6 ms·

> This is not happening. Because forests don't produce surplus oxygen. Our atmosphere doesn't work that way. This is just plain wrong. The blogger is completel

by EB66 7y ago

> This is not happening. Because forests don't produce surplus oxygen. Our atmosphere doesn't work that way. This is just plain wrong. The blogger is completely wrong on this point as well. In normal atmosphere conditions, photosynthesis does result in net oxygen gain. Plants do require oxygen for respiration, but they require far less oxygen than what they produce during photosynthesis. Furthermore, at night when there's no light, plants do absorb oxygen and give off carbon dioxide in order to continue respiration -- but the amount of oxygen given off during the day is typically ten times greater than the quantity of oxygen consumed at night. > This reminds me, as we should all be reminded on a regular basis, the bulk of the things you read in the popular press are at best skimming the surface and at worst outright misleading due to grabbing onto one obscuring factoid instead of the most important pieces of information. Similarly, we should all be reminded that when skimming blogs and comments you're likely to come across misleading and inaccurate content. Scientifically inaccurate content like this gets posted on HN and blindly upvoted all the time.

nearbuy 7y ago
Then where is the carbon going?
- EB66 7y ago
  We're talking about oxygen production. Not carbon sequestration. Regarding sequestration: the carbon goes into the trunk, branches, roots and leaves of the tree. Leaves fall off the tree, rot and become soil. The tree eventually dies, rots and becomes soil. Some carbon will be given off by various decomposition processes, but the overall net effect is by far a carbon sink.
  - nearbuy 7y ago
    > We're talking about oxygen production. Not carbon sequestration. BurningFrog said the carbon from CO2 goes into plants. Since plant matter isn't accumulating, carbon can't be accumulating, and therefore oxygen can't either. You replied, "This is just plain wrong". So you're saying the part that is sequestered goes into the soil. That means some significant fraction of the 20 billion tonnes of carbon the Amazon photosynthesizes each year is turning in to soil. You're claiming the amount of soil increases by this amount each year, correct?
    - EB66 7y ago
      > That means some significant fraction of the 20 billion tonnes of carbon the Amazon photosynthesizes each year is turning in to soil. Correct. That fraction is obviously reduced when the forest is burned.
      - nearbuy 7y ago
        Then why is the soil layer in the Amazon only about a meter deep after millions of years of carbon sequestration? The rainforest photosynthesizes about 3 kg of carbon per square meter per year.
        baq 7y ago
        Bacteria and fungus eat the rest? Consider the Azolla event where dead plant material sank into very salty and oxygen poor water, which left several meters of carbon on the bottom of the polar ocean after 800k years.
        nearbuy 7y ago
        If fungus or aerobic bacteria eat it, then the Amazon doesn't produce surplus oxygen from it. Eating involves recombining the carbon with oxygen into CO2. The biomass of the Amazon is not, for the most part, sinking into very salty water.
        Ericson2314 7y ago
        I assume the Amazon and it's tributaries wash most of it away.
        nearbuy 7y ago
        Most of the soil is kilometers away from the nearest tributary. And it wouldn't explain why it washes away everything except for the last 1 meter of soil. Or why the organic matter wouldn't re-enter the food chain once it reached the ocean, thereby recapturing the oxygen. If 3kg of carbon sequestration per year per square meter were accumulating as soil, and the rainforest has existed at least 30 million years, the soil would be over 2,000,000 meters deep (with rich organic soil being about 9% carbon). If even 1% of the carbon captured through photosynthesis was sequestered in soil, we should still have much, much deeper soil.
- atoav 7y ago
  Into the plant? Btw. you can easily test this yourself in a closed glas sphere.
  - nearbuy 7y ago
    I meant overall in the long term, in response to EB66 saying BurningFrog is wrong. The plants can't be net collecting carbon each year unless the Amazon contains more and more plant matter each year.
  - PeterisP 7y ago
    Exactly, it goes into the plant, and is then released as the plant decomposes - so in a stable rainforest, where the total plant mass isn't increasing, the new plants growing (creating O2 and absorbing CO2) is fully balanced by old plants decomposing or burning (absorbing O2 and creating CO2); so there's no net creation of O2.
    - varjag 7y ago
      That would be true only if you always burn 100% of biomass, which doesn't happen. Carbon gets sequestered into soil, and partly consumed by insects and animals up the food chain. All carbon in your body was once sequestered by plants.
      - PeterisP 7y ago
