Researchers: Widespread thinning won’t help lessen fire risks in beetle-killed forests |

Researchers: Widespread thinning won’t help lessen fire risks in beetle-killed forests

Bob Berwyn
Vail Daily
Post Independent
Glenwood Springs, CO Colorado

VAIL VALLEY, Colorado – Leading forest researchers say widespread thinning won’t do much good when it comes to lessening fire risks in beetle-killed forests in Colorado’s Vail Valley and elsewhere. Instead, the focus should be on managing development and growth close to forests at risk for large, severe fires, according Tom Veblen, director of the biogeography lab at the University of Colorado in Boulder.

Veblen’s findings reinforces other Forest Service research showing the most effective way to reduce the danger to homes is by concentrating on creating a defensible space within several hundred feet of structures and making sure the structures are fire-resistant.

Other studies show rapid growth in the Rocky Mountain region is occurring in desirable areas near national forests – right in the so-called red zone where fire risks are high.

The research suggests using zoning and fire regulations in those areas is a much more cost-effective way to lessen fire risks.

Veblen and other researchers have been studying the relationship between beetle-kill episodes and wildfires in Colorado using computer models, tree-ring reconstructions of past outbreaks and high-tech mapping techniques. The most recent research concludes that insect outbreaks do not dramatically increase the risk of more frequent or more severe fires in either lodgepole or spruce-fir forests.

Another study in Alaska looked back at a history of beetle events and fires and found little correlation between the two. Similar studies suggest beetle-kill was not a significant factor in the 1988 Yellowstone blaze.

Lodgepole pine forests have always been susceptible to catastrophic stand-replacing fires spread across huge areas and occurring infrequently.

Complex equation

The fire risk in a certain forest is always changing, depending on a number of factors including the kinds of fuel available, weather and the health of the forest.

After the beetles kill a stand of lodgepoles, the risk of ignition increases during the red phase. It drops when the dead needles fall off the branches and the trees turn gray.

When the dead trees have fallen to the ground – usually within 10 to 30 years – they once again contribute to an increased fire risk by serving as “ladder fuels” that can carry fire into the forest canopy.

Most of the evidence suggests climate and weather are much bigger factors when it comes to fire risk. Drought could be the single most important driver, most studies show.

Retired Forest Service insect researcher Jesse Logan has also been studying the current pine beetle outbreak. His research suggests a pattern of warmer winter temperatures is intensifying the epidemic by helping the bugs increase their reproductive rate.

According to Logan, logging and thinning can increase the negative impacts of beetle-kill, especially important watershed protection functions that remain partially in place even when the forest is dead.

The beetles have killed about 3.9 million acres of trees across the Rocky Mountain region since 1996, and some 1.9 million acres in Colorado.

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