7 ms·

Old-growth forest carbon sinks overestimated

87 points by tokai 6y ago

black_puppydog 6y ago
Am I missing sth? I don't even see an abstract there, yet they want $8.99 for it?
- sampo 6y ago
  It's in the Matters Arising section of volume 591. These are short 1-3 page long contributions, shorter than research articles. And being so short, they don't have an abstract. Table of contents: https://www.nature.com/nature/volumes/591/issues/7851 https://www.nature.com/nature/volumes/591/issues/7851 As of writing this comment, these short papers (this, and the counterargument, right after in the table of contents) don't seem to be in sci-hub. Until someone uploads them to sci-hub, they probably aren't available in the free web.
  - black_puppydog 6y ago
    Thanks for explaining. Didn't know that format. :)
- deleted 6y ago
  [deleted]
richiebful1 6y ago
Here's a non-paywalled summary: https://phys.org/news/2021-03-old-growth-forest-carbon-overestimated.html https://phys.org/news/2021-03-old-growth-forest-carbon-overe...
henearkr 6y ago
There is already a rebuttal: https://www.nature.com/articles/s41586-021-03267-y https://www.nature.com/articles/s41586-021-03267-y The rebuttal too is behind a paywall and doesn't have an abstract...
- sp332 6y ago
  I think the link is to the rebuttal, right? The original paper is from 2008.
  - sampo 6y ago
    2008: Original article [1] 2021: Rebuttal of the 2008 article [2] 2021: same issue of Nature, next 2 pages: Rebuttal of the rebuttal by 6 (out of 8) of the authors of the 2008 article [3] [1] https://www.nature.com/articles/nature07276 https://www.nature.com/articles/nature07276 [2] https://www.nature.com/articles/s41586-021-03266-z https://www.nature.com/articles/s41586-021-03266-z [3] https://www.nature.com/articles/s41586-021-03267-y https://www.nature.com/articles/s41586-021-03267-y
    - fshbbdssbbgdd 6y ago
      I’m curious if these competing rebuttals get to read each other during the editing process. Otherwise will there be two more rebuttals in the next issue?
goodcanadian 6y ago
Some basic conservation of matter arguments apply. As long as a plant is growing, it will sink carbon. When it dies and rots, it will release that carbon again. So, a growing forest will sink carbon, but a steady state one will not. This is why I have always been sceptical of tree planting as a carbon offest . . . it is short term, at best. Of course, there are a myriad of other reasons why tree planting might be desirable. The caveat to the above is the extent to which dead plant matter gets permanently buried (turned into peat or whatever) rather than rotting. Under some conditions, forests really will work as a carbon sink, but it has never been as simple as tree planting == good, and I am glad to see research acknowledging that. As with everything, it is complicated.
- wing-_-nuts 6y ago
  IMHO we need to do everything we can to buy us enough time to innovate our way out of the problem, so yeah, tree planting == good so long as the trees live long enough to do the job.
- dbingham 6y ago
  The matter is conserved: it becomes soil. Most of the carbon an individual plant absorbed when it was growing will become soil when it dies and decays. (Should note "absorbed" here refers to the carbon that became part of the structure of the plant - not the carbon the plant breathed in. Plants breath out most of the carbon they breath in.) Yes, it releases some of it during the decay process, but a lot of it (most of it) does get sequestered even after death. That's where humus comes from. And it's pretty easy to meassure that. And for deciduous trees, they are sequestering yearly as the leaves they drop decay. It wouldn't surprise me if the amount that is being sequestered is being overestimated in many studies, but the mechanism for it happening is pretty clear and that it is happening is pretty incontrovertible - it falls right out of the chemical math - and I would be much more likely to question any study that questioned that than to question that mechanism itself. It's really frustating to me that what is being posted here is basically just a headline and not even an abstract unless you have a subscription to Nature.
  - goodcanadian 6y ago
Kim_Bruning 6y ago
I remember reading about this decades ago. I guess it's still being discussed? Short summary of the theory: Trees are largely made of thin air ;-) : Carbon Dioxide provides the required (C)arbon, water that rains out of the air provides (H)ydrogen and (O)xygen, and (N)itrogen fixated from the air provides the basis for amino acids. This covers about 99% of the chemicals in the woody parts. Young trees want to grow a lot, so they make a lot of lignin and cellulose. These consist of C, H, and O. Once trees have grown tall enough, they tend to slow down, so you'd expect them to not grab as much carbon anymore.
- sp332 6y ago
  It says the original paper was published in 2008, and a reply was published last month.
- bcbrown 6y ago
  > Once trees have grown tall enough, they tend to slow down, so you'd expect them to not grab as much carbon anymore. I don't think that's accurate (or at least not very precise). Studies have shown that when evaluating the metric of annual addition of tree mass per acre in the rainforests of the Pacific Northwest, old-growth forests add as much or more when compared to "young" forests. I don't have any specific sources, but if you want to know more the research by Robert Van Pelt should be a good starting point.