        The point is that in a stable rainforest the amount of biomass isn't growing, so you obviously do burn/decompose 100% of the newly created biomass - otherwise the amount of biomass would have grown. Carbon gets sequestered into the soil in cases where soil is being enriched and is "growing in size" (for example, when a previously barren place gets forested) but in a stable, centuries-old rainforest the soil amount really isn't increasing - so as much as gets sequestered, gets released by decomposition. As the total biomass of insects isn't growing, the carbon they consume is balanced by the carbon released by decomposition of (otherwise) unconsumed insects; the same applies for animals up the food chain - if at the end of 2019 the total weight of insects and animals in the Amazon is not larger than at the end of 1919, then zero carbon has been sequestered in these insects and animals over a hundred years.
- strainer 7y ago
  Into the amazon river and out to sea basically. Rain will wash a lot of matter that way.
deleted 7y ago
[deleted]
shkkmo 7y ago
> The blogger is completely wrong on this point as well. I think you may not have read the article closely enough: >> Plants produce oxygen through photosynthesis (green arrow). However, the the same plants consume the equivalent of over half the oxygen they produce in their own respiration ... my own team's research suggests this is more like 60% >> The remaining 40% of the Amazon oxygen budget is consumed mainly by microbes breaking down the dead leaves and wood of the rainforest, a natural process called heterotrophic respiration > Similarly, we should all be reminded that when skimming blogs and comments you're likely to come across misleading and inaccurate content The "blogger" who wrote this article is "Professor of Ecosystem Science, University of Oxford" and "Founding Director, Oxford Centre for Tropical Forests" and probably knows more about this than you or I. This is not a peer reviewed paper, but it is probably more accurate than science journalism by a non-ecologist on this topic.
- strainer 7y ago
  > my own team's research suggests this is more like 60% My point was he hasn't cited that research - if it is concluded ? published? reviewed? He seems to be just having a technical rant about a contextual phrase while giving the impression that forests in general, or at least the amazon or equatorial forests do not help maintain the atmospheres oxygen content. That would certainly be a maveric proposition at this stage in Earth sciences.
  - shkkmo 7y ago
    > My point was he hasn't cited that research - if it is concluded ? published? reviewed? I am far more willing to take the word of an established and respected expert who understand the subject mater than a random internet person with a poorly contextualized citation. You can find the author's published papers on this and related subjects quite easily at the top of the article. > He seems to be just having a technical rant about a contextual phrase while giving the impression that forests in general, or at least the amazon or equatorial forests do not help maintain the atmospheres oxygen content. That would certainly be a maverick proposition at this stage in Earth sciences. He is a scientist clarifying a technical subject that has been being misconstrued. There has already been plenty of damage done by people throwing around fake facts and pictures.
navigatesol 7y ago
>The blogger is completely wrong on this point as well. Classic HackerNews, right here. His CV is public...and extensive. >Scientifically inaccurate content I'm sure Dr. Malhi'd be more than happy to debate you on the subject. Go post your arguments on his blog.
BurningFrog 7y ago
A single plant does produce oxygen while it's alive, and the carbon is bound in its growing body. But that carbon is all released back as it decomposes after its death. On a "whole forest/whole year" perspective, there is normally an equal mass of plants growing and being decomposed, and thus the net oxygen effect is zero.
- EB66 7y ago
  > But that carbon is all released back as it decomposes after its death. > On a "whole forest/whole year" perspective, there is normally an equal mass of plants growing and being decomposed, and thus the net oxygen effect is zero. Sure, if you're talking about a timespan of one hour, one month, one year, etc then it's definitely possible for biological processes in a forest to expel carbon in the form of CO2 in equal volumes that were sequestered by plants. You could even have an overpopulation of some kind of insect or fungus cause a forest to temporarily become a net contributor of atmospheric carbon. But over the lifetime over the forest, the net effect is obviously massive CO2 sequestration and massive O2 production. If the net carbon impact was zero over the lifetime of a forest, then forests would have no soil. But we know that not to be the case. Forests grow, they accumulate soil, etc. Despite constant heavy rains and erosion, soil in the Amazon rainforest is often several meters deep and spans an area of over 2 million square miles. That's a lot of carbon sequestration!
  - BurningFrog 7y ago
    I agree that for a "startup" forest, there will be an accumulation of soil. I assume it reaches an equilibrium after some time, and that the Amazon soil has remained the same "several meters" deep for many millions years. But I'll admit I don't know that, and you may have a valid point. If real, this effect has to be quite small though.
    - EB66 7y ago
      > I assume it reaches an equilibrium after some time Yep definitely and in part because CO2 only makes up ~0.04% of our atmosphere. Photosynthesis processes slow when CO2 levels fall and increase when CO2 levels rise. But as well as know atmospheric CO2 levels are rapidly on the rise and is outstripping the ability of large forests to sequester it.

by EB66 7y ago

nearbuy 7y ago

Then where is the carbon going?

