Agglomeration Externalities And Urban Labor Productivity: Mechanisms And Evidences From A Double Perspective Of "Local" And "Network"

With the arrival of economic new normal,the previous development pattern relying on quantitative expansion and extensive growth is difficult to continue.Improving development quality will become an inevitable course for our country to boost sustainable economic development.Along with optimal configuration of spatial economic resources,urbanization process plays an important role in boosting development quality improvement.Nevertheless,on the one hand,debate in academic circles on our country's urbanization development path still doesn't stop.Some researches support “metropolis dominant” while some others approve “giving priority to developing small and medium-sized cities”.On the other hand,centralized presentation of “network” development trend in many cities of the world facilitates the rising of urban network research.On the basis of urban network perspective,scholars begin to reexamine sources and functions of agglomeration externality.Under these realities and theoretical backgrounds,the paper focuses on two issues.The first issue is how to select our country's urbanization development path under the dual perspectives of “local” and “network” in cities.Whether we continue to be obsessed with selecting one from “metropolis dominant” and “giving priority to developing small and mediumsized cities” or explore a road to coordinated development of cities at all levels.The second issue is how to reflect heterogeneity in urban network and what causes differences in getting externality for different urban individuals in the same network.Centering on the above doubts,the paper launches research work.First,it breaks up traditional agglomeration externality into “local agglomeration externality” and “urban network externality” on the basis of discriminating relevant concepts and teasing existing results,then brings both of them into the research framework of urban labor productivity.Secondly,in order to scrutiny function mechanism among keynote variables,it makes the theoretical analysis with “two-step” strategy based on urban local visual threshold and urban network threshold respectively and by two NEG models.Next,in virtue of spatial pattern statistical method with time dimension and in the way of statistical description,it observes and compares spatial and temporal pattern evolution of urban size and labor productivity in our country's urban network.Thereupon,it inspects chain relation and interaction effect of “urban size---borrowed size---labor productivity” in detail through regression analysis and by utilizing econometric model.Finally,referring to investigation of existing researches on local agglomeration economy spillover,it explores function scope of urban network externality and lays policy suggestions on discussion on development strategy of northeast cities.Through research,the paper gets rich theoretical and empirical conclusions.In theory,1.From urban local perspective,exertion of local agglomeration externality relies on rational “matching” relationship formed by “urban size” and “urban high-level function”.2.Urban network externality generates in the “sharing” course of numerous small and medium-sized cities towards big cities' high-level functions on the basis of “matching” relation from the perspective of urban network,.In evidence,the entire urban network is constituted by cities at prefecture level and above.1.In the investigation of spatial and temporal pattern,we can observe the phenonmenon of “borrowed size”,which manifests that numerous small and medium-sized cities in central China,whose urban size is not so big in the east,present labor productivity feature which is on a par with that of big cities in the east in the condition that.2.Local as well as urban network externality improvement urban productivity obviously.Under linear hypothesis,the function of the latter is obviously bigger than that of the former.We discover that marginal contribution of urban size is incremental through further investigation.3.Urban network externality is more beneficial to small and mediumsized cities.Big cities or the cities located on the edge of urban network need to rely on self-development much more for the sake of seeking improvement.4.Urban network externality is restricted by distance attenuation index.When distance attenuation index goes up,sensitivity of urban labor productivity towards borrowed size declines and function of urban network externality weakens.5.“Spatial boundary” of urban network externality is near 1,100 km.Thereinto,0-900 km is the “optimal scope” of urban network externality.Spatial linkage among cities within the distance scope is the strongest and the effective of network externality is the biggest.Finally,combined with the above conclusion,the paper answers the two major issues.Firstly,compared with entirely different debate in academic circles on “metropolis dominant” or “giving priority to developing small and medium-sized cities”,the paper provides an eclectic opinion,which proposes to develop small and medium-sized cities through strengthening network connection at the time of encouraging big cities to enhance scale moderately.Secondly,the heterogenicity impact of China's urban network on urban individuals reflects in: cities inside and outside optimal scope as well as space boundary have differences in urban network “location” or distinction of “embedded” degree.Cities with a relatively central location or a relatively high degree of embeddedness,may gain more network externality resut in better opportunity to develop labor productivity.On the contrary,there will be some disadvantages.