Land degradation in drylands: Interactions among hydrologic–aeolian erosion and vegetation dynamics

a r t i c l e i n f o Land degradation in drylands is one of the major environmental issues of the 21st century particularly due to its impact on world food security and environmental quality. Climate change, shifts in vegetation composition, accelerated soil erosion processes, and disturbances have rendered these landscapes susceptible to rapid degradation that has important feedbacks on regional climate and desertification. Even though the role of hydrologic–aeolian erosion and vegetation dynamic processes in accelerating land degradation is well recognized, most studies have concentrated only on the role of one or two of these components, and not on the interactions among all three. Drawing on relevant published studies, here we review recent contributions to the study of biotic and abiotic drivers of dryland degradation and we propose a more holistic perspective of the interactions between wind and water erosion processes in dryland systems, how these processes affect vegetation patterns and how vegetation patterns, in turn, affect these processes. Notably, changing climate and land use have resulted in rapid vegetation shifts, which alter the rates and patterns of soil erosion in dryland systems. With the predicted increase in aridity and an increase in the frequency of droughts in drylands around the world, there could be an increasing dominance of abiotic controls of land degradation, in particular hydrologic and aeolian soil erosion processes. Further, changes in climate may alter the relative importance of wind versus water erosion in dryland ecosystems. Therefore acquiring a more holistic perspective of the interactions among hydrologic–aeolian erosion and vegetation dynamic processes is fundamental to quantifying and modeling land degradation processes in drylands in changing climate, disturbance regimes and management scenarios. Drylands of the world are of critical concern as they cover over 41% of the surface of the earth with over 2 billion inhabitants, mostly in the developing world (MEA, 2005). Land degradation in drylands is one of the major environmental issues of the 21st century because of its impact on food security and environmental quality (MEA, 2005). The United Nations Convention to Combat Desertification (UNCCD) defined desertification as " land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities ". The causes and consequences of dryland degradation, sometimes arguably referred to as " desertification " , Some authors even consider desertification as a potential but not necessarily an outcome of land degradation …