A comunidade de pequenos mamíferos em áreas de savana metalófila e floresta ombrófila densa na Floresta Nacional de Carajás, PA: Estrutura, estratificação e impacto da mineração

Abstract

The species of small mammals (orders Rodentia and Didelphimorphia) show greater diversity in the Neotropical region and are good indicators of changes in habitats. We sampled two types of vegetation: Forest and Canga. The objectives of this study were to evaluate it is structure, vertical stratification and the impact of mining in the community of small mammals in the areas of Canga and Forest. We sampled six distantly separated parallel lines 50, 100, 300, 600, 900 and 1200 m from the edge, in each area. 60 traps were installed 20 m apart from each other interspersed in three layers: ground, understory and canopy, for a period of six consecutive nights. And pitfall traps and fall, with 15 buckets on each track, distant 10 m from each other only in forest areas. We sampled an area of each vegetation type closer and farther away from impact during two rainy and two dry periods, from 2009 to 2011. For the analysis, the MDS was applied to show the similarity or not among the areas, ANOVA and simple regression to evaluate the effect of the impact. We found very clear differences regarding the composition and structure in both types of vegetation sampled: the richness was higher in the Forest and the total abundance was higher in Canga. Of the 24 species sampled, 15 were recorded exclusively on the ground, eight in the soil and understory and a (Glironia venusta) exclusively in the canopy. Only Micoureus demerarae was recorded in the three strata and Caluromys philander only in the understory and canopy. The impact effect is much less evident in the Forest and in Cangas. The wealth and abundance drifted in relation to the distance from the impact, so the farther the richer and abudant the species. It is important to the continuity and deepening of studies of small mammals in the Carajás National Forest, expanding the scientific knowledge to propose measures to minimize the impact caused by the mining activity in Carajás region.