On Regreening and Degradation in Sahelian Watersheds

/ Matt Artz

PNAS, 29 September 2015, Vol. 112, No. 39

By Armel T. Kaptué, Lara Prihodko, and Niall P. Hanan

“For decades, the science and policy narrative relating to the West African Sahel has focused on perceptions of overgrazing and human-induced desertification. More recent reports of regional-scale recovery (“regreening”) following the severe droughts of the 1970s and 1980s are sometimes ignored.

Averages of (A) seasonal iNDVI and (B) seasonal iR across the Sahel from July to October for the period 1983–2012. The figure also shows the location of the southwestern Niger [1], eastern Mali [2], western Mali [3], and northern Senegal [4] regions selected for further investigation.

Averages of (A) seasonal iNDVI and (B) seasonal iR across the Sahel from July to October for the period 1983–2012. The figure also shows the location of the southwestern Niger [1], eastern Mali [2], western Mali [3], and northern Senegal [4] regions selected for further investigation.

“This study provides a satellite-based evaluation of changes in watershed-scale vegetation conditions in four regions of the Sahel from 1983–2012. Though the results support earlier reports of a “greening” trend, our approach identified strong regional differences in the extent and direction of change, and in the apparent role of woody and herbaceous components in driving the temporal trend.”