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Bark beetles and wildland fire behavior – a summary of research

Bill GabbertJune 1, 2012November 21, 2018Uncategorizedbeetles, open access, research1 Comment

There are at least 39 published studies about the effects of bark beetles on wildland fire behavior. With such a bounty of government-funded work, you could hope that we would have some definitive answers, but unfortunately, while there is some agreement among the studies, there is substantial disagreement on some key issues, including the impacts of beetle-caused tree mortality in key areas such as fire behavior during the red needle phase, which is typically one to four years after a beetle attack.

This was one of the conclusions in a recent study that analyzed 39 other published works about the effects of pine beetle mortality. It is titled Effects of bark beetle-caused tree mortality on wildfire, and was written by Jeffrey A. Hicke, Morris C. Johnson, Jane L. Hayes, and Haiganoush K. Preisler.

The chart below is from their paper.

The author’s confidence in the conclusions reached about torching potential and active crown fire potential for the first ten years was low, but it is probable that active crown potential would increase for the first four years after mortality and then decrease dramatically. Torching potential would probably increase.

Surface fire properties, defined as reaction intensity, rate of spread, and flame length, would likely increase, but the confidence in the prediction for the first four years was low.

The authors pointed out that changes in fire behavior following a pine beetle outbreak…

…may only occur under some environmental conditions. For example, effects may be manifested during intermediate wind speeds (Simard et al., 2011) or in moister conditions, such as earlier in the fire season (Steele and Copple, 2009). Past controversy on this topic can be partly reconciled by this consideration of more specificity about study question, time since outbreak, and fuels or fire characteristic when describing results.

Our view of the research

It would be helpful if all of these parameters and studies could distill the conclusions into one index, which I will call Resistance To Control (RTC). Simultaneous increases in surface fire, torching, and crowning would result in more RTC. But it becomes more complicated to characterize when, for instance, crown fire potential decreases to near zero, while surface fire intensity and torching increase. Long distance spotting is a firefighter’s biggest headache and makes fires almost impossible to control, at least at the head. Crown fires are the major culprit for long distance spotting, but surface fires and individual or multiple tree torching can also create spot fires. And all of this varies, of course, with the weather. Strong winds can make ANY fire very resistant to control as long as the fuels are continuous.

If a person leaps to the possibly incorrect conclusion that all of the fire behavior parameters shown in the chart above are accurate, including the sections with low confidence, then RTC would increase one to four years after a beetle outbreak, and then would probably decrease since the crown fire potential would dramatically decline. Surface fires, including those with some torching, can be more easily controlled using tactics, sometimes with aerial support, such as direct hand line construction, hose lays, indirect line construction with burnouts, and backfiring from out ahead of the fire. When crowning is the primary method of fire spread, you usually have to wait for either the weather or the fuels to change. Air tankers and helicopters dropping fire retardant or water can be more effective when the fire is confined to the surface, as long as firefighters are on the ground to take advantage of the temporary slowing of the rate of spread, and if the wind is not too strong.

With apologies to the authors of this very good research paper, I took the liberty of adding a Resistance To Control variable to their chart:

And of course the authors of the paper included the familiar phrase, “more research is needed”, which is a mandatory section in every research paper.

The authors, who are employed by taxpayers, arranged to have the government pay a fee to have their paper published by the for-profit Elsevier corporation which is headquartered in the Netherlands. But thankfully, this time the USFS also published it on their U.S. Government web site where taxpayers can access it at no additional charge.

If you believe taxpayer-funded research should always be available to taxpayers freely over the internet, go to the White House web site and sign the petition. (Update Jan. 23, 2013: you can still read the petition at the site, but it is closed to new signers.)

Thanks go out to Tom, who, in a comment on another article on Wildfire Today about bark beetles, pointed out this new research paper.

Bark beetles and fire, recent research

Bill GabbertApril 30, 2012August 25, 2019Uncategorizedbeetles2 Comments

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.”

[…]

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.”

[…]

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.

[…]

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.”

[…]

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.

Park fights beetles with fire, not saws

Bill GabbertMarch 23, 2012April 28, 2016Uncategorizedbeetles, Photo by Bill G, prescribed fire

American Elk prescribed fire, Wind Cave National Park. October 20, 2010. Photo by Bill Gabbert

The Rapid City Journal has an article about how Wind Cave National Park in the Black Hills of South Dakota uses prescribed fire, in part, to help prevent and control pine beetles. Below is an excerpt. It may be one of the last excerpts we can show from that newspaper, since they plan to put up a pay wall on their internet site.

Wind Cave wages war on beetles without using saws

They don’t use logging machines and chain saws in the battle against the mountain pine beetle in Wind Cave National Park.

They use fire. And sometimes, they don’t use anything at all.

The federal park, which covers almost 34,000 acres in the southern Black Hills, has a management plan for the pesky bugs that is dramatically different from the logging-based attack in the Black Hills National Forest and nearby private and state forest.

It’s a plan that has been evolving since the 1970s, with fire as the main management tool — depending on funding and favorable weather conditions.

“We really don’t do any cutting of trees right now,” said Greg Schroeder, the park’s chief of resource management. “We have in the plan the ability to do some thinning if we can’t get areas burned. But if we get them burned, we’ll pretty much mitigate the pine beetle problem.”