  - hcurtiss 6y ago
    This is definitionally untrue. Forests have a maximum biomass carrying capacity, and they rarely reach that capacity, instead losing carbon to stochastic events like fire. Old growth forests "store" a lot of carbon, but their capacity to sequester is finite. https://www.fs.fed.us/psw/topics/fire_science/ecosystems/carbon.shtml https://www.fs.fed.us/psw/topics/fire_science/ecosystems/car...
    - bcbrown 6y ago
      You're not listening to what I'm saying. I'm not talking about carbon sequestration, I'm refuting the argument that "once trees have grown tall enough, they tend to slow down". Here, I pulled a source for you: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.453.5197&rep=rep1&type=pdf https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.45... > Wood production of the entire main trunk and whole crown both increased with size and age up to and including the largest and oldest trees we measured. This is even supported by your own link: > In the past, some researchers have suggested that converting old forests to young, fast-growing plantations, whose harvested wood products could store carbon for several decades, would create a net increase in long-term carbon stocks. This approach was based on the idea that old forests are slow growing and thus carbon sequestration slows down as forests age. More recent research generally does not support this idea, as a global survey of old forests found that many continue to sequester carbon and have stocks that far exceed young, managed forests.
mturmon 6y ago
There are some debates in the comments involving process-based comparisons, e.g., when carbon release from decay outweighs carbon sinking from plant metabolism. It may be helpful to give this top-level summary from the National Climate Assessment [1]: "Net storage of atmospheric carbon by forests (742 teragrams, or Tg, of CO2 per year from 1990 to 2015) has offset approximately 11% of U.S. CO2 emissions. Assuming no policy intervention – and accounting for land-use change, management, disturbance, and forest aging – U.S. forests are projected to continue to store carbon but at declining rates (35% less than 2013 levels by 2037) as a result of both land use and lower CO2 uptake as forests grow older." [1] https://nca2018.globalchange.gov/chapter/6/ https://nca2018.globalchange.gov/chapter/6/ -> "Forest Carbon Dynamics" The NCA is your best one-stop-shop for the best current synthesis on such questions, unless you're literally publishing in this specific area (in this case, carbon cycle science at decadal timescales).
omegant 6y ago
Genuine question, if old-growth forest do not work as carbon sinks, how all the petroleum we are extracting comes from? Is all from ancient marine environments?
- JamesBarney 6y ago
  The article doesn't say old growth forests don't work as carbon sinks, just that don't work as well as they initially thought.
- cedilla 6y ago
  Petroleum is mostly marine microorganisms. Coal is mostly old forests from a time before fungi developed the ability to break down lignin. Dead trees back then just continued to pile up without ever rotting.
aaron695 6y ago
Always good to remember environmentalist don't care about old growth forests or eco-systems or humans. It's just about CO2 in the air. Not even the measurable amount, most can't tell you any numbers. They have found a way to control the population that will work for decades. Who cares what old growth forests do, why are we even worrying about CO2 if it's not about getting old growth forests back? I guess because CO2 has become god.
- dang 6y ago
  Would you please stop posting flamewar comments to HN? We've asked you many times and you're not only still doing it, you've been flaming up a storm lately. This is seriously not ok and if you don't stop it we are going to have to ban you. I don't want to ban you, so please fix this. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
  - aaron695 6y ago
    'Flamewar comments' is not really accurate since only you really replied, but I get the sentiment, perhaps you mean this one "Be kind. Don't be snarky. Have curious conversation; don't cross-examine. Please don't fulminate. Please don't sneer, including at the rest of the community." Or maybe you think I'm really bad at flame wars, but... "strongest plausible interpretation" Perhaps a shadow ban and I'll aim for vouch if that's a middle ground.
8bitsrule 6y ago
Longer term storage: peat. https://en.wikipedia.org/wiki/Peat https://en.wikipedia.org/wiki/Peat " Peat forms when plant material does not fully decay in acidic and anaerobic conditions. It is composed mainly of wetland vegetation: principally bog plants including mosses, sedges, and shrubs.... " "Across the world, peat covers just 3% of the land’s surface, but stores one-third of the Earth’s soil carbon...." "In natural peatlands, the 'annual rate of biomass production is greater than the rate of decomposition', but it takes 'thousands of years for peatlands to develop the deposits of 1.5 to 2.3 m [4.9 to 7.5 ft], which is the average depth of the boreal [northern] peatlands', which store around 415 gigatonnes ... of carbon...." Now and then a well-preserved body thousands of years old has been found in a bog.

