“Operational resilience” in western US forests

Here’s a new paper that will no doubt be controversial: “Operational resilience in western US frequent-fire forests.” The full text is here. Sounds innocuous, but a Bloomberg article about the paper summarizes: “To Save Western U.S. Forests, Cut Them Way Back, Study Suggests.” This may sound radical, but the consequences of not doing this are clear, according to the authors including some well-known researchers: Malcolm P. North, Ryan E. Tompkins, Alexis A. Bernal Brandon M. Collins, Scott L. Stephens, and Robert A. York:

“The first two decades of the new century have demonstrated that disturbance complexes including drought, insect epidemics, and landscape-level, high-severity fire will be stressing and in some places, type converting dry, western U.S. conifer forests.”

USFS forest planners ought to take this into account when looking at desired future conditions.


With the increasing frequency and severity of altered disturbance regimes in dry, western U.S. forests, treatments promoting resilience have become a management objective but have been difficult to define or operationalize. Many reconstruction studies of these forests when they had active fire regimes have documented very low tree densities before the onset of fire suppression. Building on ecological theory and recent studies, we suggest that this historic forest structure promoted resilience by minimizing competition which in turn supported vigorous tree growth. To assess these historic conditions for management practices, we calculated a widely-used measure of competition, relative stand density index (SDI), for two extensive historical datasets and compared those to contemporary forest conditions. Between 1911 and 2011, tree densities on average increased by six to seven fold while average tree size was reduced by 50%. Relative SDI for historical forests was 23–28% of maximum, in the ranges considered ‘free of’ (<25%) to ‘low’ competition (25–34%). In contrast, most (82–95%) contemporary stands were in the range of ‘full competition’ (35–59%) or ‘imminent mortality’ (≥60%). Historical relative SDI values suggest that treatments for restoring forest resilience may need to be much more intensive then the current focus on fuels reduction. With the contemporary increase in compounding stresses such as drought, bark beetles, and high-severity wildfire, resilience in frequent-fire forests may hinge on creating stands with significantly lower densities and minimal competition. Current management practices often prescribe conditions that maintain full competition to guide development of desired forest conditions. Creating stands largely free of competition would require a fundamental rethinking of how frequent-fire forests can be managed for resilience.


43 thoughts on ““Operational resilience” in western US forests”

    • True. There are huge swaths of dry forest. According to the USFS, Ponderosa pine ecosystems occupy about 38 million acres across 14 states.

      Resilience in moist forests also must be addressed.

      • What percentage of the forested acres of the Western U.S. is ponderosa pine ecosystems? In Montana, for example, that type of ecosystems is only about 3% of the entire forested acres. Also, what percentage of ponderosa pine ecosystems have been logged, grazed, criss-crossed with roads, and/or otherwise developed and degraded? My guess it the percentage is much closer to 100% than 50%.

    • The majority of western forests can be considered to be ‘dry’, based on how much precipitation they get during the dry part of the year. What also should be considered is the density of trees in a given stand. We all know that having more trees per acre, compared to the annual precipitation levels causes drier soils. It also makes those stands hypersensitive to drought years. One of the pillars to my restoration ideas is to match the trees per acre to the annual precipitation levels. Is there REALLY any forest benefit to having more trees per acre than the current weather can support?

      Some of the forests I saw in Montana were truly “mixed conifer”. Those forests were full of flammable species. So much that if you took out all those flammable species, there wouldn’t be much forest left. I certainly would not consider those kinds of forests to be “wet”. I tend to think that those forests are mostly dry, during the summer months. With aspect being an important factor of what kind of forest is growing there, plans need to be site specific, unit by unit.

      Thinning projects CAN help, but it takes a keen eye to see where the stand changes, as well as the prescription. “One Size” doesn’t fit all, especially on the Bitterroot.

  1. So… I see this as a bit of a communication science to journalism problem… a very common problem. The title of the paper is “frequent-fire forests” but Bloomberg said “western forests” still if you read further…

    “A new study proposes a radical prescription for the ailing health of dry U.S. Western forests: cutting back trees by as much as 80%.

