Locating Amazonian Dark Earths: Creating an interactive GIS of known locations

Amazonian Dark Earths are anthropogenic organic-rich highly fertile soils found in relatively small patches throughout the Amazon Basin. These soils are gaining considerable attention given the relative lower fertility of the majority of Amazonian soils in which they are embedded because of their improved agricultural potential and also because of their links to Amazonian pre-colonial history. Because of their small individual extent and local nature, documenting where these soils are located in the Amazon is a challenging task. Few comprehensive maps exist, and some locations are only approximate. In this article we present an interactive GIS in which we have tried to consolidate all known locations of ADEs to date, and to note for each location a level of accuracy and specificity of both the soil and its location. This is necessary as many older sources of locations are historical and give only an approximation of where they are. For more recent ADE citations, the geo-referenced location is given when available. The source citation is given for each location on the map, making this interactive GIS at once also a bibliography of Amazonian Dark Earth locations. We also discuss the selection of the cited locations, the creation of the GIS, and reflect on the potential uses of the resource. We acknowledge that the GIS is a work in progress, and we anticipate keeping it updated as more materials are published and otherwise made available.