Dr. Law: Role of Forest Ecosystems in Climate Change Mitigation

Dr. Beverly Law recently gave a presentation titled, “Role of Forest Ecosystems in Climate Change Mitigation.”   Here’s some information on Dr. Law’s background, education and area of expertise, via  Dr. Law’s website at Oregon State University:

Dr. Beverly Law is Professor of Global Change Forest Science in the College of Forestry, and an Adjunct Professor in the College of Oceanic and Atmospheric Sciences at Oregon State University. She is an Aldo Leopold Leadership Fellow. Her research focuses on the role of forests, woodlands and shrublands in the global carbon cycle. Her approach is interdisciplinary, involving in situ and remote sensing observations, and models to study the effects of climate and climate related disturbances (wildfire), land-use change and management that influence carbon and water cycling across a region over seasons to decades. She currently serves as the Chair of the Global Terrestrial Observing System – Terrestrial Carbon Observations (supported by UNEP, UNESCO, WMO), and on the Science/Technology Committee of the Oregon Global Warming Commission.

You can view a PDF copy of Dr. Law’s presentation right here. Below, the text-only version of Dr. Law’s presentation does a nice job of summarizing the myth and reality regarding “thinning,” bioenergy/biomass and climate.

Role of Forest Ecosystems in Climate Change Mitigation
B.E. Law – Oregon State University, February 23, 2014

Key Points:

Activities that promote carbon storage and accumulation are allowing existing forests to accumulate carbon, and reforestation of lands that once carried forests.

Natural disturbance has little impact on forest carbon stores compared to an intensive harvest regime.

Harvest and thinning do not reduce carbon emissions. Full accounting shows that thinning increases carbon emissions to the atmosphere for at least many decades.

Carbon returns to atmosphere more quickly when removed from forest and put in product chain.

1. Role of forest ecosystems in mitigating climate change – Carbon storage and accumulation

Allowing existing forests to accumulate carbon is likely to have a positive effect on forest carbon in vegetation and soils, and on atmospheric carbon. Wet forests in the PNW and Alaska have some of the highest carbon stocks and productivity in the world. Fires are infrequent in these forests, occurring at intervals of one to many centuries. Old forests store more carbon than young forests. Old forests store as much as 10 times the biomass carbon of young forests (Law et al. 2001, Hudiburg et al. 2009). The low hanging fruit is to allow these forests to continue to store and accumulate carbon.

A key objective is to reduce GHG emissions. Changes in management should consider the current forest carbon sink and losses in the product chain when evaluating management options.

2. Role of natural disturbance in forest carbon budgets
Natural disturbance from fire and insects has little impact on forest carbon and emissions compared with intensive harvest.

Although wildfire smoke looks impressive, less carbon is emitted than previously thought (Campbell et al. 2007). In PNW forests, less than 5% of tree bole carbon combusts in low and high severity fires (Campbell et al. 2007, Meigs et al. 2009). Most of what burns is fine fuels in low and high severity fires, making actual carbon loss much less than one might expect. For example, from 1987-2007, carbon emissions from fire were the equivalent of ~6% of fossil fuel emissions in the Northwest Forest Plan area (Turner et al. 2011). If fire hasn’t significantly reduced total carbon stored in forests, it isn’t going to materially worsen climate change.

In the western states, 5-20% of the burn area has been high severity fire and the remaining burn area has been low and moderate severity (MTBS; www.mtbs.gov). In the PNW, 50-75% of live biomass survived low and moderate severity fires combined, which account for 80% of the burn area (Meigs et al. 2009). Physiology measurements show that current methods used to determine if trees are likely to die post-fire lead to overestimation of mortality and removal of healthy trees (Irvine et al. 2007, Waring data in Oregon District Court summary). Removal of surviving trees from a burned area will reduce carbon storage, and in many cases regeneration.

