Combustion of Aboveground Wood from Live Trees in Megafires

Here’s a new open-access publication by Oregon State’s Mark E. Harmon, with Chad T. Hanson and Dominick A. DellaSala. This is interesting and needed research, but the authors’ focus on carbon emissions from burned trees is only one part of the bigger picture. The write that “if logged and removed for biomass energy, much of this carbon could be released relatively quickly.” True, but that would offset fossil CO2 emissions. Likewise, harvesting and processing into lumber and mass timber products would sequester CO2 for many decades or perhaps longer, also potentially offsetting fossil CO2 emissions from the production of non-renewable building materials, such as concrete and steel. IMHO, Hanson and DellaSala have long campaigned against salvage logging, which seems to be their aim here.


Our field-based examination of the amount of live aboveground woody biomass combusted indicated that while rates for small branch segments can be quite high (i.e., 100%), these rates do not translate in to major losses at the stand or landscape level. This is because high combustion rates in smaller structures are countered by other factors as one proceeds from branches to trees to stands, and to landscapes. The end result in the forests we examined is that even very severe fires combust <2% of live aboveground woody biomass on average. Our work as well as that of others [10] suggests that additional field research is needed to determine how wildfires release carbon to the atmosphere in a wide range of forest structures and fire-weather conditions. We suggest that researchers and policy makers avoid using estimators that are not field-based, because they currently appear to overstate the wildfire emissions used in carbon emissions reporting. As such, they have the potential to misdirect climate mitigation policy. The fact that the vast majority of aboveground woody biomass is not combusted raises the question of when fire-killed trees actually release their carbon. If dead trees are allowed to remain in place, the natural decomposition process could take many decades to centuries to release fire-killed carbon [39]. In contrast, if logged and removed for biomass energy, much of this carbon could be released relatively quickly [40]. Therefore, additional research is also needed to determine the degree that post-fire forest management influences the temporal profile of carbon release.

10 thoughts on “Combustion of Aboveground Wood from Live Trees in Megafires”

  1. I would estimate that over 90% of the above-ground wood has been vaporized in the last 32 years, in this view of Yosemite National Park. Here is the Google Maps link to the same area. Be sure to zoom out, to see the scope of the loss of old growth trees. Additionally, parts of the Rim Fire, within Yosemite, are quite ripe for re-burns, right now.,-119.7403723,291m/data=!3m1!1e3?hl=en

    Hanson and company are very careful to ignore the realities of human-caused wildfires, and unintended consequences of their ‘opinions’.

    • Larry, I have seen the same thing on the east side of the Washington Cascades. Most of the carbon stores are not destroyed in the initial fire. It is the reburns 20 to 30 years later that really reduce carbon stores. Long term drought exacerbates the problem by drying out the heavy fuels. The hang time for carbon storage after wild fire is not that long in dry forests.

      • John, I saw a spot in eastern Oregon in which the original burn did not get rid of all the seed trees, so a nice young bunch of seedlings were raising their little heads above the jackstrawed dead trees, and the second burn came and took out the seed trees also. So there’s the seed tree factor of reburns as well as the carbon factor.

  2. This paper raises a couple of questions in my mind.
    First, if an NGO (in this case EarthNow) funds research (or at least two of the authors) and it says on their front page “Environment Now seeks to fully protect California’s national forests from commercial logging.”
    Would we think that researchers funded by them might have a particular axe (so to speak) to grind?

    “However, combustion rates are very low overall at the stand (0.1%–3.2%) and landscape level (0.6%–1.8%), because large trees with low combustion rates comprise the majority of biomass, and high severity fire patches are less than half of the area burned.”

    I think they’re saying “dead trees should be left because they are better for slowly releasing carbon over time.” But it’s not clear to me how thinking about it at the landscape or stand level changes that analysis.

    Of all the problems that people in dry forests have dealing with fire, whether to salvage log or not seems to not be all that important. And also site, landowner, and rationale specific.

    In our area, we remove many dead trees without a commercial market at all, so there’s that also.

    Even the claim that “Therefore, additional research is also needed to determine the degree that post-fire forest management influences the temporal profile of carbon release.” presupposes that
    carbon is the main policy driver for fire management activities, which I don’t think is true.

    Finally, this is an example of research that could really have been improved by co-design and co-production IMHO. What really is the question here? How do the data collected relate to the question?

    • The paper notes:

      C.T.H. and D.A.D. were funded by Environment Now foundation (#2021).

      Conflicts of Interest
      The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

  3. Also, FWIW, the journal Forests uses single-blind peer review. “The process is single-blind for most journals, meaning that the author does not know the identity of the reviewer, but the reviewer knows the identity of the author.”

    In contrast, in the Journal is Forestry, “All scientific articles are evaluated through a double-blind peer review.”

  4. Trees killed in a fire are available fuel in the next fire, so one cannot assume they’ll be there storing carbon for 100 years. But Chad doesn’t like prescribed fire.

    I’d like to see someone actually do a carbon accounting for a timber harvest. How much carbon is used to plan, move equipment to the site, log the site, haul to the mill, run the mill, move the material from the mill to another facility to be processed into something else or be distributed, etc.? The storage of the carbon will depend on the longevity of the product. That would also be interesting to know.

    I don’t think one can claim that storing carbon in wood products is viable without such an accounting.

    • Ben, after many years of observing these studies, I’d say “it depends”. It also depends on where you start and how you factor in things other than carbon concerns.

      If you are talking dimensional lumber for home construction or remodeling, first you’d have to ask “what is the lowest carbon source of material for what I want to do?” Which is a different question than “is the best thing for carbon to not cut trees?”

      Further, there is the question of cost. People talk about a housing crisis in many areas, perhaps people could choose a low carbon material and build with that, but perhaps they couldn’t afford it.

      People have actually done the kinds of analyses you ask for, but not surprisingly the answers depend on the assumptions made. CORRIM is one place that has done LCA for some time. Note the VP is also a prof at OSU.

      I totally get that some people think CORRIM may be biased.. but… who can be judged to be without bias? the only way to get at this would be to have some co-designed co-produced work to get the differences in assumptions and do sensitivity analysis on those assumptions.

      And meanwhile Home Builders is arguing for redoing the Softwood Lumber Agreement and increasing domestic production… so.. perhaps the LCA disagreements are not as closely related to policy as some might think.

    • Similarly, we also need a comprehensive accounting of the “No Action” alternative, including intense and large wildfires, and the complete loss of carbon stocks. Additionally, the missed future carbon sequestration should be easy to add to the losses, after figuring out the soils damages and loss of seed sources.

  5. I think you can also look at the salvage of fire killed trees for wood products as replacing green trees that won’t have to be harvested for wood products. The green trees can then be left growing and actively sequestering carbon. We have harvested fire killed trees and turned them into wood products that should last hundreds of years. This is just common sense to me.
    I have seen fires, then reburns that have pretty much consumed everything and have transformed moist, shaded forests landscapes into much drier and warmer prairies. The lost of the forests is nearly complete and it may take centuries for a forest to return, if ever.
    (Much like Larry’s photo at the top.)


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