Why We Disagree About Fuel Treatment: I. Fuel Treatment Basics and Nomenclature

Fig. 1. Typical increase in surface fuels, ladder fuels, and canopy bulk density in a ponderosa pine forest, 1908–1948, in western Montana. Most
of the historical trees are ponderosa pine, and most of the trees in the more recent photo are Douglas-fir. Photos from Gruell et al., 1982 (figure 19
p. 32). Copied from Agee and Skinner p. 3

One of my favorite climate change books is called “Why We Disagree About Climate Change” by Michael Hulme (here’s a micro-version of the book). In honor of that book, I’m going to call this series “Why We Disagree About Fuel Treatment”. This should be an opportunity to slowly work through observations and conclusions from various practitioner and scientific communities, and see why people disagree.. what they are disagreeing about, specifically, and what evidence can be brought to bear for each point of view.

Starting with the basic fuel treatment nomenclature.. what is a fuel treatment? If we go to the NWCG glossary here they have “Manipulation, including combustion, or removal of fuels to reduce the likelihood of ignition and/or to lessen potential damage and resistance to control.” There might be better definitions (suggestions welcome!) but those are the general ideas. In this comprehensive paper by Jain et al.(with terrific photos IMHO ) “Fuel treatments are designed to meet short-term and long-term fire management objectives. This may include altering fire behavior or influencing post-fire outcomes.”

I guess you can start anywhere, but let’s start with fuel treatment basics. Coneniently, there is a 2005 paper by Jim Agee and Karl Skinner called Basic Principles of Forest Fuel Reduction Treatments.

It has a handy descriptive table:

As Jain et al. say…

When the treatment objective is to change fire behavior and create protected space for active fire suppression, then biomass removal to aid fire suppression efforts tends to follow the suggestions of Agee and Skinner (2005): (1) reduce surface fuels, (2) increase height to live crown, (3) decrease crown density, and (4) keep large trees of fire resistant species. “

Prescribed fire is thought to be the best for reducing surface fuels (this seems to be so broadly believed and obvious that it doesn’t need a citation). But in many cases, you can’t do this without risking a crown fire, and/or burning up all the trees, without removing ladder fuels. Keeping big trees of a fire resistant species is good because you have trees with tree habitat for critters and other tree-lovers (plus I think trees store more carbon ?), plus if they are fire resistant species you can run prescribed fire through there again (or if there is a wildfire, these trees will be fine). Now, the Agee and Skinner table characterizes that as “historic structure” and I guess that’s also a good thing, but you don’t necessarily need to go there- you can choose to keep big trees for the pragmatic current and future purposes that I just described.

Based on all this… fuel treatments remove or rearrange fuels in order to change fire behavior. And where you have forests, you should ideally do 1-4 as in Agee and Skinner to do fuel treatments.

Is everyone in agreement so far? Any additions, clarifications, or ?


  1. Sharon,

    Two thoughts came to mind as I read your offering.

    1. How do economics enter in the fuel treatment equation?
    Fuel treatment costs money. Is it acceptable that fuel treatment is mostly funded by appropriated funds. There are those who don’t believe trees with commercial value should be lumped into a fuel reduction treatment.. When one considers and maybe accepts that in some forest types many of the trees that comprise the excessive stand density are of size and value to offset fuel reduction treatment costs, the commercially valuable trees can go a long way toward paying for treatment and still maintain habitat structures.

    2. Prescribed fire liability. The risk of escape and the liability associated with escaped fires have stifled Rx fire on industrial forestland in California. The agencies will do it, but nowhere close to the scale or pace that is necessary.

    Those are 2 quick thoughts.

  2. No problem with your original post. As to your comment above: 1 & 2 are either ignorance or self serving while 3 can be true or it can be naivete expecting perfect results always.

  3. I would add pruning to the list. Wouldn’t it be great to put young people to work, treating surface and ladder fuels into piles. Maybe a YCC/CCC situation would be good…. if the Congress wasn’t against funding the Forest Service.

    The Trump Forest Service will underestimate the barriers in front of their goals, just like during the Bush Administration. Any plan that doesn’t address ‘boots on the ground’ expertise is bound to fail. We will see if they will outsource the basic, lower-level fieldwork, when they find out that “Temporary Employees” cannot do very many acres, in a few months, every summer.

  4. The photo on top of Figure 1 appears to show a ponderosa pine forest following some type of logging. Could it be that past logging actually contributes to more dense stands of pines and Douglas fir post-logging? Yep.

