基于PSR模型的云贵高原湿地生态系统健康评价

威宁草海湿地生态系统健康对我国云贵高原生态安全格局建设具有重要意义。为了保护高原湿地威宁草海的基本生态系统服务功能,促进其生态系统健康发展,通过对威宁草海湿地的生态系统健康进行评价,为湿地生态恢复和环境保护提供决策支持。利用PSR(Pressure-State-Response)模型框架,从压力(P)、状态(S)和响应(R)3个方面建立评价指标体系,采用熵权法和模糊数学法建立评价模型,把草海湿地生态系统健康分为"很健康、健康、较健康、不健康、疾病"5个等级。结果表明,威宁草海湿地生态系统健康属于"不健康"等级,隶属度值为0.2934、0.3415、0.2061、0.1077、0.0513;其中,压力要素为"疾病"等级,隶属度值为0.4323、0.2862、0.1768、0.0241、0.0806;状态和响应要素均为"不健康"等级,状态要素隶属度值为0.2202、0.3174、0.2361、0.1128、0.1135,响应要素隶属度值为0.1534、0.4273、0.2307、0.0866、0.1020。压力要素的影响因素主要包括人口过多、环保压力大、化肥施用强度大、农药施用多;状态要素的影响因素主要包括湿地流域保水能力差、水量稳定性低、植被覆盖率不高、水土流失严重、土地生产力下降;响应要素的影响因素主要包括地保护意识不强、环保投入少、污水处理率低、物质生活指数不高。在草海生态系统建设过程中,应控制人口增长、减少农药和化肥施用量、提高植被覆盖率、治理水土流失。

Ecosystem Health Assessment of the Yunnan-Guizhou Plateau Wetland Based on the Pressure-State-Response Model

The Caohai Lake wetland in Weining County has played an important role in maintaining the ecology of the Yunnan-Guizhou plateau of China. In this study, an ecosystem health evaluation system for the Caohai Lake wetland was developed, aiming to protect the basic service function of the ecosystem, promote its sustainable development and provide scientific evidence for decision making on the protection and restoration of plateau ecology. Development of the health assessment system for Caohai Lake wetland was based on the Pressure-State-Response (PSR) model, which includes a pressure subsystem (P), a state subsystem (S) and a response subsystem (R), with a total of 19 indicators. Weighting for each of the 19 indicators was determined by the entropy evaluation method. A five-level ecosystem health ranking was developed with ranking levels of (1) very healthy, (2) healthy, (3) sub-healthy, (4) unhealthy and (5) very unhealthy . The evaluation of Caohai Lake wetland in Weining province was carried out using the health assessment index and fuzzy mathematics. Generally, the Caohai Lake wetland ecosystem was in an unhealthy state, and the membership values of the five rankings were, in order 0.2923, 0.3415, 0.2061, 0.1077, 0.0513. In terms of the three subsystems, the pressure subsystem was in a very unhealthy status and the state and response subsystems were unhealthy, with corresponding values of 0.4323, 0.2862, 0.1768, 0.0241, 0.0806 for the pressure subsystem, 0.2202, 0.3174, 0.2361, 0.1108, 0.1135 for state subsystem, and 0.1534, 0.4273, 0.2307, 0.0866, 0.1020 for the response subsystem. The primary pressure elements were overpopulation and high intensity utilization of fertilizers and pesticides. The primary factors limiting the state elements in the wetland basin included poor water conservation, low water stability, low vegetation cover, serious soil erosion and declining land productivity. The primary factors limiting the response elements included insufficient awareness of land protection, low investment in environmental protection, low sewage treatment rate and low material life index. Therefore, it is necessary to control population growth, reduce pesticide and chemical fertilizer use, increase vegetation coverage, control soil erosion, and emphasize environmental protection while the grassland ecosystem is being restored.