87 points by tokai 6y ago

black_puppydog 6y ago

Am I missing sth? I don't even see an abstract there, yet they want $8.99 for it?

sampo 6y ago
It's in the Matters Arising section of volume 591. These are short 1-3 page long contributions, shorter than research articles. And being so short, they don't have an abstract. Table of contents: https://www.nature.com/nature/volumes/591/issues/7851 https://www.nature.com/nature/volumes/591/issues/7851 As of writing this comment, these short papers (this, and the counterargument, right after in the table of contents) don't seem to be in sci-hub. Until someone uploads them to sci-hub, they probably aren't available in the free web.
- black_puppydog 6y ago
  Thanks for explaining. Didn't know that format. :)
deleted 6y ago
[deleted]

richiebful1 6y ago

Here's a non-paywalled summary: https://phys.org/news/2021-03-old-growth-forest-carbon-overestimated.html https://phys.org/news/2021-03-old-growth-forest-carbon-overe...

henearkr 6y ago

There is already a rebuttal: https://www.nature.com/articles/s41586-021-03267-y https://www.nature.com/articles/s41586-021-03267-y The rebuttal too is behind a paywall and doesn't have an abstract...

sp332 6y ago
I think the link is to the rebuttal, right? The original paper is from 2008.
- sampo 6y ago
  2008: Original article [1] 2021: Rebuttal of the 2008 article [2] 2021: same issue of Nature, next 2 pages: Rebuttal of the rebuttal by 6 (out of 8) of the authors of the 2008 article [3] [1] https://www.nature.com/articles/nature07276 https://www.nature.com/articles/nature07276 [2] https://www.nature.com/articles/s41586-021-03266-z https://www.nature.com/articles/s41586-021-03266-z [3] https://www.nature.com/articles/s41586-021-03267-y https://www.nature.com/articles/s41586-021-03267-y
  - fshbbdssbbgdd 6y ago
    I’m curious if these competing rebuttals get to read each other during the editing process. Otherwise will there be two more rebuttals in the next issue?

goodcanadian 6y ago

Some basic conservation of matter arguments apply. As long as a plant is growing, it will sink carbon. When it dies and rots, it will release that carbon again. So, a growing forest will sink carbon, but a steady state one will not. This is why I have always been sceptical of tree planting as a carbon offest . . . it is short term, at best. Of course, there are a myriad of other reasons why tree planting might be desirable. The caveat to the above is the extent to which dead plant matter gets permanently buried (turned into peat or whatever) rather than rotting. Under some conditions, forests really will work as a carbon sink, but it has never been as simple as tree planting == good, and I am glad to see research acknowledging that. As with everything, it is complicated.

wing-_-nuts 6y ago
IMHO we need to do everything we can to buy us enough time to innovate our way out of the problem, so yeah, tree planting == good so long as the trees live long enough to do the job.
dbingham 6y ago
The matter is conserved: it becomes soil. Most of the carbon an individual plant absorbed when it was growing will become soil when it dies and decays. (Should note "absorbed" here refers to the carbon that became part of the structure of the plant - not the carbon the plant breathed in. Plants breath out most of the carbon they breath in.) Yes, it releases some of it during the decay process, but a lot of it (most of it) does get sequestered even after death. That's where humus comes from. And it's pretty easy to meassure that. And for deciduous trees, they are sequestering yearly as the leaves they drop decay. It wouldn't surprise me if the amount that is being sequestered is being overestimated in many studies, but the mechanism for it happening is pretty clear and that it is happening is pretty incontrovertible - it falls right out of the chemical math - and I would be much more likely to question any study that questioned that than to question that mechanism itself. It's really frustating to me that what is being posted here is basically just a headline and not even an abstract unless you have a subscription to Nature.
- goodcanadian 6y ago

Kim_Bruning 6y ago

I remember reading about this decades ago. I guess it's still being discussed? Short summary of the theory: Trees are largely made of thin air ;-) : Carbon Dioxide provides the required (C)arbon, water that rains out of the air provides (H)ydrogen and (O)xygen, and (N)itrogen fixated from the air provides the basis for amino acids. This covers about 99% of the chemicals in the woody parts. Young trees want to grow a lot, so they make a lot of lignin and cellulose. These consist of C, H, and O. Once trees have grown tall enough, they tend to slow down, so you'd expect them to not grab as much carbon anymore.

