Abstract:

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.

Key words: Degraded ecosystem, Degradation degree, Diagnosis of degradation degree, Restoration ecology, Ecolog