Most of the Sahelian region in Mali (8 - 12 deg N) has experienced a pronounced greening up over the last 2 decades. With areas around the Niger River and Niger inlands Delta being excepted. Herrmann et al (2005) found a stronger greening up than suggested by rainfall alone in the Niger inland Delta, and speculate that this is due to irrigation expansion. In this study no such greening can be seen in the Niger inland Delta. Mali, together with Burkina Faso is reported to have had increases in agricultural output over the last decades (Olsson et al., 2005). The relative increase in Rain Use Efficiency in Southern Mali (Fig. 13) might hence be a reflection of better production methods. Also Milich and Weiss (2000) found a correlation between rainfall and NDVI for an agroecological transect in Mali. They hypothesized discrepancies in the rainfall-NDVI relation to depend on seed pool germination failures following dry years, biologically useless rainfall (e.g. strong down pour that generates erosion) including so called "Mango" rains falling during the February and March (dry season) and causing premature germination of the seed pool. Further north into the pastoral regions Milich and Weiss (2000) found a one-year lag between growing season rainfall and growing season NDVI. They attributed the behavior to failures of the seed pool to germinate both due to thresholds in rainfall and grazing pressure. This study shows that despite an increase i n rainfall over central Mali over the last 23 years, the vegetation increase has been negligible. The regional ranking analysis of Rain Use Efficiency indicates that the region north of the bend in the Niger River in Mali has had the poorest development in terms of RUE. Click here for NPP trend map.