The release of carbon through decomposition after fire occurs over a period of decades to centuries. About half of carbon produced by fires remains in soil for ~90 years, whereas the other half persists in soil for more than 1,000 years (Singh et al. 2012). Similarly, after insect attack and tree die-off, there isno large change in carbon stocks. Carbon stocks are dominated by soil and wood, and wood in trees that are killed transfers to dead pools that decompose over decades to centuries.

3. How do forest management strategies such as thinning affect carbon budgets on federal lands?

Forest carbon density could be enhanced by decreasing harvest intensity and increasing the intervals between harvests. For example, biomass carbon stocks in Oregon and N California could be theoretically twice as high if they were allowed to continue to accumulate carbon (Hudiburg et al. 2009). Even if current harvest rates were lengthened just 50 years, the biomass stocks could increase by 15%.

Harvest intensity – The Northwest Forest Plan (NWFP) was enacted to conserve species that had been put at risk from extensive harvesting of old forests. Prior to enactment, the public forests were a source of carbon to the atmosphere. Harvest rates were reduced by ~80% on public lands, which led to a large carbon sink (increase in net ecosystem carbon balance, NECB) in the following decades. Direct losses of carbon from fire emissions were generally small relative to harvest (Turner et al. 2011, Krankina et al. 2012).

Thinning forests – Landscape and regional studies show that large-scale thinning to reduce the probability of crown fires and provide biomass for energy production does not reduce carbon emissions under current and future climate conditions (Hudiburg et al. 2011, Hudiburg et al. 2013; Law & Harmon 2011; Mitchell et al. 2009, 2012; Schulze et al. 2012; Mika & Keeton 2012). If implemented, it would result in long-term carbon emission to the atmosphere because many areas that are thinned won’t experience fire during the period of treatment effectiveness (10-20 yrs), and removals from areas that later burn may exceed the carbon ‘saved’ by reducing fire intensity (Law & Harmon 2011; Campbell et al 2012; Rhodes & Baker 2009). Thinning does not necessarily reduce fire occurrence, particularly in extreme weather conditions (drought, wind).

Slow in and fast out – opportunity cost. Today’s harvest is carbon that took decades to centuries to accumulate, and it returns to the atmosphere quickly through bioenergy use. Increased GHG emissions from bioenergy use are primarily due to consumption of the current forest carbon and from long-term reduction of the forest carbon stock that could have been sustained into the future. The general assumption that bioenergy combustion is carbon-neutral is not valid because it ignores emissions due to decreasing standing biomass that can last for centuries.

Bioenergy still puts carbon dioxide in the atmosphere when a key objective is to reduce greenhouse gas emissions. The global warming effect of carbon dioxide in the atmosphere does not depend on its source. Per unit of energy, the amount of carbon dioxide released from biomass combustion is about as high as that of coal and substantially larger than that of oil and natural gas (Haberl et al. 2012).

Summary
Comprehensive assessments are needed to understand the carbon consequences of land use actions, and should include a full accounting of the land-based carbon balance as well as carbon losses through the products chain. In mature forests, harvest for wood product removes ~75% of the wood carbon, and 30-50% of that is lost to the atmosphere in the manufacturing process, including the use of some of that carbon for biomass energy. The remainder ends up back in the atmosphere within ~90-150 years, and there are losses over time, not just at the end of the product use). These loss rates are much higher than that of forests. Full accounting of all carbon benefits, including crown fire risk reduction, storage in long- and short-term wood products, substitution for fossil fuel, and displacement of fossil fuel energy, shows that thinning results in increased atmospheric carbon emissions for at least many decades.

15 Comments

  1. “Natural disturbance has little impact on forest carbon stores compared to an intensive harvest regime.”

    This statement is very dependent on the definitions of “Natural” and “intensive”. I also question the statement based on my Yosemite “Big Meadow Fire” example, which converted a majestic old growth forest into a scabby brushfield, in just 20 years. “Little impact on carbon stores”???

