The Joint Fire Science Program has published a report that collects some findings from recent research about the relationship between bark beetles and wildfire. Here are some excerpts from the 1.4 MB document:

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Bark beetles are chewing a wide swath through forests across North America. Over the past few years, infestations have become epidemic in lodgepole and spruce-fir forests of the Intermountain West. The resulting extensive acreages of dead trees are alarming the public and raising concern about risk of severe fire. Researchers supported by the Joint Fire Science Program (JFSP) are examining the complicated relationship between bark beetles and wildfire, the two most influential natural disturbance agents in these forests. Are the beetles setting the stage for larger, more severe wildfires? And are fires bringing on beetle epidemics? Contrary to popular opinion, the answer to both questions seems to be “no.”

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In a 2011 paper published in “Ecological Monographs” (Simard et al. 2011), Simard, Turner, and their colleagues present the startling results: a wildfire that burns in a beetle-damaged stand will probably be no more intense—that is, no more likely to develop into a crown fire—than one that burns in a green stand. In fact, the fire’s behavior in a red-stage stand may be less intense under intermediate weather conditions, because needles have already fallen from the dead trees, reducing canopy fuels significantly.

“We were surprised by this,” Turner says. The shock of seeing a red canopy may cause people to overestimate its flammability. But the modeling results showed that, while beetles and fire are linked in complicated ways, the one does not cause the other. In fact, wrote the authors, “contrary to conventional wisdom, the interaction was a negative feedback in which the probability of active crown fire appeared to be reduced.”

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The few burn trials conducted in Canada have yielded no conclusive answers. Dave Schroeder of Alberta Sustainable Resource Development (wildfire operations) and Colleen Mooney of FP Innovations Wildland Fire Operations Research Group simulated a mountain pine beetle infestation by girdling jack pines at Archer Lake in northeastern Alberta in May 2007 (Schroeder and Mooney 2009). In July 2008 they burned two of the experimental stands along with control stands of green trees. In two side-by-side comparisons, crown fire developed in both the experimental stand and the control stand within seconds of each other, making it impossible to detect any significant difference in firebehavior.

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When faced with uncertainty, scientific disagreement, and millions of dead trees, what’s a manager to do? “From the standpoint of active crown fire or severe fire,” says Turner, “I think what our results would say is, you certainly don’t have to go in and cut big trees. No evidence from our work suggests that salvage logging following beetles will reduce fire risk.” There may be other good reasons for taking out the wood, she says, “but if it’s justified by saying we’re going to reduce the risk of fire, I would say our data don’t support that.”

Yet some clearly have a different view. “Maybe not fire risk,” argues Battaglia, “but how about fire severity? Fire growth? Fire extent? These are just as important to consider.”

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The biggest wild card in the fire-beetle relationship is climate. “A warming climate,” says Turner, “is almost certainly why we’re seeing such a big infestation now.” Warmer temperatures bring drought, which stresses trees and makes them more susceptible to beetles, and warmer winters enable more beetle larvae to survive and breed.

Bark beetles continue to be in the news as the little critters’ footprints appear across large swaths of pine trees in the western United States.

Oregon

Here is an excerpt from an article at Oregonlive.com about an infested area known as the “red zone”:

As cooler, wetter weather takes hold across Oregon, relieved foresters say the state once again sidestepped a catastrophic fire in what’s called the “red zone” – a 300,000-acre section of the Fremont-Winema National Forest in Klamath and Lake counties.

A pine bark beetle infestation has decimated vast stands of lodgepole pine there, providing plenty of explosive fuel. Foresters and firefighters held their breath when lightning storms swept through in August, sparking numerous fires but sparing the Fremont-Winema.

Although a decade or more in the making, the beetle infestation and resulting damage is getting a fresh look. The Oregon Board of Forestry toured the red zone Sept. 8, and industry groups have asked the board and Gov. John Kitzhaber to intervene with federal agencies. Private timber owners have twin worries: The beetle outbreak has damaged their trees, and they believe a monstrous fire in the federal forest will consume their land as well.

Environmental groups and some forestry professionals view the beetle damage, while severe, as a natural, cyclical occurrence. Forests across the West are struggling with the beetle plague.

“Bugs in lodgepole, that’s kind of what they do,” said Sean Stevens, spokesman for Oregon Wild. “The public looks at it and gasps, but in 50 years there will be a new lodgepole forest growing up in its place.”

The U.S. Forest Service is clearing “safety corridors” along roads and has long-range plans to strategically reduce the fuel load of dead trees in the Fremont-Winema, Deputy Forest Supervisor Rick Newton said.

“Certainly we’re very concerned,” he said. “It’s hard to watch a beetle epidemic such as this one move across an area.”

South Dakota

Pine beetle impacts, 3.8 miles west of Hill City, SD in the Black Hills National Forest

Some areas in the Black Hills have been heavily visited by the bark beetles. Frank Carroll, the Planning and Public Affairs Staff of the Black Hills National Forest, recently told us about what to us is a new and user friendly method for visualizing the impacts geographically. If you download and open this 2 MB Google Earth file it will display icons superimposed on satellite imagery at the locations aerial photos were taken of bark beetle impacts. When you click on the icons you will see images like the one above. If you don’t have Google Earth yet (why don’t you have it?), you can download the program here.

