Is the Sahel greening?
Dr. Chris Reij
Recently, the issue of re-greening of the Sahel has brought lively debates among the scientific community around the world. According to some experts, a re-greening process is happening in the Sahel as a result of an increase in rainfall. Others argue it is due to changes in land and tree use legislation, which have given incentives to farmers to plant and maintain tree stocks. Some even say a re-greening process is not to the level of contributing to development.
In pursuit of this ongoing debate, a symposium titled “Green Sahel” was held on 28 October in Bonn, Germany. The symposium was organized by the German Agency for Technical Cooperation (GTZ). Intellectually stimulating contrasts were observed during the series of presentations, each of which provided its unique view on whether the Sahel is indeed greening. For example, Chris Reij, the Center of International Cooperation of the University of Amsterdam, showed how greener the Sahel is evolving. On the contrary, Hannelore Kusserow, the Institute of Geographical Sciences of the University of Berlin, explained why such a greening trend cannot be considered as a general trend in the Sahel. The two other panelists further enlightened the debate - Melchior Landolt of Terra-Verde e.V. by providing the perspectives of sustainable land management based on a project in Burkina Faso, and Thomas Hickle from Frankfurt University by showing, through theoretical model analysis, how rainfall fluctuation might be a stronger driver of observed processes than human activities.
According to Chris Reij, the re-greening process in the Sahel is evidently taking place. His study, located in Mali, Burkina, Niger and Ethiopia throughout a period running from 1955 to 2005, shows that within about 5 millions of hectares of cultivated land, there are more number of trees in 2005 than in 1955. “This is linked with human land management more than with rainfall fluctuation (…). Agroforestry techniques are spreading like a bush fire because this is the most cost-effective win-win strategy”, affirmed Dr. Reij. In his study, it is revealed that agroforestry techniques are good for the environment maintaining water cycle, biodiversity and soil life. Furthermore, greening of the Sahel helps to fight against poverty: “For the farmers it represents about 200 millions euros per year in terms of fodder, fruit, fire wood or natural fertilizers. Moreover, conflicts between herders and farmers have decreased by 80% because there is more resources available”, said Dr. Reij.
Hannelore Kusselow studied the same countries and claimed not being able to confirm such re-greening process. “In comparison with the situation before the 70s and today, the global trend is a “de-greening”, Dr. Kusselow mentioned. Furthermore, the professor noted that, as long as a sandy soil is remaining, a re-greening process is still possible; “but once crusted soils and sealed surfaces appear, desertification could be considered as irreversible, and unfortunately these sealed surfaces are increasing”, she lamented. For Dr. Kusselow, desert-like conditions are increasing in the Sahel, triggered by the increase of human demography and the decline of rainfalls over the last 20 years. “In such a trend and in a business-as-usual scenario, Sustainable Land Management techniques will not be sufficient enough to avoid land degradation to spread out”, Dr. Kusselow added.
Between these two points of view, there are some more consensual voices. As Melchior Landolt said, “both re-greening and land degradation processes exist at the same time”. In 2008, the Global Assessment of Land Degradation and Improvement showed that, between 1981 and 2003, both land degradation and recovery processes have occurred, with a balance in favor of land degradation (+24%) instead of land improvement (+16%)[1]. Then, beyond this debate, the understanding of the drivers and their respective weight in the processes are key issues to deepen in order to reverse the trend.
For more information :
Bertrand VINCENT
ARCE Unit
UNCCD-Secretariat
Hermann-Ehlers-Str. 10, 53113
Bonn, Germany
bvincent@unccd.int
[1] Bai ZG, Dent DL, Olsson L and Schaepman ME 2008. Global assessment of land degradation and improvement. 1. Identification by remote sensing. Report 2008/01, ISRIC – World Soil Information, Wageningen