  2. Burning old growth and valleys full of smoke for months don’t add carbon to the atmosphere but burning pellets in your stove does? Or just because you hardly harvest anything it is ok to burn up what you didn’t harvest? Is that how your created a carbon balance?
    I know this looks like well thought out scientific review, but all I see is a policy statement.
    Take statistics from here and there and put them together so you get the answers you want.
    It is my experience from being in the woods that the destruction of forests by fires does have a negative impact on the forests and I think therefore on the atmosphere. Anyone ever mention the difference in ground and air temperatures during the summertime between a burned forests and a green forests?
    I think I could put together a study to show how this study had a negative impact on global warming, by showing the amount of fossil fuels, electricity and paper that were used to create this report as compared to if this study was not created . I could also point out the amount of natural resources that had to be produced and sold to pay the wages of the people who created this report.
    I think many of basic premises of this study are flawed. Created wood products can last hundred of years. Thinning trees can actually add to the amount of carbon stored by the increases in the growth in the remaining trees. I don’t believe that 30 to 50 % of the wood carbon is “lost” to the atmosphere in the processing of trees. Unless there is some kind of invisible carbon that gets release when you cut a tree down?
    I just happen to disagree with Beverly because of my experience and work. I know that a lot of the negative impact of forest fires(and there are negative impacts) could be mitigated by good sound forestry practices. Seems to me that studies like these just add to the do nothing, hands off mentality.

  3. Bev Law is a classic example of the applieds versus theoreticals. Seems all she is interested in is using theory to make sure none of it is actually applied.
    Never mind the carbon bandwagon is grinding to a halt. Never mind that the spotted owls keep declining, which makes it seems that forestry wasn’t the main causal event — yet Bev never even questions that at all.

  4. Matthew

    I add my voice of agreement to those comments above.

    This is the 2nd time that you have drug her out as the goddess of all forest knowledge and seem to consider her PhD insight as superior to all research and experience that disagrees with her. You can disavow the previous statement all that you want but here you are re-posting in spite of the information given you previously which contradicts her. I’ll make a deal with you and we can discuss your post point by point but first you have to comply with Rule #1 – Parts “A” and “B”

    Rule #1: If the author/references of a post/comment has to be contacted outside of the normal post and comment process for NCFP. I will not be contacting them.

    Part A) If anyone seriously wants me to reconsider my initial cursory opinion to the post/comment then I will need to validate the post/comment for the credibility of the references and the statistical reliability of the underlying research and the appropriateness of the conclusions drawn from those studies. In such a case I will require that the person making such a request be invested in the analysis so they will have to use the off NCFP contact info in order to supply me with the the links to the references in the post/comment and the links to any secondary references that I need to question as found in the original post/comment references.

    Part B) Since I have spent much time doing such work in the past to satisfy questions only to have the questioner ignore my replies, I will also require that any such requester commit to a point by point followup discussion in the original post/thread on NCFP of my initial cursory points as well as any new significant issues found during my followup evaluation of the original post/comment.

  5. I am disappointed to see how eager some people are to dismiss evidence that does not align with their world view, and how “experience in the woods” somehow trumps carefully collected data and scientific methods. These are not indicators of a healthy debate or fruitful dialog.

    It appears that many readers have given up trying to make their mental model of how forests work harmonize with the reality of how forests work. This is revealed by statements like: “Thinning trees can actually add to the amount of carbon stored by the increases in the growth in the remaining trees.”

    In the real world, the studies line up strongly in support of the fact that a unthinned stands have more wood volume and more carbon than thinned stands. For instance:

    Curtis, Robert O.; Marshall, David D. 2009. Levels-of-growing-stock cooperative study in Douglas-fir: report no. 18—Rocky Brook, 1963–2006. Res. Pap. PNW-RP-578. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 91 p. (“In this as in other LOGS installations, the unthinned plots have consistently produced more total volume (CVTS) than any of the thinning treatments.”)

