A review of recent ecological changes in the Sahel, with particular reference to land-use change, plants, birds and mammals

This review focuses on recent ecological changes in the Sahel. While other recent reviews focused mainly on agricultural changes, remote sensing, and the evolution and distribution of biodiversity, no review focused on ecological changes over time although these changes needed to be summarized to better understand the recent and often dramatic species declines across the Sahel during the last half century. Therefore, I conducted a literature review to summarize these changes, in particular changes to (i) land-use and land-cover, (ii) wetlands, (iii) plants, (iv) birds, especially large and migratory birds and (v) large mammals. The main conclusion is that the exceptionally severe Sahel drought in the late 20th century was extremely detrimental to both human society and nature, but thereafter, rainfall, agricultural productivity and human welfare increased again. As human populations and their ecological footprint increased dramatically, the Sahel's biodiversity continued to become more and more impoverished, whereby woody vegetation, migratory birds, and large birds and mammals suffered particularly severe declines. Besides the agricultural expansion, the other main reasons for these declines are wetland conversions, increased fire frequency, overharvesting, persecution, poisoning and death caused by human artefacts and disturbance. More effective protected areas are urgently needed, which could also generate much needed tourism revenue.