Shortlisted for the 2025 Southwood Prize
About the research
Overview
Our paper investigates how to maximize the cooling effect of urban forests. We wanted to know whether a tree’s leaf traits (like nutrient content) are more important than its physical structure (like canopy size) for reducing air temperature and increasing humidity in cities. By combining traditional forest surveys with advanced LiDAR technology in Shanghai, we sought to uncover which specific traits drive these microclimate benefits at different times of the day.
Surprises and challenges
We were surprised to find that leaf nutrient traits (nitrogen, phosphorus, and potassium) were twice as important as canopy structure for cooling during the morning and afternoon. We also expected high potassium to be beneficial, but it actually reduced the cooling effect.
A critical and challenging step was the manual refinement of individual tree segmentation after integrating drone and handheld laser scanner data to create accurate 3D models of nearly 4,000 individual trees across 34 forest plots.
Next steps and broader implications
The next step is to scale up this research. We need to explore how these trait-cooling relationships hold across different climate zones, as results from Shanghai may not apply directly to arid or temperate cities. Furthermore, future studies should combine this trait-based approach with remote sensing (like hyperspectral imagery) to map the cooling potential of urban forests across entire cities, moving from plot-level studies to landscape-level planning.
Our research offers a new, practical guide for urban planners. Instead of just planting more trees for shade, we recommend planting the right trees. To combat urban heat, policies should prioritize species with high leaf nitrogen and phosphorus but low potassium—such as Salix matsudana or Acer truncatum. This shifts the focus from simply expanding canopy cover to strategically selecting trees based on their functional traits for maximum cooling.
About the author
Current position
I am currently a postdoctoral researcher at the Future Urbanity & Sustainable Environment (FUSE) Lab in the Faculty of Architecture, The University of Hong Kong, working under Professor Bin Chen.
Getting involved in ecology
I studied landscape architecture as an undergraduate and wanted to improve human environments through design. However, I realized design alone has limitations and needs scientific data for support. Therefore, I chose urban ecology for my six-year graduate studies, focusing on improving urban forest ecosystem services. My PhD supervisors, Professors Kun Song and Liangjun Da, provided invaluable guidance, helping me build a solid ecological foundation and supporting my data collection and academic networking globally.
Current research focus
Under Professor Bin Chen’s guidance, I am now investigating the patterns and mechanisms of urban forest cooling effects at a global scale. I also study how urban forests respond to extreme events and explore their potential negative effects on the urban environment.
Advice for fellow ecologists
Find an interesting research topic and dig deep into it. Persisting a little longer may lead to unexpected and rewarding discoveries.
Read the full article ‘Integrating forest inventory and LiDAR observations to uncover the role of plant traits on cooling and humidifying effects in urban area’ in Journal of Applied Ecology.
Find the other early career researchers and their articles that have been shortlisted for the 2025 Southwood Prize here!
