Urbanization’s Role in shrinking greenness Gradients: Core area vegetation Growth and convergence of Rural-Urban Green coverage in 766 Chinese cities using seven indicators

Abstract

Urbanization significantly alters vegetation greenness, yet the spatial and temporal dynamics of this change, especially in core urban areas versus rural zones, remain underexplored. This study evaluates the impact of urbanization on vegetation greenness across 766 cities in China from 2000 to 2022, using seven distinct indicators, including three newly proposed ones. Satellite-based vegetation indices, Enhanced Vegetation Index (EVI) and Normalized Difference Vegetation Index (NDVI), are used to quantify shifts in vegetation coverage, focusing on the greenness gradients from urban cores to rural areas. The results reveal a shrinking greenness gradient due to urbanization, with significant increases in vegetation coverage in urban core areas. Specifically, ΔVI (urban VI minus rural VI) decreased by 9.6 % (p < 0.05), indicating a convergence of vegetation greenness between urban and rural areas. Meanwhile, the proportion of urban VI relative to rural VI (PVI) showed no significant trend across cities (p > 0.05), but exhibited a notable increase of 15.3 % in urban core areas, suggesting a positive urbanization impact on greenness in these regions. Spatial trends showed that 73.5 % of urban areas exhibited increasing EVI values, compared to 90.6 % in rural areas. The percentage increase in EVI during the study period was 34.0 % in urban core areas, compared to 20.9 % in urban areas and 21.4 % in rural zones. This study’s novel use of seven distinct indicators offers a comprehensive evaluation of urbanization’s impact on vegetation greenness, providing valuable insights for sustainable urban planning and environmental management.