Despite online chatter, which suggests the opposite, incidents of falling trees and branches have dropped to their lowest level since recording of such cases began 16 years ago.
Though at least five cases of toppled trees and fallen branches were fingered for causing traffic jams and damaging vehicles last month, the 361 incidents reported this year are a decline of more than 85 per cent from 3,000 in 2001, the National Parks Board (NParks) said.
The number this year is also less than half of the 800 recorded last year, and involved mostly snapped branches rather than uprooted trees, it added.
NParks credits the plummeting figures to its tree management programme, in which trees are inspected and pruned rigorously, and those deemed to be in danger of falling are replaced.
"We are also currently developing modelling techniques to better understand the behaviour of trees under varying environmental conditions," said Mr Oh Cheow Sheng, group director of streetscape at NParks, which manages about two million trees along the streets, in parks and on state land.
NParks has also been replacing storm-vulnerable species, such as the rapidly growing Albizia and Spathodea trees, in forested areas next to roads. For instance, a plot opposite the Bukit Batok Nature Park was cleared recently by the agency over safety concerns. It had been covered with Albizia trees, which are vulnerable to storms and more prone to falling because of their brittle wood structure and shallow roots. NParks is replanting the plot with native plants.
Other enhancements to the tree management programme, introduced in May last year, include pruning and crown reduction before periods of more severe weather events, such as the north-east monsoon in December. This is done on top of normal tree pruning.
The critical role of tree maintenance was brought to the fore after a 40m-tall tembusu heritage tree in the Botanic Gardens fell and killed a woman in February. St George's Church in Minden Road had a 30m-tall tembusu tree on its premises inspected after the incident, and it was chopped down as it was deemed unhealthy.
During regular tree inspections and pruning, a detailed visual assessment is first carried out on the root collar - where the trunk and roots meet - as well as the trunk and canopy of the tree.
Where necessary, a second-level advanced tree inspection is conducted, involving the use of specialised diagnostic equipment.
Botanist Shawn Lum, a senior lecturer at Nanyang Technological University's Asian School of the Environment, said even with regular inspections and maintenance, an accident can still happen due to unexpected natural elements, such as a sudden strong gust of wind, or a long bout of heavy rain that loosens the soil.
"There are so many variables that it would be impossible to have zero tree falls or fallen tree branches... but what can be done is to keep them to a minimum," he said. "The alternative is to have a treeless city."
