Measures Implemented to Minimise Risk of Trees Falling Due to Heavy Rainfall

Ms Hany Soh asked the Minister for National Development (a) in the past month, how many trees have fallen due to heavy rainfall; and (b) what measures has NParks implemented to minimise the risk of trees falling due to heavy rainfall during this period, especially in areas of high human and vehicular traffic, such as parks and roads.

The National Parks Board (NParks) manages over two million urban trees in Singapore’s parks, park connectors, state lands and along roads. In July this year, there were 28 incidents of uprooted trees under its management due to adverse weather conditions, such as heavy rain and strong wind. There were no injuries reported for these incidents.

NParks’ tree management regime is based on the guidelines of the International Society of Arboriculture, which sets the benchmark for international standards on tree care, including tree inspection and operations, such as pruning, pest management, transplanting and risk management. Regular tree inspections are carried out by trained inspectors every six to 24 months, with trees that are close to areas with high pedestrian or traffic activity inspected more frequently.

In 2012, NParks further strengthened the tree management programme by implementing crown reduction or crown thinning. Before the onset of periods of adverse weather conditions, crown reduction is carried out on mature trees to manage the overall height of the trees and to reduce the wind resistance of the canopy. To improve the general health of our trees, NParks also carries out mulching to supplement the regular application of fertilisers.

This rigorous regime of tree inspection and maintenance is complemented by the use of technology. For instance, NParks has developed a Tree Structural Model to better assess the impact of strong winds on the stability of trees and to inform intervention measures, such as tree pruning.

With the strengthening of our tree management regime over the years, the annual number of tree incidents has fallen by 85% from about 3,100 cases in the year 2000 to around 480 in 2022.

Trees can be affected by pests and diseases as well as environmental conditions. Even healthy and structurally-sound trees can sometimes fall during storm events due to exceptionally strong winds or heavy rainfall. NParks will continue to review and adapt its tree management regime to incorporate best practices to minimise such occurrences.