Uso de hábitat de mamíferos terrestres em fragmentos de floresta estacional decidual

Abstract

The constant environmental degradation, in special the habitat fragmentation, has leading to alterations in mammal populations around de world. Into the Campos de Instrução de Santa Maria (CISM), Santa Maria, State of Rio Grande do Sul/Brazil, it is not different, since the human colonization has led to habitat loss and fragmentation. In this region the Campos Sulinos (southern grasslands) and Atlantic forest, form a landscape where fragments of Deciduous Seasonal Forests are surrounded by grasslands now used for cattle-raising, agriculture, and military activities. In this study I evaluated utilization of forest fragments and grassland by mammals, focusing on their frequency of occurrence, richness, diversity, and abundance in three types of habitats (large forest fragments (FG) - > 193 ha, small forest fragments (PE) between 18 and 47 ha, and open areas (CA). I established "trapping" grids with six footprint traps, baited with banana, bacon and "gland lure". For each bi-monthly trapping session I revised the traps every four days after setting them, recording all footprints found. For a total of six trapping sessions between Aug/04 and Jul/05, where I obtained 364 records of mammal groups (formed for one or more species of the same family). Mazama sp. deers use large fragments more frequently whereas the canids (Pseudalopex gymnocercus and Cerdocyon thous) were more generalist in habitat use. The larger fragments showed higher richness (FG=9; PE=7 and CA=3), diversity and abundance of records than the other areas. However, there are significant differences only in the samplings of Nov-Dez/2004 and Jan-Feb/05, which the P values were 0,031 and 0,022 for richness and abundance. For the diversity the values of P were 0,042 and 0,010 in the same months. These differences occurred only between large fragments (FG) and grasslands (CA). Results indicated that large forested areas harbour a higher richness, mainly when compared to the grasslands. Larger forest fragments are important for mammals, but in our study grasslands shelter characteristic species of such areas, increasing beta diversity. In the CISM, even with the relatively high disturbance of the grasslands and Deciduous Seasonal Forest, the results showed the importance of different habitats into the idea of beta diversity (dissimilarity between habitats). A proper management of these areas would be important for mammal conservation of both Atlantic Forest and Campos Sulinos.