Study On The Value Of Multi-functional Protection Of Cultivated Land In The Process Of Urbanization

China has 22% of the world's population, but only 8.71% of the arable land in the world. The lack of reserve resources, uneven distribution and many more potential threatens of the quality exacerbate the importance and urgency of protecting arable land. Since 1987, the Chinese government unveiled a series of laws, regulations and policies to protect farmland. Although the implementation of these policies makes the decrease of cultivated land has been controlle, the situation of farmland protection remains grim; Especially in economically developed areas, with industrialization and rapid urbanization, and the diversity and level of land use needs are also significant, and the level of gradually manifest conflict between human and more prominent. For example, Guangdong and Zhejiang, whose farmland area per capita is 0.030 hectares and 0.038 hectares, only accounting for 40% of the national average,so the farmland protection is particularly urgent.The reason of inadequate protection of cultivated land lies in lack of knowledge on the versatility of cultivated land, and the value of it has not been properly reflected. While in all types of land use, land has an absolute advantage in terms of a single function neither, but the economic, social and ecological functions of land in such form of use has a very strong symbiosis and synergy as well as comprehensive comparison advantage, which is called the value of land greater versatility. Therefore, the research on the theoretical basis of cultivated land, the value of the structure, and scientific evaluation of the contribution of land to the society has theoretical and practical significance on the effective development and implementation of land protection policy.The research achieved the following results:Firstly, from the nature meaning and value of the inherent characteristics of land, this dissertation constructs the multi-value farmland multi-level logic model:Secondly, from the total value of the versatility of the two factors (multi-unit area of land value and the total cultivated area), this dissertation discusses choice of the method of value of the land evaluation, and the introduction of support vector machines studied on conversion factors of rapid urbanization of farmland. Thirdly,On the base of the philosophy essence of value and the intrinsic properties of the farmland, this dissertation constructs a model for multi-function conservation value of cultivated land which is in multi-level logic structure on the base of the three dimensions:the functional dimension (Supply Dimension), the utility dimension (Demand Dimension) and the values spindle, also with the analysis of its features.Secondly, With the comparison of various evaluation methods such as cultivated in the value of economic output, the value of social security, and ecological service value, this dissertation constructs the multi-functional protection of cultivated land value rating system. And take the case of Ningbo city from the aspects of economic output value, the value of social security and the ecosystem service value and analyzes the change rule since its 1996-2007. The results show that in this period, the unit value of arable land in Ningbo urban area increased 1.9 times, with the total value increased 1.16 times. From the change of the total value,this rate of growth is far from the rate of the overall socio-economic growth and non-agricultural transformation of cultivated land is the main reason to explain the reduction of total value of arable land. From the change of value structure, the value of economic output is the basis for achieving the value of social security and the value of ecological services and its growth is reasonable; The structural changes in the value of land multifunctional proves that economic output value is the base of the implement of social security value and ecological service value, and it's increasing is reasonable.It is the change in the focus of demand that leads the share of the value of social security showing a downward trend; The smooth change in ecological value notes the lack of the supply of arable land ecological function, and the amount of cultivated land is an important aspect to reflect the ecological value.Thirdly, from the variation of value, the main reason for the total value of farmland reduction is farmland conversion, which is also an important factor of affecting the value of a particular function of the total cultivated land. In order to find the factors of farmland conversion in areas of rapid urbanization, this dissertation introduces the support vector regression machine theory, choosing the total population, the proportion of non-agricultural population, per capita GDP, the first industrial added value, industrial added value, tertiary industry, investment in fixed assets, the ratio of per capita net income of rural residents and per capita disposable income of urban residents, the ratio of rural households operating net income and net income, grain yield, the total power of agricultural machinery, food production price index, food consumption price index, farmland protection policy totally 14 factors as input variables, and the area of arable land as the output variable to build the socio-economic driving forces model of the cultivated land area change, then make an empirical analysis based on the data of the year 1985-2007 of the urban area of Ningbo. The results show that the forecast error of SVM model is less than 3% which achieves a high accuracy. On this basis, it also analyzes the influence of the 14 factors above on the accuracy of the model, ranking the 14 factors according to their importance to the output variable through the method of excluding one by one, and divides into three levels.Fourthly, this dissertation constructs an urbanization cost-effective evaluation system which is consists of 10 index system, that is the price losses of agricultural production, the cost of land development, the costs of urban infrastructure construction and maintenance, the costs of urbanization and land environmental management, the value loss of ecosystem services of land, the costs of maintain food security, the value loss of social security of land, gross domestic product value, the value of farmland development rights and tax. The result of authentic analyze of Ningbo shows that the cost of urbanization in Ningbo urban area increases gradually with slow trend, and the effectiveness increases gradually with relatively rapid changes. Integrated the cost and effectiveness, the net benefits of urbanization in Ningbo urban area is increasing.Fifthly, based on above analysi, and combined with the experience of Japan and Taiwan,this dissertation puts forward the protection countermeasure for multi-function of farmland in the rapid urbanization area, including setting the concept of protecting the multi-function of farmland, evaluating the multi-function value of farmland, reconstructing reasonable mechanism for financial compensation, developing eco-agriculture activly, improving the effectiveness of land intensive utilize, adding the technical investment, etc.