sp332 6y ago
It says the original paper was published in 2008, and a reply was published last month.
bcbrown 6y ago
> Once trees have grown tall enough, they tend to slow down, so you'd expect them to not grab as much carbon anymore. I don't think that's accurate (or at least not very precise). Studies have shown that when evaluating the metric of annual addition of tree mass per acre in the rainforests of the Pacific Northwest, old-growth forests add as much or more when compared to "young" forests. I don't have any specific sources, but if you want to know more the research by Robert Van Pelt should be a good starting point.
- hcurtiss 6y ago
  This is definitionally untrue. Forests have a maximum biomass carrying capacity, and they rarely reach that capacity, instead losing carbon to stochastic events like fire. Old growth forests "store" a lot of carbon, but their capacity to sequester is finite. https://www.fs.fed.us/psw/topics/fire_science/ecosystems/carbon.shtml https://www.fs.fed.us/psw/topics/fire_science/ecosystems/car...
  - bcbrown 6y ago
    You're not listening to what I'm saying. I'm not talking about carbon sequestration, I'm refuting the argument that "once trees have grown tall enough, they tend to slow down". Here, I pulled a source for you: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.453.5197&rep=rep1&type=pdf https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.45... > Wood production of the entire main trunk and whole crown both increased with size and age up to and including the largest and oldest trees we measured. This is even supported by your own link: > In the past, some researchers have suggested that converting old forests to young, fast-growing plantations, whose harvested wood products could store carbon for several decades, would create a net increase in long-term carbon stocks. This approach was based on the idea that old forests are slow growing and thus carbon sequestration slows down as forests age. More recent research generally does not support this idea, as a global survey of old forests found that many continue to sequester carbon and have stocks that far exceed young, managed forests.

mturmon 6y ago

There are some debates in the comments involving process-based comparisons, e.g., when carbon release from decay outweighs carbon sinking from plant metabolism. It may be helpful to give this top-level summary from the National Climate Assessment [1]: "Net storage of atmospheric carbon by forests (742 teragrams, or Tg, of CO2 per year from 1990 to 2015) has offset approximately 11% of U.S. CO2 emissions. Assuming no policy intervention – and accounting for land-use change, management, disturbance, and forest aging – U.S. forests are projected to continue to store carbon but at declining rates (35% less than 2013 levels by 2037) as a result of both land use and lower CO2 uptake as forests grow older." [1] https://nca2018.globalchange.gov/chapter/6/ https://nca2018.globalchange.gov/chapter/6/ -> "Forest Carbon Dynamics" The NCA is your best one-stop-shop for the best current synthesis on such questions, unless you're literally publishing in this specific area (in this case, carbon cycle science at decadal timescales).

omegant 6y ago

Genuine question, if old-growth forest do not work as carbon sinks, how all the petroleum we are extracting comes from? Is all from ancient marine environments?

JamesBarney 6y ago
The article doesn't say old growth forests don't work as carbon sinks, just that don't work as well as they initially thought.
cedilla 6y ago
Petroleum is mostly marine microorganisms. Coal is mostly old forests from a time before fungi developed the ability to break down lignin. Dead trees back then just continued to pile up without ever rotting.

aaron695 6y ago

Always good to remember environmentalist don't care about old growth forests or eco-systems or humans. It's just about CO2 in the air. Not even the measurable amount, most can't tell you any numbers. They have found a way to control the population that will work for decades. Who cares what old growth forests do, why are we even worrying about CO2 if it's not about getting old growth forests back? I guess because CO2 has become god.

dang 6y ago
Would you please stop posting flamewar comments to HN? We've asked you many times and you're not only still doing it, you've been flaming up a storm lately. This is seriously not ok and if you don't stop it we are going to have to ban you. I don't want to ban you, so please fix this. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
- aaron695 6y ago
  'Flamewar comments' is not really accurate since only you really replied, but I get the sentiment, perhaps you mean this one "Be kind. Don't be snarky. Have curious conversation; don't cross-examine. Please don't fulminate. Please don't sneer, including at the rest of the community." Or maybe you think I'm really bad at flame wars, but... "strongest plausible interpretation" Perhaps a shadow ban and I'll aim for vouch if that's a middle ground.

8bitsrule 6y ago

Longer term storage: peat. https://en.wikipedia.org/wiki/Peat https://en.wikipedia.org/wiki/Peat " Peat forms when plant material does not fully decay in acidic and anaerobic conditions. It is composed mainly of wetland vegetation: principally bog plants including mosses, sedges, and shrubs.... " "Across the world, peat covers just 3% of the land’s surface, but stores one-third of the Earth’s soil carbon...." "In natural peatlands, the 'annual rate of biomass production is greater than the rate of decomposition', but it takes 'thousands of years for peatlands to develop the deposits of 1.5 to 2.3 m [4.9 to 7.5 ft], which is the average depth of the boreal [northern] peatlands', which store around 415 gigatonnes ... of carbon...." Now and then a well-preserved body thousands of years old has been found in a bog.