长江中游城市群城市土地利用效率的动态演进及空间收敛

Dynamic evolution and spatial convergence of urban land use efficiency in the middle reaches of the Yangtze River

探寻碳排放和工业污染物排放双重视域下城市土地利用效率(ULUE)的区域差异及协同提升路径是实现区域可持续发展的根本要求和必然选择。本文以长江中游堿市群2003-2015年数据为研究样本,在考虑城市土地利用碳排放和工业污染物排放对ULUE的双重影响下,构建“规模+结构+效益”的ULUE测度指标体系,并运用随机森林算法、核密度估计及空间收敛模型从时间和空间两个维度对ULUE时序差异的动态演进及空间差异的收敛性进行研究。结果显示:在考虑碳排放和工业污染物排放后,长江中游城市群及其各子城市群ULUE的增长相对缓慢,说明在土地利用过程中ULUE存在双重生态损耗,但ULUE总体上仍不断上升,且基本呈现“南高北低”、“西高东低”的空间非均衡格局。从时间维度上来看,根据核密度估计结果,长江中游城市群及其各子城市群内的ULUE都出现过不同程度的极化现象,但整体上ULUE的地区差距逐渐缩小。其中,长江中游城市群总体、武汉堿市群、环鄱阳湖城市群的ULUE经历了一个先扩大、后缩小的起伏波动过程,地区差异先增加后降低,而环长株潭城市群、江淮城市群ULUE的区域差异呈现先扩大、后趋于稳定的状态。从空间维度上来看,在考虑空间效应的情况下,长江中游城市群内既存在武汉城市群和环长株潭城市群ULUE的绝对β收敛,也存在包括长江中游城市群总体及其子城市群在内的全域范围内ULUE的条件β收敛。为实现环境与ULUE的协调耦合,增强区域绿色化发展能力,提出优化要素空间交流环境、加快实施创新驱动发展战略、严格执行污染排放限制标准等建议。

Exploring the regional differences and coordinated promotion path of urban land use efficiency(ULUE)under dual perspectives of carbon emission and industrial pollutant discharge is the fundamental requirement and inevitable choice for regional sustainable development.Based on data of urban agglomeration in the middle reaches of the Yangtze River from 2003 to 2015,this paper constructed the indicator system of‘scale+structure+benefit’of ULUE under considering the dual constraints of carbon emission and industrial pollutant discharge from urban land use,and then Random Forest Algorithm,Kernel Density Estimation and Spatial Convergence Model were applied to reveal the dynamic evolution of temporal differences and the convergence of spatial differences of ULUE.The results showed that:①Slower growth of ULUE in the middle reaches of the Yangtze River appeared after taking carbon emissions and industrial pollutant discharge into account.The ULUE of urban agglomeration in the middle reaches of the Y angtze River were fluctuating upward with clear spatial imbalanced characteristics,which basically presented the geographical pattern of the southern region>the northern region,the western region>the eastern region.②From the time dimension,according to the Kernel Density Estimation results,the ULUE in interior and exterior of uban agglomeration in the middle reaches of the Yangtze River had been polarized in varying degrees,but on the whole,the regional difference of ULUE had gradually decreased.In detail,the disparity of ULUE in the middle reaches of the Yangtze River,Wuhan urban agglomeration and Poyang Lake urban agglomeration manifested a distinctive tendency of‘Extending-Reducing’.The absolute difference of ULUE in Ring Changsha Zhuzhou-Xiangtan urban agglomeration and Jianghuai urban agglomeration were witnessing a process of increasing firstly and then unchanging.③F rom the spatial dimension,absoluteβconvergence only existed in Wuhan and Ring Changsha-Zhuzhou-Xiangtan urban agglomeration,but obvious conditionalβconvergence existed in interior and exterior of uban agglomeration in the middle reaches of the Yangtze River.④In order to realize the coordinated coupling of the environment and the ULUE and enhance regional green development ability,some suggstions were put forward,such as optimizing the environment for spatial exchange of elements,speeding up the implementation of innovation-driven strategies,and strict ly implementing the standards of pollution.