Long-term desertification processes


Convener: Yoav Avni, Geological Survey of Israel

Arid and semi-arid regions globe wide are currently under an aggressive soil erosion phase, causing escalating rates of agricultural soils degradation. This process is rapidly developed into a world-wide disaster undermining food security, promoting social instability among rural communities. These destructive processes are often attributed to land mismanagement, overgrazing and recent climate change, leading to desertification of vast areas in almost all continents. However, increasing volume of field observations in desert ecosystems globe wide indicate that most of the present arable soils developed some 70,000-24,000 years BP, mainly during the Late Pleistocene glacial period (OIS 4 and 3). These soils developed in agreement with past environments and climates. As the climate shifted to form the present day Holocene climate, these soils became unstable. Therefore, the current phase of massive soil erosion is promoted by geological-scale environmental shift, initiated long before human intervention became significant in the environment. As this process was already fully active during historical times, ancient desert societies took actions to combat soil erosion and to conserve the agricultural potential of their arable lands. In light of their huge efforts for land conservation aimed to achieve food security, as documented in the archeological record, we call for better evaluation of past environments and human activities. This will allowed the improvement of modern strategies for combating desertification, based on better understanding of the deep roots of desertification processes.

This session is dedicated to papers focused on various aspects of long-term records of environmental degradation in drylands. We invite contributions from different disciplines: geology, geomorphology, soil sciences, ecology, archeology, agriculture and more which (i) introduce new data and techniques to quantify and compare components of natural aspects of desertification in various datasets; (ii) identify patterns (in time/ space) of these aspects between different dryland environments; (iii) test key assumptions and predictions of long-term desertification process aiming to improve strategists to combat present desertification processes.