EB66 7y ago
We're talking about oxygen production. Not carbon sequestration. Regarding sequestration: the carbon goes into the trunk, branches, roots and leaves of the tree. Leaves fall off the tree, rot and become soil. The tree eventually dies, rots and becomes soil. Some carbon will be given off by various decomposition processes, but the overall net effect is by far a carbon sink.
- nearbuy 7y ago
  > We're talking about oxygen production. Not carbon sequestration. BurningFrog said the carbon from CO2 goes into plants. Since plant matter isn't accumulating, carbon can't be accumulating, and therefore oxygen can't either. You replied, "This is just plain wrong". So you're saying the part that is sequestered goes into the soil. That means some significant fraction of the 20 billion tonnes of carbon the Amazon photosynthesizes each year is turning in to soil. You're claiming the amount of soil increases by this amount each year, correct?
  - EB66 7y ago
    > That means some significant fraction of the 20 billion tonnes of carbon the Amazon photosynthesizes each year is turning in to soil. Correct. That fraction is obviously reduced when the forest is burned.
    - nearbuy 7y ago
      Then why is the soil layer in the Amazon only about a meter deep after millions of years of carbon sequestration? The rainforest photosynthesizes about 3 kg of carbon per square meter per year.
      - baq 7y ago
        Bacteria and fungus eat the rest? Consider the Azolla event where dead plant material sank into very salty and oxygen poor water, which left several meters of carbon on the bottom of the polar ocean after 800k years.
        nearbuy 7y ago
        If fungus or aerobic bacteria eat it, then the Amazon doesn't produce surplus oxygen from it. Eating involves recombining the carbon with oxygen into CO2. The biomass of the Amazon is not, for the most part, sinking into very salty water.
      - Ericson2314 7y ago
        I assume the Amazon and it's tributaries wash most of it away.
        nearbuy 7y ago
        Most of the soil is kilometers away from the nearest tributary. And it wouldn't explain why it washes away everything except for the last 1 meter of soil. Or why the organic matter wouldn't re-enter the food chain once it reached the ocean, thereby recapturing the oxygen. If 3kg of carbon sequestration per year per square meter were accumulating as soil, and the rainforest has existed at least 30 million years, the soil would be over 2,000,000 meters deep (with rich organic soil being about 9% carbon). If even 1% of the carbon captured through photosynthesis was sequestered in soil, we should still have much, much deeper soil.
atoav 7y ago
Into the plant? Btw. you can easily test this yourself in a closed glas sphere.
- nearbuy 7y ago
  I meant overall in the long term, in response to EB66 saying BurningFrog is wrong. The plants can't be net collecting carbon each year unless the Amazon contains more and more plant matter each year.
- PeterisP 7y ago
  Exactly, it goes into the plant, and is then released as the plant decomposes - so in a stable rainforest, where the total plant mass isn't increasing, the new plants growing (creating O2 and absorbing CO2) is fully balanced by old plants decomposing or burning (absorbing O2 and creating CO2); so there's no net creation of O2.
  - varjag 7y ago
    That would be true only if you always burn 100% of biomass, which doesn't happen. Carbon gets sequestered into soil, and partly consumed by insects and animals up the food chain. All carbon in your body was once sequestered by plants.
    - PeterisP 7y ago
      The point is that in a stable rainforest the amount of biomass isn't growing, so you obviously do burn/decompose 100% of the newly created biomass - otherwise the amount of biomass would have grown. Carbon gets sequestered into the soil in cases where soil is being enriched and is "growing in size" (for example, when a previously barren place gets forested) but in a stable, centuries-old rainforest the soil amount really isn't increasing - so as much as gets sequestered, gets released by decomposition. As the total biomass of insects isn't growing, the carbon they consume is balanced by the carbon released by decomposition of (otherwise) unconsumed insects; the same applies for animals up the food chain - if at the end of 2019 the total weight of insects and animals in the Amazon is not larger than at the end of 1919, then zero carbon has been sequestered in these insects and animals over a hundred years.
strainer 7y ago
Into the amazon river and out to sea basically. Rain will wash a lot of matter that way.

