厦门市土地利用变化下的生态敏感性

当前,城市化与全球变化背景叠加,海岸带生态系统发生了巨大的变化,沿海城市在全球变化下的脆弱性、敏感性与适应能力等问题已经成为政府和科学界关注的重要问题.土地利用变化是导致生态系统敏感性的重要因素之一.以厦门市作为沿海城市的典型代表,对近20 a土地利用变化下的生态敏感性进行系统研究.分析了城市建设用地扩张、围填海等主要土地利用活动对生态敏感性的影响机制;其次建立土地利用变化下的生态敏感性指数,并分析其变化过程;最后通过ArcGIS图层叠加计算功能,获得生态敏感性空间分布状况.结果表明:1987-2007年厦门市城市建设用地面积由1987年的67.48 km2,增加为2007年的308.21 km2,扩张了4.57倍,主要为蚕食农业用地和林地而来;海岸线长度由1987年的290.19 km,增加为1992年的343.23 km,而后减小为2007年的299.93 km,围垦养殖活动使得岸线变得曲折,填海造地活动导致岸线变得平滑.厦门市土地利用强度由1987年的2.44逐年增加为2007年的2.52,生态系统服务价值总体呈现减小的趋势,由1987年的7.39×109元减少到2007年的7.02× 109元,土地利用强度与生态系统服务价值呈现负相关关系.土地利用变化下的生态敏感性指数由1992年的1.50增加为1997年的4.94,而后减小为2002年的4.12,再增加为2007年的4.47.整体而言,近20a来厦门市生态系统对土地利用变化的敏感性灵敏响应程度不很剧烈,生态敏感性高的区域主要位于沿海区域.

Ecological sensitivity of Xiamen City to land use changes

The coastal zone is considered as the most dynamic natural environment, providing goods and services essential to human beings. Due to diverse natural and human pressures, many coastal cities are experiencing severe environmental problems such as climate change, sea level rise, coastal erosion, environmental pollution and so on. Land use change is the apparent and widespread consequences of urbanization and global environment changes, which has important impacts on coastal zones, such as directly altering geomorphological configurations, influencing ecosystems and ecosystem services provision, and increasing coastal city's vulnerability.The presence of a perturbation or stress, sensitivity of the affected entity and the system's capacity to cope or respond (resilience) are major elements in the vulnerability analysis of a social-economic-natural complex ecosystem. Sensitivity in this sense is defined as the interaction within the system, between the systems or inside the complex ecosystem used to characterize the response level the system according to changes in its internal or external factors. This paper presents a new approach to ecological sensitivity assessment under the vulnerability research frame, and the sustainable supply of ecosystem services is employed as a measurement of human well-being under the influence of global change threats, such as land use change.The paper took Xiamen, a coastal city in Fujian Province, as an example to study ecological sensitivity to land use changes from the year 1987 to 2007. Firstly the ecological sensitivity mechanism of the major land use activities was analyzed, such as urban construction land expansion and reclamation. Then the Ecological Sensitivity Index (ESI) to land use change was defined as the ratio of the variation of ecosystem services value to the variation of Land Use Intensity, and the dynamic changes of ESI are calculated in detail from the year 1987 to 2007. Finally, using the layer calculation function of Geographic Information System (GIS) technology, the spatial distributions of ecological sensitivity were derivate. The results showed that construction land area increased significantly from 67.48 km² in 1987 to 308.21 km² in 2007, as much as 4.57 times. The sustained expansion of construction land came from agricultural land and forest. From the year 1987 to 2007, shoreline length of Xiamen City experienced an increase-decrease process, from 290.19 km in 1987, 343.23 km in 1992, to 299.93 km in 2007. The reclamation aimed at aquiculture causing the coastal line to zigzag and fragment, while the reclamation for transportation or construction land causing the shoreline smoother and shorter. The Land Use Intensity increased from 2.44 in 1987 to 2.52 in 2007, while the ecosystem services value showed a generally decreasing trend of 7.39×10⁹ Yuan in 1987 to 7.02×10⁹ Yuan in 2007. The mechanism research of the ecosystem sensitivity to land use change indicated that Land Use Intensity and the ecosystem services value showed an opposite trend and Land Use Intensity increased inversely with the decline of the ecosystem services value. The ESI increased from 1.50 in 1992 to 4.94 in 1997, then decreased to 4.12 in 2002, and finally increased slowly to 4.47 in 2007. Overall, in the past twenty years, the level of ecosystem affected by land use changes was not very severe. Most of the high ecological sensitivity areas located in the coastal area.