An ecoregion is defined as a geographically dinstict assemblage of plants and animals that share similar environmental conditions and interact in such ways as to enhance their collective long term survival.
The Nile Basin is divided into sixteen terrestrial ecoregions, reflecting the great expanse of the basin. These are Victoria Basin forest savannah mosaic, Miombo woodlands, Acacia –Commiphora bushlands and thickets, the Ethiopian montane grasslands and woodlands, Sudanian savannah, Sahelian Acacia savannah, saharah desert and the Saharan woodlands and steppe.
Moving through the basin from south to north, there is a gradual change in elevation and climatic conditions, producing a striking latitudinal gradation in vegetation and fauna. This gradation in ecoregions is accompanied by a marked decrease in the diversity of plant and animal species.