BICSA · Biophysical Changes in the Sahel: Ground and Satellite Based Evidence Across Scales and Disciplines

Biophysical Changes in the Sahel: Ground and Satellite Based Evidence Across Scales and Disciplines

Human and climate induced desertification/degradation of arable lands has been of major concern for livelihoods and food security in drylands during recent decades. In this context, the semi-arid Sahel region in West Africa has been subject to intensive international research including several controversial and mutually contradicting studies. Recent Earth Observation (EO) studies show a positive trend in rainfall and vegetation greenness over the last decades (known as the re-greening of the Sahel). This has been interpreted as an increase in biomass and contradicts prevailing narratives of a vicious cycle of widespread degradation caused by human overuse and climate change. Apparent oppositions in definitions and scientific outcome result from a lack of detailed data and little investment in studying long-term ground-based observations, making many conclusions on greening/degradation premature and speculative. This project aimed at applying new satellite data with a high level of detail combined with coarse satellite data covering several decades, as well as field observations to shed light on the environmental conditions and changes in Sahel. The project will improve the scientific understanding of linkages between ground and satellite based data across various spatial and temporal scales, the integration of the datasets and their applicability. New monitoring methods of biophysical variables address challenges in land management and food security in response to climatic changes. The major objectives were to: 1. Evaluate the ability of long-term satellite vegetation data to reflect long time biomass dynamics in the Sahel. 2. Assess 3 decades of changes, dynamics and spatial heterogeneity of biophysical parameters (tree-, herb production and their species) by means of ground measurements. 3. Assess the interrelationship between ground measured biophysical parameters and EO data, model and extrapolate across spatial and temporal scales. 4. Transfer of knowledge: Translate observed changes in ecosystem services and effects on livelihoods.

Data: CORDIS, © European Union