生态系统退化程度诊断：生态恢复的基础与前提

 生态系统退化程度诊断是进行生态恢复与重建的基础和前提。然而目前的生态系统化程度诊断大多停留在定性的水平,如何对退化生态系统的退化程度进行定量的诊断就成为恢复生态学与生态恢复实践所面临的一个迫切且十分关键的问题。在综述前人研究的基础上,比较系统地论述了生态系统退化程度诊断的一系列问题：绘制了描述生态系统退化程度的概念模型;认为在实践中退化程度诊断的参照系统可以选择相应的受人类或自然干扰程度比较轻的“自然生态系统”;归纳了生态系统退化程度诊断的生物途径、生境途径、生态过程途径、生态系统功能/服务途径、景观途径;把诊断方法分为单途径单因子诊断法、单途径多因子诊断法、多途径综合诊断法;分析了生态系统退化程度诊断的可能指标（体系）;给出了生态系统退化程度诊断的策略与流程,并对生态系统退化程度诊断及生态恢复过程中应注意的事项进行了讨论。建议我国加强典型生态系统退化程度的综合诊断研究。

DIAGNOSIS OF THE DEGREE OF DEGRADATION OF AN ECOSYSTEM: THE BASIS AND PRECONDITION OF ECOLOGICAL RESTORATION

Diagnosis of degradation degree of ecosystems is the basis and the precondition of ecological restoration . Currently, the diagnosis of degradation degree of ecosystems is at the qualitative level. It is an urgent and key issue in the field of restoration ecology theory and ecological restoration practice to diagnose the degradation degree of ecosystems quantitatively.A series of questions about diagnosis of degradation degree of ecosystems was discussed systematically in this paper by summarizing former studies, and a conceptual model of the degradation degree of ecosystems was pictured. The conceptual model is the basis of diagnosis of degradation degree of the ecosystem and upholds the viewpoint that many thresholds determined by the comprehensive effects of different factors may be involved in the process of ecosystem degradation. To certain extent, the scale of understanding of the process of ecosystem degradation with this model is less than that with previous models. "Natural ecosystem" characterized by little disturbance from human beings or nature was suggested to be a reference ecosystem of diagnosis of the degradation degree of the ecosystem; we provided a transformation model of ecosystem structure and function followed over time, modified from Bradshaw (1997).The ways of expression of degradation degree of ecosystems were classified into three types, the third type of expression was encouraged in the relative study and practice because the third bridges the relationship between the degradation degree of ecosystem and ecosystem succession. Diagnostic approaches were presented as follows: biological approach, habitat approach, eco-process approach, ecosystem function/service approach, landscape approach. Diagnostic methods were classified into single approach and single factor diagnostic methods, single approach and multi-factorial diagnostic methods, and multi-approach comprehensive diagnostic methods. The possible indices (system) about diagnosis on degradation degree of ecosystem were analyzed. The strategies and steps for diagnosis of degradation degree of an ecosystem were provided by a case analysis. Some critical points during diagnosis of the degradation degree of an ecosystem and ecological restoration were discussed. We suggest that the study of comprehensive diagnosis of degradation degree of ecosystems should be strengthened.