Why We Disagree About Fuels Treatment II. Prescribed Burning and Fine Fuels

A prescribed fire in the central Sierra Nevada is set to reduce fuel that could otherwise feed a catastrophic wildfire. (Jason Moghaddas photo) from Berkeley News here

Some of the fuels folks I’ve spoken with think you shouldn’t bother doing mechanical fuels treatment (in forests) unless you also do prescribed burning. The question to me is whether prescribed burning is 1) the only way or 2) the best possible, sort of the gold standard, but in some cases, fuel treatments can work without prescribed burning.

When you think about the world of fine fuels, it is easy to think about subdivisions and how we don’t run fires through them. So I looked at Firewise. In Firewise Zone 3, 100-200 feet from the house, it tells you here

“Zone 3 (High Hazard Areas) Thin this area, although less space is required than in Zone 2. Remove smaller conifers that are growing between taller trees. Remove heavy accumulation of woody debris. Reduce the density of tall trees so canopies are not touching*.”

Which sounds like getting rid of “heavy accumulations”, not exactly the same as burning, or mowing, or raking finer fuels.
(*Question that relates back to the “crown thinning” discussion: is this the same thing as “crown thinning”.. so is Firewise advice “wrong” to people who don’t think crown thinning is helpful for fuels treatments? Am I missing something here?)

Here’s an example of another paper about mastication in the Southwest. It talks about examples in which mastication without burning was successful in changing fire behavior, but it had to do with making sure the fuels were distributed across the site to avoid soil burning. You certainly get a feel for local differences in reading this paper.

I was hoping that there would be one paper that describes the situations where and why people do or don’t do burning and why, and how it works, but it seems that most of this work is thought and written about by fuels practitioners and at the local level based on their own experiences.

Potential Points of Agreement

1. Prescribed burning is generally best for fuels reduction in terms of fine fuels.
2. Due to long- term fire suppression, there are heavy accumulations of biomass in some areas. In these cases, you may need to do some kind of mechanical treatments in advance of prescribed burning, so you can run fire through and not kill them all.
3. There are situations (here, some mastication, and in wildland-urban interface, others?), in which you can’t do prescribed burning and mechanical treatments alone can be still helpful.
4. (I think the mastication paper is very helpful with this) It is hard to generalize because fuels and fire behavior tend to vary locally. Local fuels specialists may know the most about what works and what doesn’t.

Does everyone agree? Do you want to restate/clarify any of these?

(Note: this is not about the cultural, economic and environmental issues related to prescribed fire- that will follow later as we see where everyone is on the utility of prescribed burning for fuel treatments).


  1. While some fuel management folks might think fuel reduction that focuses on ladder and canopy fuel should not be done unless prescribed fire it done there are many instances where the mechanical treatment altered fire behavior sufficiently to improve suppression success. I share this paper again: http://qlg.org/pub/miscdoc/HFQLGtreatmenteffectivenessreport.pdf here is another paper: https://www.fs.fed.us/psw/publications/ritchie/psw_2007_ritchie001.pdf where the authors find that the surface fuel that resulted from a 20 year old harvest treatment contributed to higher mortality than the stand that had been mechanical treated and Rx burned. A complicating factor that has not been address is when a biomass harvest is the mechanical treatment. Biomass harvests remove most of the total tree (bole and branches). Not all of the branches are removed but surface fuel and ladder fuel is greatly modified.

    Another issue to consider is that when treatments focus on large scale it may be years before the Rx fire is implemented because of the many constraints to Rx fire.

    I have suggested edits to your list below. [xxxx] = strike, XXXX = add this text.

    1. Prescribed burning is generally best for fuel[s] reduction in terms of [fine} SURFACE fuel[s].

    2. Due to [long- term] DECADES of fire suppression, there [are] MAY BE heavy accumulation[s] of biomass CREATING EXCESSIVE LADDER AND CANOPY FUEL in some areas. In these cases, [you] IT may BE NECESSARY [need] to [do some kind of] CONDUCT A mechanical treatment[s] in advance of A prescribed burn[ing], so THAT A PRESCRIBED FIRE TREATMENT CAN BE CONDUCTED WITHOUT EXCESSIVE RESIDUAL TREE MORTALITY [you can run fire through and not kill them all].

    3. There are situations (here, some mastication, and in wildland-urban interface, others?), in which you can’t do prescribed burning and mechanical treatments alone can be still helpful.

    4. (I think the mastication paper is very helpful with this) It is hard to generalize because fuels and fire behavior tend to vary locally. Local fuels specialists may know the most about what works and what doesn’t.

