中国东部亚热带地区流水侵蚀所引起土地退化的形成,是由其生态环境自身的脆弱性决定的。土地退化不仅表现为土壤退化,还表现为植被退化和土地状况恶化,其发展过程是植被退化-土壤退化-地表状况恶化过程多重循环的结果。据此,提出了中国东部亚热带丘陵山地土地退化评价指标。

Land degradation caused by water erosion in South China took place mainly due to the vulnerabilities of its ecological environment,such as thin layer of top soil,poor nutrition and moisture and low erodibility of subsoil as well as a marked summer drought.Depletion of vegetation cover induced by adverse human activities provides a breakthrough point for its initiation,and abundant rainfall and frequent rainstorms and typhoons in summer act as the exogenous agent for its development.Land degradation in South China manifests itself as not only soil degradation but also vegetation degradation and deterioration of land surface.Its development could be considered as a multiple vicious circle of the process:vegetation degradation soil degradation deterioration of land surface.Tentative criteria for land degradation assessment were set up,including vegetation types and cover,types and percentage of surface materials exposed as well as erosional morphology and its percentage.