Fifteen years after the ice storm
Some species proved resilient, while other suffered: researchers
A Carleton University professor who has been studying the damage in Gatineau Park over the years says the subtle changes still evident today carry a message,
Gatineau Park has bounced back from the 1998 ice storm, but with subtle differences still apparent all these years later — and with a message.
Damaging ice storms are a normal part of the life-anddeath cycle of our forests, just as forest fires are much farther north.
So says Doug King, a geography professor at Carleton University who has been studying Gatineau Park since its trees were coated in 50-plus millimetres of ice.
“Forests are dynamic places and ice storms are a major mechanism of forest dynamics,” he said in an interview. “It helps the forest to continually regenerate itself by continually breaking old vegetation down.”
King and PhD student Evan Seed have gone back to the park year after year.
They found different trees responded in different ways: ❚ The two species that most often survived and regained their health despite heavy damage are the sugar maple and red oak. Beech, black cherry and red maple did less well, and basswood, ash and ironwood did very poorly. ❚ Trees suffered the most if they were on high ground or on slopes facing east, south or southwest. ❚ It took about five years after the storm to sort out the survivors from the doomed trees. King and Seed tagged 1,800 trees and measured how much damage they sustained. By 2004, 18.2 per cent of the more heavily damaged trees died, compared to 9.2 per cent of those with less damage.
But survival wasn’t the whole story.
Those that weathered the storm in fairly good shape grew by 12.5 per cent by 2004 (measured by the diameter of the trunks.) Those that suffered heavy damage, even if they lived, grew by just 4.3 per cent. ❚ The composition of the forest has shifted. The sugar maple population increased by 10.5 per cent while the white ash decreased by 47.8 per cent. However, a new generation was responding to the opportunity: ash saplings in sunny gaps grew by an average 1.2 metres per year. ❚ Young white birches that were bent over with their tops on the ground often popped back, unless the crowns froze to the ground. The same happened last December. ❚ Mid-sized trees were a puzzle. Many shot up right after the storm but then became more sickly by five years later, perhaps as canopies grew in overhead, shading them.
King and Seed are giving a 45-minute presentation on their work Saturday at 2 p.m. at the park’s visitors’ centre on Scott Street in Chelsea. It’s in English. There’s also a bilingual presentation on peregrine falcon research at 1:15, and one in French on mosses and other non-vascular plants at 3 p.m.
Old trees were more likely to suffer major damage with massive branches falling, while middle-aged trees with dense canopies of small branches “resisted the ice accumulation a lot more,” King said.
“The ice accumulated in those older (forest) areas and sort of accelerated the aging process. It’s a standard mechanism. We get ice storms all the time like that one last December, (when) they had to clean out all the trails.
“Every couple of years there’s enough branch loading to cause breakage.”
That opens up gaps, lets in sunlight and brings a new burst of growth from below.
“Forests recover to the point where they might not be exactly the same.” There may be a shift in species “but sooner or later the more shade-tolerant trees will continue and you’ll have this continuous cycling. It sort of resets itself.”
Since the initial boom in sugar maple, it’s possible that other species are catching up, he said. “There are all kinds of seeds brought in.”