Many of the branches that have given way under the weight of the ice in recent hours are new shoots that sprouted 25 years ago from the wounds of trees damaged by the historic 1998 ice storm, say forestry engineers consulted by The Press.
Engineer and forest pathologist Pierre-Émile Rocray, who worked for the City of Montreal for more than 25 years, called them “pickle pickers”. These stunted trees in the aftermath of the ice storm have, in most cases, survived the historic storm. “Their branches have grown back on the wounds, and they have grown considerably over the past 25 years. But they are often poorly attached,” he says.
In many cases, these branches were decayed or affected by what experts call “included bark”, a structural defect between the branch and the trunk, which makes them more vulnerable to overloading.
“Just by seeing the images that have been broadcast for 24 hours, we notice from the coloring of the wood that these branches had defects. It precipitated their breakage,” adds forest engineer Gabriel Daigneault, president of Xylème, a firm specializing in urban forestry that does business with several boroughs of the City of Montreal.
The wind, which kicked in on Wednesday night, also had a significant impact, said Bruno Chicoine, forest engineer with the National Capital Commission, who worked for the City of Montreal for four years. “In 1998, it took a lot more ice accumulation before the trees broke. Wednesday, the wind was coming from everywhere. Where I was, ice accumulated on three sides of the building,” he said.
In the aftermath of the ice storm, Mr. Rocray and several tree inspectors from the City of Montreal made an exhaustive inventory.
“We drove around in a vehicle with a driver to list them, and classify public trees according to the danger they represented,” he recalls. Of approximately 450,000 trees, 250,000 were severely affected by the ice. About 150,000 were pruned, and 14,000 felled.
“These trees that I called pickle pickles, ideally, they should have been cut down at the time,” says Mr. Rocray. But that was a huge cost. In the end, they played their role well for several years. »
Lack of maintenance
Bruno Chicoine nevertheless believes that better maintenance could have avoided some of the damage that occurred on Wednesday. “These are problems that could have been corrected by maintenance,” he believes. Our trees lack maintenance. We should be more proactive, especially with trees that have already suffered damage. »
Most municipalities have tree plans specifying what percentage of trees need work, but resources are limited, and there is a long backlog of execution.
Bruno Chicoine, forest engineer at the National Capital Commission
“Several boroughs are catching up. The cities do not carry out all the maintenance work that should be done, confirms Mr. Daigneault. But the fact remains that ice storms are extremely stressful for trees. It imposes a load well above their capacity, it’s much heavier than the leaves, “he says.
The good news is that if the spectacle in the streets of the Montreal region is desolate for the moment, most of the trees will recover, assure the three forest engineers. “Nature gets rid of dead branches and rotten wood,” summarizes Mr. Rocray. But the tree, he wants to survive, it is in his nature to make new branches. »