Does Thinning Work for Wildfire Prevention? High Country News Weighs In

 

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Several people, including WUI residents doing mitigation work, brought this High Country News article to my attention.

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Some of my pet peeves include redefining English words and making up abstractions, simply because those behaviors tend to increase disagreements just by misunderstandings.  So here we go:

Thinning is not logging. To its opponents, thinning is a form of “silviculture by stealth,” as wildfire historian Stephen Pyne put it. Pyne, however, says thinning is more like “woody weeding.” Logging, he explained, harvests large, mature trees over large areas, while thinning mostly removes small trees. Logging makes money; thinning almost always costs money.

In plain old Helms Dictionary of Forestry, thinning is a cultural treatment made to reduce stand density.  Now, Pyne, is a fire expert for sure, but Steve just posted about the Mount Baker-Snoqualmie project that, according to the Courthouse News article:

The Forest Service approved between 2,000 to 3,300 acres of commercial thinning and 1,060 acres of noncommercial thinning.

Now in plain English “commercial” means that you can make money from the stuff.  So conceivably the old way of thinking “must be traditional sized sawtimber” to make money.. it could also be commercial firewood or chips or material for engineered wood products or biochar or….

Please everyone, let thinning mean thinning and commercial mean commercial!

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I hadn’t seen this open-access Commentary by Jones et al, called “Counteracting Wildfire Misinformation” but maybe someone posted it previously. Short and worth a read.

A continually changing media ecosystem presents challenges and opportunities to mitigating the spread of misinformation. Here, journalists and news organizations have a weighty responsibility, playing a critical and often insufficient role in reducing misinformation.

More later on that.

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And here we go….

Thinning should be followed by prescribed fire. “If you don’t follow it up with the right fire, then it’s worthless, and in many cases may have made it worse,” said Pyne. Thinning and prescribed burning are the one-two punch that will knock out many severe wildfires. Prescribed fires do have drawbacks: They are complicated to plan and execute, they dump unwanted smoke on communities, they’re subject to litigation, and in rare instances they can spark destructive burns. Nevertheless, they are sorely needed, and without them, thinning rarely succeeds.

Thinning by itself is “worthless” and it “rarely” succeeds.  It seems to me that it’s more complicated than that.  Certainly thinning without removing the material could make things worse.  But what fuels practitioner would design a project that doesn’t remove the thinned material?  The discussion in the 10 common questions paper (cited in the HCN article) is more nuanced.

Thinning from below reduces ladder fuels and canopy bulk density concurrently, which can reduce the potential for both passive and active crown fire behavior (Agee and Skinner 2005). For instance, Harrod et al. (2009) found that thinning treatments that reduced tree density and canopy bulk density and increased canopy base height significantly reduced stand susceptibility to crown fire compared to untreated controls.

Some studies show that thinning alone can mitigate wildfire severity (e.g., Pollet and Omi 2002, Prichard and Kennedy 2014, Prichard et al. 2020), but across a wide range of sites, thin and prescribed burn treatments are most effective at reducing fire severity (see reviews by Fulé et al. 2012, Martinson and Omi 2013, Kalies and Yocom Kent 2016).

 

When we talk about “prescribed fires” , pile burning is not the image that springs to mind of  “prescribed fire”.  Even though it is prescribed fire..  When I looked around for a definition of all the kinds of prescribed fire, I thought this was a pretty good explanation from the BLM. And pile burning is not as complicated to plan and execute as other kinds.  Fuels folks across the west have been doing it for years.

I find this discussion a little more confusing than it needs to be.

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Kelly Andersson of Wildfire Today had a piece today on this..

Opponents of thinning and other fuels treatment methods really need to take a look at the history of Lick Creek in Montana. The Lick Creek Demonstration – Research Forest studies were established back in 1991 in western Montana to evaluate tradeoffs among alternative cutting and burning strategies aimed at reducing fuels and moderating forest fire behavior while restoring historical stand structures and species compositions.

