It's lighting up our lives, but the trees suffer

PUBLISHED : Monday, 06 June, 2011, 12:00am
UPDATED : Monday, 06 June, 2011, 12:00am


The light-festooned trees that brighten malls across the city may look pretty for shoppers but spare a thought for the trees.

They're suffering, a green group says, being tricked by the lights to perform functions at night that they usually do only in daytime while the wires binding them interfere with their circulation.

The problem came to light when the Conservancy Association checked on greening projects carried out jointly by the Urban Renewal Authority and property developers. 'We conducted a check because the Urban Renewal Authority is about to launch a big greening project called Central Oasis at the Central Market building,' association campaign manager Peter Li Siu-man said.

Li said they found that the most basic element - the health of trees - was ignored. The projects they checked were the Vista private housing estate in Sham Shui Po and shopping malls Citywalk in Tsuen Wan and K11 in Tsim Sha Tsui.

Among the problems they found was that the light-emitting diodes (LED) strung on the trees caused them to perform photosynthesis - a chemical process that converts carbon dioxide into organic compounds using the sun's energy - at night.

'Light emitted from LED lighting makes the leaves continue to carry out the photosynthesis process at night, thus affecting their health,' said tree expert Professor Jim Chi-yung of the University of Hong Kong's geography department.

Girdling the trees with wires also damaged the phloem, the inner layer of bark that carries water and nutrients to the roots, Jim said.

The URA said the lights brightened up the area for safety reasons and they did not harm the trees.

But Jim disagreed and said there were plenty of other places to hang lights. 'Property management companies have many other options, such as light poles and facades of shops, to hang the lighting decorations. Why do they pick living trees?'

The association also said that dead plants over an extensive stretch of vertical greening at Citywalk had not been replaced.

The authority said the problem was noted by the property's landscape contractor but replacement of plants could only be done during fixed monthly schedules because frequent replacement would inconvenience shop owners and the public.

A spokeswoman for K11 said it hired a gardening company to do daily maintenance. Sino Estates Management, that manages Vista and Citywalk, said it engaged a landscaping contractor and was keeping a close watch on the trees' growth.