This technology could be very useful for displaying photos taken of a large wildfire.

The Mountain Pine Beetle and Fire forum that we told you about on April 26 is was live-streamed. I listened to a couple of hours of the forum in the morning and left with the impression that there was a consensus among those two or three presenters that:

• The dead needles following a beetle outbreak, the “red” stage, ignite more easily than green needles on a healthy tree. During this stage, lasting one to three years, an active crown fire is more likely to occur than in a healthy stand of trees.
• After the needles are shed from a beetle-attacked tree, an active crown fire is less likely to occur than in a healthy pine stand. During this stage a fire may produce larger burning embers, slabs of bark for example, that may be more likely to ignite spot fires, compared to embers from a green stand of trees.
• After the needles and some of the branches fall, and later the entire tree, the fuels on the ground are likely to be more continuous than before, will carry a fire easily, and the fire will burn with more intensity, but generally on the surface. There will be an increase in the amount of 100- and 1,000-hour time-lag fuels.
• I did not hear anyone discuss the resistance to control of a fire during the various stages of a beetle attack. But obviously, an active crown fire is extremely difficult to control, while an intense surface fire or a passive crown fire would be somewhat easier.

Below are some sample slides from the presentations.

Credit: Matt Jolly

The term “gray stage” as used in the illustration above, refers to a tree that has been attacked by beetles and the needles have passed through the “red” stage and have fallen. “Passive crown fire” is defined this way in the NWCG Glossary of Wildland Fire Terminology:

A fire in the crowns of trees in which trees or groups of trees torch, ignited by the passing front of the fire. The torching trees reinforce the spread rate, but these fires are not basically different from surface fires.

Here are a few more slides from the forum. Unfortunately, it was not always possible to determine who the presenters were. The streaming consisted only of audio of the speakers and slides from their presentations. There was no other video.

Continue reading →

An ecologist working for the U.S. Forest Service says pine needles killed by a mountain pine beetle infestation ignite faster than green needles. Here is an excerpt from the Missoulian:

HELENA – The red needles of a tree killed in a mountain pine beetle attack can ignite up to three times faster than the green needles of a healthy tree, new research into the pine beetle epidemic has found.

The findings by U.S. Forest Service ecologist Matt Jolly are being used by fellow ecologist Russ Parsons to develop a new model that will eventually aid firefighters who battle blazes in the tens of millions of acres from Canada to Colorado where forest canopies have turned from green to red from the beetle outbreak.

The new model incorporates a level of detail and physics that doesn’t exist in current models, and it is much more advanced in predicting how a wildfire in a beetle-ravaged region will behave, Parsons said.

“It gives you so much more information about what to expect,” he said. “Are these people safe here or should they run away? If we put a crew on the ground here, can they make it to the top of the ridge in ample time?”

Many communities in the Rocky Mountain West have beetle kill forests in some proximity.

And the new research dispels the notion that beetle-killed trees present no greater fire danger than live ones, a theory that had gained traction after a couple of wet, cool summers tamped down fire activity in the region, Jolly said.

On the contrary, beetle-killed trees can hold 10 times less moisture than live trees, Jolly found. That means they not only ignite more quickly than live trees, but they burn more intensely and carry embers farther than live trees, Jolly said.

He found that it takes less heat for wildfires to spread from the ground to the crowns of beetle-killed trees, making a wildfire in a forest with beetle-killed trees potentially much more difficult to contain.

Mountain pine beetles also start losing their moisture before the needles change to that tell-tale red, Jolly said, meaning even a healthy-looking pine tree could pose an increased fire threat to an unsuspecting firefighter.

Jolly took more than 1,000 tree moisture content measurements and conducted hundreds of ignition tests last year in four states, using foliage from trees with red, yellow, orange and green needles.

Jolly and Parsons will present their research Wednesday in Helena at a seminar on wildfires and the mountain pine beetle held by the Montana Department of Natural Resources and Conservation. The seminar will also host researchers from the University of Idaho and British Columbia, where the beetle infestation covers an estimated 43 million acres, which is more than 67,000 square miles.

So far this is information presented by a reporter. It will be interesting to read the actual findings of Mr. Jolly’s study. The article does not say what species of trees was involved in the study nor does it describe the ignition tests.

Research on lodgepole pines in the Greater Yellowstone area has yielded this information:

Modeling results suggested that undisturbed, red, and gray-stage stands were unlikely to exhibit transition of surface fires to tree crowns (torching), and that the likelihood of sustaining an active crown fire (crowning) decreased from undisturbed to gray-stage stands. Simulated fire behavior was little affected by beetle disturbance when wind speed was either below 40 km/h or above 60 km/h, but at intermediate wind speeds, probability of crowning in red- and gray-stage stands was lower than in undisturbed stands, and old post-outbreak stands were predicted to have passive crown fires. Results were consistent across a range of fuel moisture scenarios. Our results suggest that mountain pine beetle outbreaks in Greater Yellowstone may reduce the probability of active crown fire in the short term by thinning lodgepole pine canopies.

Wildfire Today has written frequently about the effects of pine beetles on wildfire.

More information about the May 4, 2011 forum “Mountain Pine Beetle and Fire which will be broadcast live on the internet.

Thanks Dick