GO KATHY RENWALD
Trees in the wind
Looking for answers: Why did roof shingles fly off in last Friday’s windstorm, but magnolia flowers are still on the tree?
THE
QUESTION has to be asked: Why did my roof shingles fly off in last Friday’s windstorm but the magnolia flowers are still on the tree?
Hamilton had the highest wind gusts in Ontario, recorded at 126 kilometres an hour. Shingles were flying, waves crashed all around Hamilton Harbour, and trees were uprooted and lost limbs.
But once the storm was over, the magnolia flowers looked unperturbed. Even the delicate cherry blossoms held on through the mayhem.
Look at a magnolia flower and see that it is firmly attached to the tree branch by a node. My thought is: the node is strong, it doesn’t present a big target for wind damage and therefore it rides out windstorms.
Not so with big trees.
“In 31 years, I’ve never seen so much tree damage, it’s almost like a state of emergency,” says Dave Morgan, an arborist with Beswick Tree Service in Ancaster.
Most storms leave an isolated path of destruction, Morgan says, but this left damage everywhere.
“It really caught the evergreens. Over 90 per cent of our calls were for spruce and fir trees, healthy ones that were knocked down. The wet ground contributed to trees being uprooted too.”
A physics study published in 2016 concluded that all trees break in winds of 151 km/h and upward. The study used experiments and storm data, but it was based on trees in a forest setting.
A tree in the open, at your home or in a park has different sorts of stresses.
What kind of soil is it planted in, how or if it has been pruned, whether it’s in a wind tunnel — these and more factors determine its fate in a storm.
We were lucky the trees hadn’t leafed out when the storm struck May 4. Then you have a mass of leaves acting like a sail and adding windage to the equation.
In almost 40 years living in the North End, I have never seen wind like what we endured last Friday.
It was most visible on Hamilton Harbour, where big sections of the water turned white with froth, and continuous water spots were visible.
The wind direction was different than the April storm that sunk large sections of the breakwall near Pier 7, but just as intense.
Two severe storms within a month should cause us to think about the trees we plant.
“Trees that are narrow, small, streamlined in form — these are less likely to break,” says Susan Dudley, a biologist at McMaster University.
As Dudley points out, there are numerous lists of wind-resistant trees one can consult before making a planting choice. Though many of the recommendations are specific to areas prone to hurricanes, there are suitable choices for our climate.
Though we love the idea of towering maple and oak trees, urban gardeners should also consider smallstature trees. Various lists of small, wind-resistant trees turn up online, including dogwoods, serviceberry, magnolia, redbud, some amur maples, and cherry trees.
Three days after the storm, I went out to see the cherry trees at the Royal Botanical Gardens Arboretum.
Some are ancient and massive, some are in decline, but all were still standing after the storm.
And they were gathering a crowd, all there to look at the blossoms, delicate but defiant on a calm May day.
“Trees that are narrow, small, streamlined in form, these are less likely to break.” SUSAN DUDLEY
Biologist, McMaster University