| When the granaries are full,the world is safe.Grain security is the"Stabilizing Force"and"Ballast Stone"of economic and social development,meanwhile,grain trade is the"control valve"and"pressure regulator"of grain security.The Food and Agriculture Organization(FAO)of the United Nations released"the State of Agricultural Commodity Markets 2020"in September 2020 and pointed out that trade is the core of the grain and agricultural development process.As a country with a large population,China must pay close attention to grain security and grain trade.Since 2004,the Party Central Committee has issued the"No.1 Document"for 18 consecutive years,paying close attention to agriculture,farmers,and rural areas,and has repeatedly put forward important guiding opinions on grain security and grain trade.In recent years,under the background of profound changes of a kind unseen in a century,epidemics,and hard constraints on domestic resources and the environment,China’s grain supply and demand have faced a"tight balance".Therefore,it is of great significance to discuss the impact of the evolution of the world’s grain trade network on China’s grain security and the countermeasures.Based on Trade Network Theory,Industrial Security Theory and Market Equilibrium Theory,taking the relationship between the evolution of the world’s grain trade network and China’s grain security level as the main line of research,this thesis uses Social Network Analysis,QAP analysis,VAR modeling and other research methods such as the OLS regression model,in order to conduct in-depth studies on the impact of the World Grain Trade Network on China’s grain security,in the meantime,multi-level verification has been carried out based on historical data.The thesis is divided into 9 chapters for systematic elaboration.Chapter 1 and Chapter 2 are(respectively)introduction,concept definition and related literature.Chapter 3 is the theoretical basis and influencing mechanism,which mainly analyzes the relevant theories involved in this article and proposes the influencing mechanism of the evolution of the grain trade network on grain security.Chapter 4 shows the evolution of the world grain trade network and the change of China’s status in the network.More specifically,it explores the overall network characteristics and individual network characteristics of the world grain trade network,verifies the influencing mechanism of geographical,economic,institutional and cultural factors on the world good trade network,and attempts to display China’s status in the trade network in a virtual panorama.Chapter 5 is the assessment of China’s grain security level,which builds an evaluation index system based on systematic and scientific principles,evaluates China’s grain security level from 1988 to2019,and clarifies the problems faced by China’s grain security.Chapter 6 is a preliminary analysis of the influence of the evolution of the world’s grain trade network on China’s grain security level.Based on the calculation results of Chapters 4 and 5,a VAR model is constructed to preliminarily analyze the impact of the grain trade network on China’s grain security level.Based on Chapter 6,Chapters 7 and 8 are aimed to further verify the impact of the evolution of the grain trade network on China’s grain security level from the level of grain types and provinces.Chapter 9 entails the conclusion and recommendations.Through theoretical and empirical analysis,the following main conclusions are drawn:(1)Based on the world’s grain bilateral trade data from 1988 to 2019,using social network analysis to construct an unweighted and weighted grain trade network,it can be seen that the characteristics of the world’s grain trade network are reflected in both the characteristics of the overall network and the individual network.The characteristics of the overall network include the obvious trend of network expansion,the increasing trade reciprocity,the greater volatility of the network center,etc.;the characteristics of the individual network entail the uneven distribution of trade space,the high degree of concentration of the trade network,the strong heterogeneity of the trade network,and actors follow the rule of"the higher the effective scale index,the lower the restriction index".By extending the traditional gravity model and adopting the QAP analysis method,it shows that the distance difference network(DIST),the economic scale difference network(GDP),the output difference network(PRO),the logistics performance difference network(LPI),and the legal level difference network(RL),and other variables are significantly related to the World Grain Trade Network(W_g),but the degree of correlation differs in different periods;GDP,PRO,POP,DIST,CONT,LPI have a strong influence on Wg,among which,the influence coefficient of GDP,PRO,CONT are positive,and other variables are negative.(2)As one of the important participants in the trade network,China’s grain trade status has gone through a stage of"continuous fluctuations—significant improvement—significant decline—stable and upward",and its grain trade position advantage is not significant.More specifically,it shows high out-degree centrality,low in-degree centrality,low-level out-intensity,rapid growth in in-out intensity,and small fluctuation in structural hole index,which also confirms that China’s grain trade is facing an international environment with increasing complexity,concentrated sources of imports,and strong import dependence,problems among which need to be resolved urgently.