2000—2017年中国城市绿化水平的时空演变及其影响因素研究

城市绿化是城市建设的重要内容，是实现城市生态文明、生态宜居的重要途径。选取中国292个地级及以上城市，基于变异系数、泰尔指数、空间自相关和地理探测器等方法，刻画了2000—2017年中国城市绿化水平的时空演变和影响因素。结果表明：（1）2000—2017年中国城市绿化水平呈阶段性波动增长态势，全国城市绿化水平增幅为6.73%，其中西部地区绿化水平增加最为显著，改变了2000—2014年保持的“东—中—西”逐渐递减的绿化格局，形成了由沿海向内陆跃升的绿化格局。（2）2000—2017年中国城市绿化水平的总体差异与东、中、西三大区域的差异均呈降低趋势。从泰尔指数变化趋势来看，总体差异主要由区域内差异引起，且区域内差异与区域间差异在逐渐缩小。（3）东部形成一定规模的稳定性热点区，西部形成局部性热点区与一定规模的稳定性冷点，从而使得我国由“东—中—西”逐渐递减的绿化格局转变为由沿海向内陆跃升的绿化格局更为显著。（4）自然因素是城市绿化水平的基础性影响因素，经济发展水平和政府管理为阶段性关键因子，是促使各时段城市绿化格局演变的动力因子。

Spatiotemporal evolution of urban greening in China and theaffecting factors between 2000 and 2017

Urban greening has emerged as a major priority of urban development.It is a significant step in the process of realizing a sustainable urban civilization with ecological livability.Our research aimed to examine the current level of urban greening in China and provide scientific support for designing and constructing high quality urban green spaces.We analyzed the spatiotemporal differentiation of urban greening,and the factors that influence it,by determining of coefficients of variation,Thile indices,EDSA,and geographical detectors.Our findings revealed that China’s urban greening index was growing in fluctuations and showing stage change characteristics: its growth rate increased to 6.73% in the study period of 2000-2017.While eastern China has consistently led the way in terms of urban greening,we found that the urban greening index of western China increased significantly,and this region surpassed the greening index of central China.China’s overall inequality and regional disparity in terms of urban greening declined during the study period.The coefficient of variation decreased from 0.354 to 0.256,which reflected a reduction in the overall urban greening gap.The Theil index decreased from 0.132 to 0.071,the inter regional inequality tended to expand,and the intra regional inequality tended to narrow.These all reinforce the finding that the inter and intra regional inequalities were shrinking.Meanwhile,intra regional inequality was the main contributor to overall inequality.The spatial distribution of urban greening changed greatly dramatically 2000 and 2017.High-level greening cities were mainly distributed in the eastern coastal areas of the Yangtze River Delta,Beijing-Tianjin-Hebei,and the Pearl River Delta; while low-level greening cities were clustered in Yunnan,Guizhou,and Gansu.General speaking,high level greening cities were mainly located along the eastern coast,while areas with low level greening were almost in line with plateau and mountain.The values of Moran’s I for our dataset were greater than zero and the rangeability was small.The changes in the values illustrated that the urban greening level had positive correlation agglomeration characteristics in its spatial distribution.The spatial relationship of urban greening followed a trend of stabilization.Regions with large-scale and stable hotspots formed in the east,with a local hotspot and a large-scale and stable cold point formed in the west.These changes showed that the greening level increased from coastal to inland more significant than gradually decreased from east to west in China.Finally,natural factors,such as precipitation,were a foundational influence on urban greening level.Economic development and government management were key metrics at different stages,and each was a driving factor that promoted the spatial evolution of urban greening in its respective period.