Vegetation changes due to climate and human impact in Sahelian countries are rarely documented at species composition level[ The decrease or disappearance of certain plant species reduces vegetation cover and enhances the exposure of soil surfaces to wind and water erosion leading to increased land degradation[ Men and women in Niger were asked to note plant species and relate their numerical development to pre!de_ned observation criteria comparing the present and past[ Plant species in decline or that had disappeared were reported more often than species that had increased or were newly introduced[ The increasing species that were mentioned were often in use for di}erent purposes and seem to be robust enough and well adapted to the semi!arid environment[ But the interviewed farmers also stated the loss of many valuable species that they used for construction and hand tools\ consumption\ medicine or fodder[ Those declining species are of socio!economic importance for individual households and the rural ecology[ Men mentioned 07 species that had disappeared[ Di}erences in the perception of men and women could be found[ Women seemed to have a better perception for species which had increased or were newly introduced\ whereas men perceived more a decrease or disappearance of species.