More Studies on Bark Beetles and Fire: Does It Matter, and If So, Why?

Fire Science - The devastation of our forest lands by the pine-bark beetle has subjected vast regions to increased risk of castastrophic wild fire, especially west of the Continental Divide. Geoloigic maps are used to assess soil characteristics that might affect post-fire debris flows and intense erosion. This photo shows the northern Williams Range Mountains where beetles have killed more than 80 percent of mature lodgepole pine over many square kilometers.

Note: you may agree or disagree with the caption to this photo; I just copied it from a USGS science site (Central Mineral and Environmental Resources Science Center) here.

My fire colleagues alerted me that posting of the our previous post here, with simply the introductory paragraph, could have led to the wrong impression of the current scientific thinking.

I think fire managers would like to know better how bark beetle killed or otherwise dead and dry
trees affect fire behavior. But I don;t think that historic vegetation ecology is going to tell folks that. It seems as if some people think that “science” can prove that fires are no different with dead trees, then we wouldn’t have to do fuel treatments. But that doesn’t make sense, since we still do fuel treatments with live trees. Is it about investing more in live tree fuels treatments?

Here is how I frame the question:

Should we, in the interior west, manage tree vegetation outside the WUI (assuming we have agreement in the WUI, some days I am not so sure) to provide possible fire lines, help in some way with suppression of large fires, or to protect other resources?

Framed that way, many more disciplines that fire behavior modeling or historic vegetation ecology might have something to say. Plus of course “should” is a normative (value), and not a science (empirical) question.

And let’s involve a couple of other disciplines right now: hydrologists and fish people don’t seem to be as sanguine about the effects of fire as some vegetation ecologists are; for example, this quote in the JFSP article (pg. 13).

Schnackenberg would like to see much more
operational burning on the Medicine Bow-Routt. “My
opinion as a hydrologist is, I would rather see all that
dead stuff burn right now. It’s standing, and if we wait
for it to fall there may be places where it will burn a
little hot, and you’ll get hydrophobic soils and erosion.
And if you have heavy fuel loads on the ground in 15
years and a fire comes, what happens to the hydrology

I do agree with the statement at the end of the JFSP piece:

That is a big “how.” And, as with most knotty
management problems, the science can guide, but it
cannot direct. Wildfires and bark beetles don’t lend
themselves to controlled studies, and the findings don’t
usually point to neat, out-of-the-box solutions.

More than that, even the most undisputed
ecological knowledge is inflected by political,
economic, and social considerations. A set of findings
like Simard’s, however accurate and useful in theory,
may or may not govern management response at the
level of stand, forest, or watershed. Any prescription
will also rely on other research and on-the-ground
experience, and any action will hinge on local
constraints and opportunities.

As JZ posted in his/her comments, I think this piece by Keeley in 2009 explains better why people seem to be partially confused just by the terminology.

In the same set of comments, Larry said:

Additionally, the fire folks don’t like to address the issues of re-burn, which often results in more actual damage than a fire burning in green lodgepole. The damages totaled up for fires burning in green trees often doesn’t include the probability of a re-burn. In dry forests, the remaining fuels from a fire just sit there, until the next inevitable fire incinerates everything in its path. Even fire-adapted species have their limits of fire survival.

I, too, have seen this; near Hells Canyon, burned area with jack-strawed dead lodgepole and lodgepole coming back through the dead trees, another burn of the jack-strawed dead, and the young lodgepole are toast, with few or no nearby seed trees.

But for those who just can’t help getting involved in the fires and bb’s debate, here is another paper that recently came out that specifically examines the areas of agreement and disagreement.

Here’s the abstract


Millions of trees killed by bark beetles in western North America have raised concerns about subsequent
wildfire, but studies have reported a range of conclusions, often seemingly contradictory, about effects on fuels and wildfire. In this study, we reviewed and synthesized the published literature on modifications to fuels and fire characteristics following beetle-caused tree mortality. We found 39 studies addressing this topic with a variety of methods including fuels measurements, fire behavior simulations, an experiment, and observations of fire occurrence, severity, or frequency. From these publications, we developed a conceptual framework describing expected changes of fuels and fire behavior. Some characteristics of fuels and fire are enhanced following outbreaks and others are unchanged or diminished, with time since outbreak a key factor influencing changes. We also quantified areas of higher and lower confidence in our framework based on the number of studies addressing a particular area as well as agreement among studies. The published literature agrees about responses in many conditions, including fuels measurements and changes in stands with longer times since outbreak, and so we assigned higher confidence to our conceptual framework for these conditions. Disagreement or gaps in knowledge exist in several conditions, particularly in early post outbreak phases and crown fire behavior responses, leading to low confidence in our framework in these areas and highlighting the need for future research. Our findings resolved some of the controversy about effects of bark beetles on fire through more specificity about time since outbreak and fuels or fire characteristic. Recognition of the type of study question was also important in resolving controversy: some publications assessed whether beetle-caused tree mortality caused differences relative to unattacked locations, whereas other publications assessed differences relative to other drivers of wildfire such as climate. However, some disagreement among studies remained. Given the large areas of recent bark beetle and wildfire disturbances and expected effects of climate change, land and fire managers need more confidence in key areas when making decisions about treatments to reduce future fire hazard and when fighting fires.

