发表期刊：Ecological Indicators
分区：中科院一区TOP
影响因子：7.0
Urban expansion irreversibly alters the structure and function of terrestrial ecosystems, yet the specific impact on the carbon sequestration capacity of vegetation (characterized by net ecosystem productivity, NEP) in and around urban areas remains unclear. Previous studies confined to urban boundaries may have underestimated the full ecological impacts of urban expansion; therefore, this study explores the impact of urban expansion on the NEP at multiple scales across urban boundaries for 2904 cities globally using multiple global remote sensing datasets. The results indicated that differences within urban areas lead to significant heterogeneity in the inter-annual changes in NEP. There were insignificant changes in urban areas, a slow upward trend in old urban, insignificant changes in new urban, and a slow upward trend in suburban. When further differentiated by country level, NEP shows a clear upward trend in all urban areas of developed cities, whereas in developing cities, no urban area shows a clear upward trend. The impact of urban expansion extends significantly beyond urban boundaries, with megacities and supercities exhibiting a radius of influence of 70-80 km, compared to only 30-40 km for large, medium, and small cities. The negative impacts of global urban expansion caused a significant decrease in NEP over an area of 320,350 km2, while the positive impacts increased NEP over an area of 86,710 km2, offsetting the negative effects by approximately 27.1 %. The negative impacts of urban expansion on NEP increase, while the positive impacts decrease, with decreasing city size. The dominant factors for negative and positive impacts vary by city size: for negative impacts, the main drivers are POP, HF, and UI in megacities and supercities, and UI, POP, and HF in large, medium, and small cities; for positive impacts, the main drivers are GDP, UI, and POP in megacities and supercities, and POP, GDP and EVI in medium and small cities. This study lays the foundation for future cross-regional ecological management and sustainable planning, and holds significant scientific value in promoting human-land harmony and addressing global change.
