Report: Prior fuel treatments ineffective at moderating Fourmile Canyon Fire

The U.S. Department of Agriculture Forest Service’s Rocky Mountain Research Station has just released an August 2012 study titled, “Fourmile Canyon Fire Findings.”   We’ve discussed the 2010 Fourmile Canyon wildfire outside of Boulder, CO a few times before on this blog, including this post from Andy Stahl titled, “Fourmile Canyon Fire Report Confirms Firewise.”

Here’s an excerpt from the Rocky Mountain Research Station’s abstract to their new study:

“Fuel treatments had previously been applied to several areas within the fire perimeter to modify fire behavior and/or burn severity if a wildfire was to occur. However, the fuel treatments had minimal impact in affecting how the fire burned or the damage it caused….This report summarizes how the fire burned, the damage it caused, and offers insights to help the residents and fire responders prepare for the next wildfire that will burn on the Colorado Front Range.

On Tuesday, Bob Berwyn wrote this article for the Summit County Citizens Voice titled, “Report: Wildfire mitigation work largely ineffective in moderating Fourmile Canyon Fire.” Below are some excerpts from Mr. Berwyn’s article:

A report on the 2011 Fourmile Canyon Fire will probably raise more questions than it answers for firefighters and land managers, concluding that, in some cases, the ferocious fire near Boulder may have burned more intensely in treated areas than in adjacent untreated stands.

That may have been due to the relatively high concentration of surface fuels remaining after treatments, as well as the higher wind speeds that can occur in open forests compared to those with denser canopies, Forest Service researchers concluded in the report published last month….

The report also concluded that beetle-killed trees had “little to no effect on the fuels within the area burned by the Fourmile Canyon Fire, the fire’s  behavior, or the final fire size,” explaining that crown fires are “driven by abundant and continuous surface fuels rather than beetle-killed trees.”….

In the end, the report found no evidence that fuel treatments changed the progression of the Fourmile Canyon Fire, and that the treated areas were “probably of limited value to suppression efforts on September  6.” Large quantities of surface fuels in the treatment area also rendered them ineffective in changing fire behavior.

Satellite photos taken after the fire clearly showed that the fire burned just as intensely inside treatment areas as it did in adjacent untreated stands. In some cased, the fire appears to burned more intensely in treated areas, the investigators said, explaining that additional surface fuels, as well as higher wind speeds, may have been factors….

[T]he report once again calls for a change of approach — instead of increasing expensive fire protection capabilities that have proven to strategically fail during extreme wildfire burning conditions, efforts should be focused on reducing home ignition potential within the immediate vicinity of homes, the investigators concluded.

Certainly one new study about one wildfire isn’t the be-all, end-all. However, how does the new research and scientific findings coming from a comprehensive look at the Fourmile Canyon Fire mesh with the constant drum-beat supporting logging for “fuel reduction” and “thinning” we see coming from some quarters at this very blog?


  1. Andy- when I’ve read the various 4 Mile fire reports…I have always gotten the picture that the fuel treatments were not large enough to make a difference and were not complete (well, duh, you need to remove the fuels to finish the job). I believe that home treatments and other treatments are both useful..we just need to understand why homeowners don’t do theirs and how best to design the others.

    Let’s review what the paper says about fuel treatment efficacy also, people on the blog might want to look at the photos of the fuel treatments on pages 25-27. (which seem kind of light to me, but I’m not a fuels person) and the maps and aerial photos on pages 55-58.

    Approximately 600 acres of fuel treatments had been performed during the last 7 years within the area ultimately burned by the Fourmile Canyon Fire (Figures 21, 45).
    However, because of the varied prescriptions used, the intentional leaving of piles of large material in several instances, lack of reducing and maintaining a clean forest floor with the application of prescribed fire, and several areas where the planned treatments were not complete, no general inference can be made on fuel treatment efficacy.
    In addition, after any fire, little evidence remains of when and how treatment areas were encountered and burned. This creates considerable uncertainty as to the explanations behind what can be observed post-fire. For example, treatment effects can be very different if the fire was heading (with the wind and or slope), flanking, backing down slope,
    or if the treated area burned as a result of a mass ignition by spotting (Figures 30, 32, 33).

