Bird Communities in Amazonian White-Sand Vegetation Patches: Effects of Landscape Configuration and Biogeographic Context

摘要

Vegetation growing on white-sand soils is patchily distributed across the Amazon and is characterized by scrublands or open vegetation types (white-sand campinas) and by forests (white-sand forests) surrounded by contrasting habitat types. We studied birds in patches of white-sand campinas in contrasting landscapes in four regions located in distinct biogeographic units delimited by major rivers. Our aim was to investigate the contribution of landscape configuration and biogeographic context to patterns of species diversity and distribution. Araca and Virua landscapes (on opposite sides of Rio Branco) are composed by large and continuous patches of white-sand campinas, while Jau, Novo Airao and Uatuma landscapes (on opposite sides of Rio Negro) are composed by small patches of white-sand campinas isolated by continuous terra firme forests. Birds were sampled using mist-nets and qualitative censuses, and were classified as white-sand vegetation specialists or non-specialists. Bird species diversity was significantly different among studied regions, and composition was significantly different for both, specialists and non-specialists birds. Local variability in species diversity and composition was best explained by white-sand campina area, patch proximity, and distance to major rivers. We conclude that landscape configuration and biogeographical context influence patterns of bird diversity, abundance, and composition in Amazonian white-sand campinas.