With the rapid development of China’s economy,China’s population agglomeration phenomenon began to enter a rapid development mode.Large scale population migrated to large cities in pursuit of better self-development,bringing rich human capital to the local area,thus laying a reliable labor base for the further development of urban economy.According to the sixth census data,the number of migrant population in China reached Of the 260 million people,170 million of them choose cities as their migration destinations,and the phenomenon of population agglomeration to cities is particularly significant.In the national population development plan(2016-2030)issued by the State Council in 2016,it is pointed out that the population scale should be basically stabilized in areas with critical and suitable living environment,and population should be encouraged to shrink and gather in key cities and towns.For areas with suitable living environment and no overload of resources and environment carrying capacity,attention should be paid to improving the quality of population urbanization,cultivating the spatial carrier of population agglomeration,guiding industrial agglomeration,and enhancing population absorption capacity [national population development plan(2016-2030)].Based on this,this paper starts with the development status of population agglomeration,industrial agglomeration and innovation agglomeration,and focuses on the impact mechanism of agglomeration effect of domestic mega cities.Meanwhile,the residence intention of floating population in domestic mega cities is included in the logistic regression model,and the influence mechanism of various variables on the long-term residence intention of floating population in megacities is analyzed,and then the panel vector autoregression is used Finally,according to the research conclusion,this paper puts forward the countermeasures and suggestions of the three agglomeration effects of megacities in the future.After combing and summarizing the existing literature at home and abroad,it is found that scholars at home and abroad have made fruitful achievements in the study of population agglomeration,industrial agglomeration and innovation agglomeration,but there are three deficiencies.Firstly,most of the literature analyzes the impact of population agglomeration on industrial agglomeration,or the impact of Industrial Agglomeration on innovation agglomeration The research literature on innovation agglomeration is relatively small,and the research results that integrate the three into the research framework are even less.Secondly,in part of the research results of the three agglomeration effects,the mediating conduction effect or threshold effect of a factor is not considered,which leads to the failure of a comprehensive research system.Finally,at present,most of the literature research objects are provincial level samples or prefecture level samples,lack of longitudinal comparison of the same level cities,and the comparative study of domestic mega cities is still in the link to be improved and supplemented.Therefore,based on the three shortcomings of the existing literature,this paper follows the idea of "research basis-reading classic theoretical literature-analyzing the current situation of problems-constructing theoretical model-Empirical Analysis-summarizing conclusions-putting forward countermeasures and suggestions"First,after constructing the comparative framework of population agglomeration development in Beijing,Tianjin and Shanghai,it is found that Beijing has the characteristics of higher education level of permanent residents and more proportion of migrant population in Shanghai.At the same time,according to the calculation of population agglomeration index,Beijing’s population agglomeration index has the fastest growth compared with the other two cities.After calculating the spatial association pattern of population agglomeration in Beijing,Tianjin and Shanghai from2000 to 2015 by Arc GIS technology,the results show that the population agglomeration of domestic megacities,such as Beijing,Tianjin and Shanghai,presents a "center periphery" and "point axis" distribution structure,and the change range of jurisdiction level is small,which maintains long-term and stable consistency The results of I index and Lisa chart show that China’s megacities have strong spatial dependence,and the overall trend is rising steadily.In terms of cities,Beijing’s population agglomeration has begun to shift from Dongcheng District and Xicheng District to the surrounding urban areas,and has begun to form a stable development pole.The phenomenon of population agglomeration in Tianjin is consistent with long-term stability.The change range of population agglomeration in Shanghai is small,but the spatial structure of Pudong New Area is not significant due to the influence of policy adjustment.Second,through the comparison of three domestic super cities,such as Beijing,Tianjin and Shanghai,it is found that the natural growth rate of population in the three cities is increasing year by year,and the immigrating population is generally male,and has the characteristics of similar industry and rapid rising education level.In the empirical study,there are significant regional differences in the influencing factors of the floating population’s residence intention in China’s mega cities.The long-term residence intention of the floating population in Beijing is affected by their marital status and the working hours of this week.The