Urban Core Greening Balances Browning in Urban Expansion Areas in China during Recent Decades

Abstract

China has experienced a rapid urbanization during recent decades, strongly affecting vegetation dynamics in areas undergoing a transformation from rural to urban areas. At the same time, national greening policies have been implemented to promote urban sustainability and urban greening in China in recent years. However, it is unclear how urban greening compensates vegetation losses from urban expansion at national scale. Here, we use Moderate Resolution Imaging Spectroradiometer and Landsat satellite normalized difference vegetation index time series to study 974 major cities (urban area > 20 km 2 ) in China during 2000 to 2020 and develop an urban vegetation change typology including 5 types of vegetation dynamics (greening, browning, stable, reversal, and recovery). We document a rapid urban expansion associated with a browning in urban areas before 2011, followed by widespread regreening of the urban areas after 2011. This recovery in greenness was found in 63.45% of the cities, while 14.68% showed a continuous browning, and 8.13% a continuous greening. Our findings reveal to what extent, where, and when vegetation browning from urban expansion is balanced by urban greening in urban core areas, which may indicate that initial vegetation losses are offset by urban greening initiatives.