Small mammals of the southeastern Amazon and the ecological consequences of selective logging

The ecological consequences of the low-intensity selective logging that has occurred over vast areas of the Amazon Basin are often assumed to be minimal; however, few studies have tested this assumption. Additionally, although small mammals play important roles in tropical forests, they have been surveyed in few areas in the Amazon, survey methodologies are poorly developed, and the effects of selective logging on the fauna have not been examined. Thus, this study has three main objectives: (1) document the small mammal fauna at an unsurveyed site in southeastern Amazonia and compare the effectiveness of different trapping methods, (2) examine relationships between small mammal abundances and key habitat and resources variables, and (3) examine the effects of logging on small mammal communities, habitat structure, and seed predation. Small mammals were live-trapped in a variety of habitats, with traps of two types placed at three heights (ground, understory and canopy). Species abundances, habitat structure, resource abundances, and seed predation rates were examined at 300 trap stations in two logged and two unlogged sites. In total, 1,178 individuals of 8 marsupial and 17 rodent species were captured at the site. Including canopy traps, in addition to ground and understory trapping did little to increase the rate of species accumulation, a result attributed to the lack of a well-defined canopy stratum at the site. Analysis of habitat use indicated that many of the species were most abundant in disturbed habitats, in part driven by increased resource abundances. Across all sites, few significant changes were seen as a result of logging, suggesting that the low-levels of harvesting had a minimal impact on forest ecology. However, when examined separately the two logged sites had markedly different responses to logging, indicating that important site differences are mediating logging effects. These results indicate that although the effects of low intensity logging appear to be minimal and localized high degrees of local and regional variability complicate the extrapolation of these results beyond the study system. Indicating that under some conditions logging could greatly impact tropical forests especially if logging intensity are increased.