    The study suggests that forests in the Sierra Nevada and nearby ranges”

    I see Matthew’s point… research in the Sierra applies no more to “western forests” than research on the west side of Oregon applies to the Sierra..

    Anyway back to our question of how much ponderosa pine? Here’s what Graham and Jain said here..https://www.fs.fed.us/psw/publications/documents/psw_gtr198/psw_gtr198_a.pdf

    “Ponderosa pine is the principle species on over 11 million ha (27 million ac.)
    and for every 2.8 ha (7 ac.) it dominates, it is present on an additional 1.4 ha (3.5 ac.).
    Within the western United States, California alone contains the greatest
    concentrations of ponderosa pine (2.07 million ha (5 million ac.) closely followed by
    Oregon with 1.9 million ha (4.7 million ac.) and, when combined, Arizona and New
    Mexico contain an additional 2.5 million ha (6 million ac.) of ponderosa pine (Van
    Hooser and Keegan 1988). ”

    Nevertheless, what the study says is that historically stands were much less dense, and (I’ve also heard) much less dense than people want to see them today. They’ve been saying this for a while.

    • A study of forests in the Sierra Nevada and nearby ranges is applicable to dry forests throughout the west, and even to moist forests to some extent.

      • Well, I don’t know that. That’s a problem with using historic records and using HRV as a target not as information. It could be that Native American burning patterns were different there. The soils and climate are different there from other places.

        To know that these historic results apply it seems to me that you would have to look at the stand history of other areas.

  2. New Mexico has been home to much larger aspen communities in the fairly recent past. Because it reproduces clonally underground from adult trees aspen (Populus tremuloides) is one of the first plants to reestablish after fire.

    Ponderosa pine sucks billions of gallons from aquifer recharges, needles absorb heat and accelerate snow melt while aspen leaves reflect sunlight in the summer months and hold snowpacks in winter. Insects like the mountain pine beetle and spruce bud worm can help promote drought- and fire-tolerant species like aspen.

  3. Lodgepole pine and Douglas Fir have been extirpated from the Black Hills for nearly a century: the oldest aspen was virtually logged out during European settlement; yet, tiny stands of old-growth ponderosa pine can still be found in the Hills.

    Ponderosa pine contains a much higher level of volatile organic compounds (VOCs) than many other cone-bearing trees and tends to be more explosive in wildfire conditions especially when under drought stress. Beetle-affected trees are pockmarked with ‘pitchouts’ that burst into flames during wildfires and torch more readily.

    • Sooooo, you’re implying that the pines have to be removed?!?! And that dead and dying pines should be harvested?? That doesn’t seem like a solution to anything. In the Sierra Nevada, incense cedar is extremely flammable, with the green foliage always ready to burn. The ladder fuels on cedar are also quite ready to burn. White fir is also extremely flammable, especially in the understory.

  4. University of Montana entomologist, Diana Six has been studying the relationship of forests, fungi and bark beetles for decades. Her work outlines how insects are clearing clogged watersheds being decoupled by the Anthropocene.

    Global warming has been accelerating since humans began setting fires to clear habitat, as a weapon or just for amusement. Evidence that we humans have eaten or burned ourselves out of habitats creating catastrophes behind us is strewn throughout the North American continent. European settlement and the Industrial Revolution in the New World took hardwoods for charcoal then humans allowed fast-growing conifers to replace lost forests. Desertification driven by agricultural practices, overgrazing, concentrated animal feeding operations (CAFOs) and urban sprawl have turned much of the United States into scorched earth.

    The Rocky Mountain Complex and the Black Hills have been home to a much larger aspen community in the fairly recent past. Ponderosa pine sucks billions of gallons from aquifer recharges, pine needles absorb heat and accelerate snow melt. Clear that second growth pine, conduct fuel treatments, restore aspen and other native hardwoods, build wildlife corridors and approximate Pleistocene rewilding using bison and cervids.

