Science Review Shows Fuel Treatments Reduce Future Wildfire Severity

This is not news to most foresters, but it’s good to have such a review from three parties, including TNC. Will the review help courts make decisions in cases where enviro groups claim that thinning, etc., do more harm than good? The debate, as ever, centers on whether taking any tree considered mature or old-growth. (Thanks once again to Nick Smith for the link.)

Comprehensive Science Review Shows Fuel Treatments Reduce Future Wildfire Severity

Researchers from the USDA Forest Service Rocky Mountain Research Station, The Nature Conservancy and the University of Montana examined 30 years of fuel treatment effects on wildfire severity.


Researchers found overwhelming evidence that in seasonally dry mixed conifer forests in the western U.S., reducing surface and ladder fuels and tree density through thinning, coupled with prescribed burning or pile burning, could reduce future wildfire severity by more than 60% relative to untreated areas. The study results were recently published in Forest Ecology and Management. You can download this Science You Can Use in 5 minutes for an overview of the research methods, key findings, management considerations and links to related publications.

13 thoughts on “Science Review Shows Fuel Treatments Reduce Future Wildfire Severity”

  1. There are a couple of problems that you ignored. First, even these researchers say that such reduction typically has a time limit. I.e. vegetation grows back quickly, thus the effectiveness is short-lived.
    This gets to the issue of probability. Of course the researchers did not look at the probability if a fire will encounter the treated landscapes in the time when they could be effective.

    Third, there is abundant evidence that wind and extreme fire weather overrides most treatments. I have visited dozens of large fires burning under ext reme fire weather which, if it had any effect on fire spread, often led to higher severity blazes and burning–due to wind penetration.

    • Look at WUI treatments that have instituted “Restoration” management. It will tell a whole other story of successes on stopping, or at least modifying fire behavior to allow for firefighters to safely engage. Lots of research out of NAU, where fires have burned through research plots, using varying methods of treatments. I’ve seen it, I’ve experienced it, but those stories of successes are always drowned out by the naysayers….

      As for the time element regarding treatments in general forest areas, of course forests grow. They even respond and grow very well when they are managed to respond to silvicultural treatments.

      National Forests lands were, by design, offer a multiple use concept, including growing timber. As for fuels management, it is a follow-up process to logging. Logging; what we supposed to do to manage stands….

    • George,
      Thanks for commenting here! It’s good to hear from you.

      As you know, the time until treatments are less effective varies greatly by the characteristics of a given area. It also depends on exactly what grows back..grasses, shrubs or trees or all of the above.

      But I think the key question here is how you frame the question.

      I think the question most broadly is “should people be doing mechanical treatments and prescribed fire to reduce fuels?” People think it is useful, have observed its utility through experience, and are, in fact doing it. You argue that the probs of fuel treatments occurring and changing fire behavior is low, but that’s not what the R6 Fuel treatment monitoring dashboard shows .

      You state that (1) fuel treatments don’t work in specific conditions (windy and extreme fire weather). Again I have seen with my own eyes, grazed vs. ungrazed on the Marshall Fire (wind), where reducing fuels worked in extreme wind conditions. I think it probably depends on a variety of factors, and making generalized pronouncements is probably not accurate. In the case of “extreme fire weather” what weather do you mean specifically? What “abundant” evidence do you have?

      (2.) You state that you have observed “dozens of large fires burning under extreme fire weather which, if it had any effect on fire spread, often led to higher severity blazes and burning–due to wind penetration.” I’m curious as to what you mean by “severity” as it can be a bit confusing in the wildfire literature. If I go by this definition
      and I think of ppine thinning and underburning, I have never seen worse severity in thinned and underburned ppine stands than in unthinned stands. But perhaps things are different where you are, can you tell us more about the specific fires and locations where you have observed this? I think we could all learn something from these situations.

      3. Thinning seems to be a tool in home fire mitigation. As in Colorado State’s write-up on home mitigation. So are they wrong?