(3)Along with the four first-level dimensions of availability,access,stability and sustainability,the entropy weight method is used to construct an evaluation index system to evaluate China’s grain security level from 1988 to 2019.It can be seen that China’s grain security level was constantly changing.Furthermore,the change trend of the comprehensive cereals safety index can be divided into three stages:slow decline(1988～1994),steady(1994～2004),and steep increase(2004～2019);the change trend of the comprehensive soybean safety index can be divided into three stages:fluctuation(1988～1995),decline(1995～2003),and rise(2003～2019).At present,the availability,access,stability,and sustainability of China’s grain security have exposed the urgent need to resolve security issues such as increased difficulty in increasing production capacity,low level of involvement of scientific and technological forces,unbalanced spatial distribution of production and demand,and irrational import structure.(4)Based on the key indicators of China’s grain security level and the evolution of the world’s grain trade network from 1988 to 2019,an in-depth analysis of the VAR model shows that the evolution of the world’s grain trade network has a Granger causality relationship with China’s grain security level.From a short-term dynamic perspective,taking cereals as the research object,it can be seen that changes in the centrality and intensity of grain input are the Granger reasons for the changes in China’s grain security level;taking soybeans as the research object,it can be seen that the world’s soybean trade network density and the out-degree centralization has a one-way Granger causality relationship with China’s grain security level.At the same time,China’s grain security relies on a stable world trade network,and China’s key position in the world’s grain trade network will change or reshape the overall network structure.(5)Using the key indicators of the security level of China’s main grain types from 1988 to2019 and the evolution of the world’s main grain types to construct a fixed effects model,it can be seen that based on the subdivision of grain types,the evolution of the world’s grain trade network has a significant impact on China’s grain security level.The density of the world’s grain trade network has a significant positive effect on China’s grain security level,and the export centrality of the trade network has a significant negative effect on domestic grain security,and the degree of influence of the former is greater than that of the latter;the in-degree centrality of China’s grain trade has a significant positive effect on the level of domestic grain security,and income intensity has a significant negative effect on the level of domestic grain security,and the former has a greater degree of influence than the latter.Through mechanism testing,it can be seen that the overall grain trade network will have a significant impact on grain security through substitution and polarization effects,and China’s grain trade status will have a significant impact on grain security through crowding out and transmission effects.(6)Based on the key indicators of the grain security level of China’s provinces(cities,districts)and the evolution of the world grain trade network from 2000 to 2019,a fixed-effect model is constructed.It can be seen that the evolution of the world’s grain trade network has has a significant impact on the level of food security in China’s provinces(cities,districts).The influence of the density and the out-degree centralization of the world’s grain trade network on China’s provincial-level grain security is(respectively)positive and negative.The centrality and intensity of China’s grain trade have significant positive impacts on China’s provincial-level grain security.Further analysis of the heterogeneity of grain types and production areas shows that the network density has a significant positive impact on the main grain types,with the degree of influence,from large to small,which are corn,rice,soybeans,and wheat;Out-degree centralization has a significant negative impact on the main grain types,from large to small,which are soybeans,rice,wheat,and corn;China’s in-degree centralization has a significant positive impact on major grain types,and the degree of influence in descending order is corn,wheat,rice,and soybean;the direction of influence of the input intensity on wheat is negative,and the direction of influence on rice and corn is positive,with the greatest degree of influence on corn,followed by cereals,and wheat the least.The density of the world’s grain trade network has a significant positive impact on the main grain producing areas and non-main grain producing areas,but the degree of influence on the main grain producing areas is lower than that of the non-primary grain producing areas;the influence of the out-degree centralization of the network on main grain producing areas and non-main producing areas is significantly negative,but it has a greater degree of influence on non-main grain producing areas;the effects of main producing areas are all significantly positive,but the impact on non-main producing areas is greater.In summary,the complex networks formed in space by countries of the world have a profound impact on China’s grain security level.At the same time,as China is an important node country in the world trade network,improving the level of grain security is conducive to the stability and expansion of the grain trade pattern,and the two"resonate at the same frequency."Therefore,in order to ensure that China’s grain security is stable and compact,it is necessary to balance the use of the two major international and domestic markets and two resources as the goal,and to enhance China’s grain trade status as a means to fully play a combination of ensuring grain security.For example,it is recommended to accelerate the process of grain security legislative amendments,improve the quality of grain supply,tap the potential of grain trade,expand the circle of trade friends,and enhance network participation,etc. |
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