Research On The Mechanism Of The Spatial Structure Of Urban Agglomerations On Economic Growth

Economic activities need to be carried out within a certain spatial scope,and revealing the laws of human socio-economic activities from a spatial point of view was an important research field of regional economics.With the increasing complexity of the distribution pattern of economic activities in space,regional economics has begun to take the urban system as the object of study,and to study the agglomeration pattern and interaction relationship of economic activities in space.The central place theory proposed that the spatial distribution and vertical connection of core cities and hinterland cities together constitute the spatial structure of the urban system,and that the only center city dominated the economic pattern of the urban agglomeration.However,Krugman,Fujita and other scholars have proposed that the urban system evolved towards a polycentric spatial structure under the spontaneous organization of the urban hierarchy.The polycentric city system model relaxed the assumed restrictions on the size,spacing and functions of cities,providing a new perspective for the study of the spatial structure of urban agglomerations.In recent years,China had increased its efforts to promote the construction of polycentric urban agglomerations.The 14 th Five-Year Plan explicitly proposed the establishment of urban agglomerations that are multi-centred,multi-level and multi-nodal,forming a new pattern of urban agglomerations leading the development of urban agglomerations and urban agglomerations driving regional development.General Secretary Xi Jinping published "Major Issues Concerning China’s Strategies for Mid-to-Long-Term Economic and Social Development" in Qiu Shi,proposing that the internal spatial structure of urban agglomerations should be optimised,the size of large cities should be reasonably controlled,and multiple central cities should be consciously nurtured to avoid the situation of "one city dominating the others".Therefore,the polycentric spatial structure of urban agglomerations was bound to influence the future development pattern of China’s economy.In the new context of the evolving spatial pattern of China’s urban agglomerations,what form of spatial structure are China’s urban agglomerations in? What is the relationship between the spatial structure of polycentric urban agglomerations and urban economic growth,and what is the mechanism behind it?Based on the above analyses,this paper explored the impact mechanism of the spatial structure of urban agglomerations on economic growth by taking urban agglomerations as the basic analysis unit,relying on urban connections,and taking urban network externalities as the research entry point.In terms of theoretical research,this paper summarized the mechanism by which the spatial structure of urban agglomerations affect economic growth.Firstly,the mechanism for the division of urban functions.As urban agglomerations tended toward a networked polycentric structure,enterprises would have more city choices.Cost savings from shared labor and intermediate inputs would prompt them to optimize location selection based on production requirements,prioritizing regions where multiple enterprises within the same industry cluster.With the aggregation,renewal,and optimization of enterprises in cities,central and non-central cities would gradually develop specialized production functions,and a good functional division of labor will emerge between cities based on complementary industrial relations.The central city will have an impact on small and medium-sized cities through its radiation-driven effect,prompting the entire city cluster to deepen the level of division of labor and cooperation,thus improving the economic growth of each city.Secondly,the mechanism of knowledge spillover.As urban agglomerations tended to polycentric structures,the multipoint agglomeration of polycentric spatial structures shortened the physical distances between cities,which prompted closer interactive links between cities.Broader input-output linkages between cities increased the range of trade options available to firms in cities,leading to the movement of factors of production,such as knowledge,from non-central cities to cities at higher,lower or the same level.Due to the non-exclusivity,communicability,non-competitiveness,and externality of knowledge,it was more easily replicated and utilized by collaborative urban entities.Knowledge may show multi-directional diffusion such as vertical or horizontal under a polycentric spatial structure,which increased the likelihood of knowledge spillovers occurring between cities.Thirdly,the mechanism of factor allocation.Polycentric networked urban agglomerations not only involved physical proximity to larger central cities,but also entailed horizontal and vertical cooperative relationships between cities.The multi-point agglomeration of the polycentric spatial structure contributed to the frequent and rapid degree of agglomeration and diffusion of economic factors between cities,which played the function of dispersing commodity factors to neighboring cities.At the same time,wider input-output linkages increased the range of trade options available to firms in cities,inducing a flow of resources from sectors with low marginal outputs to those with higher marginal outputs,which alleviated factor congestion and resource allocation distortions caused by over-agglomeration.Regarding the empirical research,this paper provided a preliminary empirical analysis of the relationship between the spatial structure of urban agglomerations and economic growth,showing that the polycentric spatial structure of urban agglomerations had a significant role in promoting economic growth.Aiming at the mechanism of the impact of the polycentric spatial structure of urban agglomerations on economic growth,the following empirical research was conducted in this paper:First,the mechanism of division of urban functions was empirically tested.Based on the perspective of enterprise choice,this paper constructed a multi-sector specialization division model with polycentric spatial structure in Chapter 4,and analyzed the possible impact of polycentric spatial structure on urban functional division of labor.Based on the registration data of 20 industries in each