关中-天水经济区生态系统服务权衡与协同关系

陆地表层植被作为生态系统主体,具有调节气候、水文调节、净化水质、保持水土等生态系统服务。理解生态系统服务权衡与协同的表现类型、形成机理、尺度依存和区域差异,对于制定区域发展与生态保护"双赢"的政策措施具有重要意义。以关天经济区为主要研究对象,利用相关模型,计算关天经济区生态系统NPP,固碳释氧,水文调节,水土保持,粮食生产等生态系统服务价值,利用ESCI和ESSI两个指数研究其生态系统服务价值时空变化,利用相关系数和空间制图的方法研究它们之间的相互权衡协同关系。结果表明:从时间角度分析,各项生态服务价值都呈现逐渐增加的趋势;从空间角度分析,2000年和2010年存在相似的空间分布格局,从北向南,NPP和固碳释氧的价值逐渐增大,水土保持价值变化量的大小也呈现不断增加的趋势,北部变化量小,南部变化量大,水文调节价值从西向东增大,从北向南增大,粮食生产价值量最小的是西安市市区,粮食生产价值量最大的是西安市的郊区和郊县及咸阳市。2000年到2010年间,调节型生态系统服务与供给型生态系统服务之间存在着此消彼长的权衡关系;各个区县的总生态服务价值指数从北向南、从西向东是不断增大的。

Ecosystem service trade-offs in the Guanzhong-Tianshui economic region of China

The Millennium Ecosystem Assessment (MEA) has highlighted the dependence of human well-being on ecosystem services. In recent studies, the links between nature and the economy are often described using the concept of ecosystem services, which is the flow of value, measured as the quantity of natural resources, to human societies. Natural ecosystems provide society with important goods and services. With the rapid increase in human population and the excessive utilization of natural resources, humans frequently enhance the production of some services at the expense of others. Although the need for trade-offs between conservation and development is urgent, the lack of efficient methods to assess such trade-offs has impeded progress. This study focused on the evaluation of ecosystem services under different land use practices in the Guanzhong-Tianshui economic region of China using indices such as the ecosystem services change index (ESCI) and ecological service status index (ESSI). GIS-based techniques were used to map spatial and temporal distributions as well as the changes in ecosystem services. Research on the trade-offs and synergies between these ecosystem services were based on a correlation rate model and on distribution mapping. The results of the study show that (1) the ESCI value of Net Primary Productivity (NPP) and carbon sequestration increased in the western or northwestern regions of the area under study, while there was a loss of NPP and carbon sequestration in the eastern region. The water conservation value in the eastern region significantly increased, whereas it decreased in the western part. The other areas show no change. There was a gain in agricultural production in all regions, except Xi''an city. The ESSI value was the largest in Tianshui City, and showed a decreasing trend from west to east. (2) All of these services show trade-offs and synergy. Carbon sequestration was based on the NPP value, so the correlation coefficient was 1. The spatial pattern of soil conservation and water conservation were similar, so they have a higher correlation coefficient. Lastly, (3) ecological service was prominent in Baoji City, followed by the cities of Weinan, Xianyang, and Xi''an. Supporting ecological services were the highest in Fengxian County, followed by the counties of Zha Shui, Taibai, and Hua Yin. In contrast, supporting ecological services were the lowest in Gan Gu County, followed by the counties of Da Li and Qin An. Provisioning ecological services were high with the highest being in Fengxian County followed by Xian Yang City, and lowest in Taibai County. Looking at the spatial distribution, the total ecosystem services index increases from north to south and from west to east. The indexes for the cities and counties in the north were significantly lower than for those near the southern Qinling Mountains; therefore, the index was lower for the western part than for the eastern part. Provisioning ecological services, of which agricultural production accounts for a large proportion in the central area, was stronger than in the other areas. From 2000 to 2010, the total index of ecological services increased, although there was a slight decrease in some areas, mainly in the cities of Tianshui and Tongchuan. The Qinling-Taibai mountain region did not register any significant changes. From 2000 to 2010, all of these services presented trade-offs and synergy, especially in Baoji City. The supporting ecosystem services index in Fengxian County was the highest and had a NPP and carbon sequestration of 1, but agricultural production was very small at 0.0057. The food production index was the highest at 1, but the supporting ecosystem services index was low. This study suggests that the evaluation and visualization of ecosystem services could effectively assist in understanding the trade-offs between conservation and development. The results have implications for the planning and monitoring, which can be integrated into land use decision-making, of the future management of natural capital and ecosystem services.