Quebec trees scarred for life by 1998 ice storm

Large numbers of trees throughout the St. Lawrence Valley still bear marks of the 1998 ice storm and have yet to fully recover from the damaging experience, Quebec foresters say.

It will take generations for Mother Nature to remedy the damage that warped as many as eight out of 10 trees in Quebec's hardest-hit regions — leaving them very vulnerable to extreme weather and pestilence.

At least one forester believes the ice storm, which dumped as much as 108 millimetres of freezing rain on parts of Ontario, Quebec and New Brunswick, coating the region in a thick crust of ice, taught scientists invaluable lessons about caring for trees after natural disasters.

On Montreal's Mont-Royal, "trees are doing well, but they're handicapped trees," said Pierre-Émile Rocray, a municipal forestry engineer who first surveyed the damage done on the mountain after the ice storm a decade ago.

By the time the freezing rain stopped falling in January 1998, trees were encased in thick coats of ice that bowed their trunks and snapped off branches that couldn't bear the weight. 

In Mount Royal Park, 85,818 trees were damaged to various degrees, according to figures provided by the city of Montreal.

Norway and sugar maples, in particular, took a beating, Rocray said.

Dummy limbs, weakened structure

The devastation is still visible on trees that fill the famous park slopes, especially after autumn, Rocray said. "The foliage in the summer tends to make the trees look normal. But if you look at the branches in the winter time, we see branch stubs, and we see many sprouts coming out of the stubs."

The stubs are what he calls "reaction" branches that grew where a tree's limbs were ripped off under the weight of ice.

But they are not normal branches, he said. "They're weakly attached, and they're susceptible to break in an ice storm of less intensity than we had in 1998."

They're also susceptible to decay because they are structurally weak — and that makes them vulnerable to disease and infestation, Rocray explained. 

Fortunately for the forest, many insects and diseases that commonly attack trees were weakened by the ice storm, he said.

Foresters mishandled storm aftermath

But decisions made by foresters after the storm did not provide trees with the best immunity against threats to their health, Rocray admitted.

"We thought we did the right thing at the time," he said. "In 1998 and 1999, we did two pruning cycles," which left Mont Royal's trees looking like spindly stilts.

The move further traumatized the trees, and in retrospect, foresters should have waited longer – up to five years – before the second round of pruning, he said.

Branches that were knocked off trees were quickly gathered and cleared, when they should have been left to decompose on the ground and eventually release their nutrients, Rocray said.

What would help is if Mont Royal's most damaged sections were closed to the public for a few years to let the forest regenerate undisturbed, he said.