基于生态安全的高寒牧区生态承载力评价

Evaluation of ecological carrying capacities in Gannan based on PSR model

生态承载力指在一定社会经济条件下,自然生态系统维持其服务功能和自身健康的潜在能力。本研究以甘南藏族自治州(以下简称甘南州)ETM+(Enhanced Thematic Mapper Plus)和TM(Thematic Mapper)遥感影像及统计年鉴数据为依据,应用生态安全评价模型PSR(压力-状态-响应)选取平均植被覆盖度、人均耕地面积、放牧超载率等22个指标,通过基于加速遗传算法的层次分析法(AGA-AHP)获得各指标权重,采用状态空间法定量研究2000、2004和2008年甘南州各县(市)生态承载力状况。结果表明,在2000、2004和2008年,玛曲县、迭部县、舟曲县、临潭县、合作市生态承载力都处于超载状态;夏河县2000和2004年处于超载状态,而2008年处于可载状态,生态承载能力上升;卓尼县2000年生态承载力评价值为1.081 0,而2004和2008年分别为0.934 8、0.924 3,生态承载能力上升;碌曲县2000和2008年生态承载能力都处于超载状态,2004年处于可载状态。该研究可为高寒牧区生态承载力评价及相关研究提供有效的方法。

Ecological carrying capacity refers to the natural ecosystems to maintain their service functions and health potential in a certain socio economic conditions. The evaluation system of the ecological carrying capacity was established by using satellite imagery （TM, ETM＋） and the census data in Gannan region. The 22 indexes including average vegetation coverage, area of cultivated land per capita, grazing overload rate etc. were determined by using the PRS （Pressure-State-Response） ecological safety evalutation model. On this basis, the AGA AHP was used to calculate the weight value of each index. Then the eco- logical carrying capacity of each county of Gannan region in 2000, 2004 and 2008 was assessed with help of the State Space Method. The results indicated that the ecological carrying capacities of Maqu, Diebu, Zhouqu, Lintan County and Hezuo City were overloaded in 2000, 2004 and 2008. The ecological carrying capacity of Xiahe County was overloaded in 2000 and 2004, but that was in an ideal state in 2008. The ecological carrying capacity in Zhuoni County was 1. 081 0 in 2000, while that was 0. 934 8 and 0. 924 3 in 2004 and 2008, respectively, in which indicated the ecological carrying capacity was improved in 2004 and 2008. The ecological carrying capacity of Luqu County was in an ideal state in 2004, while that was excesses capacity in 2000 and 2008. This study provided an effective method for evaluation of alpine pastoral ecological carrying capacities.