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In-depth

Previous In-depths Landmark land settlement Carbon Conundrum Caribou in Canada The Mackenzie Delta Torngat Mountains Queen Charlotte Islands (Haida Gwaii) Travels with Louis British Columbia's Gulf Islands Moose on the loose Sustainable cities Icebergs Canada's musical landscape Quebec's James Bay Ottawa Valley Green with jade Hunting for cures Wild horses Canada's Bison Canada's place in the world Lessons learned in schools Power of powwows Cougars in Canada Greenland sharks Boreal birds Arctic grizzlies Lake Erie's Fire in the boreal forest Energy matters Parks for all Bighorn sheep Finding our way in the wilderness Shipwrecks of Nova Scotia Canada's grizzly bears

Contents Feature - Forest fires Let it burn! The forest of fire Smoke Jumper Canada's incendiary past GIS Safe campfire Facts Cartographer's table Games CG vault Re:sources

THE CHARRED REMNANTS of a burned forest presents a bleak and tortured picture. From afar, once-verdant evergreens stand like skeleton fingers poking the sky. Some lie on the blackened ground like fallen soldiers, the campaign against one of nature's fiercest elements lost. Yet, once the lens focuses, life is apparent. Feathery-green pine shoots stretch and grow at their parents' feet, wood-boring beetles are already turning the fallen trees into dust, and black-backed woodpeckers flit from one perch to another in search of colonizing insects.

After the glaciers receded, fire was the main method of change in the boreal forest, constantly shaping the northern ecosystem. "Biodiversity in the boreal is greatest when intermediate frequencies of fire occur on the landscape," says Vern Peters, research scientist with the Fire Research Group of the Canadian Forest Service. It promotes wildlife diversity and creates habitat for much of the northern forest's flora and fauna.

Nestled between the frozen arctic to the north and the more temperate forests and grasslands to the south, the boreal forest stretches over 1,000 kilometres north-south and covers a large portion of Canada's landmass. "Predominantly spruce and pine — it may not be as biologically diverse as the more southerly forests, but it is complex and vital for providing shelter and forage," says John Cary, director of the Ontario Forestry Association and President of the Ontario Professional Foresters Association. "It provides habitat for hosts of animals, birds, reptiles and insects."

Over time, the love-hate relationship forged between the boreal forest and its raging blazes created fire-dependent communities — populations of flora and fauna that are only able to persist when fire occurs regularly. "Jack pine woodlands are probably the best example of a fire-dependent community," says Peters. "Conifers have resinous bark and needles, and branches that readily 'wick' flames up into the canopy." The result is a firecracker ready to explode at the first spark. But jack pines evolved this way for a reason. Its cones are termed "serotinous," and will only open under intense heat — at least 50 degrees Celsius or more. "Unless the cones of a jack pine are opened by the heat of fire, the seeds will not be released, and the stand will not be renewed," says Peters.

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Plants that have fire-adapted traits, also known as pyrophytes, are usually found in these types of communities. They use whatever means available to insulate themselves from fire — having thicker bark, hiding tender buds within the stem, or using the soil as insulation for post-fire recovery. Trembling aspen use the latter method to regenerate after the scorching flames. They have a sucker network (regeneration from lateral roots under the soil) that quickly sprouts in the nutrient-rich soil left from the fire. "A stand with only five percent aspen pre-fire can become a 100 percent aspen stand post-fire," says Peters.

Like plants, animals also have evolved in response to the boreal forest's fire-prone nature. For a few years after a fire, insect populations proliferate. Wood-boring beetle species are drawn to post-fire regions where there are plenty of snags. Following in the wake of the insects, black-backed woodpeckers also search out burns. "Numerous other bird species are attracted to burns and the abundant insect populations," says Peters.

But there can be too much of a good thing. "Increased frequency and severity of fire may alter the composition of boreal communities dramatically," says Peters. There needs to be a balance where burns create a staggered mosaic of succession forests at different stages. The natural frequency of forest fires "range from approximately 75 years in the western boreal shield to about 400 years in the eastern boreal," says Peters. But this natural frequency looks to be changing. "Climate change is expected to alter fire regimes in Canada, which in turn will likely drive changes in biodiversity."

Even so, the boreal forest's ability to adapt is what has kept this ecosystem thriving for over 10,000 years. "Cases where stands fail to regenerate as a result of severe fire are rare," says Peters. "Although most of the trees are killed in these fires, the species are well-adapted to regenerate post-fire."

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