关键词: 城镇化, 生态风险, 土地利用, 土地生态系统

Abstract: Land ecosystem including nature subsystem and social subsystem is an important part of global terrestrial ecosystem, which supports human beings’ livelihood. With rapid urbanization and the social progress, the land-use of China transformed significantly and this process changed the structure and function of land ecosystem. Those changes led to further degradation of land ecosystem driven by multiple risk sources. Thus,it is of great significance to evaluate land ecological risks in order to guide the exploitation of land resource. We proposed a method to assess land ecological risks by combining the occurrence probabilities of multi-sources risks, the resistance and resilience of land ecosystem and possible damages when land ecosystem is exposed to risky environment. This paper quantified and spatialized the land system ecological risks using tools in geography information system. This paper took Sheyang County of Jiangsu Province for example. Based on the practical condition of Sheyang and the feasibility of data acquisition, several targets were selected to calculate the land ecological risk source index, nature system resilience index and damage index, social system reliance index and damage index, nature system risk index, social system risk index and complex system risk index. The result showed that: 1) The soil pollution, soil sealing and water pollution play an important role in land ecosystem risk source index. The land ecosystem risk source index is much higher in urban area than in rural area, which shows the risk sources index is closely related to the urbanization progress and the socioeconomic development. Urbanization progress brings more risk sources. 2) The town center of Sheyang is the region with the highest social system risks, while the region of the highest nature system risk locates in the nature reserve of eastern Sheyang which is bounded by the Huanghai Sea, therefore. In these two regions, more attention should be paid to ecological protection and restricted construction. 3) When it comes to the complex system risk index, the highest value appears in the nature reserve near Huanghai Sea, being less than 0.5 in the core zone of the nature reserve. The town center also shows relatively high value of the complex system risk index. Lower values distribute in large areas in the east of Sheyang and around the town center. It is suitable for urban expansion and land development in these regions. Correspondingly, it needs to restrict the expansion of the nature reserve and the town center. According to the research results, this paper proposed diversified land ecology policies in different regions of Sheyang, which can provide decision-makings for urbanization and ecological environment protection in Sheyang. It is proved by the research results that the assessment model of land ecological risks presented in this paper has high precision and can express regional land ecological conditions very well. This model can provide a reference for further work of quantifying land ecological risks.

Key words: ecological risks, land ecosystem, land use, urbanization