Islands of humid forests in the middle of the brazilian semi-arid region

mapping the highland swamps of northeastern caatinga biomine using remote sensing

Abstract

Amid the semiarid Caatinga Biogeographic Dominion of Brazil there are areas significantly wetter than the surroundings, resulting from orographic rainfall that sustain enclaves of semideciduous or evergreen forests: the Brejos Nordestinos de Altitude (BNA). These areas are remnants of Pleistocene climate fluctuations and are considered priority areas for conservation, protected under the Atlantic Forest Law. However, a detailed map of these environments within the Caatinga is still unavailable. Using NDVI, digital elevation models, and satellite image processing, we generated a map of BNA occurrences in the Caatinga. We manually inspected the data and digitized the polygons. Our map reveals the presence of BNA in nearly all Brazilian states where the Caatinga is found. We provide shapefiles to support multiple environmental studies, including research regarding conservation and biogeography of this disjunct ecosystem.