    • Mike- thanks so much for participating in this discussion! When I looked at the photos of the HFQLG treatments one of the sites reminded me of pumice soils in Central Oregon and the quasi soils in granite on the Hayman in Colorado.. not much fine fuel other than pine needles. Perhaps a variable in all this is the amount of fine fuels..and how much they need to be reduced. My other thought is that the effectiveness paper also talks about effectiveness in terms of firefighter observations, e.g.
      “However, many of the fuel treatments were effective in slowing fire progression. These treatments aided firefighters in controlling fire growth in those sections of the fire. According to firefighters utilizing these treatments in suppression efforts, the fire dropped from an intense fire, with group torching and short crown runs, to a surface fire. This fire transition allowed direct attack using bulldozers in some of these treatment areas.”
      This seems to be a difference from many scientific papers that use other measures of treatment effectiveness.

  2. In Southern Oregon Mastication seems effective in heavier fuel loadings after year two, when the fuel has compacted and begun decomp, without rx as long as resprout in minimal. The downside is you generally don’t get the canopy spacing to drop a crown fire. Additionally, you still retain ladder fuel in more open grown stands.
    Long term areas that were commercially thinned around stand age of 40 have crown spacing that drops the fire and the mechanical operation of tree length yarding reduces the fuel loading. During harvest activities the lower limbs are considerably reduced on retention trees further reducing ladder fuels.
    There are several examples of running crown fires dropping and dramatically slowing when hitting the treated areas.
    The biggest obstacle is follow up treatment especially if rx, do to smoke clearance.

  3. My biggest disagreement is pretty minor – I think it is more appropriate to refer to fire EXCLUSION, than fire suppression. The use of the term exclusion acknowledges that some places had the vast majority of fires set by people, not by lightning. Just today, BLM released statistics that noted that so far in 2017, the number of human-caused fires totals 700+. In this case, most of these human-caused fires were not for the same reasons that people used to start fires to manage their landscapes in the past.

    I also want to note the Fire and Fire Surrogates Studies that were implemented more than 10 years ago to compare the types of things that Sharon is talking about.

  4. I am a little confused by this post. Are you suggesting that we extend recommendations made for fuels within 200 feet of homes to the backcountry landscape?

    I think we need to bifurcate the landscape and the discussion of fuels management. Society may find it acceptable to make ecological compromises within a few hundred feet of structures, and conversely, that ecological goals and natural processes should take precedence outside the structure ignition zone. There might be some fuel reduction outside the structure ignition zone, but it would be a by-product of valid “restoration” motivated almost exclusively by ecological concerns.

    • That is what has been happening in the Sierra Nevada, since 1993. There are also other things away from towns that are worth protecting from firestorms, and they aren’t all man-made, either. Despite all the rain this last winter, fire intensities seem very high, this fire season, already. Could it be the fuels?!?!? Could it be fire suppression? Could it be people? (Of course, it is a synergy of many variables, causing fires that behave ‘unnaturally’.

      Multiple purposes and needs in the Sierra Nevada require more active management. Some of those purposes and needs are apart from ecology, and there was never a mandate to solely improve ‘nature’. There are ALWAYS compromises, with some winners and some losers, in the reality of this human environment. We can have some short term mitigated damages, in exchange for many longterm benefits. It is all about the site specifics, and in the Sierra Nevada, excess fuels, both live and dead, are a big problem.

    • No I wasn’t saying that at all. Sorry I was unclear… I was asking “if crown thinning doesn’t work, why is it in the Firewise guidelines? Or is that a conceptually different thing?”

      Because crown thinning seems to be something that people disagree about, so I was just trying to figure out who thinks what. Like why do the Firewise people say that, and is it “wrong.”

      When we worked on Colorado Roadless, we found it easier to talk about “200 feet”, (around communities but not backcountry 1/4 mile or ???) and “farther away from structures than that”. Maybe for now we could talk about the “midzone” and leave the distance undefined. There is some midzone, which people disagree about the size of, that is neither 200 feet, nor “backcountry”.

      Perhaps we could “trifucate” conceptually for now and see where that leads us.

      As to “ecological” goals and “natural” processes…perhaps part of our conceptual problem in discussing fuel treatments has been combining the two. That is it is good for for changing fire behavior, and also for “restoring” to the past.

      Then we set up a full employment program for historic vegetation ecologists to discuss and disagree about the past- and a laundry list of scientific papers for folks to address in their NEPA documents. Or we can say that “resilience to climate change” is a good ecological goal, but then people disagree about what that might entail (although that would be worth discussing separately after fuel treatments).

