长三角地区城市密度对碳排放绩效的影响效应与机制

城市密度是衡量城市各要素空间集聚程度的表征也是调控城市各要素资源分配效率的重要手段。过往主要围绕城市密度的物质形态测度来研究城市空间资源利用与环境问题,少有立足碳排放绩效的视角来研究城市密度的演变逻辑。立足生态效益中自然资源投入最小化与获得价值最大化的观点,从经济、社会、环境三个维度构建碳排放绩效综合评价指标,以长三角41个城市为例,基于标准差椭圆分析城市密度与碳排放绩效的时空演变及关联特征,采用地理加权回归模型与地理探测器相结合的方法,确定城市密度对碳排放绩效的影响效应及机制。结果表明:(1)城市密度与碳排放绩效均升高,城市密度增速减慢,而碳排放绩效增速加快;二者均呈东南-西北向发展且关联性不断增强。(2)城市密度分指标对碳排放绩效的影响效应存在时空差异,东南部多数城市各分指标影响系数增大且作用方向不变;西北部人口密度负向影响显著增强,经济密度的影响由负转正,而空间密度的影响由正转负。(3)城市密度与其他经济社会因素交互后对碳排放绩效产生影响,其中经济密度与产业结构协同作用对碳排放绩效的影响最大,且与因子独立作用相比,人口密度与其他影响因素的交互效应增幅最大。理清城市密度对碳排放绩效的影响效应及机制,可以为城市空间结构的合理优化提供依据。

Low-carbon development effects and mechanisms of urban density in the Yangtze River Delta region

Urban density is a representation of the spatial clustering degree of various elements within a city and is also an important means regulating the efficiency of resource allocation among these elements. Previous studies have predominantly focused on the physical form of urban density to examine the utilization of urban spatial resources and environmental concerns, with little consideration for carbon emission performance in studying the evolutionary logic of urban density. This study is grounded in the viewpoint of maximizing ecological benefits by minimizing natural resource input and maximizing value gained. A comprehensive evaluation index of carbon emission performance is constructed from three dimensions: economic, social, and environmental. Taking 41 cities in the Yangtze River Delta as an example, the spatio-temporal evolution and correlation characteristics of urban density and carbon emission performance were analyzed based on standard deviation ellipse. The geographic weighted regression models and Geodetecor were used to determine the impact effect and mechanism of urban density on carbon emission performance. The results indicate that: (1) Both urban density and carbon emission performance have increased, with the growth rate of urban density slowing down while the growth rate of carbon emission performance accelerating. The development pattern exhibits a southeast-to-northwest development pattern with continuously strengthening correlation. (2) There are spatiotemporal differences in the impact of sub-indicators of urban density on carbon emission performance. In the southeastern region, most cities show an increase in the impact coefficient of each sub-indicator, maintaining directions of influence. Conversely, in the northwestern region, population density''s negative impact significantly intensifies, economic density changes from negative to positive influence, and spatial density''s impact shifts from positive to negative. (3) The interaction between urban density and other economic and social factors influences carbon emission performance. The synergistic effect between economic density and industrial structure has the greatest impact on carbon emission performance. Additionally, compared to the independent effects of factors, the interaction effect between population density and other influencing factors experiences the most significant increase. Clarifying the impact and mechanisms of urban density on carbon emission performance can provide a basis for the rational optimization of urban spatial structure.