Lick Creek Montana fuels projects

Firefighters and numerous studies over many years credit intensive forest thinning projects with helping save communities like those recently threatened near Lake Tahoe in California and Nevada, but dissent from some environmental advocacy groups still roils the scientific/environmental community. An Associated Press story out of Sacramento in October of 2021 noted that environmental advocates say data from recent gigantic wildfires support their long-running assertion that efforts to slow wildfires have instead accelerated their spread. “Not only did tens of thousands of acres of recent thinning, fuel breaks, and other forest management fail to stop or slow the fire’s rapid spread, but … the fire often moved fastest through such areas,” Los Padres ForestWatch, a California-based nonprofit, said in an analysis joined by the John Muir Project and Wild Heritage advocacy groups.

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It sounds like some groups say.. (1) thinning with burning doesn’t work (as the above statement in the AP story)

others (2) thinning plus mechanical removal doesn’t work without burning the smaller material left over, but that depends on site-specific conditions.

I ran across this paper by Cram et al. from NM and Arizona that said, for example,  increasing surface fuels may have advantages in terms of suppression tactics.

Furthermore, when forest canopies are opened up via mechanical means, fine understory fuels can be expected to increase. The silver lining in increased fine surface fuels is the improved potential and efficiency to use back-burns ahead of a wildland-head fire, not to mention a key ecological role in the symbiotic relationship between fire and pine forests. Backfires burning through fine surface fuels are more effective and efficient in burning out understory fuels as compared to a closed canopy forest with a deep, but compacted, litter understory. Estimates of fireline intensity indicated that hand and dozer lines would have been effective containment techniques in treated stand.

IMHO this topic could really use some reporting by interviewing fuels and suppression folks and dig into the specifics of their experiences in different parts of the country. Quoting the usual academic and interest suspects is not adding much value.

23 thoughts on “Does Thinning Work for Wildfire Prevention? High Country News Weighs In”

  1. When I read this story a week or so ago, I knew there would be a lot of generalizations throughout after reading the first paragraph, which lumped all western forests into the same box. I don’t know how many times I’ve had to explain to people that what they read about the AZ ponderosa pine fire regime doesn’t apply to our subalpine spruce-fir forests or even our ponderosa pine forests on the east side of the San Juan Mountains of Colorado. The story was written with a broad brush.

    Reply
  2. Some people will only tolerate non-commercial thinning. Some people think thinning should include large trees (over 30″ dbh). Many people don’t know that a ‘commercial log’ is 10″ on the large end, 7″ at the top and at least 10.5 feet long (depending upon Regional standards).

    Both extremes use their semantics to further their agendas. “Thinning from below” is a common form of thinning, and the term should always be used when describing projects that follow that style. (And, yes, “Thinning from below” can include large trees growing under larger trees.)

