Soil erosion-desertification and the middle Eastern Anthroscapes

A 5-year (2001-2005) joint study of research teams from the Palestinian National Authority, Jordan, Israel and Turkey explored the responses to land management of dryland watersheds in each of the respective countries. The study watersheds differed in their land uses and applied management but were unified by apparent land degradation expressed in water-driven soil erosion due to removal of vegetation cover, and causing on-site loss of land productivity and off-site clogging of water reservoirs. The study describes and quantifies the rainfall-vegetation-runoff-erosion and the rainfall-soil moisture-soil organic matter-vegetation chain links associated with specific site and management attributes of the study watersheds, spanning from semiarid to arid drylands and from dry woodland to dry rangeland ecosystems. The effectiveness of trees in controlling soil erosion was reaffirmed while discovering that in-spite of their transpiration trees in drylands need not necessarily reduce soil water storage more than the herbaceous vegetation. It was also found that transforming rangelands to planted forest does not necessarily reduce overall plant biodiversity but does change its species composition; that runoff-harvesting practices become less effective as the inherent site's aridity increases; that traditional runoff-harvesting practices (e.g. terraces) are effective but non-traditional ones (i.e., large-scale furrowing) are both simple and effective too.