The aim is to determine the relationship between the diversity of small mammals and the structural heterogeneity and/or secondary successional stages in an Atlantic forest fragment at Viçosa (Minas Gerais). We used Sherman and hook live traps to sample this fauna, monthly from may 1992 to april 1993 in three areas: an abandoned plantation of Melinis minutiflora (campo) and two distinct forest areas (capoeira and mata). The structural heterogeneity was determined as a function of the presence of dead trees, pioneer species, epiphytes, the distances between trees, the tree height and basal area measured by a modified quadrant sample method (Cottam & Curtis 1945). lt was sampled a total of 340 individuals belonging to 17 species. The homogeneous plantations had the highest diversity (H' = 1,67). Among the two forests stands the less heterogeneous capoeira had similar diversity (H' = 1,19) than the more heterogeneous stand, the mata (H' = 1,13). The unexpected higher diversity and species richness in the more homogeneous habitat may be explained by some hidden factor which decrease the competition for resources in this community.
Community structure; habitat heterogeneity; small mammal diversity