deleted 7y ago

[deleted]

shkkmo 7y ago

> The blogger is completely wrong on this point as well. I think you may not have read the article closely enough: >> Plants produce oxygen through photosynthesis (green arrow). However, the the same plants consume the equivalent of over half the oxygen they produce in their own respiration ... my own team's research suggests this is more like 60% >> The remaining 40% of the Amazon oxygen budget is consumed mainly by microbes breaking down the dead leaves and wood of the rainforest, a natural process called heterotrophic respiration > Similarly, we should all be reminded that when skimming blogs and comments you're likely to come across misleading and inaccurate content The "blogger" who wrote this article is "Professor of Ecosystem Science, University of Oxford" and "Founding Director, Oxford Centre for Tropical Forests" and probably knows more about this than you or I. This is not a peer reviewed paper, but it is probably more accurate than science journalism by a non-ecologist on this topic.

strainer 7y ago
> my own team's research suggests this is more like 60% My point was he hasn't cited that research - if it is concluded ? published? reviewed? He seems to be just having a technical rant about a contextual phrase while giving the impression that forests in general, or at least the amazon or equatorial forests do not help maintain the atmospheres oxygen content. That would certainly be a maveric proposition at this stage in Earth sciences.
- shkkmo 7y ago
  > My point was he hasn't cited that research - if it is concluded ? published? reviewed? I am far more willing to take the word of an established and respected expert who understand the subject mater than a random internet person with a poorly contextualized citation. You can find the author's published papers on this and related subjects quite easily at the top of the article. > He seems to be just having a technical rant about a contextual phrase while giving the impression that forests in general, or at least the amazon or equatorial forests do not help maintain the atmospheres oxygen content. That would certainly be a maverick proposition at this stage in Earth sciences. He is a scientist clarifying a technical subject that has been being misconstrued. There has already been plenty of damage done by people throwing around fake facts and pictures.

navigatesol 7y ago

>The blogger is completely wrong on this point as well. Classic HackerNews, right here. His CV is public...and extensive. >Scientifically inaccurate content I'm sure Dr. Malhi'd be more than happy to debate you on the subject. Go post your arguments on his blog.

BurningFrog 7y ago

A single plant does produce oxygen while it's alive, and the carbon is bound in its growing body. But that carbon is all released back as it decomposes after its death. On a "whole forest/whole year" perspective, there is normally an equal mass of plants growing and being decomposed, and thus the net oxygen effect is zero.

EB66 7y ago
> But that carbon is all released back as it decomposes after its death. > On a "whole forest/whole year" perspective, there is normally an equal mass of plants growing and being decomposed, and thus the net oxygen effect is zero. Sure, if you're talking about a timespan of one hour, one month, one year, etc then it's definitely possible for biological processes in a forest to expel carbon in the form of CO2 in equal volumes that were sequestered by plants. You could even have an overpopulation of some kind of insect or fungus cause a forest to temporarily become a net contributor of atmospheric carbon. But over the lifetime over the forest, the net effect is obviously massive CO2 sequestration and massive O2 production. If the net carbon impact was zero over the lifetime of a forest, then forests would have no soil. But we know that not to be the case. Forests grow, they accumulate soil, etc. Despite constant heavy rains and erosion, soil in the Amazon rainforest is often several meters deep and spans an area of over 2 million square miles. That's a lot of carbon sequestration!
- BurningFrog 7y ago
  I agree that for a "startup" forest, there will be an accumulation of soil. I assume it reaches an equilibrium after some time, and that the Amazon soil has remained the same "several meters" deep for many millions years. But I'll admit I don't know that, and you may have a valid point. If real, this effect has to be quite small though.
  - EB66 7y ago
    > I assume it reaches an equilibrium after some time Yep definitely and in part because CO2 only makes up ~0.04% of our atmosphere. Photosynthesis processes slow when CO2 levels fall and increase when CO2 levels rise. But as well as know atmospheric CO2 levels are rapidly on the rise and is outstripping the ability of large forests to sequester it.