Here’s the paper. I do like the fact that they attempt to make sense out of the different studies and approaches, from a scientific point of view. But I am not so clear on the utility of any of it toward management or policy other than improving fire behavior models. Perhaps we could discuss this further here?

11 thoughts on “More Studies on Bark Beetles and Fire: Does It Matter, and If So, Why?”

  1. The past says:
    “Here is how I frame the question:

    “Should we, in the interior west, manage tree vegetation outside the WUI (assuming we have
    agreement in the WUI, some days I am not so sure) to provide possible fire lines, help in some
    way with suppression of large fires, or to protect other resources?”

    This seems to assume that fire is not a natural and sometimes desirable ecological processes.

    Maybe the question should be frames as …. “Under what conditions is it appropriate to interfere with the self-organizing systems that create and maintain the evolutionary anvil?”

    • Tree,
      I am fine with fire being natural and sometimes desirable.
      The question is what we are going to do when it’s undesirable, and that has nothing to do with it being natural. Let’s look at a 2 x 2 matrix.


      Sorry you have to click on the file to see the matrix, couldn’t figure an easier way to do it.
      I hope you see my point, that things can be good or bad regardless of whether they are natural or unnatural.

  2. TreeC123 :

    Maybe the question should be frames as …. “Under what conditions is it appropriate to interfere with the self-organizing systems that create and maintain the evolutionary anvil?”

    IF our forests (and only IF) are “unnatural”, then we need to intervene. Much of preservationism is based on assuming that today’s forests “have been doing just fine for millions of years”. I really doubt that many would stick to that assumption (although I continue to see that phrase used), these days. Indians knew that lodgepole forests needed to be constrained, with “prescribed” fire.

    Also, the WUI needs to be expanded and defended from bark beetles, as well as from firestorms. It is important that the WUI remain green, instead of letting the high intensity fires burn to its edge. No residents want to see their WUI turn brown from bark beetles, putting their communities at risk. The WUI should also protect communities from bark beetles, too.

  3. Maybe this is all too academic, since we as a nation and as forest managers don’t have the will, nor the funds, nor the political support to do the right thing, even if we knew what was the right right tool to use, the saw or more fire or bug sprays or ????

    If we are really determined to protect the communities at risk in the WUI (the real WUI, not the 10 mile zone that some folks want), then we should totally clearcut, plant and maintain a city park forest cover with green lawn below, with lots of sprinklers and fire hydrants. In actuality this silly prescription may be cheaper than some of the “management ” Rxs proposed by some.

    Then the question becomes this…are these communities worth the cost? Are these communities willing to have their adjacent “natural” forest converted to a truly fireproofed park? Are they willing to help pay the enormous cost to save them from perdition?
    These discussions are proving that we don’t have the answers. I am sure the researchers love it, since it gives them more reasons to exist and go on with their search for the Holy Grail.

    Does make for great discussions, however.

    • Let’s take this a step farther, then. Since law enforcement agencies have been ineffective and quite expensive, we should set up a crime urban interface, where crime is reduced within a small distance of homes only. We cannot afford to reduce crime where businesses exist. It’s their own fault for setting up business outside of the protected CUI. They should have to supply their own law enforcement, and we shouldn’t have to pay for their costs.

      Silliness aside, there are numerous cost-effective treatments that can be done to better protect rural communities. Pretending that 150 feet is adequate for fire safety is as silly as limiting law enforcement services by a line on a map. It’s not just about saving physical houses. It’s about saving “community values”, including areas within walking distance of homes.

  4. Ed, remember this tree-free fuels reduction post here? Cutting the brush has to be cheaper than your “green lawn” prescription. there are many, many western communities surrounded by either brush or trees; if they are not “worth the cost” then we are talking about a massive population redistribution, from the east side of the Cascades, south to the Siskiyous, central California and east to the Rocky Mountain front, in the west. Fires are also an issue in the East but I don’t know the details (I remember a field trip about fire and the wildland urban interface on a visit to North Carolina).

    It could be that removing excess fuels around communities and using them for something may be less disruptive than moving people out of the forests.

  5. Sharon said, “My fire colleagues alerted me that posting of the our previous post here, with simply the introductory paragraph, could have led to the wrong impression of the current scientific thinking.”

    Funny, Sharon, but did your “fire colleagues” not mind that the publication “Fire Science Digest” from the Joint Fire Science Program posted the SAME EXACT introductory paragraph to open up their 16 page article?

