Studying forest fires

Oct 16, 2003, vol. 28, no. 4
By Marianne Meadahl

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Ken Lertzman, (left) with a section from a mountain hemlock cut during the logging that preceded the creation of Cypress Provincial Park, showing 924 years of growth at the height at which the stump was cut. The tree was likely more than 1,000 years old when cut, an age record for the species.

The summer of 2003 will go down in the history books as B.C.'s worst forest fire season in recent memory.

The fires' reign throughout the province will change landscapes, alter wildlife habitat, and fuel debate over how forests can best be managed - all of which have the attention of SFU forest ecologists Ken Lertzman and Alton Harestad.

The aftermath of fire gives Lertzman a good starting point on better understanding forest processes. He can read a forest's past and predict its future by studying what fire leaves behind.

An associate professor of resource and environmental management (REM), Lertzman tracks the effects of natural disturbances on forests, such as windstorms or fires from lightning strikes, and how they've historically shaped the forest landscape.

He then applies what he learns to forest conservation and resource management. Eight years ago, he began research on a 400-year-long history of the Stein Valley, a region where fewer natural fires in more recent times have changed the makeup of the forest.

“There will be a huge research opportunity to look at the ecological effect of these fires and understand how variable they are on the landscape,” says Lertzman. His graduate students are currently involved in a number of studies, targeting the historical dynamics of forest fires as well as the impact of management practices, from prescribed burning to the evolution of ecosystem-based management, which involves foresters working with natural processes - like fire - rather than suppressing them.

Lertzman says solutions are needed, for example, to address such issues as continuing tree encroachment in meadows and open forests, which may have been maintained historically by frequent fires. A collaborative study underway in Skagit Valley Provincial Park, involving REM graduate student Darren Witt, and researchers from B.C. parks and the Sto:lo nation, is investigating the experimental use of fire to restore ecosystems changed because of a lack of fire.

“When you have a summer like this one, people are interested in looking at any potential tools,” says Lertzman. “But a lot of other things need to be considered. Think about the population growth in the Southern Interior. There are issues around regional and municipal planning.

“There is a huge need for research to really nail down the historical occurrence of low and high severity fires in different ecosystems in the region,” he adds. “And for research that tests the effectiveness of different tools, like thinning and prescribed burning, for managing the risk of fire at the urban-wildland interface.”

Forest fires have been on the rise for two decades, notes Lertzman. He says the past summer raises a lot of red flags regarding the possible effects of modern climate change. “With hot, dry and windy conditions, fires burned with much greater severity than we are used to. The ecological effects of such extreme fire events can be quite distinct from more typical conditions.”

Colleague Alton Harestad says that was clear as some Interior fires raged out of control. Both researchers point to the impact of a long history of successful fire suppression on accumulation of fuels.

“One key issue in this summer's experience is that we've become really good at putting out fires,” says Harestad, noting the role of accumulated fuel in raising fire's intensity. “In some ecosystems fire is a regular occurrence. So you get a situation where instead of a natural system of frequent small fires that burn lightly, the fires are now hot enough to kill trees.”

The biology professor says that from an ecosystem management approach, fire is one of the processes, like rain or snow, which shape forest landscapes and create habitat for wildlife. Low severity fires create open, parkland type forests with wildflowers and grass.

Because of the summer's fires, Harestad says some speciessuch as marten and red squirrels lose habitat, while others such as mule deer, benefit. “The whole community of animals will rise and ebb with these changes in habitat,” he says. “If we look at the broad landscape we'd see different ages of forests. Those that burned this year will eventually become a new forest stand.

“There's more to the story than what we see now,” adds Harestad, in response to public concern over the loss of forests. “Wait for the ending. It'll be good.”

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