Abstract: Different degree degradation of grassland ecosystem has been found under the stress of population increasing and impact of modern agricultural and industrial demands.The degradation of grassland ecosystem includes qualitative and quantitative changes in grassland composition,structure,process and function.They are the foundation and precondition of ecological restoration for the understanding of degraded grassland concept,driving forces,process and diagnosis of degradation degree.A series questions about grassland degradation was discussed systematically in this paper by summarizing former studies,and a conceptual model of grassland degradation was made."Natural grassland ecosystem" characterized by mild disturbance from human beings or nature was suggested to be "Model Grassland Ecosystem" for degradation research from an ecological point of view.Diagnostic approaches of grassland degradation were summarized as biological approach,habitat approach,function/service approach.The available diagnostic methods and their indices(system) related to grassland degradation degree were analyzed;and integral critical point during diagnosis of degradation degrees and the restoration precautions of degraded grassland were discussed.

Key words: Grassland degradation, Process, Successional model, Diagnosis of degradation degree

摘要： 随着人口的不断增加和现代工农业文明的冲击,草地生态系统出现不同程度的退化,导致草地生态系统组成、结构、过程和功能等方面发生量和质的变化;对草地退化的系统理解是进行草地恢复与重建的基础与前提。本文综述了草地退化的内涵、驱动力、退化过程与特点,以及草地生态系统退化程度诊断等一系列问题,绘制了描述草地退化程度的概念模型;建议从生态学角度研究草地退化程度诊断时选择相应的气候顶级系统或受干扰程度较轻的"自然生态系统";从草地经营学角度研究草地退化程度诊断时选择适度放牧草地作为参照系统。归纳了退化草地生态系统诊断的生物途径、生境途径和功能服务途径;分析了草地退化程度诊断的方法与可选择的指标体系,并对草地退化程度诊断及草地恢复中应注意的事项进行了讨论。

关键词: 草地退化, 过程, 演替模式, 退化程度诊断