| In2012, the gross import volume of grain exceeds10%of the gross domestic output in China, which demonstrates that our grain security issue is not optimistic enough. Given that China is a big country with1.3billion people, grain security is related with the stable development of our country and the stability of our society, and cultivated land is the foundation of grain production. General Secretary Xi Jinping also emphasized during his survey in Hubei this year (2013) that"grain security relies on us." Guaranteeing grain security firstly means the gross balance of grain supply and demand. However, China is a vast territory and regional responsibility sharing of grain security is an important content of our grain security. Most of the existing studies are focused on grain security or cultivated land protection in the macroscopic layer. Among the three largest grain areas in China, there are also more studies on grain production of primary production areas, but rarely do studies focus on grain security and cultivated land protection of grain production and marketing balance areas from the angle of regional responsibility sharing of grain security. Among the eleven provincial administrative areas with balanced production and marketing, ten of them are in the west of China, which means they have similar eco-environmental characteristics and bear the same urgency in economic development. Taking grain production and marketing balance areas as the target, this dissertation selects Chongqing Municipality, which is highly typical and representational, as the sample, and constructs a grain security model for production and marketing balance areas by defining the connotation of grain security of these areas on the basis of analyzing the characteristics of grain security of the three grain areas. Also, it forecasts grain security and conducts scenario simulation regarding grain security, further studies subareas for the management of cultivated lands from the perspective of grain security, and puts forward countermeasures of cultivated land protection based on the result of area division. See the work and research methods below:(1) Regional analysis of Chinese grain security. This dissertation conducts a comparative analysis of gross domestic output, grain acreage and variable characteristics of the per unit area yield of grain of our three grain production areas (primary production area, production and marketing balance area, primary marketing area) in fourteen years from1997to2010. Furthermore, it applies variation coefficient method to describe the variable characteristics of the per unit area yield of grain of the three grain production areas, based on which it analyzes the contradictions underlying in the balance of grain security areas from the angle of gross grain and per capita grain, and clarifies the great position and significance of production and marketing balance areas in our grain security.(2) The construction and demonstration study of grain security model for grain production and marketing balance areas. On the foundation of identifying grain security of the three grain areas, this dissertation constructs a grain security model for production and marketing balance areas by defining the connotation of grain security of these areas, and takes the area (Chongqing Municipality) as the example to demonstrate the model.(3) Grain security model-based forecast of grain security level. It analyzes the variability and fluctuation index characteristics of gross domestic output, the per unit area yield of grain and grain acreage of this region in fourteen years from1997to2010, and further determines the current situation of grain security of the region based on its population; analyzes the quality of resources, quantitative characteristics and variances of cultivated lands in this region, and depicts the sensitivity of grain security toward the quantity and quality of cultivated lands; by means of natural increase, regression analysis and horizontal analysis, it forecasts relevant factors respectively, including population, cultivated land, per capita grain demand, the per unit area yield of grain, multiple crop index and the ratio of acreage of grain crops and farm crops, and calculates the grain security level of the region to be studied in the target year (2020) and resources that the cultivated lands might need under different levels of grain security.(4) Grain security and policy model simulation under different conditions of management by objectives. Through the vertical variance analysis and horizontal comparison of per capita grain demand, four levels of per capita grain demand objectives of the region are determined; different management and decision-making conditions are simulated from single-factor and comprehensive multiple-factor management perspective under different demand objectives and grain security levels.(5) Grain security-based management division of cultivated lands and strategies of cultivated land protection. From the perspective of the relations between human beings and grain, the bearing capacity of cultivated lands and the exponential model of the bearing capacity of cultivated lands are constructed, temporal and spatial variance of the bearing capacity index of cultivated lands of the region from1999to2010on the basis of the divided areas and counties is analyzed, and by virtue of standard deviation classification, the bearing capacity of cultivated lands of different areas and counties is graded and divided, and the temporal and spatial variance characteristics and rules are analyzed. With the purpose of better reflecting the external pressure variance of cultivated land protection and putting forward targeted strategies for cultivated land protection, this dissertation selects indexes of social and economic development through principal component analysis and calculates the comprehensive economic development level of different areas and counties, and grades them by standard deviation classification; it also realizes one-to-one correspondence between the index classification of the bearing capacity of cultivated land resources and the classification of social and economic development level, formulates rules of hierarchical classification, and classifies corresponding scenarios of these two; based on the result of classification and area division, this dissertation puts forward strategies of cultivated land protection.See the conclusions of the study below:(1) From1997to2010, the three grain production areas in China have witnessed a steady rise of grain output in primary production area, a decrease year by year in primary marketing area and the most substantial fluctuation of grain output in production and marketing balance area; the net grain surplus in primary production area increases slowly, the net grain mismatch in production and marketing balance area and primary marketing area increases day by day, all of these reflect increasingly prominent contradictions underlying in the regional balance of gross grain output; although grain production and marketing in production and marketing balance area basically maintain a balanced level, the degree of mismatch is gradually expanding. Thus, macroscopically speaking, grain security guarantee and cultivated land protection is an important constitution of grain security in production and marketing balance areas.