African Isobioclimates

Climate - in terms of temperature, precipitation and continentality - is a primary determinant in the distribution of vegetation. Salvador Rivas-Martinez and Salvador Rivas-Saenz (2004) developed a global bioclimatic classification system that quantifies key bioclimatic indices reflective of vegetation distributions. These indices can be used to model thermotypes (i.e. hot-cold gradients) and ombrotypes (i.e. wet-dry gradients). Their model was translated into GIS spatial algorithms during modeling of the US ES bioclimate data (Warner et. al. 2008). These spatial models were used (with minor adaptations) with Worldclim climatological data (Hijmans et. al. 2005) to model/map thermotypes and ombrotypes. These two maps were then combined into an isobioclimate map with a total of 157 composite classes. The African isobioclimate data was developed as a primary input dataset for an African Ecological Footprint mapping project undertaken by the U.S. Geological Survey and The Nature Conservancy. The project used a biophysical stratification approach - combining isobioclimate, surficial lithology, land surface forms, landcover, topographic moisture potential, and biogeographic ecological divisions - to generate ecological footprints. The composition and distribution of these unique footprints of the physical and biological landscape was then reviewed by regional vegetation and landscape ecology experts and attributed (labeled) to an intermediate scale African ecosystem class.