    See: http://rintintin.colorado.edu/~cana4848/papers/Naficy_et_al_2010_Ecol_App.pdf

    Also, the Forest Service, some researchers and the timber industry have in the past falsely presented a post-logged ponderosa pine forest as being representative of historical condition, which is clearly not true. See: http://swanview.org/reports/Ponderosa-Poster-Child.pdf

    • Thanks, Matthew.. two things, if you noticed I said, you could talk about this without looking at”historic conditions” at all. Because that in itself leads to a lot of controversy and the addition of a whole nother set of disagreements. I’m wondering if folks can never agree on “what used to be there” and maybe that’s something that (with climate change making us question if “what used to be there can still be there”) we could leave off for the time being.

      • Hi Sharon, I guess I took a look at the top photo, and the photo caption that you picked to run with this and assumed that someone was talking about ‘historic conditions.’ It seems very clear to me that Fig. 1 is attempting (through image and text) to falsely present a recently logged forest as the normal ‘historic condition’ of that forest. I mean, what other conclusion could anyone really draw from it?

    • Thanks for the link, Larry. Here’s an expanded view of the ecosystem (or what’s left of it) that surrounded Larry’s thinning project, which was located on the bottom right of the image.

      But, it looks pretty hacked and hammered in that part of the world. I’m sure a bunch of the clearcuts are on private industrial lands, but still….

      • Of course, there is a rich history of wildfires in the American River Canyon, including the Wrights Fire, the Cleveland Fire and the Freds Fire. Just look at the south-facing slopes above Highway 50. I used to call this the “Scenic Burn Zone”.

        AND, remember, that clearcutting in the Sierra Nevada National Forests was banned, 24 years ago. Ditto for old growth harvesting. Yep, go ahead and sign a petition then mail it to Sierra Pacific Industries. I DARE ya!

  5. First, this is about “dry forests.” That isn’t the only place that people want to treat fuels.

    Second, I think the term “commercial” is probably a shorthand for the size of trees being removed as either ladder fuels or components of crown density, and this is probably the main objection to fuel treatments. If the Lick Creek conditions pre-harvest are the desired conditions, then I doubt if there are many large trees that would need to be removed to get there. I think there is also disagreement with the idea that we should cut down large trees on public lands to pay for the fuel treatments.

    Also, I think that disagreement might have a lot to do with how useful fuel treatments are when they are far from homes and there is no effort to reduce risk adjacent to the homes. I think we are more likely to agree with fuel treatments on public lands where there is commitment to do the same on private lands.

    • The Sierra Nevada National Forests have been doing “commercial” thinning since 1993, eliminating clearcutting and old growth harvesting. Some people are still in favor of ending “commercial” thinning projects. They won’t be happy until lumber mills are a thing of the past.

    • Jon, that’s an interesting comment. There are two studies I referenced in the post. One is from Agee and Skinner and what they mean by “dry forests”

      “This means that not every forest is a high priority candidate for treatment. Many forest types, including wet Sitka spruce, coastal Douglas-fir, and high elevation forests such as mountain hemlock or subalpine fir, historically burned infrequently but with high intensity (Agee, 1993). Where trees that are 300–800 years old have never experienced a wildfire, it is difficult to argue that a serious fuels problem exists (Brown et al., 2004). There is certainly a lot of biomass on site, but much of it is unavailable for combustion under most conditions. Conversely, there are other forests that have long dry seasons each year and have easily combusted forest floors, such as ponderosa pine, mixed conifer, and drier Douglas-fir forests (Skinner, 2002), where the types of fires occurring today are very uncharacteristic of the historic fires. While some intense fire activity did occur in such forests, it was not the modal type of fire severity that exists today in such forests. There is broad consensus that active management of some type is needed in such forests (Allen et al., 2002; McKelvey et al., 1996), and that such treatment will be needed as a continued maintenance activity.”
      The Jain et al paper is about “dry mixed conifer forests”.
      Jon, do you have any specific projects in mind that are not in “dry forests”?

      Practically speaking, II don’t understand how you would link “home treatment” to fuel treatments “far from homes”. Functioning CWPP’s?? Firewise “certification” for subdivisions?

      • Rather than a specific project, I’d look at any thinning project in lynx habitat. Lynx habitat is typically not “dry,” but there seems to have been a lot of thinning desired there (which is bad for hares and lynx, and therefore is limited by the lynx amendments, and seems to end up in court). Maybe it’s not always a “fuel treatment,” but with the incentives for that label I assume much of it is.

        Firefighters triage homes based on their defensibility. I don’t see why fuel treatments couldn’t be prioritized based on the same thing.

