What Do We Know About Carbon and Wildfires?

One of my ideas for this blog was to be a place where we could share information and learn about topics from others who know more- as well as share alternative framings of an issue.

One topic that recently came up in my office relates to carbon and wildfires. (Yes, the other main topic of interest is the “orderly government shutdown.”)

Is it simply that there is vegetation, and soil, and that ultimately no matter how severe the fire, everything will grow back, the soil will redevelop, and it will be carbon-neutral? Or are there other ways of thinking about this?

In many parts of the country, people like to thin pine trees to either create “historic” conditions, to reduce fuels and change fire behavior (to protect communities), or to decrease stocking so that pines will remain healthy, especially in a potentially warming environment, or all of the above. Many of the carbon discussions seem to be about what happens if you thin trees and either sequester them in various kinds of products, or use them to replace fossil fuels- and how that relates to the carbon you might have released by burning up the stand.

So my question is whether conditions that keep fires from being intense enough to destroy carbon in the soil, are “good” for climate mitigation.

Some of this may relate to timing. Like soil will “grow” back unless something has happened to make that impossible. But if it takes 1000 years, by which time we will have decarbonized our society, should we still count it? Obviously it’s easier to know about replacing trees than replacing soil. Or understanding the damage that fires can do and what it takes to reverse it. Or understanding how changes in climate will affect future development of soils and vegetation.

Here’s one paper I found by Bormann et al. Here’s another one by Hurteau et al.

15 thoughts on “What Do We Know About Carbon and Wildfires?”

  1. Sharon asks an important question:

    my question is whether conditions that keep fires from being intense enough to destroy carbon in the soil, are “good” for climate mitigation.

    Let’s add a few more, whether or not important: How many fires, and on what percent of the burned areas, burn intensively enough to destroy [significant amounts of] carbon in the soil? How can we sort out whether or not significant fire-related soil carbon destruction is a result of fuels-buildup v. climate change — i.e. hotter, dryer conditions than we’ve previously seen? Where does it make sense to even look for active forest management “solutions,” when we factor in costs, needed scale of endeavors, etc.?

    One place where some researchers now suggest we not look/act to find “carbon sequestration” solutions via active forest management is on Westside PNW forests, although they do not rule out Eastside PNW forests. Here’s a snip from an article pointing to an (2009) Ecological Applications paper:

    The lead author was Stephen Mitchell, who conducted the work as part of his doctoral thesis while at OSU, and is now at Duke University. Among the findings:

    – Fuel reduction treatments that have been proposed to reduce wildfire severity also reduce the carbon stored in forests;

    – On west side Cascade Range and Coast Range forests, which are wetter, the catastrophic fire return interval is already very long, and the additional levels of fuel accumulation have not been that unusual;

    – A wide range of fire reduction approaches, such as salvage logging, understory removal, prescribed fire and other techniques, can effectively reduce fire severity if used properly;

    – Such fuel removal almost always reduces carbon storage more than the additional carbon the stand is able to store when made more resistant to wildfire, in part because most of the carbon stored in forest biomass remains unconsumed even by high-severity wildfires;

    – Considerable uncertainty exists in modeling of future fires, and some fuel reduction techniques, especially overstory thinning treatments, could potentially lead to an increase in fire severity.

    The study authors concluded that fuel reduction may still make more sense in east-side Cascade Range and other similar forests, but that the west-side Cascades and Coast Range have little sensitivity to forest fuel reduction treatments – and might be best utilized for their high carbon sequestration capacities.

    • It’s a lot more complex than just considering carbon. What is the carbon footprint of 22 million acres of dead forests? What are the differences in GHG’s when you compare rotting trees versus burning trees? There are also those other extreme wildfire effects to consider, accelerated erosion and losses of endangered species habitats, for example.

      With the abundance of plantations in the Coast Range in Oregon, those lands will continue to need management. We’ve already seen increases in wildfires and intensities in western Oregon, due to mismanagement from both sides. Site-specific science has to rule, due to the diverse landscapes there. It takes a keen eye to see those differences, in places.

