Characterization of primary productivity levels of Niger by means of NOAA NDVI variations

Abstract

Usual ecoclimatic zonation schemes are based on ground collected information such as meteorological and topographic data. Such schemes are not capable of identifying all the complex environmental factors which can affect vegetation dynamics. On the other hand, the NDVI (Normalized Difference Vegetation Index) acquired by NOAA AVHRR can be a direct indicator of vegetation quantity, type and condition on a regional scale. In the present work a characterization of a Sahelian country, Niger, according to its primary productivity levels is developed based on the analysis of intra and inter‐year variations in NDVI. The mean NDVI levels of the sub‐districts from four successive rainy seasons were first compared to the relevant ground derived estimates of primary productivity. Then, by an analysis of the seasonal NDVI profiles, the identification of three main zones with different ecological characteristics (woodland, Sahel, desert) was performed. Given the enormous ecological and social importance of the area, which is subjected to desertification phenomena, a straightforward zonation scheme like this could be of great utility for assessing the state of the environment and for planning future activity.