    Reply
  3. Thinning is one of my favorite subjects because it’s so misunderstood by a very few loud people.
    The tragedy is that those misunderstandees pass themselves off as authorities on the matter when they have no experience with working in the woods or applying the practices. Especially when their agenda won’t allow them to accept proven practices.
    I like how this article starts off with “pet peeves include redefining English words and making up abstractions”. That’s exactly what happens with “thinning”.
    Thinning in its purist form is removing a percentage of trees(could be anywhere from 1% to 50% or more depending on the stand and forest type) from a given stand as opposed to clearing the whole stand whether you sell the trees or not. Some so called thinning projects put out by large timber companies come way too close to a clearcut to still be called thinning. One must understand that many timber industry folks don’t consider thinning to be logging even though you can make $10k per acre and more from a thinning project that barely scratches the tree density per acre. In fact many folks across the nation think of clearcuts when you talk about timber harvesting.
    It is true that thinning opens up the canopy thereby increasing light to the forest floor. This in turn increases surface fuels such as grass and shrubs. These kinds of plants end up being what is called 1 and 10 hour fuels. 1 and 10 hours fuels are often called “flash” fuels due to the way they burn in low humidity. Hence, the fire will spread. This is exactly why thinning(whether forest products are sold or not) and prescribed fire should be combined. In fact many(myself included) are advocating for this on the timber harvest side of things.
    It’s important to understand the 3 general types of fuels.
    1. Surface Fuels = Fuels that are on the ground. Includes fallen branches, grass, duff, twigs, small/short shrubs, downed logs laying on the ground, etc. Surface fuel flame lengths can grow to 10 feet and more with higher wind speeds.
    2. Ladder Fuels = Fuels that can take flames from ground level to the canopy. Includes tall grasses, tall shrubs, live and dead understory and midstory trees, snags of any size, dead and live branches growing on the sides of canopy trees, downed logs propped up against standing trees, etc. Ladder fuel flame lengths can grow to 50 feet and more with higher wind speeds due to the fact that there is more oxygen surrounding the fuel than on the ground.
    3. Crown Fuels = the upper portions of the trees that make up the bulk of the canopy. Includes dead and live branches in the forest canopy, snags, etc. Crown Fuels can also reach up to 50 feet and more with higher winds for the same reasons as Ladder Fuels
    All three fuels when combined together can create flame lengths of hundreds of feet. The more fuel underneath, the more heat, which can create it’s own wind, which increases flame length.
    >>note: the above categorization of fuels is a simplification often used by Forest Managers when writing fuel reduction prescriptions. Many Fire Mangers don’t differentiate between ladder fuels and crown fuels, instead they use the term Canopy Fuels and address the need to remove lower canopy fuels and remove continuity between Surface Fuels and Canopy Fuels.
    Thinning is an important tool when addressing long term forest survival. All of the catastrophic fires(catastrophic being a fire that completely destroys most or all the trees from dirt to sky. i.e. stand replacing fires) that have taken place in the forest setting are a result of tree densities being too high. Removing Ladder Fuels helps. However, Surface Fuels can be blown into Crown/Canopy Fuels and will spread other trees if trees are too close. Hence the need for breaking up the canopy with Thinning. Forest stands that survive large wildfires with most of the trees still living have a lower density than the forest stands that have a high density.
    It’s important to understand what fire did historically when talking about whether or not we should thin the forest. Some people still say that thinning doesn’t work. That tells me that don’t understand their forest science. The fact of the matter is historic fire regimes kept the forest regularly thinned. Knowing this to be true. Why can’t we use thinning(forest products removed or not) to mimic what historic fires did and use prescribed fire to manage the fuels afterward. We use wood. Wood is the least destructive resource that we use for our building needs. And it’s the nicest feeling. Living in a concrete shell sucks and it’s made from limited resources. Wood is unlimited if we care for the forest properly by not cutting too much and not letting it all burn up because we refuse to care for it properly.
    Most forests across the Earth have fire regimes. Some are lower intensity and some are higher intensity. Even the lush Olympic Forests in WA and the Redwood Forests of CA had fire regimes.
    The intensity will only increase as the climate continues to warm. Even higher elevation areas such as in the high Rockies and Cascades will experience more frequency of higher intensity fires. This is all the more reason to be proactive with our stewardship practices.
    Thanks for reading through.

    Reply
  4. Can someone explain why the Forest Service always makes a distinction between commercial and noncommercial thinning? I’ll opine that objections to vegetation management are often tied to the fact that removing larger material has greater impacts (wildlife, soils, aesthetics). Whether money can be made is also related to the size of the material, but labeling it as “commercial” or not is a distraction.

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    • A distraction from what? it seems like a useful distinction to make to me. And to FS folks and buyers of the stuff. We don’t really have a word that describes “what portion of what trees of what species and size are taken out in what spatial configuration?” which might be more relevant. Also “how is the material removed?” which would have impacts on soil. I’m not sure that “removing larger material” has an impact on aesthetics.. in some places larger is still not large enough to be commercial. In other places, smaller stuff can be commercial.

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    • Commercial thinning is usually more intensive — requires large equipment and roads to move and haul logs. Noncommercial thinning can be done by crews with chainsaws, but sometimes machines are used. Anyhow, noncommercial thinning is usually much lighter on the land.

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      • My point is just that “lighter on the land” is more important to the noneconomic objections to vegetation management, and using economic language to describe it makes it harder to focus on the real issues.