  2. I am curious about how much carbon is stored and where in the forest. I would assume that the trees and including roots have the lions share, and duff, down logs and assorted brush, forbs and what not also have carbon, but I wasn’t aware that soil had major amount of carbon, I suppose the organic layers would. Of course I’m used to looking at areas with frequent fires regimes in the Intermountain West, where the organic layers are not all that deep. I’ve also heard that rotting wood and vegetation gives off CO2. And I also know that some of our older stands have mortality exceeding growth due to insects, disease, overcrowding and what not. It may be my Forestry bias coming through, but I’d assume that a forest where growth exceeds mortality would be pulling more CO2 out of the air, while a stand where growth is less that mortality might not be if decomposition of woody biomass gives off CO2. I would tend to assume the more green the more photosynthesis.
    The intensity or severity of the fire does make a difference in the organic layer. Hot fires of longer duration do cook the soil more, and effect it’s nutrients and microbes. But Morel mushrooms do seem to like burn areas. So in a way fire can free up nutrients, like burning dead grass in the spring makes for greener grass in the summer. It’s that red soil that shows up where it burnt hot that losses it’s nutrients.

    • Underneath the true firs, where the organic layer is deeper, is where you find the finest ash, indicative of complete combustion. Water doesn’t penetrate well, at all. The losses of mega-nutrients Carbon and Nitrogen cannot be easily replaced, especially deeper in the soil. Some people discount the levels of carbon stored within forests, because it is part of the above-ground carbon cycle. It’s also a convenient way to ignore forest stewardship and carbon sequestration.

      Here in the Sierra Nevada, Indians knew that burning off the flammable bear clover would allow grasses and deer to come back. They learned the tricks to burning without the dangerous damages. I think that bear clover, long the nemesis of clearcutting, could still play a big beneficial role in accomplishing prescribed fires.

  3. Context is everything. I didn’t give enough context about why the question came up. We are unlikely to change practices solely due to carbon. as others have pointed out.

    So we were discussing the question in a NEPA context. CEQ has had a series of meetings around their guidance for climate change and NEPA this week. Most of the agencies agreed that to us, it is just another environmental impact. If it is raised in scoping, we need to disclose those effects.

    Now it may not seem like the most productive investment for those kinds of vegetation projects we usually do, like fuels treatment projects or thinnings. We could write lovely descriptions of the added resilience of pines because they are thinned and the fascinating scientific debate about different carbon releases based on wildlife predictions under climate change in different soil types. We could plant trees back, when we need to, and mix biochar in with the soil. Many dead tree bodies will be used – and we can be off to the case law coevolutionary races about how much analysis is the right amount.

    Dave said that

    How can we sort out whether or not significant fire-related soil carbon destruction is a result of fuels-buildup v. climate change — i.e. hotter, dryer conditions than we’ve previously seen? Where does it make sense to even look for active forest management “solutions,” when we factor in costs, needed scale of endeavors, etc.?

    I don’t think it really matters how we got here. I agree about looking for active forest management solutions when we have the costs, scale issues, etc. But perhaps a side note is that while mechanical treatments are controversial to some, many people are talking about “restoring fire to the ecosystem” through prescribed burning.

    I have questions about whether that is a strategy we can really afford financially, at least the sum of funding to do it regularly, throughout areas that had frequent fires in the past.

    Of course, that’s a different question than the environmental benefits of writing more NEPA documentation on carbon for vegetation management projects. How many more beaver reintroductions or biomimicry beaver dams could we fund if we exempted an agreed-upon set of common vegetation treatments from analysis of carbon in NEPA?

    • How many more beaver reintroductions or biomimicry beaver dams could we fund if we exempted an agreed-upon set of common vegetation treatments from analysis of carbon in NEPA?

      Here’s the rub: Who are “we”? Too many times in recent past history the Forest Service and/or the Administration, sometimes the Congress, have run off quickly to “categorically exclude” (CE) things from NEPA without adequate vetting of issues, concerns from such CEs. Yes, it would be nice to be able to use money for work on the ground, but such work is supposed to be “agreed upon” work, not just work the Forest Service deems “good”. Remember Gifford Pinchot’s advice:

      National Forests are made for and owned by the people. They should also be managed by the people. The are made, not to give the officers in charge of them a chance to work out theories, but to give the people who use them, and those affected by their use, a chance to work out their own best [interests].

