基于生态系统服务价值重构的干旱内陆河流域生态安全格局优化——以张掖市甘州区为例

干旱区内陆河流域的生态环境极为脆弱,生态系统的微小变化也可能给流域生态安全带来巨大影响。甘州区位于干旱内陆河流域,生态问题突出,重视生态系统自身安全、构建合理的生态安全格局是保障该地区生态安全的有效措施。通过当量因子法估算2000、2005、2010年甘州区生态系统服务的静态价值,在充分考虑各项生态系统服务功能变化率及空间集聚程度对功能发挥影响的基础上,采用生态系统服务优先指数和空间丰富度指数,对甘州区2010年生态系统服务静态价值的估算结果进行动态重构。利用重构后的生态系统服务价值构建了甘州区3种不同安全水平情景下的生态安全格局。结果表明:1)甘州区生态系统服务价值总量逐步上升,各项服务多年变化率差异不大。2)重构后生态系统服务价值量为1438.21—390993元/hm~2,大部分地区为中低值。3)低、中、高安全水平生态安全格局中,生态源地面积分别为155.75 km~2,191.25 km~2和224.5 km~2。基于生态系统服务价值构建的生态安全格局是立足于生态系统服务现状提出的规划策略,可为区域生态保护规划和生态文明建设提供重要依据。

Establishment of ecological security patterns based on ecosystem services value reconstruction in an arid inland basin: A case study of the Ganzhou District, Zhangye City, Gansu Province

With increasing populations and acceleration of urbanization, there is increasing worldwide concern about the importance of ecological security. Ecological security is premised on ecosystem services provided by ecosystems to humans. The construction of ecological security patterns is an effective measure to maintain normal ecosystem function and safeguard ecological security. Ganzhou District is located in an arid inland basin and the ecological security is a prominent problem. The traditional approach to construct the ecological security pattern can be divided into three steps:determining ecological security sources, building ecological resistance surface, and identifying key ecological corridors. The first step of determining ecological security sources is accurately identifying the ecosystem service value (ESV). Presently, most local studies have used the ESV unit area of Chinese terrestrial ecosystems to estimate the ESV. However, ecological systems are dynamic rather than static. Therefore, this cannot reflect the differences between kinds of ecosystem services, change rate of ESV, or degree of spatial agglomeration. However, to effectively protect the fast decreasing service, the influence of the spatial agglomeration of ecosystem services on the recognition of ecological sources by affecting their functions should be considered. Hence, a static ESV was reconstructed by changing the ESV rate to measure the priority of protected ecosystem services and using the key ecosystem service indicators to quantify the degree of spatial aggregation. Using the ESV unit area method for Chinese terrestrial ecosystems, the static ESV in the Ganzhou District in 2000, 2005, and 2010 was calculated. Taking into account the changing rate of ESV and degree of spatial agglomeration influence on their functioning, the priority and spatial richness indexes were used to reconstruct the ESV in 2010. Using the spatial distribution of the reconstructed ESV for ecological source identification, the area with high value ecosystem services was selected as the source of high, medium, and low security levels. Then, ecological corridors could be identified according to the minimum cumulative resistance (MCR) model. Ecological corridors convey the transfer of ecological flow, ecological processes, and ecological functions in a region. Ecological corridors connect scattered ecological sources to constitute an ecological safety net. Therefore, ecological security patterns of different levels can be constructed. The results showed that (1) the total static ESV increased annually during 2000-2010, among which the values of soil formation and protection and waste treatment were the largest. In addition, there were no obvious differences among the changing rate of ESV; (2) the reconstructed ESV in 2000, 2005, and 2010 ranged from 1438.21 to 390993 yuan/hm², whereas most regions were dominated by low and middle values; (3) the area of low, middle, and high levels of ecological source were 155.75, 191.25, and 224.50 km², respectively. With the improvement of the ecological security level, the degree of integration of ecological sources has gradually increased, and the resistance and resilience against ecological stress have increased. Ecological security patterns could be used as a planning strategy based on the present situation of ecosystem services. They provide an important basis for urban environments to build an environment-friendly society.