能值分析理论在耕地可持续利用评价中的应用研究——以南京市为例

评价指标体系是耕地可持续利用评价研究的难点,正确选择评价理论与方法,构建科学、合理的评价指标体系,为正确认识耕地利用的可持续性及制定相应政策提供理论与实践依据。文章引入能值理论,在传统评价方法基础上对耕地利用中物流、能流等以太阳能值为统一衡量标准,建立新的指标体系,并对南京市1995~2004年的耕地利用进行评价。结果表明,研究时段内南京市耕地利用是向可持续方向发展的,且其可持续利用经历了两个阶段:①1995~1998年可持续性下降阶段,综合系数从1995年的1逐渐下降到1998年的0.9570;②1998~2004年可持续性上升阶段,综合系数逐年上升到2004年的1.1123。与传统评价方法相比,引入能值理论后的评价结果更能全面、客观地反映耕地利用的可持续状况。

Application of the Theory of Emergy Analysis to the Sustainability Assessment of Cultivated Lands - A Case Study of Nanjing

In the study of sustainability assessment of cultivated land use, it is crucial but difficult to establish an index system. Although some research progress has been made recently, there're still many problems to be solved. For instance, traditional evaluation indices of economic profit can be influenced by various factors, including market supply and demand, fluctuation of monetary value, unit yields and growth periods of different crops. Furthermore, the traditional methods do not take the consumption of free environmental resources and their contributions into consideration. The theory of emergy analysis presented by H. T. Odum overcomes these insufficiencies in the eco-economic system evaluation by the traditional cost theory and market value theory, and offers an important standard to measure the rationality of cultivated land use. However, when the theory of emergy analysis is applied to the evaluation of sustainable cultivated land use independently, it's difficult to analyze agricultural pollution, policies and some other factors, which can be done directly or indirectly by traditional methods. Accordingly, on the basis of the traditional evaluation methods, the emergy theory is introduced and a new index system is established, in order to offset the deficiencies of both traditional methods and the theory of emergy analysis, and make contributions to the research of sustainable use of cultivated land.Taking Nanjing as an example, the study combines the traditional methods with the theory of emergy analysis to establish a new index system from three aspects of economic, ecological and social sustainability. And then, the study computes the weights of all indices by the method of AHP, to evaluate the cultivated land use from the year 1995 to 2004. The research indicates that the sustainable use of cultivated land in Nanjing experienced two phases. In the first phase (1995-1998), the sustainable use index of cultivated land decreased by 4.30%, from 1 in 1995 to 0.9570 in 1998, mainly because the economic sustainability index decreased to 0.8036 in 1998; in the second phase (1998 to 2004), the sustainable use index of cultivated land increased to 1.1123 in 2004, the highest level in the research period, mainly because the economic sustainability index increased to 1.0898, and the ecological sustainability index to 1.1762 in 2004. On the whole, the cultivated land use system is developing towards sustainability, conforming to the conclusions of some relative researches. All these indicate that it is feasible to apply the theory of emergy analysis to the evaluation of sustainable use of cultivated land. Compared with the traditional evaluation methods, the evaluation index system established in this paper can reflect the sustainability of cultivated land use more objectively.