STONE WALL TREES (石牆樹), Central-Western District (中西區), Hong Kong

Entangling roots stretch across the surface of granite walls might remind people of the Ta Prohm Temple at Angkor Wat instead of the city of Hong Kong. Commonly known as “Stone Wall Trees” (石牆樹), the urban scenery of Chinese Banyan (Ficus microcarpa 細葉榕) enrooted on historical granite walls is a unique scene in Hong Kong, especially in Central-Western District where the heart of the old Victoria City was located. In 1841 when the British first landed in Hong Kong, the bare, rocky and hilly terrain of the island posed a huge challenge for establishing a settlement. Apart from land reclamation along the coast, the British also create habitable land by constructing flat terraces on the slope of Victoria Peak (Tai Ping Shan 太平山). From the mid 19th century onwards, local granite was used to construct retaining walls for the terrace constructions. To make the relatively bare island more habitable, trees were planted across the city to provide shade and visual interest. Many foreign tree species from other British colonies such as India and Australia were brought to Hong Kong. Due to its suitability to the local climate and ability to grow rapidly, Chinese Banyan (細葉榕) were widely planted. From these banyan trees, birds and bats ate the figs and spread the seeds all over the city, and into stone joints of the retaining walls. This led to the birth of the stone wall trees.

In 1996, scholar C.Y. Jim found 1275 trees with 30 or so species on about 505 stone walls. Ficus Microcarpa or Chinese Banyan is the most common type of stone wall trees. With hardly any soil to clinch into, these banyans take the wall as their host and spread their intertwining roots on the stone surfaces. After 50 to 100 years, these banyans gradually mature into shading crowns that we see today. Many of these old stone wall trees have survived to the present day, especially in Central – Western District which contains the city’s largest concentration of stone wall trees. The emergence of stone wall trees in Hong Kong, however, was no coincidence. Perfect climate conditions, suitable stone wall surface, and some good fortune of surviving the WWII when many old trees were cut down by the Japanese for timber, all played a part in the story of stone wall trees. After WWII, stone was soon replaced by concrete for retaining wall construction. Concrete walls left little room for new trees to enroot themselves by chance. After a few generations, the resilient stone wall trees have become iconic features for various old neighbourhoods.

Despite over a century serving to improve the micro-climate of the city, cultural and ecological significance of the stone wall trees have gone unnoticed until the recent two decades. In light of the government’s intention to demolish the former Police Married Quarters (PMQ) and its iconic stone wall trees in 2005, the local resident group “Central and Western Concern Group” was formed to fight for preserving the stone wall trees as well as the heritage building. Not only has their effort succeeded in convincing the government to preserve the PMQ, they have also increased the public awareness of the stone wall trees. In 2007, the Mass Transit Railway (MTR) decided to relocate a proposed exit for the new Kennedy Town Station in order to preserve the stone wall trees at Forbes Street. The admirable effort decisively preserved the largest concentration of stone wall trees in Hong Kong. Though not all cases were success stories. In 2015, five 150-year old stone wall banyans at Bonham Road were fell sneakily overnight, just because one of their neighbouring trees toppled some time ago due to heavy rain. In name of public safety, the five healthy trees were cut down before the arrival of a potential typhoon. No detailed study was made before the decision, and that particular typhoon didn’t even come close enough to pose any thread. The hasty action of the government led to a huge loss for the community and sparked public outcry. More and more people become aware that there is an urgent need to develop a strategic plan for protecting these unique urban stone wall trees before it is too late.