      • Re: the caption accompanying your photos … protect property? YES!

        Healthier Forest? In what way is it healthier? By what measure?

    • When we have million acre wildfires, the chances for fuels treatments to be effective go way up. If the wind conditions are extreme, no treatments are going to actually stop the fire. It is more about altering fire behavior and having some trees survive the inevitable wildfires. The “No Treatment” alternatives ensure that the fire will burn hotter and be more hazardous to us humans. We already know that the “Whatever Happens” plans are bad for nature, and bad for us.

  2. This statement “in cases where enviro groups claim that thinning, etc., do more harm than good?” sounds like it makes the assumption that wildfire severity is the only, or primary, definition of the cause of unhealthy forests. It is far more complex and “the enviro groups” only goal is a healthy and standing forest for future generations. The one absolute scientific fact that we know for certain regarding forest “management” is that mankind’s previous and ongoing destruction of our forests is the primary source of our contemporary forests’ ills.

    • There is plenty of blame to go around regarding the state of our public forests, especially in the west. Fire suppression for many decades cannot be mitigated in a few short years. Similarly, even-aged management, through clearcutting, doesn’t lead to fire safety, or resilience. Thinning projects are NOT “ongoing destruction”.

      • Well, yes clearcutting can lead to a more fire resilient stand. Take a look at mixed conifer sites in eastern Oregon and Washington, where the ponderosa has been removed (high-graded) leaving Doug fir and tolerant fir as an understory. The bigger Doug fir are also gone. Now put in a series of clearcuts to break up the fuels, do a good job of BD, replant with larch or PP. You’ve stepped back the tolerance and Primary species to fit the site (early seral). Manage the stand through intermediate thinnings and Rx burns.

        Been there, done it, proud of my work!!

        • So you’re saying that in the extreme case of human-caused type conversion (where there are no big trees), the best approach to restoration is starting over? You might not get a lot of argument with that.

          • Argument, or agreement; I guess I don’t get your point. The past is full of “overachievers” who went out and high-graded valuable timber stands. That happened, wasn’t good; what I’m saying is that yes, these stands were converted to tolerant spruce fir when they were originally Ponderosa, or mixed conifer (dry-site Ponderosa and Doug fir). Not in climax, but along the travel way. We can fix these issues but it takes bold initiative and collaboration!

            • Argument. I don’t think these kinds of decisions would see many challenges. (At least I’m not seeing them in lawsuits.)

  3. Steve said: “The debate, as ever, centers on whether taking any tree considered mature or old-growth.” Why aren’t the researchers looking at this question?

    “reducing surface and ladder fuels and tree density through thinning, coupled with prescribed burning or pile burning, could reduce future wildfire severity by more than 60%”

    Is tree density an independent variable or is that what results from reducing surface and ladder fuels? Is it really saying that if you don’t reduce tree density enough with ladder fuels, you need to cut overstory trees? Or that cutting overstory trees achieves the same result as cutting ladder fuels so one may be substituted for the other?

    Steve could have highlighted this conclusion: “Thinning without removing surface fuels was less effective—an average reduction in fire severity of 27 percent—and in some cases led to higher wildfire severity than in nearby untreated areas.” While this research may be used to support the specific prescription cited, any discussion of generic “thinning” should adjust this figure downward to reflect that actual nature of probable thinning programs (as well as the likelihood of the benefit being realized through an actual fire). I guess the “COULD reduce fire severity” needs to be emphasized.

    “Treatments were still helpful in lowering wildfire severity overall, even in the studies with the warmest and driest fire weather conditions.”

    Does it matter what level of fire severity they started with? They appear to be saying that the 60% applies to every level of fire severity, which seems doubtful to me (that would mean more of an absolute benefit with higher severity fires). It is also not clear that the fires they included in this study were a representative sample of fires that are likely to occur over the life of the future treatments.


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