Alarm at chopping of wall trees' roots
Inquiry after workers damage banyans
The government is investigating why the roots of old banyan trees growing on an old stone wall in Mid-Levels have been removed - work an expert said could hamper the trees' growth and cause them to topple over.
Workers were spotted last month cutting back the roots, which spread down the wall at the junction of Hornsey and Conduit roads. Most of the roots have been removed, except for the trunk root of the biggest banyan.
Tree expert Jim Chi-yung said none of the roots should have been touched. 'The roots of these banyans penetrate from the joints into the wall to reach the soil. If they are cut back excessively, the trees will lose their natural balance and the risk of them collapsing will increase,' he said.
Central and Western District councillor Man Chi-wah said the Civil Engineering and Development Department had been carrying out maintenance on a nearby slope since last summer. He said he would look into the case.
However, a spokeswoman for the Development Bureau said the slope was maintained by the Architectural Services Department and the bureau was looking into why workers had cut back the roots.
Professor Jim said the oldest of the four banyans on the wall was about 100. There were 500 old stone walls on which banyans and other trees grow, Professor Jim said. The open joints between the stones used to build these walls - many of which date to before the second world war - have allowed the trees to grow.
Conservationists consider such walls and the trees that had grown on them an important part of the city's cultural heritage. However, they enjoy no protection under the law.
Professor Jim said the walls should not be overmanaged because the trees were very unlikely to fall or cause a public nuisance. 'The roots will usually extend to areas where they can find the soil. They seldom reach too far out onto the pavement,' he said.
The best way to deal with such walls was to do nothing. 'It is very rare that walled trees will collapse. The roots anchor to the wall very well.'
Ken So Kwok-yin, a certified arborist who works for the Conservancy Association, said cutting the roots of banyans could affect the fine roots attached to them, and that could affect the tree's health. 'The fine roots are where a banyan absorbs water. If a lot of fine roots are affected by the trimming, the tree may decay.'
He said the government should give priority to tree protection when balancing slope safety with other needs. 'Any discussion of slope maintenance must take into account the requirements of trees.
'Tree experts should be involved to consider the best way to avoid the trees being touched or chopped down.'