  6. Here is a great example of fuels reduction via salvage logging.


    Of course, opponents of salvage logging claim all sorts of “destruction” when they complain about salvage logging. We left ample snags, back in 1991, but I’m sure they have all fallen since then (except for maybe some ‘buckskin’ pine snags). No new roads were built, as this was a helicopter project. There were some temp roads, going to temp landings but, I’ll bet you cannot find it, today, on the aerial photos.

  7. Two points –

    First, I agree with Jon Haber, there needs to be a “Principle 0” – Treat Fuels only where they need to be treated. That is, mostly in ecosystems with a naturally frequent fire regime that have missed multiple fire cycles, AND immediately proximity of structures. We do not need to do fuel reduction in moist forests with relatively infrequent fire regimes, such as the Douglas fir forests of western Oregon and Washington, but indeed they do propose fuel reduction just such places.

    Second, there is not a lot of evidence to support the need for canopy fuel reduction. Canopy fuel reduction is a real mixed bag. One can make a strong argument that retaining canopy fuels results in more net benefits than reducing canopy fuels, because canopy fuels help maintain cool, moist, less windy microclimate, AND helps suppress the grow of future ladder fuels, AND helps keep small fuels high out of the way of most fires. Reducing canopy fuels therefore makes the stand hotter, dryer, windier, stimulates the growth of ladder fuels, and moves a lot of hazardous small fuels from the canopy to the ground where they are more available for combustion.

    Even Agee says “Reduce Crown Density … DON’T START HERE!!!!! ” (emphasis in original). http://www.fws.gov/oregonfwo/ExternalAffairs/Topics/DryForestWorkshop/Documents/2005/PowerPoints/Agee%20NSO-Bend-Agee.ppt.

    Omi and Martinson (2012) prepared a review of the literature for managers and concluded — “That no relationship (r2<0.06) was found between canopy fuel variables and the effectiveness of either surface reduction treatments without thinning or thinning treatments without subsequent slash treatment supports the assertion that surface fuel reduction is of primary importance in influencing treatment effectiveness. " Omi & Martinson 2012. Effectiveness of Fuel Treatments for Mitigating Wildfire Severity: A Manager-Focused Review and Synthesis. Joint Fire Science Program. Final Report. JFSP Project Number 08-2-1-09 http://www.firescience.gov/projects/08-2-1-09/project/08-2-1-09_finalreport08-2-1-09.pdf

    Models show that maintaining canopy cover is a useful way to reduced fire hazard, while removing canopy increases fire hazard. "Compared with the original conditions, a closed canopy would result in a 10 percent reduction in the area of high or extreme fireline intensity. In contrast, an open canopy has the opposite effect, increasing the area exposed to high or extreme fireline intensity by 36 percent. Though it may appear counterintuitive, when all else is equal open canopies lead to reduced fuel moisture and increased midflame windspeed, which increase potential fireline intensity." Rutherford V. Platt, Thomas T. Veblen, and Rosemary L. Sherriff. 2006. Are Wildfire Mitigation and Restoration of Historic Forest Structure Compatible? A Spatial Modeling Assessment. Annals of the Association of American Geographers, 96(3), 2006, pp. 455–470. http://www.colorado.edu/geography/class_homepages/geog_4430_f10/Platt%20et%20al_Wildfire%20Mitigatnion_AnAAG_2006.PDF.

    "Opening up the stand significantly will dry surface fuels due to increased light levels, surface winds and temperatures. This may increase surface fire intensity and rate of spread unless total surface fuel loading is reduced. In addition, thinning that allows significant light to reach the forest floor may result in the regrowth of small trees and shrubs, which over time become new ladder fuels." Stephen Fitzgerald and Max Bennett. 2013. A Land Manager’s Guide for Creating Fire-Resistant Forests. EM 9087. OSU Extension. http://www.nwfirescience.org/sites/default/files/publications/A%20Land%20Managers%20Guide%20for%20Creating%20Fire-resistant%20Forests%20.pdf

    Modeling shows that canopy fuel reduction is accomplished at the expense of increasing surface fire intensity. "Modifying canopy fuels as prescribed in this method may lead to increased surface fire intensity and spread rate under the same environmental conditions, even if surface fuels are the same before and after canopy treatment. Reducing CBD to preclude crown fire leads to increases in the wind adjustment factor (the proportion of 20-ft windspeed that reaches midflame height). Also, a more open canopy may lead to lower fine dead fuel moisture content. These factors increase surface fire intensity and spread rate. Therefore, canopy fuel treatments reduce the potential for crown fire at the expense of slightly increased surface fire spread rate and intensity." Scott, Joe. 2003. Canopy Fuel Treatment Standards for the Wildland-Urban Interface. USDA Forest Service Proceedings RMRS-P-29. 2003. http://www.fs.fed.us/rm/pubs/rmrs_p029/rmrs_p029_029_038.pdf.

