A Quantitative Evaluation of the Multiple Narratives of the Recent Sahelian "Re-greening"

Abstract:

We present an interdisciplinary spatial analysis that aims to assess the evidence for ecological, climate, and social dimensions of the "re-greening" of the Sahelian environment. We explore human-environment interactions by creating an archival database of donor-funded interventions in Burkina Faso, Mali, Niger, and Senegal from 1979 to 2001. We examine the spatial distribution of these interventions in relation to population density and to trends in precipitation and in greenness using the Normalized Difference Vegetation Index, or NDVI.

We classify three categories of environmental change using the spatial distribution of re-greening, its relation to precipitation, and population density: (A) regions at the northern grassland/shrubland edge of the Sahel, where NDVI varies interannually with precipitation, (B) densely populated cropland regions of the Sahel where significant trends in precipitation and NDVI decouple at interannual time scale, and (C) regions at the southern savanna edge of the Sahel, where NDVI has increased independent of precipitation.

Examination of the number of projects implemented from 1979 to 2001 in the three respective areas brings to the fore a diversity of relationships between greening, precipitation, number of development projects, and population density over the western Sahel. The most interesting of these characterizations is category B, covering the cropland areas where population density and "re-greening" are higher than normal, particularly where agricultural projects are present. These areas coincide with emerging hotspots of "re-greening" in northern Burkina Faso and southern central Niger known from case-study literature. In examining the impact of efforts to rejuvenate the Sahelian environment and livelihoods in the aftermath of the droughts of the 1970s and 1980s against the backdrop of a varying and uncertain climate, our findings support the transition from desertification to "re-greening" discourses in the context of adaptation to climate change.