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Mind-Boggling Trees Growing Out of Buildings and Walls Keep Hong Kong Clean and Green



Growing trees in urban areas is often a challenge. On one hand, the green anti-carbon-emissions weapon requires constant management and careful planning, and on the other hand, there is a direct competition for space.

The latter might be a bit difficult to comprehend, as in Europe and the U.S., seeing trees being planted along sidewalks and roads is so common, that we often take it as a given. But in Asia, space is of an essence, and in places like Hong Kong, trees are allowed to grow on buildings and retaining walls. Is this a sign of weak management, or is it something that the city officials encourage? Read further to find out.

A picture gallery entitled the Wild Concrete, containing truly amazing, and slightly unbelievable photos taken by the photographer Romain Jacquet-Lagrèze and published by Gizmodo, shows trees that grow directly out of building walls. The images reminded me a bit of a scene from the movie “I am legend“, where all people, but one, were killed by a plague, and the abandoned town was overgrown by shrubs and trees.

The photographer described the phenomenon in Hong Kong as an example of nature being more powerful than men and no control measures are stronger in preventing it from taking over. This explanation sounds great, but referring back to the movie, it got me thinking- Hong Kong is nothing like the fictional version of New York, where no people are seen. Just the opposite, It is a highly populated and extremely technologically advanced city, so there must be another reason to why this is allowed.

Digging up some facts, it seems it is all part of a strategy to overcome the lack of space for greenery in the city. This is actually why the trees that come out of buildings and walls are left untouched, besides having a sentimental and cultural value to residents. City officials see it as a solution to the problem created by architects and engineers, who years ago did not allow any space for urban trees when designing the city road network.

This of course does not answer the question to how the trees ended up there to start with. What actually happened is that the Hong Kong government that was ruling before World War II, had to find a way to deal with severe landslide hazards, which damaged main roads and developments. They decided to construct walls, and it seems also buildings, out of masonry stone. The cracks between the stones allowed water and soil to accumulate, and turned into a perfect habitat for tree seeds to be deposited by birds and wind. As the trees grew larger, they provided even better support, and made the walls even stronger. Unfortunately, this type of construction material is now being replaced by concrete, and it is highly unlikely that new trees will grow out of it.

These trees can be seen pretty much everywhere in Hong Kong. They are part of the cultural heritage of the city as some trees are as old as the oldest residents. The greenery not only improves air quality but also preserves biodiversity by providing suitable conditions for birds and insects to live. The big challenge now, however, is to preserve the trees as they reach the end of their lifespan, and they are currently not protected by policies.

Let’s hope one of the most impressive monuments in Hong Kong, the urban forest, can last for many more years to come. The environmental benefits, and the cultural value is so great, that it cannot even be measured.

Image (c) Romain Jacquet-Lagrèze

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  1. Trees on roofs could be managed but on walls, although they are pretty, the normal dropping of leaves and limbs is a pedestrian hazard not likely to be tolerated anywhere else.   Not to mention that roots in wall cracks would make those cracks bigger.  Ever seen roots heave sidewalks or roads?


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