    Talbert and Marshall. 2005. Plantation Productivity in the Douglas-fir Region Under Intensive Silvicultural Practices: Results From Research And Operations. Journal of Forestry. March 2005. pp 65-70 citing Curtis and Marshall. 1997. LOGS: A Pioneering Example of Silvicultural Research in Coastal Douglas-fir. Journal of Forestry 95(7):19-25. (“[T]he data have not supported early expectations of ‘bonus’ volume from thinned stands compared with unthinned. … [T]hinnings that are late or heavy can actually decrease harvest volume considerably.”)

    Clark, J., J. Sessions, O. Krankina, T. Maness. 2011. Impacts of Thinning on Carbon Stores in the PNW: A Plot Level Analysis. College of Forestry, Oregon State University. Corvallis, OR. (After thinning, carbon pools remain lower throughout a 50-year period. Carbon pool estimates for thinned stands remained lower even after accounting for carbon transferred to wood products. )

    Our values clearly differ when it comes to forest ecosystems as well as what constitutes an honest debate.

    We are never going to agree on forest policy if we can’t agree on forest facts.

    • Now, if you don’t exclude harvested (and sequestered) carbon, do unthinned forests still lock up more carbon? Sure, it is easy to say that the harvested wood is “lost carbon storage” but, I think that carbon is still locked up and being “stored” in wood products. That is a fact. Ironically, when forests burn, that carbon goes directly to our atmosphere, for the most part. Eventually, the dead trees return all of their carbon back to our atmosphere, sometimes in the form of more powerful GHG’s.

      You cannot isolate impacts and benefits. We must total up those impacts and benefits, applied to site-specific realities, to decide which treatments for which lands are best, for all of us.

    • 2nd Law – I too am disappointed.

      1) Re: “I am disappointed to see how eager some people are to dismiss evidence that does not align with their world view, and how “experience in the woods” somehow trumps carefully collected data and scientific methods.”
      a) –> Isn’t that exactly what you have done in the past and are still doing in spite of my consistent appeals, since joining this group, to have point by point discussions.
      b) –> Why do you deliberately ignore the science that supports “experience in the woods” – You seem to be setting up a straw man here by claiming that your views are supported by science and experience in the woods isn’t. Science supports sound forest management but where science doesn’t exist for odd ball situations, it takes on the ground experience to say that science fits except for in this one detail. There just aren’t enough researchers or researcher dollars to cover every possible condition that pops up in the field.
      – we can have a point by point facts based discussion of this anytime that you want but you are going to have to be willing to invest your time in such a scientific discussion.

      2) Re: “In the real world, the studies line up strongly in support of the fact that a unthinned stands have more wood volume and more carbon than thinned stands”
      a) –> You are correct, EXCEPT for unusual planting spacings and dying or overly dense stands, every study will agree with you. BUT, considering greatly over mature dying stands, with no oncoming regeneration, whose carbon storage is declining, there are cases where your statement is wrong. In addition, as our national forests continue to age without a succession of younger stands to replace them and as the vigor of the stands deteriorate with increasingly overly dense stands and the propensity for catastrophic loss increases, the case you make becomes more and more unlikely.
      b) –> But you have constructed a straw man by saying that Bob S said something that he didn’t say. What he said, as you quoted, is that “Thinning trees can actually add to the amount of carbon stored by the increases in the growth in the remaining trees” Read it again – “stored” includes stored in product, not just stored standing in the forest as you have implied. Again his statement is increasingly probable as the proportion of the forest in extremely over mature and overly dense stands increases the probability of catastrophic loss.
      – we can have a point by point facts based discussion of this anytime that you want but you are going to have to be willing to invest your time in such a scientific discussion.

      3) Re: “Our values clearly differ when it comes to forest ecosystems as well as what constitutes an honest debate.
      We are never going to agree on forest policy if we can’t agree on forest facts.”
      –> AGREE 100% and with further discussion we might be able to agree on my point 2-a above fairly quickly. But “we can’t agree on forest facts” if we only deal in meaningless generalities and one size fits all statements that need to be qualified before policy decisions are made. We can only have an honest debate and have some hope of coming to some agreement if we take the time to discuss each point and sub-point of difference in a scientific manner that starts with the most basic/fundamental principles and considers them on a narrow, detailed point by counter point basis. The discussion must begin with the underlying scientific principles that all other conclusions must be logically consistent with.
      – I’m ready when you are but you are going to have to be willing to invest your time in such a scientific discussion.

