| Land resource is one of the most valuable natural resources of human. It is very important to humans. As early as in primitive society, humans began to make use of the land. The relationship between humans and land resource become the history of human society’s most basic production relation. In human production and life, ecological security maintains the health and the complete degree of ecological system and social environment, also becoming the key factor of regional and even national development. Among them, the land ecological security as one of the important aspects of ecological security is also the core of the sustainable utilization of land resources and protection. In recent years, with the rapid growth of population and the speeding up of urbanization and industrialization, important changes have taken place in land use mode and intensity. Humans tend to only pay attention to economic benefits and ignore ecological benefits. Land ecological security suffers major threat.It is mainly manifested in the land ecosystem structure and function of damage, ecological fragility, its weak ability to provides the high-quality service for the society and economy. It causes enormous ecological damage. Land resource scarcity makes us realize that only to keep the land ecological security at higher levels, human can toward sustainable development path. Wanzhou district as the regional central city of the three gorges reservoir area in Chongqing is a typical ecologically fragile region. Its city size is big and immigration onerous. It not only bears the construction of the Yangtze river three gorges reservoir area of important mission for green ecological barrier, also affects the characteristic economy development of Yangtze river. Studying of Wanzhou district land ecological security level has important significance. This paper is on the basis of relevant theories, index system and evaluation method for land ecological security evaluation research around the world. It is based on PSR model framework and the entropy weight method to selecting 20 evaluation index from the pressure,state and response of land ecological security. It builds accord with the actual situation of Wanzhou district land ecological security evaluation index system. The matter-element analysis model is adopted to establish the comprehensive evaluation model of land ecological security. This paper evaluates dynamically the land ecological security level of Wanzhou district from 2003 to 2012.Also it evaluates the land ecological security level of seven counties in the three gorges reservoir area.Through analysis, this paper concludes the following main conclusions:(1) on the basis of the present situation of land use in Wanzhou district, this paper applies the relevant concepts and theories of land ecological security to summarizes current main problems of regional land ecological security. The main problems include serious soil erosion, serious water pollution, forest resources and structural imbalance, poor stability of ecological land.(2) From 2003 to 2012, land ecological security level shows the tendency of stage to improve in Wanzhou district. But due to the comprehensive correlation degree is in range (1,0), the state is still unstable. During 2003～2004, the land ecological security level is for "to unsafe". The main restriction factors are economic density, per capita GDP, per capita net income of residents, environmental governance investment such as a share of GDP which closely relate to the social and economic development indicators. During 2005～2007, the land ecological security level is for "to less safety". It presents the momentum of improvement. The factors that make important contributions to economic density in Wanzhou district land ecological security level are the natural population growth, urbanization rate, forest coverage, authors unit cultivated land area of applying pesticide content, effective evaluation, industrial wastewater emissions success rate. During 2008～2012, the land ecological security level is from "to critical security" to "to safer". It’s very close to the stable level, but there is still some ecological problems. Land ecological security level is still more sensitive to the social economic indicators such as economic density, urbanization rate, per capita net income of rural residents. The indicators such as coverage rate of afforestation in developed area, cultivated land area of agricultural machinery. But problems such as the lack of arable land per capita, chemical fertilizers and pesticides in the area of soil pollution still exist. Land ecological security status is not stable.(3) After the comparation and analysis of land ecological security level of Wanzhou, Changshou district, Fuling, Fengdu, Zhongxian, Yunyang, Fengjie county, along the Yangtze river, the land ecological security level reduces gradually from upstream to downstream. The deeper the three gorges reservoir area centre, the land ecological situation is worse. Comparative analysis on land ecological security pressure layer, the pressure of Wanzhou district and fengjie county is in the medium level. Changshou, Fuling district and Fengdu county are less pressure and Zhongxian and Yunyang county are bigger pressure. The main causes of stress are the pesticide, fertilizer and sewage problems. Comparative analysis of land ecological security status layer, the land ecological security situation of Wanzhou, Changshou district and zhongxian county is in general, to be able to maintain a relatively stable state. The land ecological security situation of Fengdu, Yunyang, Fengjie county is good while Fuling district is poor. Comparative analysis of land ecological security response layer, Wanzhou district and Zhongxian county are in the security level. Land ecological security response measures have played a certain improvement effect. The response of Changshou, fuling district is good, while Fengdu, Yunyang and Fengjie county fail to reach the ideal effect. |
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