基于PSR模型的土地生态系统健康时空变化分析——以北京市平谷区为例

论文基于“压力-状态-响应”模型（PSR）和“活力-组织-弹性-功能”理论,以网格作为评价单元,评价了平谷区土地生态系统健康状况,并利用Moran指数测度了全局和局部的空间分异情况。研究结果显示,平谷区土地生态系统健康状况总体较好且相对稳定,1993、2011年平原区健康状况平均值分别为0.53和0.51,而丘陵山区则为0.62和0.65,丘陵山区显著优于平原地区。健康状况空间集聚程度增强,1993—2011年间平原区和丘陵山区的Moran指数分别由0.49和0.41升为0.61和0.46,表明平原病态区域集聚程度增加,而丘陵山区生态环境得到改善。作为北京市的应急水源地和生态涵养区,当前平谷区土地生态系统管理应着眼于三个重点区域：维持四座楼自然保护区周边生态系统健康,加强生态廊道建设,避免产生保护区“孤岛效应”;对于丘陵山区土地生态系统健康状况趋坏的区域,应协调经济发展与生态建设,维护关键性生态用地;对于健康状况较差的中心区域,应限制建设用地拓展,推行生态型土地整治,缓解土地生态系统压力。

Temporal and Spatial Variation of Land Ecosystem Health Based on the Pressure-State-Response Model:A Case Study of Pinggu District,Beijing

Data resources and assessment frameworks are key requirements for ecosystem health assessment. High-precision land-use survey data ensuring the accuracy of results is introduced in this paper. In terms of assessment frameworks, the Pressure-State-Response (PSR) model can incorporate both the influence of human factors and the response of the environment. Under the PSR framework, a Vigor-Organization-Resilience-Service (VORE) assessment index system is developed to diagnose the regional land ecosystem health in Pinggu District of Beijing. The same-sized grids that present land ecosystem health on a diminutive scale was used as the assessment unit. Spatial distribution characteristics of land ecosystem health were analyzed using spatial autocorrelation. The conclusions are as follows: more than 70% of the total area had a health condition equal to or better than Level III. A slight decline in ecosystem health condition occurred between 1993 and 2011; the average value of ecosystem health condition was 0.59 in 1993 and 0.57 in 2011. In general, ecosystem health within Pinggu District was good. Urbanization and industrialization processes have led to the deterioration of land ecosystem health in the central urban area. In the central hilly areas, the nature reserves have helped to improve the local land ecosystem health condition. In addition, the increase in environmental management investment has improved land ecosystem health condition in the southern plains. There is still considerable spatial heterogeneity in land ecosystem health throughout the region. The paper concludes that the ecosystem health condition in the hilly and mountainous areas is superior to that in plain areas. Global Moran’s I was 0.49 in 1993, and increased to 0.61 in 2011. Greater spatial agglomeration resulted in an increase in the Global Moran’s I. In plain areas, Global Moran’s I for ecosystem health condition increased from 0.42 in 1993 to 0.46 in 2011. In hilly and mountainous areas, Global Moran’s I for ecosystem health condition increased from 0.41in 1993 to 0.46 in 2011. The results indicate that the ecosystem health condition in plain areas is declining, and that of hilly and mountainous areas has markedly improved. Human factors play a critical role in land ecosystem health. In plain areas, human influence leads to the replacement of natural and semi-natural landscapes with highly modified landscapes. Nevertheless, human factors have also made major contribution to the natural landscape in the hilly and mountainous areas near the Sizuolou region through the construction of a natural conservation area. As the emergency water sources and ecological conservation areas, Pinggu District should put emphasis on three key regions to improve its ecological condition. It is essential to maintain ecosystem health near Sizuolou region. Through the construction of ecological corridors, the “isolated island” effect of the reserves can be avoided. As for the hilly and mountainous areas where land ecosystem conditions become worse, the paper recommends to make full use of its resources advantage to coordinate the economic development and the ecological construction. The expansion of the central urban area in Pinggu District should be limited to alleviate the pressure of the land ecosystem. Ecological land consolidation in the central areas is necessary to achieve the goal of sustainable development.