city from 2003 to 2021,the spatial structure characteristics of 19national-level urban agglomerations and the functional division level of each city were measured,and the impact of polycentric spatial structure on urban functional division of labor was empirically tested.Firstly,the study found that the more balanced polycentric structure of the city cluster significantly promoted the functional division of labor of cities.In addition,this paper used replacing the core explanatory variables and replacing the sample data to conduct the robustness test,and the research results were still highly robust.Secondly,there were obvious differences in the effects of the more balanced polycentric structure of urban agglomerations on the division of urban functions.The promotion effect of city cluster polycentric spatial structure on the division of urban functions in the second-tier city clusters,the first-tier city clusters and the third-tier city clusters was weakened in turn.This paper further analyzed the differences in the impacts of large cities,small and medium-sized cities,as well as provincial capitals and municipalities directly under the central government,showing that the polycentric spatial structure of urban agglomerations had a greater impact on the division of productive service functions in small and medium-sized cities.Finally,the study found that the division of labour among urban functions had a significant positive impact on urban economic growth,and it was an important mechanism for the spatial structure of urban agglomerations to promote economic growth.Second,the knowledge spillover mechanism was empirically tested.Chapter 5 of this paper revealed the important influence of polycentric spatial structure on knowledge spillover based on endogenous growth theory,and empirically examined the relationship between polycentric spatial structure of urban agglomerations,knowledge spillover and economic growth by using the data of 64,562 pairs of city patents and cooperation of urban agglomerations in the period of2003-2021.Firstly,the study found that the polycentric spatial structure of urban agglomerations had a significant positive impact on knowledge spillover.After making endogeneity tests using instrumental variables further as well as robustness tests using replacement of estimation models and substitution of core explanatory variables,the results of the study were still highly robust.Second,the impact of polycentric spatial structure on knowledge spillover varied according to the level of urban agglomerations and the relative importance of cities.The polycentric spatial structure of urban agglomerations significantly contributed to knowledge spillovers within the first tier of urban agglomerations,and its effect on knowledge spillovers within the second and third tier of urban agglomerations was not significant.Moreover,the polycentric spatial structure of urban agglomerations had a higher impact on knowledge spillovers in small and medium-sized cities than in large cities.Finally,the study found that intercity knowledge spillovers had a significant positive impact on urban economic growth,and it was an important mechanism for the spatial structure of urban agglomerations to promote economic growth.Third,the factor allocation mechanism was empirically tested.Chapter 6 provided a further and deeper study of the mechanisms by which the spatial structure of urban agglomerations affects economic growth from the perspective of factor allocation,and introduced the urban agglomeration spatial structure as the key factor to improve factor allocation into the HK factor mismatch model,and then explored the impact of polycentric spatial structure of urban agglomerations on factor mismatch.This paper further measured the degree of capital and labor mismatch between cities using data from 214 cities at prefecture level and above in 19 national urban agglomerations,and found that there were serious labor mismatches and capital mismatches at the city level,and the degree of labor mismatches was higher than the degree of capital mismatches.From the perspective of production factor mismatch direction,capital factor was changing from capital allocation deficiency to capital allocation excess,while labor factor was in a long-term state of allocation deficiency,and both of them showed a gradually worsening trend.Second,the polycentric spatial structure significantly improved the allocation of production factors in cities.By constructing time-varying instrumental variables for endogeneity test,and by replacing core explanatory variables,considering the impact of special events and municipalities,etc.,the research results still had strong robustness.Thirdly,the impact of polycentric spatial structure on factor allocation varied according to the mismatch direction and urban agglomeration level.The polycentric spatial structure significantly improved the labour allocation efficiency of the first tier urban agglomerations.In terms of the direction of factor misallocation,the polycentric spatial structure significantly improved the problems of labour allocation.Finally,the polycentric spatial structure of urban agglomerations would improve labor mismatch,and the allocation of production factors between cities was an important mechanism for the spatial structure of urban agglomerations to promote economic growth.Based on the above research conclusions,this paper further put forward some policy suggestions.First,the division of labor between cities should be promoted to accelerate the process of economic integration of urban agglomerations.Second,the development of relevant systems and policies for the coordinated management of urban agglomerations should be accelerated,and market and administrative barriers that impede urban linkages should be broken down.Third,the layout of transportation networks in urban agglomerations should be optimized to enhance the connectivity of cities within urban agglomerations.Fourth,the economic radiation power of central cities to small and medium-sized cities should be enhanced,and the development of urban agglomerations in the direction of multi-centers,multi-levels and multinodes should be accelerated.Cities should enhance social,economic and cultural bonding between cities and promote the integration and interactive development of central and noncentral cities.