Pan-tropical 30m map of wetlands

Wetlands support rich biodiversity, filter excess nutrients and pollutants from water, mitigate flooding and droughts, and have the highest rates of carbon sequestration of all ecosystems. However, since 1900 we have lost more than 50% of the world's wetland area. Additionally, despite their high conservation value, we still lack accurate maps of wetlands for much of the world, making it more difficult both to assess the current situation and to protect what is left. In this study we developed a pan-tropical map of wetlands at 30m resolution. This map was created using a multi-sensor approach combining Landsat 7 and 8 multispectral time-series metrics, topographical indices derived from Shuttle Radar Topography Mission elevation data, and L-band radar data from PALSAR. A bagged classification tree model was developed using existing regional maps of wetlands as training. The wetlands class is divided into forested wetland, shrub/herbaceous wetland, and open water classes. The open water class is defined as pixels that were identified as open water in ≥90% of all clear Landsat observations 2000-2018, forested wetland is delineated using the forest cover product of Hansen et al. (2013), and shrub/herbaceous is the remaining vegetated wetland area. Using these methods and additional training data we will extend the analysis to create a global 30m map of wetlands that can be used for both scientific inquiry and land-use planning.