The response of bats to landscape structure in amazonian forest: an analysis at multiple scales

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2007-05

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Habitat loss and fragmentation are currently the most serious threats to conserving biodiversity. This is especially the case in the Amazon Basin where species richness and diversity are at their peak, and deforestation is increasing at an alarming rate. Bats achieve their highest functional and taxonomic diversity in the Neotropics, and provide a suite of ecosystem services critical to maintaining tropical forests. However, very little is known regarding the response of populations and assemblages to spatially explicit aspects of landscape structure. The responses of 24 phyllostomid species and 4 assemblage characteristics to landscape structure were analyzed at each of 3 focal scales at 14 sites.

Satellite imagery was classified into two land-cover types (i.e., forest and non-forest) and processed with FRAGSTATS to quantify characteristics of landscape composition and configuration. Assemblage, trophic guild, and population responses to landscape characteristics were scale dependent. Frugivores responded more to landscape composition, whereas gleaning animalivores and assemblage characteristics responded only to landscape configuration. In general, the abundances and richness of species were higher in moderately fragmented forest than in continuous forest. This is likely due to the dominance of frugivores in assemblages and the abundance of fruits provided by successional plant species, suggesting that bats may be important in promoting secondary succession. Although frugivorous bats may increase when deforestation and fragmentation is small compared to the size of the regional landscape, changes in land use, specifically conversion of forest habitat, likely enhance the vulnerability of bats with specialized ecological requirements. Consequently, even moderate amounts of fragmentation can affect local populations and may thereby alter the structure of assemblages.

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