Dead trees pose smaller fire risk
Published: May 21, 2012 11:24AM
Updated: May 21, 2012 11:29AM
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Al Hartmann | The Salt Lake Tribune Homeowner Jim McHugh, left, and Mike Scadden, Summit County Assistant Fire Warden with the Utah State Lands Division walk up slope to his home near Jeremy Ranch where thick stands of pine trees and Scrub Oak have been cleared to create a defensible perimemeter for his home should a wildfire break out. Clearing the trees have allowed the native grasses and wildflowers to grow again.

Editor's Note: This story originally appeared in The Salt Lake Tribune on September 25, 2011.

Dead trees are just seasoned firewood waiting for ignition, right?

Conventional wisdom has long held that dry, beetle-killed trees elevate fire threats to forested communities and that millions of standing logs lurking across the Western horizon will explode when torched.

That wisdom is fast falling away among scientists. Most times, beetles actually seem to reduce the hazard. It's the live trees, packed tightly after decades of fire suppression and then subjected to drought, that burn fast and hot.

Yes, pine and spruce needles are like oiled kindling when red and dry, the year after a beetle attack. And while they are still on the limb or piling up below it, they are a serious hazard.

"You should be [frightened]," Utah State University forest science professor Mike Jenkins said of that early stage. "If you have red trees around your log cabin, I'd be worried, too."

A couple of years later, though, those needles are gone, the most volatile fuel has decayed, and the shrubbery that's left may be less flammable than a crowded living forest.

"No fuel, no fire," Jenkins said.

He and colleagues study fuel loads in three classes of Western forests: the green, the recently attacked and the post-beetle standing dead. They then run the numbers through models predicting how those fuels will burn when ignited.

The result - a prediction that beetle-killed trees not ignited shortly after infestation won't increase fire hazards - is replicated in a growing number of studies, including at the University of Colorado.

Jenkins called it a new consensus.

-- Brandon Loomis