Atlantic Forest according to the landscape continuum model

摘要

There are several factors that can determine the pattern of habitat use by species in fragmented habitats. Here we investigated the applicability of the continuum model, which predicts that habitat use varies in a continuous way and not categorically like habitat and not-habitat, for small mammal habitat use. We also investigated if habitat-related guilds of species can change their habitual pattern of habitat use in an extremely altered landscape. This study was conducted in a highly fragmented area of Atlantic Forest in Brazil, where forest fragments are immersed in a pasture matrix. We captured mammals using pitfall traps placed in six sampling sites. In each of these sites, we selected four of five different habitats that were available in the local landscape: high-elevation forests without stream, low-elevation forests with stream, forest edges, pasture matrix without stream, and pasture matrix with stream. This study revealed that the theory of the continuum model can be applied for investigating patterns of use of fragmented forests by small mammals. We also observed, in general, low tolerance of forest species to the most disturbed habitat, the pasture matrix without stream. However, a small increase in the complexity of the vegetation, as observed in riparian pasture matrices, seems to mitigate this negative effect, making the abundance, richness, and diversity of small mammals comparable to forest habitats. These results indicate that the presence of streams may facilitate the use of the pasture matrix, contributing for the maintenance of the original community in the fragmented forest.