Remote sensing in the study of Brazilian mangroves: review, gaps in the knowledge, new perspectives and contributions for management

The incidence of anthropogenic pressures and the richness of mangrove areas in Brazil highlight the importance of multiscale/multitemporal studies, by the use of remote sensing technology, to provide information and data for Integrated Coastal Management. This review presents and discusses the applications and limitations of different remote sensing products for the study of Brazilian mangroves, shows the application of these tools for coastal management, and highlights gaps and new perspectives in this field of study. In the last three decades, the use of aerial photography and Landsat images, in a qualitative approach, predominated in the study of Brazilian mangroves, while images of other optical sensors and Synthetic Aperture Radar images, in a quantitative approach, are still expanding. The use of these remote sensing tools has generated very important results for the ecological knowledge of the ecosystem, for the planning and sustainable use of mangroves in the face of human pressures and for decision making in the integrated coastal management, in local, regional and national levels. Despite these advances, there are gaps and new perspectives of studies such as: use of new optical images with high spectral and spatial resolutions for mangrove species mapping; SAR images to estimate above-ground biomass; the use quantitative approaches as OBIA and vegetation index and calibration of remote sensing data with field data to estimate biomass. Here we show a framework to aid in the selection of appropriate remote sensing tools for studying mangroves in the perspective of integrated coastal management.