  4. But who gets to “agree on” it? If anyone in the country says “no” does that mean it is not “agreed upon”? That’s a hard standard to meet. I would say most WUI fuel treatment projects have wide support, and I am not talking about a CE for them, I’m talking about a specific exemption from carbon calculations.

    Some would argue that philosophically there are probably people out there that think all public land investments should not be done- as the land should be sold to the highest bidder and we can save all that funding.. so those folks would be against all projects that require government funding.

    How do we give people a “chance to work out their own best interests”; and if they don’t, a decision still needs to be made.

    • Who gets to “agree on” it? If anyone in the country says “no” does that mean it is not “agreed upon”?

      Short answer, no single entity or person gets a veto right, under current law/practice or under any that I would support as an alternative. If we had a working Adaptive Governance process, with “appropriate decision containers” set up at workable scale and scope so that interest groups could collaborate in meaningful ways, then people could grapple with tough issues via thoughtful deliberation, and appropriate governmental entities could make policy calls. The three levels of planning in the 2011 Draft NFMA rule militate against setting up appropriately framed “decision containers.” There are other ways too that the Draft rule militates against appropriately framed decision containers, but I’ll await discussion of these.

      … How do we give people a “chance to work out their own best interests”;

      Under an Adaptive Governance approach, NEPA scoping, including setting up categories for “exclusion” (CEs) could (and maybe would) allow for a much more meaningful “decision containers” and meaningful decisions. Right now categories are set up without what I consider meaningful deliberation, and are sometimes struck down in the courts. So too with more site-specific “calls” as to what fits into any given categorical exclusion. There is, in my opinion, way too much haste and too little collaborative deliberation in setting up categories, as well as too much haste in fitting things into CE containers.

      … and if they don’t [agree on shared interests], a decision still needs to be made.

      Just today I was discussing the “objections process” built into the Draft NFMA rule with a friend. We agreed that under a more inclusive governance process, there would be no need, arguably, for an objections process outside the deliberative process built into the process. Why continue to allow for “appeals,” whether or not “pre-decisional” as a separate “objections process” (Sec. 219.50-59 in Draft NFMA rule)?

      Give me a couple of weeks to put some flesh on my proposed approach, as embedded into a NFMA rule and we can discuss further, and more specifically.

  5. When portions of the public want “Gaia” to save their forests, how can we politely (and officially) ignore their “Fairy Tale”? (Hmmm, seperation of church and state?) You don’t see the FDA and other governmental organizations listening to the extremists who don’t like vaccinations, new medicines and such. You don’t see the public having much control over the military tactical decisions. You don’t see the public being consulted over Federal Highway engineering. Simply put, the public thinks that they know forestry and forests better than the government experts they won’t trust. Even when the process is “open and transparent”, eco-groups won’t trust the Forest Service to follow “the best available science”. They won’t even give the Forest Service a mere chance to earn trust. That doesn’t sound “progressive”, AT ALL.

  6. Sharon mentioned being able to afford the costs of non-commercial treatments. It is a good question that in my opinion is not asked enough. I remember a few years back when a FS specialist told me that economic should not be considered in natural resource decisions. That specialist is now a ranger. It seems like there is an attitude among some groups that making money from the sale of products (mostly timber) off of NF lands is a crime. Other groups don’t want it subsidized and it (the project) should pay for itself. Quite a gap between the groups.
    I’ve been recently involved in a large scale landscape restoration project. It is one of those evolving collaborative projects with the public i.e. interest groups from both sides participating. The project involves commercial thinning, lots of prescribed fire, road decommissioning, and potential bio-mass utilization. When it comes down to the bottom line economics, the timber harvest pays for additional treatment inside harvest units, but not much else. So it will take somewhere over a million dollars to implement the project without any bio-mass utilization which will require additional subsides. So now the local District and the Forest must hunt up funding sources and compete with other projects from other Forests for funding. So if funding is not secured, do they partially implement it? I don’t know but the project level economics does play an important role. Budgets are tight and in all likely hood will become tighter.

  7. Dave- I have been involved in the development of some categorical exclusions, including at least one that have held up in court. Here’s a summary of the decision.

