The Sahelian agroecological zone (from 200 to 600 mm rainfall) is characterized by severe degradation of natural resources and the fight undertaken since several decades against this phenomenon of desertification has not yielded the expected results. A study was conducted in the framework of a transect approach and a multiscale characterization from watershed to plot levels, on the identification and characterization of the vegetation dynamics and the fertile islets in the Sahelian zone of Burkina Faso.The results revealed that Accacia raddiana Savi represents 83 per cent of the total vegetation population and that 73 per cent of the fertile islets are under this specy. The fertile islets, identified obviously for the first time in the Sahel through our study, have a morphological double structure with predominant material of 75µ, a highest organic matter and available phosphorus contents, comparatively to soils in situ. But their low pH and a low CEC are similar to those of the surrounding sandy soils. The weight of dry roots in the fertile islets is twice to five times superior to the one the standard crusted and sandy surface soils. These micro hills are mostly favorised by the presence of branches at a height less than 1 m from the soil. They have shown to have clear impact on vegetation and pedo- fauna development in the drylands. Facilitating their development in the Sahelian landscapes could contribute significantly to desertification control.