Long-term trends in urban vegetation greenness and its causal relationship with built-up land expansion - A case study of the Yangtze River Delta, China (Full)
19 thg 5, 2025 | 10:42

Long-term trends in urban vegetation greenness and its causal relationship with built-up land expansion - A case study of the Yangtze River Delta, China (Full)



Urban vegetation provides crucial ecological and social benefits, but rapid urban built-up land (UBL) expansion and subsequent environmental alterations have impacted it multifacetedly. However, the causality between UBL expansion and vegetation changes remains unclear. Here, we analyzed 30-m resolution satellite observations from 1990 to 2019 to investigate the long-term trends in vegetation greenness and its connection with UBL expansion within the urban area of the Yangtze River Delta (YRD), China. We found that vegetation greening and browning trends coexisted in the urban areas, with greening and browning concentrated in the urban core and suburban respectively, accounting for 31% and 55% of the UBL pixels in YRD. Moreover, the proportion of greening UBL pixels was higher in the cities with high urbanization level and the UBL that expanded early. 

We also demonstrated that vegetation greening positively correlated with initial UBL (1990) and population density, while negatively correlating with aggregation and irregularity of UBL. Using the Synthetic Difference-in-Differences model, we revealed that the average causal effect of UBL expansion on vegetation greenness was −0.048 (p < 0.001), indicating a 33.8% decrease compared to the average vegetation greenness in 1990. This negative causality trend followed a “U-shape”, initially strengthening and then diminishing. These findings offer novel insights into the long-term effects of urban expansion on vegetation, supporting effective urban vegetation management and promoting sustainability.










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Urban vegetation provides crucial ecological and social benefits, but rapid urban built-up land (UBL) expansion and subsequent environmental alterations have impacted it multifacetedly. However, the causality between UBL expansion and vegetation changes remains unclear. Here, we analyzed 30-m resolution satellite observations from 1990 to 2019 to investigate the long-term trends in vegetation greenness and its connection with UBL expansion within the urban area of the Yangtze River Delta (YRD), China. We found that vegetation greening and browning trends coexisted in the urban areas, with greening and browning concentrated in the urban core and suburban respectively, accounting for 31% and 55% of the UBL pixels in YRD. Moreover, the proportion of greening UBL pixels was higher in the cities with high urbanization level and the UBL that expanded early. 

We also demonstrated that vegetation greening positively correlated with initial UBL (1990) and population density, while negatively correlating with aggregation and irregularity of UBL. Using the Synthetic Difference-in-Differences model, we revealed that the average causal effect of UBL expansion on vegetation greenness was −0.048 (p < 0.001), indicating a 33.8% decrease compared to the average vegetation greenness in 1990. This negative causality trend followed a “U-shape”, initially strengthening and then diminishing. These findings offer novel insights into the long-term effects of urban expansion on vegetation, supporting effective urban vegetation management and promoting sustainability.










LINK DOWNLOAD (TÀI LIỆU VIP MEMBER)

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