All publications and documents

Climatic changes and human activities have caused major environmental change in the Sahel. Remote sensing studies detect various vegetation trends; however, explanations are rarely studied in detail. We present a methodology using time series, high-resolution imagery and fieldwork to validate trend analyses for two regions in the Sahel of Mali and Senegal. Both study areas show significant…

Degradation in arid rangelands is an on-going concern, as they appear to be trapped in a vicious circle of desertification–marginalization–impoverishment. Recent theoretical developments in dryland research strive to provide keys to understanding linked social-ecological systems and land management. One approach, the desert-syndrome, depicts the socio-ecological evolution of drylands as being…

The paper is a response to the surprise with which some policy makers responded to news that greening had been detected in the Sahel. It first views Sahelian environmental change and related policies through the lenses of scientific models of pastoral and agricultural systems. For pastoralism, the lenses are models of equilibrial ecology, those of state-and-transition and those of more recent…

In the early 1980s, the situation on the northern part of the Central Plateau of Burkina Faso was characterized by expanding cultivation on lands marginal to agriculture, declining rainfall, low and declining cereal yields, disappearing and impoverishing vegetation, falling ground-water levels and strong outmigration. This crisis situation provoked two reactions. Farmers, as well as technicians…

Various reports have suggested that there has been a “recovery” of the rainy season in Sahelian West Africa in recent years. In this study, rainfall time series for West Africa are updated to the year 2003 by using rainfall estimates from the Tropical Rainfall Measuring Mission (TRMM). Emphasis is on the period 1998–2003. Analyses include time series for eight zones, in the latitudes from 12°N to…

NOAA = National oceanic and atmospheric administration. AVHRR = The advanced very high Resulotion Radiometer. Remotely sensed measurements from NOAA-AVHRR expressed as normalized difference vegetation index (NDVI) have generated a 23-year time series appropriate for long-term studies of Sahel region. The close coupling between Sahelian rainfall and the growth of vegetation has made it…