退化生态系统的诊断特征及其评价指标体系

退化生态系统具有结构和功能简化、生产力和抗逆力低、生物多样性下降等基本诊断特征，由于区域背景和人类活动干扰的差异，生态系统退化具有不同的类型、过程和阶段。为了定量地研究退化生态系统，文中分别建立了土壤、植被、大气、水体，以及农业生态系统、区域自然－人类复合生态系统退化的评价指标体系，其中，土壤退化指标包括物理退化、化学退化、生物退化和土壤污染四类指标；植被退化则从数量、结构、功能与生产力、品质四个

THE DIAGNOSTIC FEATURES OF DEGRADED ECOSYSTEM AND INDEX SYSTEMS FOR DEGRADATION EVALUATION

Degraded ecosystems have basic diagnostic features including simplification of structure anddegeneration of function, decreasing of productivity and biodiversity. Because of differences of regional environment and disturbance of human activities, ecosystem may have different processes,types and stages. The index systems for evaluating degraded ecosystems including soil, vegetation, atmosphere, water body, agroecosystems and regional naturaLhuman complex ecosystemsare put forward in this paper. Soil degradation index system consists of physical, chemical, biological and pollution indices; vegetation degradation can be evaluated by four kind of indices suchas quantity, quality, structure and function of vegetation; air degradation index system includesindices of air composition, pollution and meteorological disasters; the degradation of water resources can be appraised from their quantity and quality; the index system of agroecosystemdegradation includes seven kinds of indices such as productivity, stability, sustainability, biodiversity, equilibrium, openness and quality of products; degradation assessment of PREES systemcan be divided into five sub-systems, each of which is subdivided into several indices.