Dry Wood Burns Differently- Scientists Learn

Another great photo from Bob Berwyn, Summit County Voice

I know, I know. What you have long observed in your fireplace or woodstove turns out to be more generally true..

New study shows beetle-killed trees ignite faster

(AP) – 7 hours ago

HELENA, Mont. (AP) — 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.

“I think this is a first step,” DNRC director Mary Sexton said of the new research. “I think overall this has been an area where folks are just beginning to have guidance or definite information.”

In Montana, beetles are estimated to have attacked about 4 million acres of forest over the past decade. A survey taken last year shows the beetle activity may be declining in some of the most ravaged parts of the state between Helena and Butte.

But that may be because the beetles are simply running out of trees, Sexton said. Meanwhile, beetle activity in the central and northwestern part of the state is still increasing, she said.

South of Montana, the beetle epidemic has spread to about 4 million acres in Colorado and southern Wyoming, according to forestry officials.

Research hasn’t been able to keep up with the fast spread of the mountain pine beetle infestation over the past decade, Parsons and Jolly said. Even now, much of the research is dedicated to the long-term ecological effects of the outbreak, something of little use to firefighters, Jolly said.

“They’re not concerned with 10 years from now. They’re concerned with how a fire is going to behave now,” he said.

The new model isn’t ready to be used by fire managers in the field, so the old models shouldn’t be thrown out yet, Parson said. Only a few people in the Forest Service and collaborating institutions are using the new one, he said.

“Our hope is that this kind of modeling will increasingly become an important part of the decision-making and it will provide the science that feeds into fire management decisions,” Parsons said.

This quote:

Research hasn’t been able to keep up with the fast spread of the mountain pine beetle infestation over the past decade, Parsons and Jolly said. Even now, much of the research is dedicated to the long-term ecological effects of the outbreak, something of little use to firefighters, Jolly said.

“They’re not concerned with 10 years from now. They’re concerned with how a fire is going to behave now,” he said.

makes me wonder if we could improve the connection between people who need questions answered and the way research questions are framed.

9 thoughts on “Dry Wood Burns Differently- Scientists Learn”

  1. FS employee Matt Jolly said “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”

    I have not heard any credible voices saying that fire hazard is lower in the “red-needle” phase after beetle outbreaks. It is during the period after the needles have fallen from the trees and before the trees have fallen to the forest floor that is likely to have reduced fire hazard. Note: the red-needle phase is much shorter than the bare tree phase.

    A few “wet, cool summers” does not refute this observation.

    Reply
  2. It’s always nice when common sense and personal experience are finally vindicated by scientific testing — and then transformed into a “model.”

    Yes, dry, pitchy firewood ignites easier, burns hotter, and spreads more rapidly than green, living wood. I won’t write “duh” here, without surrounding it with other words, mostly in order to be polite. People have known this for thousands of years. Many thousands of years.

    This type of “revelation” is exactly why people don’t trust New Age computer modeling as a planning tool. People still trump computers — except in federal forest planning. That’s why these models are used almost exclusively by universities and agencies and shunned by private land owners and experienced wildfire managers.

    Not trying to be mean or demeaning here, but very clear. This “news” indicates (exactly) why. Garbage in, garbage out — same as always. The voice of legitimate experience needs to be given more credit and credibility.

    Reply
  3. Yes, and the post-red-needle phase is also fairly short-lived. When those snags fall to the ground (which is massively a longer time than the post-red-needle phase), the risk of soil-damaging fire is off the scale. An intense ground fire that sterilizes soils can set back “passive restoration goals” back by decades, if not an entire century. When a “natural” wildfire (whatever that really is) burns in an unnatural forest, you end up with an “unnatural” fire, which causes “unnatural” damages. While catastrophic wildfires ARE sometimes “natural”, that surely does not make them desirable.

    Reply
    • Thanks Sharon, I couldn’t find it online. Looks like good stuff, but not exactly earth-shattering. I think some of the more informed, nuanced reporting on this issue has already pointed out that there is a “rise-and-fall” aspect to the ignition potential of the dead trees.

      Reply
  4. Anybody besides me find this comment a bit suspicious:

    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.

    I can’t quibble with the first part, but the idea that wildfire in forests can be contained in any general sense strikes me as fantasy. Mostly the best that can be done is to fight to contain borders, particularly around communities, etc. But maybe my anecdotal, bystander experiences watching wildfires and containment attempts during my many years in the Forest Service were tainted by my worldview (i.e. “believing is seeing”), and my longstanding position that the agency has wasted a whole lot of money through the years in trying to contain fires that had long since jumped into spaces where containment was not likely to happen.

    Too many times I’ve seen weather, e.g. late-summer/early-fall storms, contain the fires for me to easily believe stories about being able to contain wildfires, particularly when they are in the crowns. But maybe that was the only point the researcher was attempting to make. If so, my question becomes, How effective are logging attempts to remove red-needled trees from the forest on a scale that would reduce fires, in the short window (see #1) before the needles fall?

    Reply
    • Dave’s point makes sense to me. Rocky Mountain lodgepole pine isn’t very prone to burn to begin with, whether dead or alive. I remember the Dillon, CO district ranger at my first post-forestry school job telling me that his was an “asbestos” forest.

      Lodgepole forests burn under severe climactic conditions on the order of once every couple of hundred years. Think Yellowstone. The live/dead condition of Yellowstone’s lodgepole forests in 1988 was irrelevant to firefighting efforts. The moisture content of both dead and live trees was so low, the dried grass fuels so abundant (due to Spring rains), and the winds so strong that the fires were uncontrollable.

      Reply
  5. Here’s another story from the seminar. It sums up nicely the opinions of local USFS fire fighters who get their hands black fighting them. The 80-20-20 rule is interesting.

    http://helenair.com/news/article_f9e71da0-76df-11e0-9ec6-001cc4c002e0.html

    I’ve heard Lodgepole called “asbestos forests” before. It’s why Colorado hasn’t had a real fire in 100 years. When you walk through them one can see why. Of course the self pruning means there are no low hanging branches for ladder fuels. They’re so dense and dark there are no real brushy flashy surface fuels. It’s almost like a mowed park. Very easy to walk through. It’s neat seeing small suppressed shade tolerant spruce-fir just waiting for their day in the sun.It’s only when the canopy opens up through old age attrition or MPB that the shade tolerants take off and the surface fuels pile up. Yellowstone was an old growth forest that had all the classic characteristics of text book succesion.

    There’s no doubt the MPB increases fire hazard, but the fire weather window is still the prime driver.

    Reply

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