Knowledge gaps abound in beetle-kill forest fires

Knowledge gaps abound in beetle-kill forest fires

04 May 2011

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USA — Researchers are taking the first steps toward closing wide knowledge gaps in the behavior of wildfires in millions of acres of Western forests devastated by the mountain pine beetle epidemic, a University of Idaho professor said Wednesday.

Over the past decade, the rice-sized beetle has decimated some 9 million acres of forest in the Rocky Mountain West and nearly five times that in Canada. But there is relatively little scientific research into how fire behavior changes in forests with beetle-killed trees, particularly in stands where there is a mix of live and dead trees.

Research has been slow in developing because of the difficulty to conduct fire experiments in forests near populated areas, said professor Jeffrey Hicke. There also are disagreements between existing studies because they often failed to consider the same criteria, he said.

Many of the gaps are baseline information, such as how fire behavior changes depending on the percentage of dead trees in one stand. But new studies presented at a Helena seminar on pine beetles and wildfires show that progress is being made.

“We’re pretty close to making large steps to greater understanding,” Hicke said.

One such study by U.S. Forest Service ecologist Matt Jolly shows for the first time that the needles of beetle-killed trees contain 10 times less moisture and a different chemical makeup than healthy trees. That means the red needles of beetle-killed trees can ignite three times faster and burn more intensely than healthy trees, Jolly found.

Jolly called his findings a “duh” moment that should seem obvious, but his is the first such study conducted. It’s necessary to answer these base questions to dispel theories that there is no significant difference in fire threat between a healthy pine tree and one killed by mountain pine beetles.

“We’re going back to these roots to dispel the folklore,” he said.

Jolly’s findings are being used by Forest Service ecologist Russ Parsons to develop a model that will eventually aid crews who fight blazes where forest canopies have turned from green to red from the beetle outbreak.

Parsons and Jolly say the models being used now aren’t valid because they don’t account for beetle-killed trees and the changes in a fire’s intensity and speed.

“There is a lack of fundamental data. We need more research,” Parsons said.

It will take some time, perhaps years, to take the new scientific research out of the laboratory and create models that firefighters can use in the field, Hicke said.

While fire managers are waiting for the new research and models, they will have to keep sending firefighters into a very different landscape from even just a few years ago, said Brad McBratney, a forest service fire management officer.

“The scary part for me is that transition until they figure it out,” he said.

The Helena and Lewis and Clark national forests’ combined 2.2 million acres are now covered by one fire protection program. Within those two areas, about 950,000 acres are infested, creating an increased risk for the 250 people in the fire program, McBratney said.

There are ways to apply some of the research now, Jolly said. One is increasing the safety zones for firefighters at blazes in forests with beetle-killed trees.

Another is the recognition that an ember from a beetle-killed tree can carry a quarter- to a half-mile in the air, farther than the ember of a healthy tree, Jolly said.

If that ember touches down in the crown of another tree with red needles, the chances are greater for that second tree to ignite, whereas an ember sparking a crown fire in a healthy tree is far more unlikely, he said.

In Montana, beetles are responsible for attacking an estimated 4 million acres of forest over the past decade. South of Montana, the beetle epidemic has spread to about 4 million acres in Colorado and southern Wyoming, according to forestry officials. In British Columbia, the beetle infestation more than 40 million acres.

That’s double the size of Montana’s forested land, said Dana Hicks, a British Columbia fire manager.

The British Columbia outbreak is further along than that in the Rocky Mountains, peaking in 2005-06. Great swaths of British Columbia forests are now standing dead trees, damaging the timber industry, the region’s main economic driver.

But the threat of fire hasn’t diminished with the loss of the red needles, he said. The dead, gray trees still burn quickly and intensely.

“Think of this as a 75-foot tall grass,” Hicks said.

After one blaze, there was a public push to cut down the gray stands of dead trees. But while the trees are dead, the forest is still alive with greater diversity of birds and invertebrates, Hicks said. A new growth of green forest is also springing up beneath the dead trees, he said.

More alarming is a new study from University of Alberta researchers that found the pine beetles may be attacking not just lodgepole pine trees concentrated in Canada’s west, but also jack pine trees prevalent across that nation.

If that happens, then the potential exists for an outbreak to spread across all of Canada, Hicks said.

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