    • I still think if you thin the forests the remaining trees do grow bigger and faster than when the trees are crowded together. They also seem healthier. I mean eventually the forests will thin itself out. I have see this time and time again. I also know that a large tree has many times the volume of smaller trees.
      Maybe they used this study to show that it makes no sense to thin the forests but just to clear cut them?
      Please remember we can have different opinions and still try and have a conversation, and that “facts” can be put together in many different ways.

  6. I would agree with 2ndLaw’s general point (as I interpret it) that if we claim an interest in science-based forest management, but then cherry-pick which science to listen to, it isn’t a constructive approach. I’m not an arbiter of “sound science” vs “agenda science”, and I doubt anyone else here is either, so phrases like “goddess of all forest knowledge” merely sound petulant. One bottom line is that Bev Law has the credentials to have a voice that’s listened to, in the big picture of forest management & climate change, and whining about her won’t earn anyone here a seat at that table. I doubt that Bev Law spends much of her day complaining about people’s posts on NCFP. But she probably does have to consider reputable evidence and theories that contradict her own, and it would be nice to see some of those posted here as a counterpoint to her position, rather than just somebody’s gut feeling that she must be all wrong for some anecdotal reason.

    I think Larry’s last point about totaling up impacts and benefits on a more site-specific basis is a very good one. And, about exploring the numbers behind carbon sequestered in wood products, and for how long, vs carbon dioxide evolved through decomposition and released by combustion events (planned or natural). I think we may have seen a few carbon LCA studies referred to here, but it seems like the jury is still out on that. I can understand the logic behind a statement like “Thinning trees can actually add to the amount of carbon stored by the increases in the growth in the remaining trees,” and appreciate 2ndLaw’s citations suggesting otherwise. I can also imagine that there might be specific scenarios where that statement would be true (thinning a decadent hardwood stand back East? Something like that?) It would be great to see some other forest science either supporting or opposing that idea.

    • “so phrases like “goddess of all forest knowledge” merely sound petulant.”

      “Petulant”….Yes. But I also thought that Gil’s statement sounded a bit sexist as well.

      And while we are on the subject, Gil wrote:

      This is the 2nd time that you have drug her out as the goddess of all forest knowledge and seem to consider her PhD insight as superior to all research and experience that disagrees with her.

      As a simple matter of fact, is there anything I wrote above in this original post that comes close to backing up Gil’s allegation? Fact is, 98% of the words in my original post are taken directly from Dr. Law’s presentation and/or Dr. Law’s official website at Oregon State University’s College of Forestry.

      The only sentences I wrote myself were these:

      Dr. Beverly Law recently gave a presentation titled, “Role of Forest Ecosystems in Climate Change Mitigation.” Here’s some information on Dr. Law’s background, education and area of expertise, via Dr. Law’s website at Oregon State University….You can view a PDF copy of Dr. Law’s presentation right here. Below, the text-only version of Dr. Law’s presentation does a nice job of summarizing the myth and reality regarding “thinning,” bioenergy/biomass and climate.

    • There IS great value in adjusting stand densities to match annual precipitations. Even budgeting a little “water buffer” would ensure maximum growth and carbon sequestration. Putting growth into long-lived forests seems like the best thing to do, in areas where management is feasible and economical. Some areas do need management but, the benefits might not outweigh the impacts. Those areas should be low on the list, or written off as “whatever happens”. Like it, or not, we will lose important forests to catastrophic wildfires. We should be maximizing this form of restoration, especially in areas that are overstocked, subject to drought and choked with fuels, both live and dead.

      • Larry

        Agree – there just is no such thing as a one size fits all solution. Tailored solutions require clear cut objectives that are not self defeating nor replete with objective components or laws that require contradictory prescriptions to achieve multiple objectives.

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