Environment chief Sarah Liao Sau-tung appeared before legislators yesterday to defend the felling of trees growing from walls in a Shekkipmei housing estate park - and said some would be spared the axe. She said 18 trees growing from the wall along a nullah needed felling to allow work to cover the waterway, which residents say gives off a foul stench in summer. Conservationists have been fighting to retain the trees, most of them banyans, in Lung Chu Street. They say they are of important ecological and environmental benefit to the area. Dr Liao, the secretary for the environment, transport and works, said that following objections from environmentalists, the Drainage Services Department, 'in an all-out effort to preserve that batch of trees as far as practicable, has revised the design on the decking works after consulting the Environment and Food Committee of Shamshuipo District Council'. 'Three masonry wall trees which [were to have been] removed originally are thus [being] preserved, reducing the number of trees to be felled to 18,' she told the Legislative Council. She insisted that none of the affected trees was classified as 'important'. Under government criteria, important trees are those on the Register of Old and Valuable Trees; those greater than 100 years old; those of cultural, historical or memorable significance; rare or precious trees; those of outstanding form; or those with a trunk whose diameter when measured a metre above the ground is greater than 1 metre. The work is part of a decking project involving 16 nullahs throughout Hong Kong, in the course of which 51 trees will be cut down or transplanted, Dr Liao said. Legislator James To Kun-sun queried whether the government had assessed in the past two years if existing legislation was sufficient for protecting trees. Dr Liao responded that current laws guarding the preservation of trees on government and private land were adequate and effective.