HKU-Led Study Highlights the Resilience of Urban Greenery

Urban green spaces may be more resilient to climate stress than their rural counterparts, suggesting that sustainably managed urban vegetation could serve as a critical buffer against climate change, according to a global study led by researchers at The University of Hong Kong (HKU).

Published in the Proceedings of the National Academy of Sciences (PNAS), the study, titled “Global divergence in urban-rural vegetation resilience driven by broken ecological trade-offs,” analysed satellite observations from 751 cities across 109 countries between 2001 and 2022.

The team, led by Professor Jin Wu of the School of Biological Sciences and Professor Yuyu Zhou of the Department of Geography with Dr Zhengfei Guo as first author, looked at the “resilience” of vegetation, defined as the capacity of vegetation to recover following disturbance. They found that vegetation in urban cores was more resilient than surrounding rural vegetation in 78% of the cities studied.

The study also found that the urban–rural resilience gap has widened over the past two decades, primarily driven by declining resilience in rural vegetation while urban vegetation remained comparatively stable. The advantage was particularly pronounced in hot and arid regions, where vegetation is strongly constrained by water availability.

In 32% of cities, urban vegetation demonstrated a “dual advantage,” experiencing smaller greenness losses during disturbances and recovering faster afterwards than rural counterparts.

This challenges the prevailing view that cities uniformly harm ecosystem stability, Professor Zhou said, suggesting instead that sustainable management could allow urban green infrastructure to play a vital role in climate adaptation.

“Vegetation remaining within cities can show unexpectedly strong recovery capacity under environmental stress,” Professor Wu added. “This highlights the potential of well-designed and sustainably managed urban green infrastructure.”

For Hong Kong, the findings offer practical insights for building more climate-resilient urban green spaces, as integrating sustainable water management, appropriate canopy structure, and long-term green-infrastructure planning could help maintain vegetation resilience as the city faces increasing climate stress.