  5. Here’s a look at a lawsuit involving a fuels project — this is exactly what we’re discussing in this thread. It is important to look at what the enviro groups say and compare it to what the agency has said in its documentation.

    An article in yesterday’s East Oregonian explains that the “Wallowa County Board of Commissioners has voted to file as an intervenor in the lawsuit filed by environmental groups Oregon Wild and Hells Canyon Preservation Council to stop the Lostine Corridor Safety Project…. The project is an attempt by the U.S. Forest Service to remove hazardous trees and allow some logging while also performing proscribed fire treatment along the 11-mile corridor, which the Forest Service contends is at high to extreme risk for wildfire…. The suit alleges that the Forest Service project violates the law on several counts: The Forest Service violated the National Environmental Policy Act by categorically excluding the project from environmental analysis and not using a collaborative process to develop the project, which they contend is mandated under the categorical exclusion.”


    Here’s how the USFS describes the project (https://www.fs.usda.gov/detail/wallowa-whitman/news-events/?cid=FSEPRD490761):

    The Lostine Corridor is a cherished landscape by many local residences and visitors, with outstanding scenic, fisheries, wildlife and botanical values. There are also many historic and recreation values, including a Civilian Conservation Corp (CCC) era guard station, 7 campgrounds and 3 developed trailheads. Private lands with residential developments are located within the corridor. For many decades, the vegetation in the corridor was only lightly managed so as to avoid impacts to the many corridor values.

    Unfortunately, the result has been forest stands in decreasing health that are currently posing high risks to the public who use and enjoy the corridor. Residents, visitors and emergency services agencies have shared concerns about the increasing number and frequency of downed hazard trees along roadways and campgrounds, and increasingly dense and declining forest stands and heavy fuel loads. Many recognize that the values they love in the corridor are at risk of loss as the forest stands become less resilient, and are now asking the Forest Service to address these issues.

    The primary concern and purpose of this project is to address the public safety issues in the corridor. Secondly, the project will address risks to the other values in the corridor including infrastructure (homes, cabins, recreation improvements, roads), the natural resource values. To reduce risks to these values the Forest Service is proposing the following within the project area boundary (approx. 2,110 acres):

    * Removal of hazard/danger trees that pose a risk to people traveling within the corridor, historical sites, and infrastructure.
    * Creation (through removal of vegetation) of defensible space around identified historical areas (ex. Lostine Guard Station).
    * Remove fuels to increase canopy spacing and decrease both ground and ladder fuels and to decrease the risk of potential high intensity wildfires.
    * Thin dense forest stands to improve forest health and resilience to insects, disease and wildfire.

    And here’s a bit of Oregon Wild’s position (http://www.oregonwild.org/forests/forest-protection-and-restoration/lostine-corridor-faq#5):

    What’s so bad about the project?

    This is not a light thinning of trees near homes or campgrounds. This is an industrial logging project on a small footprint. The Forest Service is planning to sell off 4 million board feet of trees. The Lostine Corridor is 11-miles long with a width sometimes best measured in yards. Lined end-to-end, the logging trucks from this project would stretch for 8 miles!

    As proposed, they will prioritize commercially logging some of the largest, most fire-resistant trees out of the forests over stands of smaller trees that could actually benefit from thinning. Furthermore, there is scientific evidence that logging in this type of forest will not decrease the severity of fire. The Forest Service is claiming to improve fire safety while likely increasing fire severity risk in a forest like this.

    My two cents worth:

    4 MMBF is not a large amount from 2,110 acres. I haven’t found anything in the USFS documentation to indicate that the agency plans to “prioritize commercially logging some of the largest, most fire-resistant trees.” In fact, the USFS analysis says that “Resiliency” thinnings on about 450 acres will remove trees only up to 21” dbh. Sounds like they might take a few larger trees if they are infested with mistletoe or otherwise are unhealthy, or are hazard trees. IMHO, the Wallowa-Whitman National Forest did quite a bit of analysis and documentation for a CE project.

    • Indeed, there is also the fact that older trees along roads have more rot in them, as well as old wildfire catfaces. Just letting trees fall where and when they may isn’t a good option, for us humans. ‘Nature’ doesn’t care if they fall on something, or someone. Tree fallers can directionally fell trees, keeping damage from such bigger hazard trees to a minimum, without unnecessary impacts to both locals and tourists, alike.

      Is there room for compromises? I guess we’ll see.

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