        An even more important distinction that gets lost in the term “thinning” might be the amount of overstory removal involved (as in “thinning” large, shade-tolerant trees on dry sites).

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        • In the PNW and the Sierras, overstory removal — cutting large, shade-tolerant trees on dry sites — or on moist sires — is rare, these days. Some enviro groups would like folks to believe otherwise.

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          • Overstory removal is not the same as thinning. In the PNW that term is often used to some logging practices on federal land in the 1960s and 1970s that high-graded old-growth stands or that reflected the final removal of a shelterwood or seed tree harvest.

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        • Jon,
          Good about “lighter on the land”.

          And you’re absolutely right about the distinction that gets lost in the term thinning.
          Thinning is a prescription and requires supporting specification.
          If you were to tell a forest operator that we’re going to thin a particular stand he/she would ask what are the Specs.
          It would be like telling a surgeon we’re doing surgery without telling them what they’re going there for.
          For communication with the public, the media often believes that the public needs it in simple terms which mostly true. But for something so scrutinized as forest management, I think it’s time we some details in an attempt at public education is included in media messaging.
          Thanks for being part of the conversation

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    • Commercial vs Non-Commercial is easy.
      It has to do with whether or not the treatment being used has will produce forest products that can be sold on a commercial market.
      The reason for this language is due to the Forest Service’s original directive it to care for the Forest to create a consistent supply of timber. So the point of reference starts with what can be used as forest products and what can’t.
      Many in the Ecological Forest Management side of things often call it ecological thinning with or without timber harvest because the point of reference starts with stewardship for the sake of all the services a forest provides as opposed to starting with how much timber is available.
      For decades now the USFS has gone more in the way of stewardship as well as timber harvest, but they still use the language of harvest or not.

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      • Joseph, I wonder whether this actually goes back to the “continuous supply of timber” language or is something more pragmatic. For example, commercial vs. personal use firewood. We don’t think of firewood as “timber” (or do we?) and yet we make that distinction. Or commercial special forest products vs. personal use.
        Forest Products Permits
        Non-timber forest products, or special forest products, include foods such as plants, wild edible mushrooms, fruits and nuts; medicinal plants and fungi; floral greenery and horticultural stock; fiber, oil resins, and other chemical extracts from plants, lichens, and fungi; as well as fuelwood and small diameter wood used for poles, posts, and carvings.

        Special forest products are a vital part of local and regional economies in the Pacific Northwest and many products hold significant cultural value which represents a long history of ecological knowledge and local use.

        Personal and Commercial Use permits are required in order to gather many special forest products. Permits may require a fee payment and must be obtained from Forest Service offices. Availability may vary by season and district office.
        https://www.fs.usda.gov/main/r2/passes-permits/forestproducts

        Reply
        • Sharon,
          You bring up some good points. I believe it does go back to the “continuous supply of timber” language. But that’s mostly on the Forest Service side. I think that it’s the human condition to look at the land for what we can get out of it as opposed to what we can do for it.
          For example: PCT(pre-commercial thinning) when implemented without future timber harvest in mind might be called an ecological thinning or a stand enhancement, or even a fuels reduction and provide benefits to the forest, the wildlife and the plants, eve though it looks the same and produces the same results.

          The small products such as the various resources you mentioned I don’t believe are considered commercial because of the scale of extraction.

          I think the main factor is how timber influences such a massive part of our society where as wildcrafted and gathered forest products aren’t used by the vast majority of people. In this country at least. Which I think is a good thing because in areas of South America, Africa and Southeast Asia the non-timber resources are being depleted due to over gathering and hunting by humans.

          I am extremely concerned about the amount of people that attempt to gather non-timber products from the forest. There’s just too many of us. Timber on the other seems to be able to keep up just fine so long as we don’t loose from fire and we enforce better engineering practices in home building. But that’s another topic.
          Back to thinning.
          Thinning can be done to produce a commercial product or not produce any product that leaves the woods.
          Some folks want to advocate for under burning only without thinning but I want to stress that will only work in few places. And besides, we use wood products. Why can’t we thin and then burn? We can do it while keeping Ecological priorities at the forefront.

