Padrões de distribuição de mamíferos de médio e grande porte em paisagens fragmentadas

Abstract

Habitat fragmentation is defined as the breaking of a continuous habitat in “patches” or fragments. This process leads to environmental changes capable of affecting communities in different ways, causing species composition changes. Beta diversity measures can show the variation between the composition of different communities, where two ecological patterns can be found: turnover and nestedness. In turnover the variation in community structure is a consequence of species replacement, while in the nestedness poor communities are nested in richer communities. Here I tested: (I) how habitat fragmentation affects the presence of large e medium sized mammals in different functional groups; (II) if the variation in beta diversity in fragmented landscapes is caused by turnover or nestedness, and (III) if the variation observed was due to habitat fragmentation. I used 19 Semidecidous Forest patches in the Brazilian Cerrado, from the State of Goiás. Landscape metrics from 2.5 km around the patches were obtained from classifications and measurements. For the analyses, I made four sets based in diet, size, diet amplitude and all previous three together. I calculated the beta diversity with Sorensen indices, turnover with Simpson indices and nestedness with Nestedness indices. The natural area size influenced the group B3- felines and the core area percentage, the groups A1-carnivores, larges and B3-felines. The core area percentages were the most important character in fragmented landscapes for mammal communities. The felines were the most sensible group. This group was affected by natural area availability and by the core area percentage. The beta diversity pattern in the fragmented landscapes was turnover, but it was not related to environmental variation or spatial distances between the landscapes. Both nestedness and beta diversity were affected by spatial distance, but beta diversity was also affected by environmental variation linked to landscape connectivity. The changes in different landscapes cause different responses in species and allow the creation of a fragmentation gradient, driving the turnover phenomenon. The carnivores were the species most sensible to habitat fragmentation, mainly because they need large home ranges. Thus, an understanding of how diversity reacts to habitat fragmentation may provide support to the implementation of conservation areas and research upgrading which focus specific species groups. Managed areas with large core areas and good connectivity should bring desirable results for large and medium sized mammals conservation status. This affirmative is true, especially for larger mammals and carnivores.