SATELLITE-BASED HERBACEOUS BIOMASS ESTIMATES IN THE PASTORAL ZONE OF NIGER

Pastoralists in the Sahel of northern Africa are entirely dependent on their livestock, which graze on the annual vegetation produced during a relatively short summer rainfall season. The satellite-based normalized difference vegetation index, calibrated with ground-truth sampling of herbaceous biomass throughout the pastoral zone of Niger, was used to estimate standing biomass for the entire Nigerien pastoral zone, Data were obtained and analyzed during a 5-year period from 1986 through 1990. Techniques developed allow officials with the Government of Niger to estimate herbage available to support animal populations throughout the pastoral zone at the end of the growing season and plan grazing strategies for the impending dry season. End-of-season herbage standing crop varied from less than 200 kg ha(-1) to nearly 1,700 kg ha(-1) with locations and years. Strong biomass gradients were evident from mesic conditions in the southern pastoral zone to xeric conditions in the north.