Tree pruning stepped up to boost safety

Since May, 4,200 have had crowns trimmed; 800 storm-vulnerable trees chopped down
Grace Chua Straits Times 1 Dec 10;

IF ROADSIDE trees have been looking thinner on top lately, it is because the National Parks Board (NParks) has been pruning more of them.

Safety is the reason for the stepped-up work, which began in May, ahead of the year-end wet weather and high winds, which can topple the trees.

Between May and October, NParks inspected 107,600 trees, up from the 90,000 checked in that period last year.

But even with the extra work, a tree along Yio Chu Kang Road still fell onto a car during a storm in July, killing the driver. It was a healthy tree that had been uprooted by a 'microburst', which is a brief rush of strong winds with speeds of up to 65kmh.

NParks streetscape director Simon Longman said via an e-mail that the agency was committed to minimising 'tree failures', but it was impossible to prevent them. Healthy trees can succumb to strong winds and heavy rain, and waterlogged soil can cause root and soil failure. 'Trees are living organisms and not engineered structures,' he said.

The work by NParks and its contractors involves inspecting and pruning mature trees in heavy-traffic areas, trimming heavy crowns so they do not catch the wind like sails, and removing 'storm-vulnerable' trees in which defects have been found.

Since May, 4,200 trees have had their crowns trimmed, and 800 storm-vulnerable trees have been removed.

NParks' work has not gone unnoticed. Long-time Yio Chu Kang resident Lim Pheng Suan, 55, said she noticed that Yio Chu Kang Road has seemed brighter of late, and that she feels safer with the mature trees there having been pruned.

Seletar resident Jayanthi Gopal, 45, who said she has not noticed pruning work in her area, confessed to 'being in two minds' about the tree-pruning programme. 'With all these thunderstorms, it's good to take precautions. But it's sad - these trees have taken years to grow, they are beautiful and they provide shade.'

Ms Jeanne Pang, general manager of Prince's Landscape and Construction, said older pruned trees can still grow back their foliage if they are in good soil, and may have to be pruned twice a year.

The stepped-up pruning has meant good business for tree-care contractors. For instance, business at Prince's Treecare+ arboriculture division has risen by 50 per cent in the last few months.

Ms Pang noted that, besides the tree pruning by NParks and town councils, construction activity also drives up business for companies like Prince's; trees in construction sites marked for preservation are often pruned so they do not interfere with building work.

There is such a thing as overpruning. Mr Veera Sekaran of landscape firm Greenology said trees that have been too aggressively pruned go into 'survival mode', putting out many weaker branches at the same time.

Urban tree management is a delicate balancing act, he said. The crowns of tall, straight trees, like the khaya, can be hard to reach and maintain, but they do need looking after, especially if they are old.

He said: 'I don't envy NParks. Everyone loves Singapore's 'green infrastructure' because it looks nice and provides shade, but every time a tree comes down, NParks is in trouble.'