    A recent study of crown damage related to the Biscuit fire showed that

    The most important predictors of total crown damage were the percentage of pre-fire shrub-stratum vegetation cover and average daily temperature. … The median level of damage was 32% within large conifer cover and 62% within small conifer cover. Open tree canopies with high levels of shrub-stratum cover were associated with the highest levels of tree crown damage, while closed canopy forests with high levels of large conifer cover were associated with the lowest levels of tree crown damage.

    [Random forest analysis] RFA explained 45% of variation in total crown damage. Shrubstratum cover was, by far, the most important predictor variable (Fig. 4); increasing shrub-stratum cover was associated with increasing crown damage (Fig. 5). Average temperature and burn period were similarly important and were ranked second and third, respectively. Large conifer cover was ranked fourth and was associated with decreasing total damage.

    Furthermore, the ability of conifers to resist fire damage increases with age, as the height to the base of the crown rises and the insulating capacity of the bark increases. This is consistent with the fact that, within the Biscuit Fire, median crown damage within large conifer cover was 32%, compared to 62% within small conifer cover.

    In addition, mixed-sized conifer cover experienced levels of damage that were intermediate between small and large (median = 52%), which suggests that multi-storied conifer stands did not increase the level of damage by increasing vertical fuel continuity. Instead, it seems likely that the small tree component of the mixed-sized stands was damaged, while the large tree component was not.

    Jonathan R. Thompson, Thomas A. Spies 2009. Vegetation and weather explain variation in crown damage within a large mixed-severity wildfire. Forest Ecology and Management 258 (2009) 1684–1694. See also, Jonathan R. Thompson. 2008. Patterns of Crown Damage within a Large Wildfire in the Klamath-Siskiyou Bioregion. PhD dissertation. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/9025/Thompson_Dissertation_FINAL.pdf.

    • I saw many examples of pure old growth with very high mortality rates in the Biscuit Fire. Cherry-picking and ignoring important human issues can lead someone to believe that doing nothing in crowded and unhealthy forests is a good option. What about when historical forests had far less tree density, less fuels and less canopy density? Did those forests have more mortality and damage than firestorms in thick forests? Yep, I didn’t think so.

      • The “narrow ecological goals on the left” are codified in NFMA and its planning regulations, which limit the discretion for multiple use that is contrary to those goals. For example, thinning is restricted in Canada lynx habitat because of its effect on snowshoe hares.

        • There are people who are against thinning, here in California. Those people prefer a hands-off situation, despite drought, bark beetles and firestorms. Those are the same people who want ‘free-range’ fires, even if they are intense and very large. Then, they blame fire suppression and climate change, instead of inaction, for the incinerated forests.

          • “Then, they blame fire suppression and climate change, instead of inaction, for the incinerated forests.”

            Interestingly, NASA earlier this year posted research on how “Wildfires & Fires” period (especially agricultural) were the cause of these severe “Droughts” & not the other way around as some have boldly stated in this forum. That’s a switch and put globally altogether these 84% human caused fires are what are creating the climate change. This is something never brought up in the debates. I guess because the Agricultural Fires & prescribed burns are science-based. They are science-based because the justification has always been used, The Indians or Indigenous peoples did it. And yet these same indigenous people in Africa lighting fires for the good grazing for livestock are what is causing the problem. Funny, this throws the whole “Because Native Americans did it” out the window.


            • Wherever you see giant pines, in the Sierra Nevada, you can bet that Indians expertly used cool burns to produce such majestic forests. They passed down the knowledge from generation to generation, and certainly learned to use the right techniques, in order to not kill the shade they enjoy in summer. They also had the intensely-flammable bearclover to help the fire carry. They certainly covered much of the middle elevations of the Sierra Nevada.

    • It seems like this is where people can disagree about the utility of thinning crowns for fuel treatments based on different studies, in different locations, where treatments were conducted in different ways, and studies that use different analytical approaches..

      This reminds me a bit of this in the Jain paper Research Note here..

      Treatment Effectiveness and Economic Feasibility
      According to the analysis, most dry mixed conifer forests currently have high fire hazard, but only a fraction of those forests can be effectively treated (at least by the fuel treatments currently relied upon in the dry mixed conifer region). While it might sound discouraging that prospects for effective treatment are limited to a relatively small subset of the forest, it does make the fuels management problem more tractable in that one can justifiably focus on treating the more limited area of the forest where success is attainable. It also suggests that on many other acres, there are few options for achieving significant hazard reduction.