    .in fire effects on residual vegetation that can be related to changes in fire behavior and sometimes changes in fire progression. It was clear from photographic evidence that the fire readily burned through the treatments and pervasive spotting (0.5 mi at 1000 and 1.0 mi by 1400 on September 6) during the Fourmile Canyon Fire allowed the fire to
    easily breach the narrow fuel treatments located throughout the fire area (Figure 21, 45). No evidence was found that the progression of the Fourmile Canyon Fire was altered by the presence of fuel treatments and the treated areas were probably of limited value to suppression efforts on September 6 (Figure 32). In some cases, because there were large amounts of surface fuels present in the fuel treatments, they appeared to be ineffective in changing fire behavior. Moreover, it was suggested that the large amount of surface fuels present in many of the treated areas was because that they had not been
    maintained (Boulder Incident Management Team 2010). After September 7 the fuel treatment areas on the eastern perimeter of the fire near Lee Hill and the Church Camp were used by fire crews to access the fire edge. However, the fire never reached these fuel treatment areas and the final fire perimeter was not coincident with the location of the known treatment areas (Figure 45). The changes in fire activity in this area were apparently a result of changing weather (increases in air humidity and decreases in wind speed, see Figure 28) and topography (northerly aspect) rather than any changes in forest structure and composition resulting from a fuel treatment. Several miles of roadside fuel treatments were designed to allow for better driving sight distances along the steep and narrow roads but it was impossible to assess the possible role these treatments had in assisting evacuations (Figures 45, 46).

    Post-fire satellite imagery clearly showed the absence of moderated burn severity inside treated areas compared to neighboring untreated stands (Figure 45). In some cases, treated stands appeared to burn more intensely than adjacent untreated stands, perhaps because of additional surface fuels present as a result of the thinning and higher
    wind speeds that can occur in open forests compared to those with denser canopies (Figure 46). One clear example of this comes from near Gold Hill where the piles of slash were scattered in the understory of a thinned stand but where the intended slash burning had not yet been completed. This situation reinforces the notions that fuel treatment
    performance metrics should be described and treatments need to be executed as planned to be effective (Figure 47).

    The description and documentation of fuel treatments performed in the area where the Fourmile Canyon Fire burned did not mention the weather conditions under which they were intended to be effective nor the methods for maintaining surface fuels (litter, grasses and herbaceous fuels) in a treated condition. The amount and condition of surface fuels present in a forest is the major determinant in fire ignition, spread, and ultimate burn severity (Graham 2003, Graham and others 2004).

    Canyon Fire were often chipped or piled for later burning, no broadcast prescribed fire was conducted. If low intensity prescribed fires had been applied throughout the area at frequent (e.g., 10 years) intervals, they would have consumed litter layers, killed shrubs and small trees (ladder fuels), and pruned the lower branches of overstory
    trees by scorching (Graham and others 2004, 2007). By increasing the crown base heights of trees and decreasing surface fuels the occurrence of tree torching may have been reduced (Figure 25).

    Based on past studies of treatment performance and under the weather conditions at the time of the fire, the surface fuel conditions in these treatments almost certainly produced high fire intensities and rapid spread rates (Figures 45-47). Even where intensities could have been reduced by the treatments, long duration flaming associated with continuous surface fuels ultimately ignited and torched residual trees (Figure 31).
    Claims of fuel treatment performance around homes by the owners are consistent with the knowledge that the removal of surface fuel plays an important role in changing fire behavior. Evidence of these effects is seen in the live and minimally scorched tree canopies on their property after a low intensity surface fire most likely burned their
    property (Figure 48).
    Treatment units were located adjacent to roads and on ridge-lines, which confounds treatment effects with those of topographically related changes in fire behavior (Figures 34, 49). Clear evidence of topographic effects is visible in the post-fire burn severity images where north-facing slopes and canyon bottoms suffered minor impacts but had received no treatment (Figures 34, 45). The slim boundary between forest consumed completely by fire and intact north facing forests is coincident with ridgelines and slope changes whether treatments were present or not (Figure 49).
    Elsewhere, (Gold Hill, Sugarloaf, Bald Mountain, Melvina Road; Figures 45, 47) patterns of burn severity (living and consumed conifer foliage) were found to vary independently of fuel treatment locations (Figures 29, 45). Therefore, it is impossible to distinguish the various causes of burn severity, including the efficacy of the fuel treatments.

