The Great Green Wall is an unprecedented project designed to mitigate the effects of climate change and combat land degradation and poverty in the Sahelo-Saharan zone. The project represents much more than a simple reforestation initiative on the edge of the desert. It mobilizes scientists, engineers, governments' technical services, local associations and international organizations in order to preserve a threatened environment and to sustainably improve the livelihood of rural populations.
Desertification is not a fatality! And the countries that are particularly vulnerable to climate change bordering the south of the Sahara have decided to act against this phenomenon. The initiative comes from African leaders, the former Senegalese and Nigerian presidents Abdoulaye Wade and Olusegu Obasanjo, who launched in 2007 a project to reforest a 7,000 km long and 15 km wide cordon, stretching from the Atlantic to the Indian Ocean.
The valorization and the sustainable use of the scarce water resources of the Sahel are two of the essential objectives of the project.
© IRD
This project has been undertaken by the African Union, it has been endorsed by twenty countries of the continentAlgeria, Burkina Faso, Benin, Cape Verde, Chad, Djibouti, Egypt, Ethiopia, Gambia, Libya, Mali, Mauritania, Niger, Nigeria, Senegal, Somalia, Sudan and Tunisia 1 and it mobilizes numerous international organizations, research institutions, and local and community-led associations. Its implementation is steered by an international institution, the Pan African Agency for the Great Green Wall, and by as many national agencies as there are member countries.
From reforestation to integration of rural populations
"Initially introduced as a reforestation project to halt the degradation of soil and water resources, the Great Green Wall then took on a much more sophisticated and practical dimension," says Robin Duponnois, an IRD microbiologist specializing in symbioses between tree roots and mycorrhizal fungi. The initial ambition was to restore the density of the ligneous cover, in the zone where rainfall allows it400 mm/m2/year. In the Sahara itself, where almost nothing grows, it is 100 to 200 mm/m2/year.1 , by massively planting trees. Their presence allows graminae to settle underneath, it attracts new pollinators and thus favors the restoration of biodiversity and soils. The approach adopted by the Great Green Wall differs from comparable projects based on the planting of fast-growing exotic species, which have often been bound to fail: each of the countries involved has thus identified a set of local species useful for reforestation, based on the species' ability to adapt to the environment and on their value to local populations in the area involved.
Faidherbia albida trees, which lose their leaves in the rainy season and, conversely, provide protective shade for crops in the driest season, are valuable allies in Sahelian agroforestry.
© IRD - Tiphaine Chevallier
The ambitions have since been broadened. It is no longer just a matter of reforesting environments, but rather to achieve sustainable management of ecosystems, edaphicsoil characteristics as an ecological environment resources and water resources, to develop the activities and income of local populations, to improve their health conditions, to fight against extreme poverty and to ensure food security...
Improving ecological and human well-being
“In this vulnerable area where populations live mainly off agriculture and livestock, environmental and social issues are multidimensional and interdependent," explains Sougueh CheikSougueh Cheik was granted a research allowance for a thesis in the South (ARTS), a research capacity building program for countries in the South funded by the IRD.1, an agro-pedologist at the Study and Research Center of Djibouti (CERD). “Acting effectively on one of the aspects without integrating the others is unrealistic!” Therefore, action programs aim to improve both ecological and human well-being. And they now take the form of a mosaic of integrated activities, adapted to each territory and social context
The involvement and commitment of local communities, from the design to the implementation of the project - which must benefit them - are essential conditions to its success.
© IRD - Fatou Diouf
What works in Senegal, for example in a given area where a form of activity combining plant and animal exploitation is practiced, cannot be transposed to the Horn of Africa, at the other end of the Great Green Wall, or even to the neighboring region of Mali or Mauritania! "And for this to be successful, the operations must more than ever involve local communities. They must be participating in the definition of the projects that concern them, owning them, implementing them and benefiting from them in tangible terms," says the specialist in cultivated soils.
From the very start scientific research has contributed greatly to the project, notably by focusing on the local species that perform best in semi-arid conditions, on reforestation techniques suited to the issues at stake, and on interactions with the rural population. In this new dynamic, where it is a matter of working in total synergy with the reality of local contexts, a multidisciplinary approach to challenges conditions the success of each intervention and, ultimately, of the Great Green Wall as a whole.
© IRD
The presence of trees adapted to the semi-arid environment allows the development of graminae underneath and promotes the restoration of biodiversity.
© IRD Editions
Le projet majeur africain de la Grande Muraille Verte
Concepts et mise en œuvre
Sous la direction de Abdoulaye Dia, Robin Duponnois
IRD Éditions
Collection : Synthèses septembre 2010
© IRD Editions
La Grande Muraille Verte
Capitalisation des recherches et valorisation des savoirs locaux
Sous la direction de Abdoulaye Dia, Robin Duponnois
IRD Éditions
Collection : Synthèses septembre 2012
