Jim poses in front of a tree at the Singapore Botanic Gardens in Singapore in 2003.[Photo provided by Xinhua]
In the midst of Hong Kong's high-rises and concrete sprawl, where space for greenery is at a premium, there is a man who has spent the past 40-plus years preserving and creating pockets of nature in the most unexpected places.
Known affectionately as "Dr Tree", Jim Chi-yung stands out as a champion of Hong Kong's green heritage. His pioneering work in urban forestry has helped transform the city's skyline into a greener, more sustainable space, offering a model for other cities grappling with the environmental challenges of rapid urbanization.
"People often think of my field as purely technical, but urban forestry is an interdisciplinary science," says Jim, a research chair professor and adviser of Geography and Environmental Science at the Education University of Hong Kong, and a former head of the Department of Geography at the University of Hong Kong. "It demands that we balance conservation with the many competing needs of urban development."
In September, a ranking by Standford University named Jim the world's leading forestry scientist, out of more than 35,000 researchers, who not only retained his top spot in the "Single-Year Impact List", but also topped the "Lifetime Impact List".
On the rooftop of CLP Power Hong Kong Limited (CLP)'s Chui Ling Road substation in Tseung Kwan O lies Hong Kong's largest "sky woodland". The rooftop brims with native trees, its walls draped with climbing plants, creating a strikingly verdant contrast amid the cityscape.
A walk through this green canopy feels like entering a natural forest, a haven for urban wildlife in the heart of a bustling city — a brainchild of Jim's decades of research initially on soil science and later on arboriculture and urban ecology.
Jim's efforts are particularly evident in his preservation of "champion trees" — mature, often ancient specimens that form the backbone of Hong Kong's green heritage. Many of these trees, such as the century-old camphor trees on Haiphong Road, Tsim Sha Tsui, were threatened amid urban expansion and typhoons. Fortunately, Jim came to their rescue with his expertise.
"Champion trees are vital to Hong Kong's natural and cultural identity, and cannot be left unattended," Jim says. His advocacy also led to the creation of a government registry for ancient trees.
Jim Chi-yung, professor of Geography and Environmental Science at the Education University of Hong Kong, conducts microclimate research at the university in 2015.[Photo provided by Xinhua]
For decades, Jim has been trailblazing in shaping policies that protect these natural monuments. His influence was crucial in influencing the Mass Transit Railway Corporation's decision to preserve the stone wall trees at Forbes Street during the construction of West Island Line's Kennedy Town Station.
Perhaps the most recent and transformative aspect of Jim's work is his focus on green infrastructure, transforming rooftops and walls into sustainable ecosystems. Unlike traditional green roofs that often rely solely on grass or shrubs, Jim incorporated native trees to create self-sustaining and biodiverse spaces.
Besides the CLP rooftop forest, Jim has designed more than 20 green rooftops in Hong Kong, including projects for the University of Hong Kong and Tai Po Market Station. "The environmental benefits of these green spaces go beyond aesthetics," says Jim. "They help cut energy costs through natural insulation, extend lifespan for roof waterproofing, improve air quality, and support biodiversity, which in turn helps cities adapt to climate change."
At 71, Jim's work is as relevant as ever. His current projects include improving the microclimates in Hong Kong's cramped subdivided homes, where many low-income families live. "Urban ecology is not just about trees, but about the quality of life in cities, particularly in areas where the environment has been compromised by rapid development," he says.
For decades, Dr Tree's commitment has extended beyond research into mentoring the next generation of environmental scientists, including Benedict Essuman-Quainoo, a former PhD student and now a lecturer at the Education University of Hong Kong.
Benedict, originally from Ghana in West Africa, has embraced Jim's focus on "nature in cities", working to promote sustainable and resilient urban ecosystems in Hong Kong and elsewhere in the world, including his home country.
"In a city where every square foot counts, Dr Jim has shown that there is always space for nature to flourish," Benedict says.
"Dr Jim is so meticulous, from research design, and methodology to writing style, and is punctual in everything," Benedict says. "He is such an inspiration for me, both in the past and now, with that passion for research and care for his students."