          Reply
  5. One more perspective in the thinning/logging language mix.

    Thinning is a silvicultural term. Most practitioners recognize a spectrum of tree cutting intensity ranging from single-tree selection to complete clearcutting. Thinning occupies some area within that spectrum, particularly when the intent of the treatment is to reduce stand density for some desired effect on the residual trees.

    Logging is an operational term. It refers to moving logs out of the woods, usually to a manufacturing facility. It can have a broad meaning (everything involved in getting standing trees to the mill gate) or a narrow meaning (moving a fallen tree – possibly already bucked and limbed – to a landing/log deck). So you could says something like, “The steps of logging [broad sense] are falling, logging [narrow sense], processing, and trucking.” You could replace the narrow sense with yarding or skidding, but in practice all the loggers I know just call it logging.

    Sometimes when we thin, we log some of the thinned trees to reduce the amount of material left in the woods and to utilize a valuable resource. Sometimes we don’t (drop-and-leave thinning is somewhat common in maturing alder stands in the PNW, for example).

    So I agree – let thinning mean thinning, let commercial mean commercial (not necessarily sawlogs). But also, let logging mean logging.

    Reply
    • That’s helpful, but it wouldn’t be surprising to me if much of the public thought of “logging” as the “falling” part, with a lot less interest in whether the log is removed or can be sold.

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      • For the Colorado Roadless Rule, we used the term “tree cutting” .. so that’s cutting them without regard to moving them, or selling them, or needing roads, or whatever. You can cut them (if small enough) and put them in piles and burn them on site. Or you can drag them to the nearest road or boundary or …
        To us, that seemed to clarify to people what we meant.
        Similarly, falling hazard trees is cutting them, not logging them, when they are gathered into piles and burned. IMHO.

        Reply
      • Another good point Jon.

        From what I can tell many people that have bought into the demonization of loggers believe that loggers just do it because of some nefarious drive to destroy the earth as opposed to logging because We(as a civilization) buy the wood, the demonizers included.

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  6. Something this conversation should touch on, that is often not included in such conversations, is that burning without thinning is also a tool that provides wildfire resilience. An of example of this are untreated portions of wildfires that burn at low intensity and have low and low-moderate severity effects when they burn under moderate fire weather conditions, resulting in effective fuel treatments, reducing canopy bulk density, reducing surface and ladder fuels, and increasing canopy base height. One can also Rx burn areas without pre-treatment when commercial and/or non-commercial is used to create a containment box. Are the results as surgical as a thinning and pile burning? No. Are the results effective? Definitely! In fact, the results are almost indistinguishable from a fire resilience perspective as thin + burn. There are quite a few credible fire scientists that suggest we need to do a lot more burning without thinning to get to forest resilience and it needs to be done at scale: https://www.science.org/doi/10.1126/science.aab2356

    Reply
    • With the Forest Service under the microscope on prescribed burns, the Agency isn’t going to be taking those kinds of risks, anytime soon. If the forest needs thinning for multiple kinds of resilience, then the area can be burned at a later date, with much less risk.

      Reply
  7. Larry,
    USFS and prescribed fire is a good thing to bring up.
    And I say to that:
    The solution is to do the thinning and fuel reductions but grind all the slash on slopes where equipment can access and on steep slopes just pile and hope for the best.
    Because it’s the overstocked/over dense forests that are being decimated, so we need to be proactive. It’s the overstocked/over dense forests that when burned, it burns so hot that it prevents natural regeneration. We want natural regen because we are short on seeds by over 1 billion pounds(according to the BLM in this High Country News article https://www.hcn.org/articles/scientific-research-the-recipe-for-restoring-damaged-lands-is-missing-one-key-ingredient-seeds?utm_source=wcn1&utm_medium=email&utm_campaign=2023-02-17-Newsletter )
    Fire spreads slower across a bed of chips than it does through a forest filled with brush and with trees too close together. And while the slash piles may explode when the surface fire hits, the fire won’t decimate the forest because the thinning was implemented properly(hopefully).
    Thanks for adding your thoughts.

    Reply

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