(2) The connotation of grain security in production and marketing balance area means that the regional demand for grain can be satisfied through the domestic supply on the premise of importing or exporting a certain quantity of grain varieties to balance grain production and consumption structure by trades. The level of grain security can be reflected and expressed by the self-sufficiency rate of grain, and its connotation is different from that of primary production area and primary marketing area. Its grain security model is a dynamic function with multiple factors being involved. It is suggested by model demonstration that under the standard of400kg annual grain consumption per capita, the self-sufficiency rate of grain of the sample area is86.79%and87.49%respectively in2009and2010, which approaches the acceptable grain security level of production and marketing balance area-90%; under the influence of multiple aspects, such as policies of regional management, the forecasting model function can be used as a tool to examine, evaluate and forecast the regional grain security level and relevant policies, and to avoid "backstage operation" behaviors on management decisions.(3) In fourteen years from1997to2010, grain acreage of the sample area (Chongqing Municipality) has witnessed a gradual decrease, during which,638,000hm2has been decreased. However, thanks to the increasing per unit area yield of grain year by year, the gross output maintains at a basically stable level and shows slight drop, the fluctuation index is expanding though; due to the growing population, the grain mismatch of Chongqing Municipality is still expanding, and ever since1999, grain surplus has turned into grain mismatch; in the short term, it can be seen from the sensitivity analysis of grain security that the influence of variances in the quantity and quality of cultivated lands on grain output will probably be covered by changes in climate factors, such as hydrothermal conditions. However, in terms of the accumulated variances of cultivated lands in these years, the climate conditions of an area can be relatively stable, and only the quantity and quality of cultivated lands is the basic guarantee of regional grain output.(4) Chongqing Municipality has witnessed a decrease in the quantity of cultivated lands and the per capita quantity from1997to2010. The three areas (one ring and two wings) present obvious differences in the structure of cultivated lands; per capita grain demand enhances with the social and economic growth, and according to model forecast, the self-sufficiency rate of grain of Chongqing Municipality will be78.98%by the year2020under the standard of overall well-off livelihood in per capita grain consumption (425kg per capita), which is far lower than what it required to realize production and marketing balance; the lowest acceptable level of grain security-90%of production and marketing balance area is used in calculation, and the mismatch of cultivated lands reaches313,200hm2.(5) It is suggested by scenario simulation of management policies under different grain consumption levels in the target year (2020) that it is extremely difficult to realize the balance between grain production and marketing. And since the sample area is highly typical and representational, this result can also reflect the forecast of the whole grain production and marketing balance area; all the other factors involved with management except from population are implemented and depended on the operation interface of cultivated land resources, and various malpractices of strict population management become increasingly obvious. Therefore, only the protection of cultivated lands is the fundamental guarantee of grain security.(6) As a whole, the bearing capacity index of cultivated land resources of Chongqing Municipality from1999to2010presents overloaded development with obvious spatial differences among regions; it is shown by the study on its correspondence with the level of social and economic development that such correspondence shows significant spatial distribution patterns and the same corresponding type shows obvious spatial convergence, which also shows highly spatial conformity with the "one ring two wings" economic development patterns of Chongqing Municipality.(7) The classification and area division of the correspondence between the bearing capacity index of cultivated land resources and the level of social and economic development can well reflect the tension of human-grain relations and the spatial differences of cultivated lands being non-agriculturally occupied, which means this method is scientific to a certain degree and can lay a favorable foundation for the pertinence of measures of protecting cultivated land resource. This provides a referable method and empirical example for the study of cultivated land protection in other grain production and marketing balance areas.(8) Other provincial regions of grain production and marketing balance areas show similar eco-environmental pressure and economic development impulse with the sample area. Provided ineffective utilization and protection of cultivated land resources in production and marketing balance areas, the net mismatch of grain will expand at a high speed and will gradually convert into grain import areas, which will influence the balanced pattern of national grain security and further affect our national grain security.On the basis of elaborating the characteristics of the three grain areas, this dissertation analyzes our grain security regionally and the positioning of grain production and marketing area in national grain security. By taking Chongqing Municipality as the sample area, it constructs a model of grain security of grain production and marketing balance areas, forecasts the level of grain security and simulates grain security and policy model under objective management conditions, and studies the division and management of cultivated lands and cultivated land protection, so as to conduct a more profound study on grain security and cultivated land protection of grain production and marketing balance area. This study provides helpful references to the understanding of the role production and marketing balance areas play in national grain security and the situation they confront with, as well as the formulation of policies related with grain security and cultivated land protection by our country and governments at all levels. Also, this study is of great significance in practice and shows certain innovativeness in theory. |
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