The report gives a concise account of the research carried out in Senegal from 1980 to 1984 on the inventory and monitoring of Sahelian grazing ecosystems. The method used is new in as much as it combines several techniques: orbital, aerial, and ground validation; in other words, the green herbage biomass present at the end of each rainy season is evaluated combining spatial advanced radiometer remote sensing with ground truth validation and low altitude systematic reconnaissance flights that allow for the evaluation of other parameters such as livestock and game densities. The method utilized warrants the evaluation of the 'offer" (green herbage biomass present at the end of each rainy season) and the "demand (number of animals present in the same study area). The comparison of the two sets of data thus makes it possible to forecast the management needs for the nine months of the forthcoming dry season and therefore to rationally manage range and herds at regional and local levels knowing the amount of food available and the number of stock to be fed. The project showed that this methodology is applicable on a large scale to the Sahelian grazing lands. Furthermore, the project suggests some improvements of the method and its generalization to the whole Sahel via a joint project allowing for a better and cheaper utilization of the resources and for a coordination of efforts of several states in order to reduce the cost of the availed data.