New thinking on the bark beetle epidemic

 New thinking on the bark beetle epidemic

7 April 2009

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USA — The conventional wisdom about Colorado’s growing bark beetle epidemic is that the dead trees left behind will increase forest fire risk.

It makes sense: A bunch of tinder standing about would surely ignite more quickly and easily, right?

Perhaps not. Some researchers have turned that notion on its head, which could have implications for forest management and public policy, including how scarce dollars are spent on forest health.

Researchers, including a University of Colorado geography professor, looked at the historical record of beetle kill outbreaks and forest fires and did not find that fires increased because of additional dead trees. Their recently published report says hot weather, wind and drought are more predictive of the huge crown-to- crown fires that devastate lodgepole pine forests, and in those conditions, any tree will burn, whether it’s dead or alive.

Tom Veblen, CU-Boulder professor, told Colorado Public Radio he was surprised by the finding. He expected dead trees that still had their dry needles would be more susceptible to fire than living trees, but that didn’t prove true.

It is interesting, and adds information to the tableau of knowledge that those forming public policy should consider when deciding how to use thin forests of dead trees with a small pot of money.

The public, Veblen said, has to insist thinning be done in the wildland- urban interface, which is where the forest meets civilization.

In fact, much of the work has focused on those areas, said Rick Cables, the Rocky Mountain regional forester for the U.S. Forest Service.

But there will come, in the not-too- distant future, a debate about what to do with the massive number of dead trees that have fallen to the forest floor, which typically happens eight to 5 years after a tree dies from beetle kill.

The risk of an intensely hot ground-burning fire will go up, Cables said. And considering the state is dealing with 2 million acres of infested trees, that could be a different magnitude of risk. Such heat at ground level could sterilize the soil and make it less able to absorb water, which could cause other issues.

The truth is, the totality of conditions is bringing Colorado to a place it hasn’t been before.

A huge number of dead trees, more people than ever living in forested areas, and a warming climate mean the landscape isn’t the same as it had been. We cannot necessarily count on frigid winters to kill beetles or fires to burn in the wilderness, away from people and their homes.

The lesson to be taken from this research, and the future revelations that assuredly will come, is that flexible thinking will be invaluable in crafting smart strategies to deal with forests devastated by bark beetles.

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