      Fuel treatments that are self-funding may ultimately be the most effective choices for mitigating fuel hazard, given the current and likely future Federal budget climate. Selecting acres for treatment that are not genuinely hazardous, or that cannot be shown analytically to be economically viable for a fuel treatment program, may hinder gaining and maintaining public trust in fuels management. Using models such as BioSum and FFE-FVS provides managers with the decision support that can demonstrate treatment accomplishment (effectiveness and economics) objectively and provides choices.” (my italics)

      Still if people agree about prescribed burning and ladder fuels in forests, that is something!

      • Of course, the preservationists insist that Forest Service ‘Ologists’ have opinions that are tainted. Guilt by association. Then, they offer up other ideas that ignore human issues, solely focusing on ‘deep blue’ ecology, and nothing else, because “humans are a cancer upon this Earth”. They want a human-free landscape.

          • I must have missed something here. Where did Bill Nye, or anyone for that matter, say “humans are a cancer upon this Earth?” Where did Bill Nye say he wanted a human-free landscape? Maybe some of you need a scientist to tell you that all humans will die eventually, but many of us already figured that mystery out.

              • Funny, but I did a google search on “humans are a cancer upon this Earth” and nothing really came up. But, yes, by all means, let’s make sure we use this forest policy blog to point out something crazy that someone said sometime on Facebook.

                And wait, when you say “it is those ‘Deep Blue’ people who worship fictional entities” are you talking about Christians?

                • I agree with Matt that you are getting some strange conclusions from these articles, Kevin. Bill Nye didn’t speak against humans; he spoke against ignorance.

                  “Genghis Khan has been branded the greenest invader in history” by Julia Pongratz, who headed the research by the Carnegie Institution’s Department of Global Ecology. I don’t see the connection to “main stream environmental groups.” In fact the article says “his methods may be difficult for environmentalists to accept.”

                  It’s a pretty big stretch from the actual research finding of “There is a tendency for the net influence of fire to suppress precipitation in northern sub-Saharan Africa” to your conclusion that “human caused fires are what are creating the climate change.” And this research says nothing to question “the other way around” (that global warming causes fires).

    • 2nd, I’m curious as about your statement “We do not need to do fuel reduction in moist forests with relatively infrequent fire regimes, such as the Douglas fir forests of western Oregon and Washington, but indeed they do propose fuel reduction just such places.”

      Can you be more specific about projects that you think a) have fuels reduction as part of the purpose and need and b) are in the wet part of the Douglas-fir region?
      Because the “wet” part strikes me as a small part of the total acres in the west. I’m thinking you mean west of the Cascade Crest and say north of Roseburg? or ??

      And you seem to be agreeing that fuel treatments may indeed be useful throughout the rest of the West.

  8. Many researchers who look at post-fire effects do not take into account, especially on a fire as large as the Biscuit Fire, how much of the burned area within the fire perimeter was not burned by the wildfire, but by “backburns” that are lit to reduce the fuel between the main fire and the fire line. We do a very good job mapping the change in fire perimeter, but it can be fairly difficult to tell which areas represent wildfire burning and which areas represent backburns. So I tend to be a little suspicious about post-fire analyses that do not acknowledge the backburns. Does anyone know any studies that take this into effect? I know of one on a small portion of the Biscuit Fire.

    • It’s all part of the package! The Biscuit was a very dangerous place for firefighting and they had a “column collapse”, spreading fire in all directions, for many miles in just one catastrophic event. The fire was threatening to make a run at Grants Pass and other towns in the Illinois Valley. Backfires were absolutely necessary to stop the fire. Similarly, when firefighters decide to go with indirect firelines, that is also a huge issue. Those tactics are what they are but, some decision-makers choose to want “more fire on the ground”, using safety as the vehicle. A few years ago, in Colorado, firefighters had plenty of chances to put a Wilderness fire out. That fire was only 150 acres after 9 days of burning. Instead, the fire blew up into a 100,000 acre firestorm, with a $100,000,000 price tag.

      • Yes, it is all part of one package, but the fire behavior is very different in the backfires vs. the wildfires, and research studies looking at fire effects do not take this into account or acknowledge this.

  9. “Sure, but the Forest Service gets to choose where and why those areas are to be thinned, based on Multiple Use, site-specific science and human impacts, and not just on narrow ecological goals of the left.”
    Actually they have loop holes and shortcuts to get around the rules and regulations that don’t agree with their goals. And they also seem to be well funded.


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