Résumé
Desertification - defined as land degradation in arid, semi-arid and dry sub-humid areas, linked to the impact of climate change and human disturbance - causes habitat degradation, the disappearance of many species, and the loss of ecosystem services on which people living in these regions depend. The Great Green Wall (GGW) initiative is one of the responses to the challenges posed by desertification. The objective of this pan-African initiative, launched in 2007, is to restore the degraded landscapes of the Sahel, one of the most affected regions. There remains a critical need to articulate our understanding of restoration and protection of land, social and economic development, and conservation of biodiversity, to be able to properly document the various approaches, the significant outcomes they have achieved, and the lessons learned from each approach. Coordinating actions between restoration strategies and political decisions requires a detailed analysis of the context of the different biogeographical zones, countries, and ethnic groups, of the most abundant plant species in each territory, and of the various restoration practices applied. The objective of our study is to compare the actions undertaken since the beginning of this initiative in two neighbouring countries, Burkina Faso and Senegal, pioneers in the GGW initiative, in order to understand the advantages and limits of up-scaling restoration programs. Therefore, we will bring together different elements such as the criteria used in the selection of species planted and the distribution and abundance of indigenous plant species. We compare the different restoration practices applied and study the influence of local activities and of access to land to highlight crucial elements for successful restoration in these countries. One of the conclusions is the need to have a systemic vision, which considers (i) the whole life history of the tree instead of considering actions focused only on one stage (e.g. planting); (ii) the variations in life history between species, showing the relevance of targeting restoration actions on different stages, depending on the species; and (iii) the interactions between trees and other ecosystem components.