| Cultivated land is a fundamental resource for human survival and development,a fundamental guarantee for food security,a basic resource for solving the problems of"agriculture,rural areas and farmers",an important factor for social stability and a space carrier for regional construction and development.Cultivated land is scarce and non-renewable.Under the background of rapid economic development and continuous improvement of urbanization level,China has practical problems such as small per capita cultivated land area,low utilization rate,uneven distribution,serious quality degradation and lack of backup resources,which determine the importance and urgency of rational and efficient utilization.The reason for the poor utilization of cultivated land lies in the insufficient understanding of the versatility of cultivated land.As the space carrier of agricultural production activities,cultivated land also provides social and ecological services through food production,labor absorption,ecological regulation,carbon fixation and oxygen release.However,the social and ecological functions of cultivated land have been ignored for a long time.Solve cultivated land protection problem,not just limited to the amount of stability and the improvement of the quality,more to practice of cultivated land protection "ecological trinity" quantity quality,fully cognitive versatility of cultivated and pluralistic value,understand the cause of the arable land,multi-functional dynamic change,the coordinated development of arable land,a variety of functions,provide safeguard for the arable land,multifunction protection and sustainable development.The research content of this paper mainly includes the following parts:In the first part,the origin,development and connotation of multi-function of cultivated land are sorted out.The division of multi-function of cultivated land at home and abroad,construction of index system,research methods and main research directions are sorted out.The purpose and significance of this paper are clarified,and the research contents,methods and technical routes are summarized.The relevant concepts are defined,the selection principles of indicators are clarified,and the multi-functional cultivated land is divided into production function,social function and ecological function.The second part,using the extremum method,entropy value method,comprehensive evaluation method to construct multifunctional of arable land evaluation system,based on the wuhan city circle,2000.2005,2010,2015,the cultivated land data of wuhan city circle of multi-function for empirical research,and with the aid of arable land,multi-functional dynamic change model and spatial autocorrelation method to analyze spatial and temporal evolution of arable land,multi-function.In the third part,on the basis of the results of the multi-function measurement of cultivated land,the coupling degree and coupling degree of coordination model are used to further analyze the correlation degree and degree of coordinated development among the three sub-functions of cultivated land.With reference to the existing research,driving factors are selected based on the reality of wuhan urban circle,and canonical correlation analysis,qualitative and quantitative analysis are combined to explore the driving factors of multi-functional changes of cultivated land.The main research conclusions of this paper are as follows:(1)from 2000 to 2015,the overall cultivated land function and ecological function of wuhan urban circle presented a slow "uptrend--downtrend--up" trend.The production function presented a continuous upward trend in the research area,while the social function presented a slow downward trend.(2)from 2000 to 2015,the multi-function of cultivated land in wuhan urban circle was always in the stage of high-level coupling,and there was a strong interactive relationship between the three sub-functions.The degree of coupling coordination was on the verge of imbalance and slowly improved.The coupling degree between production-social function,production-ecological function,production-social function and production-ecological function presented a dynamic development trend,which was maintained in the antagonistic stage.Although the coupling degree increased slowly,it was at a low level and showed imbalance.The coupling degree and the degree of coupling coordination between different sub-functions of cultivated land in each county are at a relatively low level,showing different spatial distribution characteristics.(3)driving factors have different effects on different functions of cultivated land.Elevation is negatively correlated with cultivated land production and ecological function,while the distance between cities and wuhan is only positively correlated with ecological function.Per capita net income of farmers and economic development have significant promoting and negative effects on cultivated land production,ecology and social function,respectively.The growth of GDP in the secondary and tertiary industries will weaken the production and ecological function of cultivated land,and the number of employees in the tertiary industry is negatively correlated with the social function of cultivated land.Urbanization can promote the productive function of cultivated land and weaken the social and ecological functions.Arable land is a fundamental resource for human survival and progress,a crucial guarantee for food security,a basic resource for solving the issues of"agriculture,rural areas and rural people",an important factor for social stability as well as a earrier for regional construction and development.Since arable land is a kind of scarce and non-renewable resource,China is now confronted with the following problems:a low level of arable land per capita,a low rate of arable land utilization,uneven distribution,severe degradation in quality,and the shortage of reserved land resource.In this context,there is an urgent need for land use in a reasonable and efficient way.In fact,the reason for the poor utilization of arable land lies in the insufficient understanding of the versatility of arable land.The production function of arable land has received widespread recognition,whereas great attention has not been attached to its social and ecological function.Actually,arable land,the carrier for agricultural production activities,provides social and ecological services through grain production,absorbing labor force,and the maintenance of ecological balance with carbon fixation and oxygen release.The protection of arable land resources