    I’m simply not going to paste an entire 16 page article right to the homepage of this blog. If posting an introductory paragraph and providing a very clear, easy to follow link to the entire article allows some people to complain that such a practice “could have led to the wrong impression of the current scientific thinking”…well, so be it.

    The Fire Science Digest article speaks for itself, as does much of the emerging science concerning bark beetles and wildfire. Thanks.

    • I don’t put much stock in the article. If they cannot get the beetle’s life cycle right, the rest of the paper is suspect. They cherry-pick their issues and find ways of ignoring the huge, long-lasting damages that firestorms bring. Of course, fire people want more wildfires, and less prescribed fires, due to the liability issue. Also, they might see that their Let-Burn program might have to actually follow NEPA, in the near future. Indeed, at least one Forest has tried to push the NEPA through on their Let-Burn program, while they thought no one was looking. It was challenged and then dropped, as they knew they would have to survey for endangered species in their “Maximum Management Areas”, of up to 100,000 acres. Imagine firefighters surveying for slugs, snails, goshawks and Cylene invisa. Instead, they are finding it easier to firebomb their way to flammable nirvana, and calling it “tactics”.

    • Matt- I didn’t mean to imply that you did anything incorrect or misleading by posting what you posted; it was the first paragraph ..

  6. Sharon/Larry, I never said or implied these forest-edge communities were not worth protecting. I guess my effort to cover such a complex political/science issue was too simple and brief. I will try a “bullet” format to summarize my thoughts more clearly;
    1. Homeowners in the high hazard zone next to fire-prone forests/brushfields need to do more inside their streets to minimize the hazard. Zoning to impose fire-resistant roofs, siding, landscaping, etc. with strict imposition of these requirements on both new and older structures is imperative. For many with sufficient income and trophy homes, they can acquire a foam fire setup that really does the job. Brush cutting and thinning needs in this developed zone of impact should be required and funded by the homeowners on a regular basis. In most western towns these simple requirements are missing or not enforced. A political problem, not a science probllem.
    2. Brush cutting in the WUI or around the structures is effective only for a few years, depending on the ecosystem. I have watched the home brushing efforts of a friends home here in Idaho revert to its original dense condition withing 5 years. In some areas I believe the brush has come in thicker than it was before treatment. So in this region brushing in the WUI would need to be repeated on a regular basis as well. Very significant maintenance costs, in my opinion that are never discussed in most fuel treatment dialogues. One treatment and then on to the next problem!
    3. The whole discussion previous involved beetle killed trees and fuel treatment options. It is clear that the experts don’t have the answer!! They are guessing, they are exploring, they are unsure of what prescriptions might work. This is great. We need more answers, or at least some educated guesses. But my concern is that even when we get “the answer”, we likely will not have the funds or staff or community will to do what is needed.
    4. My personal opinion is that some, if not many, residents who live adjacent to these forests would not appreciate the look or experience of a heavily debrushed and thinned stand of trees as compared to the original natural forest vegetation. That is a value judgement that is beyond the scope of this thread.

  7. There are excellent examples of towns barely surviving wildfires, only to have the bark beetles follow, jumping firelines and impacting people’s lives. On the San Bernardino, the towns of Idyllwild and the Big Bear communities suffered widespread mortality to bark beetles. In Idyllwild, the forests are more like the “sky islands”, with wildfires starting low and burning up into thicker fuels. After barely holding off a fire on their doorstep, the bark beetles continued farther up in elevation. Two District Rangers couldn’t get out of there fast enough, knowing that they weren’t able to stop an eventual tragedy. The town survived but, not without exorbitant costs and homeowner defaults. Some areas still continue to harbor those excessive fuels build-ups, and places like Lake Tahoe will remain at-risk for decades, if nothing is done. The huge amount of dead trees from the early 90’s bark beetle event are still there, waiting for the next inevitable spark, whether human-caused, or not.

    For most brush species, it is the shade that reduces their advance. It is not a one-time treatment that will banish the brush. Also, a thinned stand ends up looking like a park, and people DO like how well done projects look like when finished. However, such areas do need periodic maintenance, until the shade reduces brush “naturally”. That would be in the form of prescribed fires. Where I live, the highly flammable bear clover is easily burned off when conditions are right. This also serves to keep the brush species in check.

    Also, what good does it do to spend so much on reducing fuels on private homeowner’s lands, when just 200 feet away (outside of the eco’s preferred WUI) is a tangle of brush, small trees and ample fuels for ignition? I do agree that people have to take responsibility for their own fuels but, government also has a responsibility to keep wildfires manageable and less destructive. We cannot continue to preserve unnatural fuels build-ups, especially close to communities.

    We also need to protect areas outside of the WUI, as there are plenty of examples of lands deserving of wildfire protection. Indeed, there are laws that should require us to intervene and protect endangered species habitats, public water sources, cultural sites, recreation areas, botanical sites, etc, etc, etc, etc. Today’s fire policies do not reflect those responsibilities and some people just don’t care that they don’t.


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