Tree fall in 1.2km-long, 40ha swathe may be largest in a decade here
Grace Chua Straits Times 19 Feb 11;
STRONG winds from last Friday’s storm may have blown over some trees and branches in Mandai Road, but they wreaked far greater damage away from the public thoroughfare.
A 40ha, 1.2km-long swathe of trees in the secondary forest along the edge of Upper Seletar Reservoir – about 10,000 to 20,000 trees and saplings, going by a very rough estimate – also toppled or were damaged.
It was perhaps the largest tree fall in a decade here.
Mr Wong Tuan Wah, director of conservation at the National Parks Board (NParks), said: ‘We’ve had people working in Mandai for 30 years who say this is the first time they’ve seen such a thing.’
The storm was the result of land areas heating up and pulling winds in towards the island, said the National Environment Agency, which added that such storms can happen any time of the year.
The Meteorological Service equipment nearest the site, in Sembawang, measured winds of up to 77.8kmh just before 5pm; across the island, maximum gusts recorded ranged from 10kmh to 61.2kmh.
But there are some who think the winds that cut through the thick stand of full-grown hardwoods could have been stronger, perhaps up to 100kmh.
‘This is phenomenal. It’s like someone took a blade and cut through the trees,’ said landscaping specialist Veera Sekaran, who viewed the damage on Thursday.
‘It’s like something out of The X-Files,’ he added, referring to the sci-fi television series.
The trees along Mandai Road brought down last Friday blocked two of the three lanes in the direction of the Singapore Zoo, leaving NParks and its contractors to clean up and check on other trees lining the road and a cycling path there.
As for the damaged forest, the trees will be replanted, and the area given a year to regenerate, said Mr Wong.
Tree fall in natural areas is not uncommon, he noted. Trees in an area of about 9ha fell three months ago in Chestnut Avenue, and about 200 trees fell in Jurong Country Club in 2009.
The last time that a tree fall close to the magnitude of the one in Mandai took place was a decade ago, in the Upper Peirce area.
Trees in parks, nature reserves and along roads are inspected yearly or so for structural weaknesses and poor health, but checks were stepped up in the middle of last year following severe weather.
Last weekend, Nature Society member Tony O’Dempsey, who is familiar with Mandai from his regular nature walks and studies of plant and animal life there, went to survey the damage.
The 50-year-old engineering director and Australia-born Singapore resident said the damage to the secondary forest might have been wrought by winds funnelling up the narrow water channels by the reservoir’s edge, twisting and toppling trees as thick as a man’s thigh.
But he said that in tearing down so many trees, the storm also uncovered a rare pulai tree (Alstonia pneumatophora) 50m tall, still standing, just metres into the forest.
The survivor was anchored by its sprawling roots or pneumatophores, which are common to mangroves and other wetland trees. The Nature Society and NParks now plan to gather its seeds to propagate it.
National Institute of Education botanist and Nature Society president Shawn Lum said that, left on its own, the rest of the damaged forest will first grow back a crop of fast-growing ‘pioneer trees’ which thrive in exposed conditions.
‘Within two to three years, there should be luxuriant growth and within five to seven years, the casual observer may not even realise there had been a major disturbance there,’ he said.
But primary forests, that is, untouched, pristine ones, harbour more species of plants and animals, and NParks is taking care to protect those here.
For example, it has planted a windbreak along Lornie Road to shield a small patch of primary forest from winds, and has programmes to grow rare plant saplings.
New life for rare trees and plants
Amid the damage at Mandai, experts found a previously hidden gem – a rare, critically endangered tree known as Alstonia pneumatophora.
The National Parks Board (NParks) and the Nature Society hope to collect some seeds from the tree, which was discovered after surrounding trees fell.
Other rare trees and plants that have been cultivated or resurrected here are:
# Sea teak (Podocarpus polystachyus): Found at coastal cliffs, sandy beaches and mangroves, this tree is valued for its wood. It grows wild at Sentosa’s natural cliffs and is now widely planted in coastal parks such as Labrador Park.
# Aeschynanthus albidus, a member of the African violet family: This climbing plant, thought to be extinct here, was rediscovered by National University of Singapore researchers on a tree in Nee Soon swamp forest.
NParks officers collected another specimen last year and were able to cultivate hundreds of saplings. They plan to re-introduce them into the wild.
# Tiger orchid (Grammatophyllum speciosum): The tiger-striped flowers of the world’s largest orchid were last seen in the wild in Tuas and Pulau Ubin.
But the plants, which bloom once a year, can now be seen in Orchard Road, where they were planted last year in a national orchid conservation programme.
There are also tiger orchids at the Singapore Botanic Gardens and various neighbourhood parks.