Comunidade de pequenos mamíferos em um mosaico de plantações de eucalipto, florestas primárias e secundárias na Amazônia Oriental

Abstract

The Brazilian Amazon, with some of the highest levels of biodiversity in the world, is currently a prime target for expansion by the Brazilian forestry sector. However, in spite of extant political incentives for Brazil to invest in this market, little is known about possible impacts of forestry practices on animal communities. In this study fifteen sites of primary and secondary forests as well as commercial eucalyptus plantations at Jari in the northwestern Brazilian Amazon were intensively sampled to assess the impacts of alterations in habitat structure on the small mammal community. Species richness did not vary significantly among habitat types, however we observed a negative tendency within habitats with lower structural complexity. Sites with higher proportions of eucalyptus and early-stage secondary forest within concentric buffers bigger than three kilometers in radius showed a significant loss in species richness. Moreover, we observed significant differences in species composition between primary forests, and both secondary forests and eucalyptus plantations, related to the proportion of structural variables such as dead woody debris volume, tree basal area and foliage stratification. Our results suggest that although such modifications may favor some species, the loss of overall structural complexity associated with lower canopy cover and matrix permeability may bring up negative consequences for several other species, specially arboreal ones. The reduction of operation area extensions with an increasing intercalation of primary forests, and the promotion of natural understory regeneration in eucalyptus plantations are some strategies that should be adopted for mitigating negative effects of landscape-level and habitat structure changes on small mammal communities. Such actions will aggregate value to biodiversity conservation where land use is turned over to forestry sector.