Use of Fallout Caesium-137 to Evaluate the Effectiveness of the FAO-LADA Approach for Assessing Soil Erosion-Induced Land Degradation in the Chinese Loess Plateau

摘要

The Land Degradation Assessment of Drylands methodology (LADA) has been reported to be a rapid and robust approach for assessing the state and nature of soil erosion at regional, national and global levels. However, it needs to be adapted for use under different environments. The studies reported here were to: (i) compare differences | in soil redistribution rates determined by the LADA approach and by using the fallout caesium-137 (~(137)Cs) technique, and (ii) develop aval/dated LADA methodology to rapidly assess soil erosion-induced land degradation for use in the Chinese Loess Plateau. Forty two sites in three watersheds were selected (Liudaogou in Shenmu, Jiuyu-angou in Suide, and Nianzhuang in Yan'an) in the Loess Plateau. Soil erosion rates weremeasured in grassland, shrubland, forestland and farmland by the LADA approach through measurements of plant/tree root exposure, a tree mound and build up against barriers, and rills and by the ~(137)Cs technique. Both approaches revealed similar spatial patterns for soil erosion rates, although the differences between rates determined by the two approaches were greater in grasslands than in forestland and shrubland, and rates derived from the LADA approach were lower in forest and grasslands but higher in farmland than those calculated by the ~(137)Cs technique. It is concluded that the LADA methodology is very useful for quickly assessing soil erosion under different hillslopes and land use types, although an area-wide evaluation of its suitabilityis still required.