That’s easier to say and do in Wind Cave, which has more than twice the acreage of grass as it does of forest. The park also is at a generally lower elevation, where pine beetles haven’t in the past been as big of a problem in the Black Hills.

Those advantages, along with a decades-old management plan based on healthy forest standards of thinner tree stands, more variety in tree age and species, and periodic prescribed burns have created a forest that is more resistant to beetles, Schroeder said.

The Journal also has an article about their law enforcement rangers catching three people from Minnesota last weekend attempting to steal about three dozen elk antlers, as well as animal skulls and rocks.

More research surfaces about pine beetles and fire

Bill GabbertFebruary 15, 2012August 25, 2019Uncategorizedbeetles, open access, research8 Comments

Crown fire experiment 2004 — International Crown fire experiment in healthy, not beetle-killed trees. Photo U.S. Forest Service

UPDATE at 2:11 p.m. MT, Feb. 16, 2012:

We contacted Nan Christianson, the Assistant Station Director – Communications at the Rocky Mountain Research Station, and asked where they stood on Open Access, and why the study, below, was only available to taxpayers if they paid $31.50 to a private company. Within a few hours they added it to a U.S. Forest Service web site, TreeSearch, where it is available at no charge. It is still listed at the private company for $31.50. We are waiting for more detailed information from the USFS concerning their policy on the Open Access of taxpayer-funded research.

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February 15, 2012

At Wildfire Today we have previously written about mountain pine beetle research that used satellite data and computer models to extrapolate findings to fire behavior characteristics. Now there is a new study that measured foliar chemistry, moisture, and flammability in the lab and also draws a conclusion about fire behavior out in the real world.

The latter study, which is published behind a pay wall in the April, 2012 edition of Elsevier’s Forest Ecology and Management, was written by Matt Jolly and others at the U.S. Forest Service’s Rocky Mountain Research Station. In their study, foliar samples were taken periodically from multiple trees identified as green, recently attacked by mountain pine beetles, and red (dead). The fuel moisture content, chemical composition, and time to ignition of needles from each attack category were quantified. They found that in the lab, decreased moisture content and changes in foliar chemistry increased the flammability of beetle-attacked foliage, and red needles ignited much more quickly than green needles. They further extrapolated that “crown fire potential may be higher in attacked stands as long as foliage is retained on the tree”.

You can read the study, which American taxpayers paid for already, but you will have to pay the for-profit Elsevier corporation $31.50. This is not Open Access, which we have written about before. (The U.S. Forest Service should publish the results of all of their research immediately upon completion at no additional cost to American taxpayers. What is the point of the USFS funding research if the results are kept a virtual secret?)

In an earlier study, University of Wisconsin forest ecologists Monica Turner and Phil Townsend, in collaboration with Yellowstone National Park Vegetation Management Specialist Roy Renkin, examined the beetle and fire connection in the forests near Yellowstone National Park.

Using satellite data they studied burn patterns and fire occurrence data and the relationships to mountain pine beetle attacks.

Here is an excerpt from the NASA article:

Their preliminary analysis indicates that large fires do not appear to occur more often or with greater severity in forest tracts with beetle damage. In fact, in some cases, beetle-killed forest swaths may actually be less likely to burn. What they’re discovering is in line with previous research on the subject.

The results may seem at first counterintuitive, but make sense when considered more carefully. First, while green needles on trees appear to be more lush and harder to burn, they contain high levels of very flammable volatile oils. When the needles die, those flammable oils begin to break down. As a result, depending on the weather conditions, dead needles may not be more likely to catch and sustain a fire than live needles.

Second, when beetles kill a lodgepole pine tree, the needles begin to fall off and decompose on the forest floor relatively quickly. In a sense, the beetles are thinning the forest, and the naked trees left behind are essentially akin to large fire logs. However, just as you can’t start a fire in a fireplace with just large logs and no kindling, wildfires are less likely to ignite and carry in a forest of dead tree trunks and low needle litter.

A third study published in 2011 used computer models to predict fire behavior and how it was affected by beetle attacks. It was titled “Do mountain pine beetle outbreaks change the probability of active crown fire in lodgepole pine forests?” Here is an excerpt from the abstract:

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.

The paper was written by Martin Simard, William H. Romme, Jacob M. Griffin, and Monica G. Turner. A summary of their findings is HERE.

All three of these studies, while they collected some static data from the field, were executed in laboratories, and not from observed fire behavior in the real world.

So which school of thought do you subscribe to? Do you go with the most intuitive-friendly one and think lower foliar moisture content leads to more crown fires in beetle-kill areas, or do you buy into the satellite burn data and the computer model data which lean toward more resistance to crown fires in areas affected by beetles?

It may take another International Crown Fire Experiment (see photo above), like was done in Canada between 1995 and 2001, setting actual fires in healthy and beetle-affected stands, to resolve the question.

Bark beetles: Oregon and South Dakota

Bill GabbertOctober 3, 2011April 28, 2016Uncategorizedbeetles1 Comment

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

Black Hills National Forest pine beetle flight — 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.

Live streaming of the Mountain Pine Beetle and Fire forum

Bill GabbertMay 4, 2011November 21, 2018Uncategorizedbeetles

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.

Mountain pine beetle and fire — 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 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 “Live streaming of the Mountain Pine Beetle and Fire forum”

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