  5. Good discussion. But questions like this can only be answered by doing a “complete” C budget, specific to the ecosystem type, and to multiple climate-change scenarios. By “complete” I mean including the full life-span analysis of the C in the ecosystem AND of the C removed from the ecosystem as “products”. More than any other person who’s work I’m aware of, Bev Law’s career has centered around doing just that. Correct me if I’m over-simplifying but my take away from the work of her group and colleagues is that, from the POV of minimizing C release to the atmosphere, it’s usually better to leave the stand alone, even if it burns, than to “harvest’ it. But maybe that’s no longer true as we see increasing tendency of wildland burns to spread to urban areas where house-to-house spread causes substantial release of C (and other gases, including toxics) to the atmosphere.

    • Phil… I think that there are (at least) two things going on here. 1. We never manage land only for carbon, it’s one of many things (that’s why you’re thinking human health is another consideration). 2. Both things can’t be true a) with climate change trees will die or burn up and b) if we leave them alone they will go on sequestering carbon.

      The fact is that we don’t know whether a or b is closer to the truth. Using the info we have now to make decisions is not a scientific question, because scientists don’t know any more than the rest of us about a) what’s going to happen nor b) the resilience of forest trees to those stressors.

      • “scientists don’t know any more than the rest of us about a) what’s going to happen nor b) the resilience of forest trees to those stressors.” So what is the point of scientists?

        • Scientists know quite a bit that is useful. They are are often experts who know more than the rest of us about what is or what was. They can also tell us, based on that, what factors are likely to influence what will be. For example, if you asked “what will be the number of black bears expected in Colorado in 2050?” A wildlife bio might say… it depends on .. habitat, both development and climate change, managing hunting and human interactions, (are there diseases on the horizon?) and so on. They could go on to say…

          If you assume x% more housing development then y,
          If you assume … and so on.

          So scientists know something about what is and what isn’t, something about what was and what wasn’t, but not as much about what will be. The reason I think that wildlife bios, forest plant folks, and economists tend to be so clear about uncertainties is that experience breeds humility. People are continually modeling what they think will happen to animals and plants.. and the animals and plants behave differently. As do markets. And viruses.
          Or maybe humble people go into those fields?

          • The fact that scientists know less about the future than they do about the past and present does not convince me that they “don’t know any more than the rest of us” about the future (in their field of expertise).

            • I think it’s a question of how important to the answer the unknowns are, compared to the things we know. So I am a plant geneticist. I could say that based on what I know, ponderosa pines are pretty good at evolving to different climates. That’s an expert judgment, based on their track record in the past.

              But I don’t know for sure if they will adapt to changes due to climate change. Climate change folks say there might be tipping points and all that- but let’s face it, they don’t know either.
              So we do know something, but we don’t know what the future will hold. Because our knowledge is contingent on current and past experiences, and the future might not be like that at all.
              I think that’s the difference between “knowing what will happen in the future and what conditions will be then” versus “knowing how our organisms or systems might respond to those as yet unknown conditions.”
              I also think that there are more predictable and less predictable systems, and it’s easier to predict next year than in 50 years. But climate/geological/hydrological/ecological systems at the “will these trees die and how about those furry creatures?” level are to my mind eminently less predictable. So that’s what I meant, in less predictable systems, over longer timeframes, the utility of expert knowledge based on current and past experience attenuates.. to 0 at some point.

              • Some of the big uncertainties of ponderosa pine is their cone crops and their limited seed dispersal. Their fire resilience accounts for their wide distribution. Today, with fire intensities higher, the limits to their resilience has been reached. When their seed sources don’t survive, re-population takes many decades, (and that is without man’s interventions and disturbances).

                Yosemite is an excellent laboratory for fire science that includes human-caused wildfires. That is much more valuable to learn than what happens we we ‘let nature take its course’ (which Yosemite doesn’t accomplish, with all those humans running around).

            • Scientists and practitioners do have projections of future climate — see the post from today about the Climate by Forest tool, which I think is bound to be very useful.

