The Atacora mountains range in northern Benin (660 m altitude) is a special ecosystem in the sudanian zone because of the overriding importance of topographic factors and shallow soils. The vegetation over this mountain range consists of shrub and tree savannas, woodlands and fallows. More and more cattle herds graze on this range. But the functioning of this ecosystem is still unknown like many others in the tropical zone (Sene & Zingari, 2001). This study aims to determine the impact of topography and mountain side exposure on the productivity of the Atacora mountains grasslands in the Atacora mountains
