Story last updated at 3:20 p.m. Friday, August 9, 2002

Do dead trees cause higher wildfire risk?
by Chris Bernard
Staff Writer

photo: news
  Photo by Carey James, Homer News
An Alaska Division of Forestry tanker drops a load of fire retardant along the side of the fire, preventing it from spreading into surrounding timber. The fire was heavily attacked from the air before smoke jumpers and ground crews arrived.  
The spruce bark beetle infestation that hit the Kenai Peninsula during the last decade meant bad news for area spruce trees. But does it also mean bad news for wildland firefighters?

Opinions differ on whether beetle-killed forests pose a higher risk for fires.

"It takes one-sixth of the heat energy required to ignite a live tree to ignite a dead tree," said Michael Fastabend, spruce bark beetle coordinator for the Kenai Peninsula Borough. "A beetle-killed forest is going to ignite a lot quicker."

"I disagree," said Homer Fire Department Chief Bob Painter. "Spruce is a very flammable tree, dead or alive."

Spruce trees in the Homer area suffered about a 95 percent mortality rate during the infestation, Fastabend said.

"Homer historically has a lot of grass fires, which won't get up into a live canopy very easily," he said. "But once it gets into beetle-killed trees, it almost immediately becomes a canopy fire, and that's the most explosive kind."

That's because of the low-moisture content of dead trees. They burn hotter, which creates sort of a chain reaction. Because the energy released is that much greater, they create their own firestorms, he said.

"They show a high spotting behavior, which means that burning embers are being thrown off in front of the fire by the trees," Fastabend said, adding that the trees will also throw burning branches and pieces of bark.

"It becomes a crown fire which perpetuates itself in the tops of the trees instead of the ground," he said.

Painter disagreed.

"It depends more on the ladder fuels -- the lower branches," he said. "Basically, the fire climbs up the ladder fuels into the branches. If you eliminated the ladder fuels, it eliminates some of the risk of a ground fire climbing into the trees."

Weather conditions need to be right for a ground fire to jump into the canopy in a live forest, Fastabend said.

"In the Homer area, you'd normally have one to two days a year where a grass fire or other fire would go into a crown fire. But in a beetle-killed forest, you have 30 to 45 days a year where that could happen, effectively lengthening the season by a significant amount."

Painter said he thinks it depends more on the moisture of the fields.

"If it's like it was back in June, the risk is phenomenally high," he said. "But last week's fires were a fluke. Because they were lightning fires, they started in the trees and spread to the muskeg. Beetle-killed forests do burn, but they burn with the same heat and intensity that a regular fire would burn."

To combat the risks of fire posed by beetle-killed forests, the borough is planning to continue its fuel reduction program of timber sales. Of the 20 sales offered by the borough last year, 19 were completed, generating about half a million dollars, Fastabend said.

"The area on East End Road where the lightning strikes that caused that fire were, that's in the area where we were planning a future fuel reduction timber sale," he said. "It's dense there, and we're probably looking at five, six or seven years post-mortality. That wood is still valuable."

For his part, Painter said, those sales might have something to do with the disagreement.

"The Spruce Bark Beetle Task Force's purpose is to mitigate the beetle-killed forests and the danger from them," he said. "I agree that the danger to them is high, but I don't think we need to log beetle-killed neighborhoods. Instead, we need to do what we've been doing -- preventing the grass fires and ground fires in the first place by controlling the permitting process and enforcing burn suspensions.

"About 99.9 percent of fires in this area are human caused," Painter said, "though we might need to lower that by a percent after last week's two lightning-strike fires."

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