2000~2020年中国典型经济区PM_(2.5)时空变化及其与植被景观格局的关系

Spatio-temporal Variation in PM_(2.5) Concentration and Its Relationship with Vegetation Landscape Patterns in Typical Economic Zones in China from 2000 to 2020

探究典型经济区PM_(2.5)时空变化特征及其与植被景观格局的关系,对区域PM_(2.5)污染治理和大气环境保护具有重要意义.基于PM_(2.5)数据和MODIS NDVI数据集,采用像元二分模型、 Getis-Ord G*i分析、 Theil-Sen Median趋势分析、 Mann-Kendall检验、皮尔逊相关分析和复相关分析等方法,探究中国三大经济区PM_(2.5)空间聚集性、时空变化特征及其与植被景观格局指数的相关性.结果表明,2000~2020年环渤海地区PM_(2.5)主要表现为热点区扩张,冷点区缩减;长江三角洲地区冷点区和热点区面积占比无显著变化;珠江三角洲地区冷点区和热点区均发生扩张.2000~2020年三大经济区PM_(2.5)整体表现为下降趋势,改善程度由高到低依次是:珠江三角洲地区、长江三角洲地区和环渤海地区.2000~2020年三大经济区不同植被覆盖度等级下PM_(2.5)均表现为下降趋势,三大经济区PM_(2.5)均在极低植被覆盖度区域改善最为显著.在景观尺度下,与环渤海地区、长江三角洲地区和珠江三角洲地区PM_(2.5)相关性最强的植被景观格局指数分别是聚集度指数(AI)、最大斑块指数(LPI)和香农多样性指数(SHDI).在类型尺度下,与环渤海地区、长江三角洲地区和珠江三角洲地区PM_(2.5)相关性最强的景观格局指数分别是聚集度指数(AI)、斑块形状指数(LSI)和类型斑块面积比(PLAND).植被景观格局指数对PM_(2.5)的综合影响强于单个植被景观格局指数的影响.综上所述,2000~2020年三大经济区PM_(2.5)空间聚集性均发生了改变.在研究时段内,三大经济区PM_(2.5)整体表现为下降趋势.在景观尺度和类型尺度下,三大经济区PM_(2.5)与植被景观格局指数的关系均表现出明显差异.

This study explored the temporal and spatial variation in PM_(2.5) concentration and its relationship with the vegetation landscape pattern in three typical economic zones in China,which is of great significance for regional PM_(2.5)pollution control and atmospheric environmental protection.In this study,the pixel binary model,Getis-Ord Gi*analysis,Theil-Sen Median analysis,Mann-Kendall significance test,Pearson correlation analysis,and multiple correlation analysis were used to explore the spatial cluster and spatio-temporal variation in PM_(2.5) and its correlation with the vegetation landscape index in the three economic zones of China on the basis of PM_(2.5) concentration data and MODIS NDVI data set.The results showed that PM_(2.5) in the Bohai Economic Rim was mainly dominated by the expansion of hot spots and the reduction in cold spots from 2000 to 2020.The proportion of cold spots and hot spots in the Yangtze River Delta showed insignificant changes.Both cold and hot spots in the Pearl River Delta had expanded.PM_(2.5) showed a downward trend in the three major economic zones from 2000 to 2020,and the magnitudes of increasing rates were higher in the Pearl River Delta,followed by those in the Yangtze River Delta and Bohai Economic Rim.From 2000 to 2020,PM_(2.5) exhibited a downward trend in the context of all vegetation coverage grades,and PM_(2.5) had most significantly improved within extremely low vegetation coverage in the three economic zones.On the landscape scale,PM_(2.5) values were mostly correlated with aggregation index in the Bohai Economic Rim,with the largest patch index in the Yangtze River Delta and Shannon's diversity in the Pearl River Delta,respectively.Under the context of different vegetation coverage levels,PM_(2.5)showed the highest correlation with aggregation index in the Bohai Economic Rim,landscape shape index in the Yangtze River Delta,and percent of landscape in the Pearl River Delta,respectively.PM_(2.5) showed significant differences with vegetation landscape indices in the three economic zones.The combined effect of multiple vegetation landscape pattern indices on PM_(2.5) was stronger than that of the single vegetation landscape pattern index.The above results indicated that the spatial cluster of PM_(2.5) in the three major economic zones had changed,and PM_(2.5) showed a decreasing trend in the three economic zones during the study period.The relationship between PM_(2.5) and vegetation landscape indices exhibited obvious spatial heterogeneity in the three economic zones.