Impacto de estradas sobre mamíferos terrestres: o caso do Parque Estadual do Rio Doce, Minas Gerais

Abstract

Roads are essential and necessary undertaking to human life which can permit the movement of people and products carrying development and progress. However, there are little knowledge at road impacts in natural areas of Brazil. In that way this work was carried out in Rio Doce State Park (PERD), Minas Gerais, to evaluate the impacts of Ponte Queimada road (MG-122) within PERD on terrestrial mammals. It was estimated the terrestrial mammals species richness at road borders, the use intensity of the road and its borders, and the over run frequency of mammals in the road. This study also suggests a program to detect trends in medium and large mammals species richness in the borders of road. It was used sand plots (50x50 cm) to obtain medium and large mammals species tracks in two areas (1 and 2). Each grid was composed by three parallel transects at three different distance of road: 12, 82 and 152 metros inside the forest. Each transect received 20 sand plots that were observed two days per month during March until November, 2000. The proportion of each mammals species tracks in each sand plot was used as a measure of its relative abundance. From 16 identified species, Puma concolor, Leopardus wiedii and Tapirus terrestris was present in the Red Book of Threatened Species of Minas Gerais State. The more abundant species were Dasyprocta sp., Didelphis spp., Sylvilagus brasiliensis e Cuniculus paca. The number of species was different for each sampling area and the transects either differ in the number of species that use them for each sampling area (p<0,05). The results indicates that the presence of road modified, for many mammals species, the way that they use the area making a gradient of use between edge and road until 152 metros into the forest. The two areas showed different patterns of habitat use whit edge effects at least 82m and 152m to area 1 and 2, respectively. The vegetation structure at road's border seems to be the major factor that explained the different valuation species richness among areas. This study registered relative low number of traffic road kills (n=9), however, if consider that this road pass over a conservation unit fragmented, whit small and isolated populations, actions could be taken to minimize this kind of environmental impact avoiding traffic road kills in the future. The major conclusion suggest that road could be action like corridor or barrier, attracting or repulsing PERD mammals. Finally, important informations were showed to establish an analyze quantitative method using tracks of mammals like a secure procedure to Environmental Impacts and Conservation Biology studies.