Urban Trees Expansion and Exposure Improvement in China: Insights From Satellite Observations (1985–2023)

Urban tree cover plays a pivotal role in bolstering the sustainability, livability, and resilience of cities. However, the changes in urban tree cover and exposure under the backdrop of urbanization in China remain unclear. This study investigates the spatial distribution and temporal trends of urban tree cover expansion and exposure change from 1985 to 2023. Our findings highlight significant progress in enhancing urban tree cover, with the average tree cover in Chinese urban areas reaching 11.9% in 2023, representing a remarkable 116% increase from 5.5% in 1985. However, this positive trend contrasts with persistent deficiencies in forest resources, as reflected by the fact that urban forest cover in Chinese cities was only 4.1% in 2023, compared with 0.1% in 1985. Furthermore, our study revealed substantial heterogeneity in the spatiotemporal variations of urban tree cover. Only five cities exhibited a decreasing trend in tree cover during the study period, with coastal cities demonstrating significantly higher tree cover compared with inland cities. Additionally, we observed that urban tree cover and expansion rates decreased significantly with increasing latitude. Moreover, nationwide, there has been a sustained and accelerated improvement in urban tree exposure levels, with average tree exposure increasing from 0.66% in 1985 to 7.45% in 2020. The 69% of cities experienced positive changes in tree exposure levels, while only 1% exhibited negative changes. These findings offer valuable insights for policymakers, planners, and stakeholders to foster greener, more resilient, and sustainable urban environments in China.