University to fell tree amid fears of a repeat of Stanley tragedy

PUBLISHED : Thursday, 17 December, 2009, 12:00am
UPDATED : Thursday, 17 December, 2009, 12:00am
 

A 40-year-old tree in the garden of the University of Hong Kong's vice-chancellor is to be cut down because of safety fears.

Tree expert Professor Jim Chi-yung described the rubber tree near Tsui Lap-chee's lodge as an inappropriate choice at an inappropriate location.

'This species is so aggressive and intrusive that the roots have damaged the brick wall surrounding the lodge. The university shouldn't have chosen it 40 years ago,' Jim, of the university geography department said - referring to the tree as Ficus elastica, originating in India.

The tree, which stands on the margin of a slope and leans towards University Drive, was once two separate trees but grew into one over the years, sharing the same roots and nutrients, Jim said.

The tree has thick 'cable' roots - some as long as 30 metres - but the trunk's base is rotten.

Some stems have split apart and the foliage has lost much of its density. Some branch tips have died, said Jim, who has monitored the tree for three years and conducted a risk assessment.

The roots are so extensive that they have cracked and displaced a drain and pushed the lodge's perimeter wall forward about 4cm.

'This particular tree has abnormal features,' Jim said. It has many v-shaped crotches in its branches and few aerial roots - roots above the ground that form a trunk. V-shaped crotches are prone to decay and splitting because rainwater soaks into the gaps between stems.

Jim said people 40 years ago had little knowledge of the characteristics of different trees. In recent years, guidelines have been issued in Florida and Hawaii in the United States, warning that aggressive species like Ficus elastica are not suitable for places close to buildings and densely populated areas.

'If it is not removed soon, the low and heavy branches might collapse in three months, just like in the coral tree accident in Stanley last year,' he said. A university student was killed in that accident, which prompted the setting up of a tree office to monitor trees in the city.

Given the possible dangers posed to students, vehicles and residents who exercise on the campus, the university said it had approval from the Lands Department to remove the tree before Christmas after conducting a risk assessment and drawing up a compensation plan.

Under the plan, 14 colourful, local flowering trees will be planted to compensate for the loss of the tree, of which eight will be planted inside the lodge garden. Species under consideration include Scarlet Sterculia, Hance's syzygium, and Japanese Elaeocarpus, featuring vivid pink and off-white flowers when they blossom.

'Our vice-chancellor likes colourful flowers, as many of us do,' Jim said. Local species benefit the ecology by providing food and shelter for birds and insects, he said.

Jim said the removal of the tree would cost more than HK$100,000 and the contractor would be required to recycle it into wood chips and compost.

'There are over a thousand trees on the campus. It is hard to ensure every tree is healthy,' Jim said. 'But we are doing our best.'

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