    Colorado Wild v. USFS, No. 05-1265 (D.C. No. 04-M-2472) (D. Colo.) (Upholding Limited Timber Harvest Categorical Exclusion and Shaw Lake Vegetation Management Project). The Tenth Circuit has rejected a challenge to the Forest Service’s adoption of a categorical exclusion for the salvage harvest of dead and dying trees (Limited Timber Harvest (LTH) CE #13) and its application to the Shaw Lake Vegetation Management Project on the Rio Grande National Forest. In a string of holdings rejecting all of appellants’ claims the court held that: (1) the methodology employed by the Forest Service to support the 250 acre limitation in CE #13 was reasonable, (2)authorizing up to one-half mile of temporary road construction as part of the salvage harvest was reasonable in the absence of “extraordinary circumstances, (3) the Forest Service may rely on the “personal observations” of the Interdisciplinary Teams conducting the post-implementation review process as a basis for its findings, (4) establishing a higher acreage limitation for the salvage sale CE than the green sale CE was reasonable, (5) the agency adequately considered comments submitted on the LTH CE #13 proposal concerning the opportunity for public involvement in the decisionmaking process, (6) the Forest Service’s decision to use an acreage limitation was permissible and rational, (7) the plaintiffs could not show that multiple uses of Category 13 may result in cumulatively significant impacts given both the Forest Service’s duties to consider such effects associated with individual projects applying the category and the presumption of good faith implementation due the agency, (8) and finally that the mere fact that the administrative record contains some evidence pointing to a different conclusion does not render the Forest Service’s decision arbitrary and capricious.

    Here’s a link to the responses to public comment on the proposed CEs.

    I do agree with you that national rule-makings don’t have the kind of collaborative groups and discourse eyeball to eyeball that local and state level decisions can have. I know the planning rule folks have tried to do this, but without a formal collaborative group it’s difficult. There is something about working together to craft a solution that is a powerful way to move forward. One difficulty is that national rules tend to involve national groups, who perhaps have less experience with this mode of operating and also who may be influenced by the partisan rhetoric of their hometown.

    Like we used to say Q “how can you tell you’ve been in DC too long?” A. When you begin to believe your own hype.

    Looking forward to your ideas.

  8. Sharon said: “My question is whether conditions that keep fires from being intense enough to destroy carbon in the soil, are “good” for climate mitigation.”

    Even the Chief of the Forest Service recognizes there are trade-offs. “[M]anagement practices, designed to restore ecosystem health, may in the near-term reduce total stored carbon below current levels.” Gail Kimball, March 2009 Testimony before House Committee On Natural Resources, Subcommittee On National Parks, Forests, And Public Lands. http://www.fs.fed.us/fstoday/090320/02National_News/Final_USFS_Testimony.pdf

    In evaluating these trade-offs, the key considerations are: (1) how much carbon is removed from the forest in trying to restore it? (heavier thinning is harder to justify because logging will probably remove more carbon than wildfire would); and (2) how frequent is the real modern-day fire return interval? (Treatments in areas with more frequent fire increases the chances that fuel treatments will interact with fire and provide carbon benefits, while thinning in areas with less frequent wildfire is less likely to modify fire behavior and less likely to offer carbon benefits.) Trying to save carbon from wildfire via logging is confounded by the fact that no one can predict the location, timing or severity of wildfire. If fire could be predicted then thinning could be perfectly timed and located to modify fire effects, but since fire cannot be predicted, thinning must be very widespread and repeated and this results in significant landscape-scale carbon losses. Modelling being done at OSU shows that 10 times (and up to 100 times) more acres will be logged and NOT burn, compared to the number of acres that will be logged AND burn. These latter acres are effectively treated ‘unnecessarily’ but in any sound carbon accounting, the carbon removals from this unnecessary logging must be attributed to efforts toward fire modification. This renders almost all fuel reduction logging carbon-negative.

