Evolution Mechanism Of Polycentric Structure In Urban Agglomeration In The Middle Reaches Of The Yangtze River:Based On Auto Industry Value Chain

In recent years,due to the outbreak of Sino US trade disputes and epidemic situation,China’s traditional manufacturing industry’s export advantage in the world has been limited,and the problems of insufficient development in the field of import and knowledge technology have become increasingly prominent.As one of the core manufacturing industries in China,the automobile manufacturing industry has achieved rapid development in the past 40 years,but it also exposed the deficiencies in R&D,after-sales and other high-end and service links.On the other hand,in the process of economic globalization and regional economic integration,regional spatial systems with complex structure and nested scale,such as metropolitan area,urban agglomeration and metropolitan continuous belt,have been formed in the process of local production network joining the global production network.At the same time,these regions are also facing many problems,such as "weak economic growth,and uneven regional development.In this regard,this paper attempts to take the auto industry value chain as the research object,construct the mapping relationship and analysis framework between the auto industry value chain and the polycentric structure,and specifically explain that taking the automobile enterprise as the geographical location,taking the supporting relationship of parts,vehicles,logistics and after-sales in the production process as the spatial correlation,to test the polycentric structure in the form and function connection From the perspective of production,we can understand the evolution process of polycentric structure.On the basis of determining the analytical framework of polycentric structure based on the auto industry value chain,this paper aims to explain the driving force and evolution mechanism behind the evolution process of polycentric structure from the field of production,and discuss the polycentric structure from the three scales of "city(local)Urban agglomeration(regional)-National(interregional)",emphasizing the embedding of polycentric structure in different scales The spatial heterogeneity of different influencing factors on multi-scale was analyzed.In the empirical level,taking the urban agglomeration in the middle reaches of the Yangtze River as the research area,and selecting other urban agglomerations as the comparison basis and related objects on different scales,based on the location attribute and supporting relationship attribute of automobile enterprises,as well as the characteristics of the domestic automobile industry value chain,according to the number of enterprises,the power and service functions of parts and logistics and after-sales,the paper analyzes the urban agglomeration in the middle reaches of the Yangtze River The form and function of urban agglomeration are measured.Then,according to the multi-scale geographically weighted regression,the driving mechanism of different influencing factors on the polycentric structure of the urban agglomeration in the middle reaches of the Yangtze River at different scales is identified.Finally,the evolution mode and mechanism of the polycentric structure are qualitatively analyzed according to the development cases of automobile industry in the provinces of the urban agglomeration in the middle reaches of the Yangtze River.The main conclusions are as follows(1)Based on the auto industry value chain,the polycentric structure of the urban agglomeration in the middle reaches of the Yangtze River has initially appeared in form,forming a spatial structure with provincial capital as the first level center and other production bases as the secondary center.However,there are still some structural problems in the functional connection.On the one hand,the value chain of the automobile industry still stays in the production link with relatively low added value.On the other hand,there are significant inter provincial differences in the form and functional polycentric structure.Especially in the functional connection,the functional connection between provinces is relatively weak.(2)Local industrial clusters and enterprise division of production become the main ways to promote the evolution of polycentric structure.On the one hand,the automobile industry relies on the vehicle production base to form a relatively complete industrial cluster within the city,which forms a regional polycentric structure with the production base as the core;on the other hand,in the process of avoiding diseconomies of scale in enterprise production,different types of product production departments are transferred to other cities,forming a regional polycentric structure The structure between them.(3)The transformation of history and institution has become the general driving force to promote the evolution of polycentric structure of urban agglomeration in the middle reaches of the Yangtze River.The construction of automobile factories in the period of planned economy has laid the foundation for the current automobile industry.With the implementation of the market economic system,the market has become the fundamental driving force to promote the expansion of automobile production network.Cities rely on their own regional advantages to realize the expansion or introduction of automobile industry,thus promoting the evolution of polycentric structure.But at the same time,due to historical factors,the scale and type of automobile enterprises lead to the differentiation in the evolution process of polycentric structure.(4)Distance and administrative boundary are important restrictive factors for the evolution of polycentric structure of urban agglomeration in the middle reaches of the Yangtze River.In the process of automobile production,the commodity transportation of parts,vehicles,logistics and other production links has high transportation costs,which makes the automobile industry have a high degree of spatial stickiness.Therefore,without the influence of other important factors,automobile enterprises usually choose the relatively adjacent cities for industrial expansion to avoid the transportation costs caused by long-distance expansion.As an important revenue source of local finance,automobile enterprises usually do not expand to neighboring provinces,which leads to the evolution differences between provinces.