              • The uncertainty of these projections need to be considered – as well as the uncertainty of how forests will react. Look at the relative “surprises” we are already seeing with big leaf maple decline, western red cedar decline, the large tree dieoff in California, etc. There are lots of surprises to come. And most of the changes are often due to extremes, not some average change depicted on the “climate by forest” tool.

  6. Can someone explain what this sentence means: “Current management practices often prescribe conditions that maintain full competition to guide development of desired forest conditions.” For national forests, that should only be true if “full competition” is within the natural range of variation.

    • NRV most often is used to describe forest structure stages, not density. Many of the structure stage rubrics include “open” and “closed” as measures of density. NRV should also include species composition, but it rarely does.

      • With climate change and fires giving more attention to “density,” shouldn’t that be front and center in forest plan desired conditions? Desired conditions for structure stages should (and some do) have associated characteristics like canopy closure, which I suppose represents large/old trees per acre, but why not include that desired outcome directly?

  7. I believe the last 20 years have shown that the FS (and probably other fed agencies) have done little to further the cause of forest carbon beyond minimal efforts to quantify it. Whether for storage or sequestration, carbon is seldom VALUED or used an important decision criterion and/or policy driver, in spite of the fact that carbon is likely NFs most valuable resource, yet never monetized. As I’ve said on occasion, “if you don’t take care of your business, sooner or later someone else will.”

    • Jim, what makes you say that “carbon is the most valuable resource?” If it were isn’t it someone else than the FS’s role to monetize it? (I think there are NGO’s working on this, as well as maybe USDA helping small forest landowners).
      In our part of the country, I’d argue that water quantity and quality is our most valuable resource. At least to the communities down the Colorado who drink it.

      • Value exists independent of anyone’s ability to monetize it. I think everyone agrees that there are many values (often aesthetic or environmental) not captured by “the market.” If the costs of global warming were all quantified and correlated with carbon, then the value of carbon could include those avoided costs.

  8. Sharon, I said “likely” thinking that efforts to put a price tag on carbon vary (eg by Ecosystem Marketplace) but average about $3-6/ton. And “social cost” at about $50/ton. An average US forest holds about 80 tons/ac (https://www2.nau.edu/~gaud/bio226/class/ecosyst/USFScarb.htm). A conservative est of 100 million forested acres in NF estate of 192 mill, means about $400 billion on the low end and about $4 trillion on “social cost” spectrum. That doesn’t include notion of “avoided costs” mentioned by Jon in value of leaving tree carbon in situ. “Willingness to pay” concepts for free env services, like water, would likely elicit moans if we had to suddenly pay for a gallon coming from NF lands, or a ton of carbon when severed from the stump.
    Among my points is that I don’t hear ANY leaders in FS discussing forest carbon analytically, as they do with timber, grazing, recreation.

    • I’m thinking, although I don’t know for sure, if I were an FS leader (from my area) that the greatest threat to tree carbon (and future tree carbon without replanting) are wildfires. And some uncontrolled ones are bad for human safety and health, and wildlife and water. And Congress just gave them a big chunk of money to do something. By doing that (at least here) by default they will be dealing with carbon.

      And again with climate change, the currently mesic forests might burn up also. Take a log in western Oregon, if you leave it, will it sequester or get burned up? We don’t know. And all that (30 years?) of sequestering would go up in.. smoke. So there are many variables such that people can generate numbers, but how meaningful they are is another question.

      But perhaps carbon is different from timber grazing and recreation for legal reasons as they are in MUSYA? If I were in Congress, I’d want the FS to concentrate on what we told them to do.

      • We should also be thinking about the lost opportunities to sequester carbon, post-fire, due to massive tree loss. Depending upon ‘natural regeneration’ to ‘restore’ forests doesn’t seem like a good idea. In many places, it doesn’t really make sense to replant, due to dead, but unburned dry fuels, from the last wildfire. The accounting should reflect those ideas.

