Paper Info
Title
Environmental and Anthropogenic Degradation of Vegetation in the Sahel from 1982 to 2006.
Abstract
There is a great deal of debate on the extent, causes, and even the reality of land degradation in the Sahel. Investigations carried out before approximately 2000 using remote sensing data suggest widespread reductions in biological productivity, while studies extending beyond 2000 consistently reveal a net increase in vegetation production, strongly related to the recovery of rainfall following the extreme droughts of the 1970s and 1980s, and thus challenging the notion of widespread, long-term, subcontinental-scale degradation. Yet, the spatial variations in the rates of vegetation recovery are not fully explained by rainfall trends. It is hypothesized that, in addition to rainfall, other meteorological variables and human land use have contributed to vegetation dynamics. Throughout most of the Sahel, the interannual variability in growing season Sigma NDVIgs (measured from satellites, used as a proxy of vegetation productivity) was strongly related to rainfall, humidity, and temperature (mean r(2) = 0.67), but with rainfall alone was weaker (mean r(2) = 0.41). The mean and upper 95th quantile (UQ) rates of change in Sigma NDVIgs in response to climate were used to predict potential Sigma NDVIgs-that is, the Sigma NDVIgs expected in response to climate variability alone, excluding any anthropogenic effects. The differences between predicted and observed Sigma NDVIgs were regressed against time to detect any long-term (positive or negative) trends in vegetation productivity. Over most of the Sahel, the trends did not significantly depart from what is expected from the trends in meteorological variables. However, substantial and spatially contiguous areas (similar to 8% of the total area of the Sahel) were characterized by negative, and, in some areas, positive trends. To explore whether the negative trends were human-induced, they were compared with the available data of population density, land use, and land biophysical properties that are known to affect the susceptibility of land to degradation. The spatial variations in the trends of the residuals were partly related to soils and tree cover, but also to several anthropogenic pressures.
Year
DOI
Venue
2016
10.3390/rs8110948
REMOTE SENSING
Keywords
Field
DocType
productivity,vegetation,land degradation,desertification,Sahel,remote sensing,residual trends,RESTREND,NDVI,rain-use efficiency,RUE
Vegetation,Growing season,Desertification,Land degradation,Remote sensing,Normalized Difference Vegetation Index,Geology,Land use,Precipitation,Soil water
Journal
Volume
Issue
Citations 
8
11
0
PageRank 
References 
Authors
0.34
0
2
Name
Order
Citations
PageRank
Khaldoun Rishmawi122.09
Stephen Prince2245.44