Analyse du peuplement herbacé de la station sahélienne expérimentale de Toukounous (Niger): composition floristique et valeur pastorale

The condition of the herbaceous vegetation was established at the Sahelian Experimental Station of Toukounous (SSET), North-East of Niamey, through determination of the floristic composition, the covering, the floristic richness and the pastoral value in the various geomorphological units of the station. 57 species spread among 45 types and 18 families were listed. The herbaceous covering (80.7%) and the pastoral value (87.5%) are good overall. In this pasture, the annual graminaceous plants which are most dominant show a loss of floristic biodiversity to the detriment of the perennial species and leguminous plants with, respectively, a contribution to the covering of 69.5%, 0 % and 8.2%. Two types of pasture were distinguished on the basis of the floristic descriptions. They were the pastures with Dactyloctenium aegyptium (L.) Willd and Aristida mutabilis Trin. & Rupr. in the depressions and the dunes where the spatial distribution of the species was more or less regular with a great floristic diversity. On the pastures with Dactyloctenium aegyptium (L.) Willd and Tribulus terrestris L. located on the level of mixed grounds, it was observed that the phenomenon of predominance of a group of species is more marked than on the other units of landscape. The charge capacity of the station is estimated at 1,241 UBT per year (or, 3.6 ha by UBT per year).