| Sustainable utilization of cultivated land is an important foundation to ensure food security,promote ecological civilization and coordinate social and economic development.In the background of rapid urbanization and new industrialization,the land use transformation is undergoing violently with urban and rural construction land encroaching upon a large number of cultivated land,which poses a serious cultivated land use problem.At the same time,in the process of land use,the differences of cultivated land use and management mode in rural areas of China caused significant variety in the transformation of cultivated land use.Therefore,it is urgent to find out and recognize land utilization transition characteristics and the according reasons as well.This is not only a premise to reveal the transformation mechanism,but also an effective trial to enrich the theory and method of the research on cultivated land use transformation.Furthermore,it can provide theoretical guidance for the national agricultural decision-making for farmland protection,food security and ecological environment protection and at the same time,it can provide services for the agricultural modernization and the sustainable cultivated land use.There is a long history for the cultivated land use in the middle reaches of the Yangtze River.In recent years,the cultivated land use has been transformed with remarkable differences as the Yangtze River Economic Belt and Rise of central China strategy is being implemented.In this context,this research,on the theoretic foundation of land science and geography science,targets at the optimization of regional resources distribution and the sustainable cultivated land use by carrying out a deep study into Hubei province,Hunan province and Jiangxi Province in central China with the help of the modern spatial data processing technology such as data visualization,scale conversion and data integration supported by GIS and spatial statistics.The research does a detailed literature review of cultivated land use theories,and then focuses on characteristics,development stages and the mechanism of the cultivated land use transformation,including temporal and spatial evolution of cultivated land use pattern(dominant/recessive form),transformation and development stages,and land use transition mechanism system.Finally,the paper discusses how to optimize and control the transformation mode of different types of cultivated land,and puts forward some suggestions and countermeasures to coordinate the transformation of cultivated land use in the middle reaches of the Yangtze River.Based on the theory of land use transformation and previous researches of cultivated land utilization,this paper discusses the connotation,the development stages and the evolution mechanism of cultivated land utilization from the theoretical perspective.Land use transition is a temporal and spatial evolution in a specific period.The cultivated land use changes from one form to other forms according to different national or regional development goals.It shows the basic characteristics of complexity,spatial heterogeneity,dynamics in time,stage and goal-oriented etc.According to the interaction of cultivated land use patterns with different levels or types,the transformation of cultivated land use will lead to different development stage of "emergence period,rapid period,integration period and stable period".And in the transition period of the arable land use,the national or regional development goals will stimulate the use of arable land by external factors to change the pattern of land use.This kind of change will satisfy the demand for cultivated land by certain transformation pattern.From the perspective of cultivated land use pattern,this paper constructs the measurement model of cultivated land use change characteristics,and quantitatively describes the 2 elements of the cultivated land in the middle reaches of the Yangtze River,such as the dominant and recessive forms as well as the spatial and temporal patterns,which are 4 elements in total.During the period from 1990 to 2015,the pattern of cultivated land use in the middle reaches of the Yangtze River has undergone a drastic but not balanced evolution.The dominant form of cultivated land use through the "stage of decline,the rapid rise,smooth down" process shows the distribution of gradient features in Wuhan,Changsha,Nanchang and other major cities as the center outward diffusion;the recessive form of cultivated land has experienced different changes,with significant transition amplitude and relative stable transition speed.It finds that with the increase of the topographic relief,the amplitude and speed of transformation of the dominant form of cultivated land decreased gradually,while the recessive form of cultivated land shows a decreasing trend from 3 levels to the poles.From the perspective of coordination,the pattern of cultivated land use in the middle reaches of the Yangtze River in the past 25 years shows a strong spatial aggregation effect.Combined with the spatial and temporal characteristics of cultivated land use patterns,5 types of cultivated land use patterns in the middle reaches of the Yangtze River are determined;for different periods of time,there is a significant positive linear relationship with cultivated land use patterns in the middle reaches of the Yangtze River,which means that the higher the level of cultivated land use,the better the coordinated development of cultivated land use patterns.On this basis,by monitoring the position of the mutation point in the adjacent transition periods,we can get the transformation and development stages of cultivated land use in the middle reaches of the Yangtze River from 1990 to 2015: high speed transformation with low coordination phase,stable elements of low coordination phase,scale transformation approaching to the intensive transformation with moderate coordination phase,low capacity and high coordination transformation phase and scale transformation tending to be highly coordinated capacity transformation phase.Influenced by the natural geographical environment and the development of social economy,the transformation of cultivated land use in the middle reaches of the Yangtze river shows the spacial imbalance.Natural geographical environment is the basic condition for the formation of cultivated land use,and the social and economic development has a promoting effect on the transformation and utilization of cultivated land.Taking the land property rights system as an example,the land property right system has solidified the relationship between the farmers and the cultivated land,but the positive reform of land property right system can stimulate the use of cultivated land,and promote the rational use of cultivated land.In reality,the transformation of cultivated land use in the middle reaches of the Yangtze River is formed by the interaction of various natural geographical factors and socio-economic development factors,and the factors such as the slope and the change of the per capita GDP show strong spatial imbalance.The transformation of cultivated land use is not only dependent on the external factors,but also closely related to the internal ones.Combined with the goal of national or regional development together with the characteristics of cultivated land use type in the middle reaches of Yangtze River in this research,the "direct-control-ultimate" transformation goal is set up.By adopting measures suiting local conditions,scientific regulations of cultivated land use in plain,hilly and mountainous areas in the middle reaches of the Yangtze River are: in the main grain producing area,the transformation of cultivated land use should be developed to the intensive management mode of grain crops;in the hilly area dominated by Jiangnan hills,the transformation of cultivated land use should be oriented to the development of economic crops;since topography in the mountainous area of the Yangtze river changes largely,the cultivated land use should better target at the refined agricultural management. |
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