should be aimed at implementing "the three-sphere integrated plan"so as to maintain the quantity,improve the quality of arable land resources and keep the balance in ecological system.Therefore,it is of great significance to be fully aware of the functions,values and dynamic reasons for the changes in the various functions,coordinate and develop the different functions of arable land,in order to provide reliable guarantees for the protection and sustainable development of arable land.The content of this paper mainly includes the following parts:The first part presents the origin,development and connotation of the various functions of arable land as well as the division of the various functions,the construction of the index system,the research methods and the main research directions in both domestic and foreign academic circles.It also manifests the purpose and significance of the research in this paper and concludes the content,methods and technical routes of the research.Moreover,it defines the concepts concerned,clarifies the principles for choosing the indexes and classifies the functions of arable land into the following three,namely,the production function,the social function and the ecological function.The second part carries out an empirical research on the various functions of arable land in the urban circle of Wuhan to make an analysis of characteristics in the temporal and spatial distribution as well as the evolution rules of arable land through constructing the evaluation system of the various functions,selecting the data of arable lands in the urban circle of Wuhan in 2000,2005,2010 and 2015,and applying the extreme value method,entropy method and comprehensive method as well.The third part,with the coupling and coupling coordination degree moles,makes a further analysis of the correlation degree and coordinated development degree among the three functions of arable land based on the measurement results of the various functions.Adopting canonical correlation analysis,qualitative and quantitative analysis,this part carries out research on the driving factors of the changes on the functions of arable land,after referring to the existed researches and selecting driving factors based on the reality of Wuhan urban circles.The main conclusions of this paper are the following:(1)In terms of timing sequence,from 2000 to 2015,the values of the total function and ecological function of arable land in Wuhan urban circle presents a slow "uptrend--downtrend--uptrend",while the values of production function demonstrates a continuous uptrend whilethe values of the social function a slow downtrend.In terms of spatial distribution,there is a notable positive correlation between the total function and the respective sub-functions of arable land in Wuhan urban circle and the spacial differences are large.Firstly,the values of the total function of arable land are low in southern and northern Wuhan,and high in eastern and western Wuhan.Moreover,the values are low in the center of Wuhan but high in central Wuhan.In addition,during the research period that is from 2000 to 2015,the agglomeration increases while the heterogeneity decreases.What's more,the agglomerations of high values has long been concentrated in the west of Wuhan urban circle,whereas the agglomerations of low values has always been in the vicinity of Yangxin county,which is in the southeast of Wuhan urban circle.Secondly,the values of the production function are high in central Wuhan but low in the center of Wuhan,and the values are high in the east and west but low in the north and south of Wuhan.Moreover,the agglomerations of high values have decreased from two to zero,however,the agglomerations of low values have increased from one to more which are mainly concentrated in the southeast of Wuhan urban circle.During the research period,the agglomeration decreases while the heterogeneity increases.Thirdly,the values of the social function are increased from the center to the periphery of Wuhan urban circle.Besides,the agglomerations of high values have decreased from two to zero,while the agglomerations of low values has long been concentrated in Jiayu county,the southwest of Wuhan urban circle.Therefore,the values of the social function are decentralized in the spacial pattern.Fourthly,the values of the ecological function are high in western Wuhan but low in southeast in Wuhan urban circle.Moreover,the agglomerations of high values and low value are quite stable that the agglomerations of high values are mainly in the west of Wuhan urban circle while the agglomerations of low values are in the Yangxin county,the southeast of Wuhan.(2)From 2000 to 2015,the relations among the various functions of arable land in Wuhan urban circle has always been in a stage of high level coupling.Moreover,there is a strong interactive relation among the three sub-functions,and their coupling coordination degree is on the verge of imbalance but later on they are slightly improved.In addition,the coupling coordination degree among production-social function,production-ecological function and social-ecological function of arable land is in dynamic development and maintained in the antagonistic stage where the coupling coordination degree is slightly improved but still at a low level,presenting an imbalance.Besides,the coupling degree and coupling coordination degree among different sub-functions of arable lands in different regions and counties are in a very low level and present different spacial distribution characteristics.(3)The driving factors have different effects on different functions of arable land.Firstly,there is a negative correlation between the elevation and the production function as well as the ecological function of arable lands,while the distance between cities and Wuhan city holds a positive correlation with the ecological function.Secondly,the increase of rural per capita net income plays a positive role in enhancing the production,ecological and social functions of arable lands,whereas the economic development can exerts negative impact on these three functions.Thirdly,the GDP growth of the secondary and tertiary industries weaken the production and ecological function of arable land.Moreover,the number of employees in the tertiary industry bears a negative correlation with the social function of arable land.Fourthly,the further progress of urbanization can strengthen the production function but weaken the social and ecological functions of arable land. |
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