Five times as many trees were knocked over during Storm Ophelia than would have been expected in a regular storm, according to National Tree Council president Joe McConville.
Mr McConville urged homeowners not to cut down remaining trees, saying they are unlikely to pose a risk to property. In previous years people have felled trees following storms over concerns they might cause damage if blown over in a subsequent storm.
Storms such as Ophelia are very rare events, MrMcConville said. Any trees that remain standing after it are “survivors” and are likely to withstand further strong winds.
The south of the country experienced the worst of the storm, which hit Ireland on October 16th, and services in Cork city responded to 114 calls about fallen trees. In total, the storm knocked more than 500 trees across the city.
Dublin avoided the worst of Ophelia but the fire brigade in the capital still responded to more than 70 major tree falls – many of them mature trees aged about 100 years.
Structure and health
Mr McConville said no one type of tree is more susceptible to be being blown over than another. What it depends on is the tree’s structure and health, where it is growing and the type of soil it is in.
Trees on streets can be vulnerable because their roots are often restricted, meaning they can’t spread out as far as the tree would like, leaving it poorly equipped to deal with very strong winds.
Other factors which make a tree more prone to being blown over include its level of exposure, such as whether it stands on its own or in a group of trees.
If a tree suffers from a disease, such as one which affects its roots, it will also be more likely to fall in a storm.
Storm Ophelia brought variable gusts throughout the day, which caused further difficulties for trees, Mr McConville said.
When the wind blows from one particular direction, a healthy tree will endure strong gusts and then return to its normal position. But a tree finds it more difficult to deal with stresses when the wind keeps changing direction.
“It took down a lot of healthy trees that would have been expected to stay up,” Mr McConville said.
He added that because the storm struck in autumn, when trees still had nearly all their leaves, they presented a much bigger sail to the wind, making them more likely to fall over.
