Urban Land Expansion and its Driving Forces in Different Functional Cities: An Empirical Analysis Based on 137 Cities in China

Understanding the driving forces of urban land expansion in different types of cities is crucial for the differential regulation of urban land sprawl. Based on the function classification of Chinese cities,this study selected 137 prefecture-level cities from 1999 to 2011. Methods of panel data analysis and comparative analysis were used to explore the differences of urban land expansion characteristics and driving forces in four different functional cities,i. e. regional comprehensive cities,resources cities,the secondary industrial cities II,and cultural and tourism cities. The results showed that in regional comprehensive cities,the urban land expands fastest,but its urban land per capita is the smallest. In the secondary industrial cities II,the annual average growth rate,elasticity coefficient of urban land expansion,and the urban land per capita are all the highest,while in resources cities, the urban land per capita,the annual average growth rate,the expansion speed per city and elasticity coefficient of urban land expansion are the lowest. The results also indicated that urban population,economic growth and green land per capita are common driving factors affecting urban land expansion in various function cities. Among those common factors,urban population is the most important one,and the sort orders of other two factors' relative importance are the same in the two types of the secondary industrial cities,but different in the other two types of cities. The investment in fixed assets,adjustment of industry mix and the workers' average wage are special factors, of which the investment in fixed assets has effects on various types of cities except resources cities,the factor of adjustment of industry mix only affects resources cities,and the influence of those two factors are relatively small. The factor of workers' average wage only has impact on the urban land expansion of cultural and tourism cities and the secondary industrial cities II,and is the secondary important factor in cultural and tourism cities. This study confirmed that in different function cities,the different characteristics of urban land expansion exist,and the factor combinations and the driving factors' effects are significantly different as well. In order to guide reasonable expansion of urban land,differentiated land policies should be formulated for different function cities.