      • You do realize that most carbon remains in situ after a fire, don’t you? Most smoke you see is steam. It also remains true that the highest percentage of burned area is still “light” and “moderate” with many remaining live trees, able to readily regenerate young trees naturally, as they’ve done for millennia. I’m not minimizing the consequences of severe fire, but I think the Forest Service should contemplate a mission that includes BOTH a better carbon/climate change future as well as better forest fire mgmt. These are NOT mutually exclusive.

      • What Congress told them to do in MUSYA was:
        ‘‘Multiple use’’ means: The management of all the various renewable surface resources of the national forests so that they are utilized in the combination that will best meet the needs of the American people; …” Carbon is a “renewable surface resource,” and conserving it right now would benefit the American people – and probably for all of the enumerated “outdoor recreation, range, timber, watershed, and wildlife and fish purposes.” (Or are you arguing the Forest Service shouldn’t manage fuels either?)

  9. Here is how a forest scientist described the condition of much of the ponderosa (“yellow”) pine forests of southwest Oregon in the 1890s, as they were transitioning from regular Indian burning practices to regular livestock grazing and related burning practices (Leiberg 1900. Twenty-First Annual Report of the United States Geological Survey, Part V.–Forest Reserves):

    (p. 248) But the open character of the yellow-pine type of forest anywhere in the region examined is due to frequently repeated forest fires more than to any other cause.

    (p. 249) The forest floor in the type is covered with a thin layer of humus consisting entirely of decaying pine needles, or it is entirely bare. The latter condition is very prevalent east of the Cascades, where large areas are annually overrun by fire. But even on the western side of the range, where the humus covering is most conspicuous, it is never more than a fraction of an inch in thickness, just enough to supply the requisite material for the spread of forest fires.

    (p. 268) In other places fires have destroyed a certain percentage of the forest. The damage may vary from 10 to 60 per cent or higher. The destruction has not been all in one place or body. The fire has run through the forest for miles, burning a tree or group of trees here and there.

    — 2022. So much for predictions of the ground fuels, ladder fuels, and crown fires that followed a century later. Also, the effects of airplanes, automobiles, and massive increases of human populations in intervening years that made such predictions impossible for anyone, scientists or others. Even Dick Tracy couldn’t predict iPhones or the Internet, so how could anyone else, no matter the occupation? Predictions are hard, especially those involving the future.

  10. Interesting, I hadn’t noticed big leaf maple decline or red cedar for that matter. Given the chance they still seem to do well here in Western Oregon. Trouble is they don’t get much of a chance with the mono crop of the Douglas Fir plantations. I guess now also not only do we have sudden oak death but potentially the ash borer too.
    One note about Western Red Cedar, is that we are seeing a lot less of what we call wormy red cedar. I have no idea why.
    Of course in my opinion the Forest Services fire policies have caused the most destruction to our federal forest in the last couple of decades.

  11. This point seems to have overlooked in our discussion: “average tree size was reduced by 50%.” So desired conditions should be for bigger trees, and a way to achieve that would be to prohibit logging of the biggest trees.

    • So I think going back to our discussions previously. and I’m thinking Larry and the Blue Mountains folks.. there are big trees and bigger trees. Sometime there is a clump of big and bigger trees. Sometimes you need to take the smaller of the big trees to protect the bigger of the big trees. In so doing you would cut a big tree. So if you prohibit logging of “big” trees you can’t necessarily protect the bigger trees. Does that make sense?

      • Yep, and you’re right Sharon. Also remember that big doesn’t necessarily mean old, and old isn’t necessarily large. Old trees – regardless of size – are ecologically important to retain, protect, and propagate.

        • Many suppressed trees are quite old, compared to their size. Should we protect highly-flammable 125 year old 14″ DBH white firs, growing under bigger pines? I never see the eco-folks screaming for protections of such trees (other than Chad Hanson and company).

          • These are also valid points. I was only responding to the data presented here about “tree size.” If you’ve got data about historic ages or species, then prohibitions could be fine-tuned.

      • But what is the “competition” to be thinned should also be determined based on history. Was regeneration of the early seral species too dense, or have shade-tolerant species been allowed to fill in the spaces? I don’t see the former being likely, so removing those species would not be justified.


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