A strong but uneven increase in urban tree cover in China over the recent decade

Abstract

Trees play a crucial role in urban environments, offering various ecosystem services that contribute to public health and human well-being. China has initiated a range of urban greening policies to increase the number of urban trees, but monitoring urban tree dynamics at a national scale has proven challenging. Here, we used high-resolution nanosatellite images to quantify urban tree cover in all major Chinese cities in 2019 and study changes in tree cover between 2010 and 2019. We show that 11.47% of urban areas were covered by trees in 2019, and 76% of the cities experienced an increase in tree cover compared with 2010. Notably, the increase in tree cover in the mega-cities of Shanghai, Beijing, Shenzhen and Guangzhou (6.64%) was higher than that in other cities analyzed. Tree cover increases also vary between urban land use types, with public service (3.09%) and residential areas (1.79%) having the highest values. The study employed a data-driven approach toward assessing urban tree cover changes, showing clear signs of overall increases that nonetheless do not benefit all cities equally. Trees enrich cities, contributing to urban ecosystems and to the health of urban populations. This study quantifies urban tree coverage in all major Chinese cities, finding that greening efforts are successful but that certain mega-cities are benefiting more.