Guild-specific responses of bats to landscape composition and configuration in fragmented Amazonian rainforest.
Abstract
Habitat loss and fragmentation are serious threats to biodiversity, especially in the Amazon Basin, where biodiversity is greatest and deforestation is continuing at an alarming rate. Nonetheless, little is known about the responses of biotas to spatially explicit aspects of landscape structure. Bats are a promising indicator group for studying consequences of forest fragmentation in the Neotropics. Therefore, population- and assemblage-level responses of bats to landscape composition and configuration were quantified at each of three focal scales (circles of 1-, 3-, and 5- km radii) at 14 sites in lowland Amazonia. Responses to landscape characteristics were scale-dependent. Abundance and richness were higher in moderately fragmented forest than in continuous forest. Moreover, the abundance of each of nine frugivorous species decreased with increasing forest cover. The abundance of frugivores probably responded to landscape composition (e.g. percentage forest, mean patch density) because of an increase in early successional fruits and flowers in areas with reduced canopy cover. In contrast, abundances of gleaning animalivores responded to landscape configuration (e.g. edge density), probably by exploiting low-contrast edges (i.e. closed canopy forest patches embedded in secondary forest) while foraging and travelling between higher quality resource patches. Synthesis and applications. Species- and ensemble-specific responses to aspects of landscape structure suggest that both compositional and configurational aspects need to be managed effectively in conservation planning. However, conservation decisions based on associations of biodiversity metrics (e.g. richness, diversity and rarity) with landscape structure may be problematic as they are composite characteristics that mask individual responses and potentially reflect only patterns of the dominant species or groups.