    High wind speeds and the low relative humidity of the air during the Fourmile Canyon Fire are common weather conditions associated with large wildfires along the Front Range foothills (Figure 2). Thus, recognizing these conditions is critical
    when developing fuel treatment prescriptions. By doing so, and appropriately designing fuel treatments (treating surface fuels, ladder fuels, and canopy fuels in this order of importance) in and among landscapes in conjunction with treating fuels in the Home Ignition Zone across the Front Range, the efficacy of fuel treatments can be greatly improved (Figure 20) (Graham and others 1999, Graham 2003, Graham and others 2004, Graham and others 2009, Hudak and others 2011).

  2. Some people just refuse to accept the reality of this…that when you get really extreme conditions of humidity, temps,and high winds, there is no power, no planning, no treatment, no nothing that will stop a fire from going where it wants. Nada. I am tired of reading statements from pols (and others who should know better) that “demand this fire be stopped”, and usually call for more aerial attacks. We are now experiencing more and more extreme weather, for whatever reason that none of us are smart enough to explain. We will have to learn to live with these blowup fires, and concentrate our prevention efforts in and around the homes and structures along the forest perimeter.

  3. Sharon, there are many out there (who have never fought wildfires or any type of fires) in positions of responsibility who are regularly quoted in the media using exactly the type of comments I allude to. Governors and such should know better, or keep their mouths shut. I know it is simple ignorance and I guess we should be kind to the ignorant.

    Please also remember that the post was rather specifically dealing with extreme fire conditions, so I was commenting in that same vein. I don’t advocate doing nothing, but the notable losses of homes in recent large fires clearly shows that much, much more can and should be done to make these forestland homes more fire resistant. Education? More stringent insurance requirements? Better county/state building codes? Probably all.

  4. Pingback: Sen Tester claims logging bill would have prevented wildfire « A New Century of Forest Planning

  5. I think, considering all the discussion of drought and wildfire, it’s interesting that the Fourmile Canyon Fire burned after one of the wettest winters in the state’s history.

    Sharon, your point about the scale and completion of fuel treatments is well-taken and there have been other fires and other studies showing that fuel treatments have been effective in moderating fire behavior.

    I think (hope) the results of the Fourmile Canyon report will help inform planning for upcoming fuel treatment projects. And since I always like to localize my comments with knowledge that I have specific to my area (Summit County) I see a lot of the same patterns of fuel treatments here that were described in the report – small, scattered, not completely finished in terms of removing or masticating the slash, large slash piles standing for several years after the treatment.

    Maybe it all goes to show that every fire is different, and every area has very site-specific needs for treatment. the challenge is knowing in advance what those needs are.

  6. This report shows how half-fast fuel treatments work — they don’t. The ability of the environmental industry to turn landscape-scale fuel management projects (that can conceivably be performed at no cost and at great benefit to taxpayers) into scattered, highly expensive landscaping projects and THEN claim that “fuel treatments don’t work” is impressive.

    I have photographic documentation of several hundred acres of “fuel management” projects on the Umpqua NF (of 230,000 total acres documented), and they are a joke. Leaf-raking, pruning, and black plastic protected piles of dried fuel don’t greatly affect wildfires. Or rural employment opportunities. I’m guessing a similar history to this wildfire’s fuels.

    Poor resource management results in poor results. Most of these results are predictable and, thus, preventable. Having lawyers, politicians, and activists manage our forests isn’t working. We need real foresters, replicable science, and legitimate businesses in place to make actual changes for the better.

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