    Consider the conclusions of Mitchell, Harmon, O’Connell. 2009. Forest fuel reduction alters fire severity and long-term carbon storage in three Pacific Northwest ecosystems. Ecological Applications. 19(3), 2009, pp. 643–655 http://ecoinformatics.oregonstate.edu/new/FuelRedux_FS_CStorage_Revision2.pdf (“ABSTRACT: … Our simulations indicate that fuel reduction treatments in these ecosystems consistently reduced fire severity. However, reducing the fraction by which C is lost in a wildfire requires the removal of a much greater amount of C, since most of the C stored in forest biomass (stem wood, branches, coarse woody debris) remains unconsumed even by high-severity wildfires. For this reason, all of the fuel reduction treatments simulated for the west Cascades and Coast Range ecosystems as well as most of the treatments simulated for the east Cascades resulted in a reduced mean stand C storage. One suggested method of compensating for such losses in C storage is to utilize C harvested in fuel reduction treatments as biofuels. Our analysis indicates that this will not be an effective strategy in the west Cascades and Coast Range over the next 100 years. We suggest that forest management plans aimed solely at ameliorating increases in atmospheric CO2 should forego fuel reduction treatments in these ecosystems, with the possible exception of some east Cascades Ponderosa pine stands with uncharacteristic levels of understory fuel accumulation. Balancing a demand for maximal landscape C storage with the demand for reduced wildfire severity will likely require treatments to be applied strategically throughout the landscape rather than indiscriminately treating all stands.”)

    Note: The only treatment that showed some promise in this study was understory removal (not canopy removal) in fire-suppressed dry pine stands with a frequent fire regime, but the carbon storage benefit from reduced fire severity in this best case scenario was minuscule, only about 0.6-1.2%. The modeled treatments on the eastside of the Cascades failed to include canopy removal which is a common practice in fuel reduction efforts and one that removes more carbon than understory treatments. Also, this analysis might give too much credit to fuel treatments because they excluded climatic variation from the analysis (meaning that in their analysis the treated stands never burned uncharacteristically in spite of the treatments.)

    Similar results were found at the stand scale by Reinhardt and Holsinger (2010): (“We simulated effects of fuel treatments on 140 stands representing seven major habitat type groups of the northern Rocky Mountains using the Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS). Changes in forest carbon due to mechanical fuel treatment (thinning from below to reduce ladder fuels) and prescribed fire were explored, as well as changes in expected fire behavior and effects of subsequent wildfire. Results indicated that fuel treatments decreased fire severity and crown fire occurrence and reduced subsequent wildfire emissions, but did not increase post-wildfire carbon stored on-site. Conversely, untreated stands had greater wildfire emissions but stored more carbon. … The results do not support the use of fuel treatments soley to protect carbon stocks or reduce emissions. Although wildfire emissions were reduced by fuel treatments, the fuel treatments themselves produced emissions, and the untreated stands stored more carbon than the untreated stands even after wildfire.”) [and even considering carbon stored in wood products derived form treated stands.] Reinhardt, Elizabeth, and Lisa Holsinger 2010. Effects of fuel treatments on carbon-disturbance relationships in forests of the northern Rocky Mountains. Forest Ecology and Management 259 (2010) 1427–1435.

    • Yes, we CAN make predictions about wildfires, using past fire occurence to predict future fires. Combining that with stand inventory data, we can predict which individual stands are likely to burn in the next 20 years. For example, on the Stanislaus NF, just west of Yosemite NP, there has been 13 wildfires in the last 100 years, in one area. Of course, during that time, fuel loadings have increased since Indian burning ceased. I think that in some areas it can be assumed that wildfire WILL return in the short term, even with disregarding human-caused ignitions.

      In the end, models provide very limited site-specific conclusions. Remember, catastrophic wildfires extract GHG’s from the soils as well as from the vegetation. What do you think of projects that “thin from below”, and take trees with an average diameter of 14″ dbh? These kinds of projects also do some crown seperation, taking excess unhealthy trees between 20-30″ dbh. This locks up more carbon in wood products, while also allowing the remaining trees to be more vigorous and suck up more CO2, while making forests more healthy and resilient. Unfortunately, there currently is no market in California for the biomass that is piled into house-sized slash piles, burned on the landing. Mobile biomass burners could remedy that situation, reducing the huge transportation costs.

  9. Thanks, Doug, I was really focused on the question of “if you are thinning for fuels reduction (or hazard tree removal) in pine stands (E side or Rockies), what are the climate pros and cons of “pile and burn” vs. “bioenergy” vs. “lumber”.

    As described, the studies may have been designed to answer different questions, especially not on the west side of Oregon, where there are not the classic pine/fire systems.

    So it seems like there might be useful info in the Hurteau and Reinhardt and Holsinger papers. I would be particularly interested in research that compares model assumptions and projections to empirical data (I spent time earlier in my life comparing vegetation model projections to stand measurements).


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