long-term residence intention of the floating population in Tianjin is positively affected by the length of education and the floating time,and the long-term residence intention of the floating population in Shanghai is affected by the number of years of education and floating time However,in general,the age status of the floating population in China’s mega cities has a poor impact on their long-term residence intention,and the distribution of different age groups has a relatively low impact on their willingness to stay.At the same time,gender,housing expenditure and other factors have a relatively low impact on the long-term residence intention of the floating population.Thirdly,according to the dynamic panel model and panel vector autoregressive model,the empirical analysis results show that the secondary industry agglomeration and light industry agglomeration are affected by the urban industrial transformation and upgrading,which will significantly affect the development of population agglomeration,and present a negative impact mechanism.From the short and medium-term point of view,the cumulative effect of industrial agglomeration on population agglomeration is negative,and the cumulative effect on population agglomeration is negative However,from a long-term perspective,this negative effect will appear inflection point with the optimization of industrial structure,and gradually form an impact mechanism to promote the effect of population agglomeration.With the diffusion of high energy consuming industries to surrounding cities,the thrust of industrial agglomeration is enhanced,bringing about the sustainable development of population agglomeration.Fourthly,based on the empirical analysis of dynamic panel model and panel vector autoregressive model,we find that innovation agglomeration has a significant role in promoting population agglomeration.From the short and medium-term point of view,the positive effect of university project density will continue to be amplified over time,but from a long-term point of view,University projects are dense The overall impulse function model presents an inverted U-shaped curve,and the positive effect will gradually decrease,while the positive effect of patent licensing density also has the inflection point effect,which will gradually decrease with the further development of population agglomeration.Fifthly,in the research on the mediating transmission effect of population agglomeration,industrial agglomeration and innovation agglomeration,this paper uses the mediating effect model test method of Wen Zhonglin and ye Baojuan(2014)to explain the transmission theoretical mechanism of the three agglomeration effects.The empirical analysis results show that in the process of innovation agglomeration affecting population agglomeration,industrial agglomeration as an intermediary variable has a negative effect However,from the overall point of view,the impact mechanism of innovation agglomeration on population agglomeration is still positive.As an intermediary effect,industrial agglomeration has a low degree of explanation for the total effect,that is,in the process of innovation agglomeration promoting population agglomeration,10.2% is achieved through industrial agglomeration,so the intermediary effect of industrial agglomeration on population agglomeration is not a complete intermediary effect,but a partial intermediary effect.Sixth,in the research on the threshold effect of population agglomeration,industrial agglomeration and innovation agglomeration,Hansen’s(1999)threshold effect model is used to explain whether there is a threshold effect in the process of industrial agglomeration affecting population agglomeration.It is found that there is a single threshold effect in the process of industrial agglomeration affecting population agglomeration,and the estimated threshold value is-0.063 7.When the industrial agglomeration of domestic megacities is lower than-0.0637,the regression coefficient of innovation agglomeration to population agglomeration is 0.0437,and when the industrial agglomeration coefficient is greater than-0.0637,the regression coefficient increases to 0.0716,which means that the promotion effect of innovation agglomeration on population agglomeration has increased.At the same time,through the threshold effect,it is concluded that there is a single threshold effect of industrial agglomeration on population agglomeration,and the estimated threshold value is-0.1657.When the industrial agglomeration index is greater than-0.1657,the regression coefficient of industrial agglomeration decreases from-0.2073 to-0.664,indicating that the blocking effect of industrial agglomeration on population agglomeration has increased.Through the analysis of threshold effect on innovation agglomeration and population agglomeration,it is found that innovation agglomeration has double threshold effect on population agglomeration,the threshold values are-4.2649 and-1.8766,respectively.When the innovation agglomeration index is in the range of-4.2649 and-1.8766,the regression coefficient of innovation agglomeration to population agglomeration increases from 0.0077 to 0.0414,and when the innovation agglomeration index is greater than-1.8766,the innovation agglomeration has double threshold effect The regression coefficient of agglomeration increases to 0.0838,which indicates that the promotion effect of innovation agglomeration on population agglomeration will gradually expand with the increase of innovation index. |