[EB66]

> I think you may not have read the article closely enough

I did read the article closely :)

>> 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

The author is stating that the Amazon rainforest is in perfect equilibrium without citing any studies or evidence. There are plenty of studies that indicate otherwise, such as this 30 year survey involving 100 researchers: https://www.nature.com/articles/nature14283

> While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation.

But even if we accept the author's argument that today the Amazon is in perfect equilibrium -- I think it was misleading of the author not to clarify that in order for any forest to grow, it must be a net carbon sink and net oxygen producer up to that point in the forest's lifetime.

Now the comment that I originally replied to said something different. That comment argued that forests cannot be net producers of oxygen because there aren't "ever growing [piles of wood]" and then he provided the Wikipedia article for photosynthesis as evidence supporting that. That's wrong as I explained above.

You can have forests that are net carbon sinks and net producers of oxygen and you don't need "ever growing [piles of wood]" in order for that to happen.

[shkkmo]

> The author is arguing that the Amazon rainforest is in perfect equilibrium without citing any studies or evidence

The author argued no such thing, You are making up claims adn attributing them to the author, so perhaps an even closer reading of the blog post would be beneficial.

>> So, in all practical terms, the net contribution of the Amazon ECOSYSTEM (not just the plants alone) to the world's oxygen is effectively zero. The same is pretty much true of any ecosystem on Earth, at least on the timescales that are relevant to humans (less than millions of years).

The paper you cited is talking about carbon dioxide, not oxygen. The net effect on global O2 levels of carbon sequestration is minimal and not significant on human time scales. That same carbon sequestration has a significant impact on global CO2 because there is much less CO2 in the atmosphere.

[EB66]

> The author argued no such thing, You are making up claims adn attributing them to the author, so perhaps an even closer reading of the blog post would be beneficial.

Please go read the article again. That's exactly what he's saying. He is saying that Amazon rainforest O2 production and consumption are in equilibrium.

> The paper you cited is talking about carbon dioxide, not oxygen. The net effect on global O2 levels of carbon sequestration is minimal and not significant on human time scales. That same carbon sequestration has a significant impact on global CO2 because there is much less CO2 in the atmosphere.

For heaven's sake, please read the study. If you'd rather not read the study, then just Google until you find a satisfactory source that explains that net O2 production and net CO2 sequestration strongly correlate with one another.

[shkkmo]

> He is saying that Amazon rainforest O2 production and consumption are in equilibrium.

where?

> net O2 production and net CO2 sequestration strongly correlate with one another.

yes, but we have ~500 times more O2 than CO2 in the atmosphere so the effects on atmospheric composition are not anywhere close to equivalent.

edit: Let me put it another way. We have so much oxygen that if we were to use any significant amount (say 1%) of that oxygen burning sequestered carbon (rainforests, oil, etc) we would have increased the carbon dioxide in the atmosphere by something like ~2000% (and would already be totally screwed in many, many ways)

[EB66]

I think you need to look up the definition for "equilibrium" and then re-read the article once more...

Either way I'm done with this tangent.

[shkkmo]

> The author is stating that the Amazon rainforest is in perfect equilibrium without citing any studies or evidence. There are plenty of studies that indicate otherwise, such as this 30 year survey involving 100 researchers: https://www.nature.com/articles/nature14283

Y. Malhi, one of the authors of that paper, is also the author of this blog post. That makes sense since he a preeminent rainforest ecologist who publishes lots of papers on the carbon cycle.

[EB66]

Yes, you also pointed out this fact up above in the comment chain as well. And as @strainer pointed out, it leaves us with more questions than answers. Specifically: how could he have participated in the study but publish a blog post that contradicts the primary conclusions of the study?

[shkkmo]

> how could he have participated in the study but publish a blog post that contradicts the primary conclusions of the study?

Short answer: Because the article doesn't contradict the study at all.

1) The rainforest is a carbon sink: It holds carbon that would otherwise be present in the atmosphere as CO2.

2) The rainforest is currently a net carbon sink: As an ecosystem it takes in more CO2 than it releases.

3) The rainforest (like most ecosystems) operates fairly close to equilibrium: The amounts of CO2/O2 consumed and produced tend to be pretty close.

4) Major ecological net carbon sinks depend less on the amount of photosynthesis in the ecosystem than they do on the sequestration of bio-matter into the ground.

5) There is ~500x more O2 than CO2 in the atmosphere. This means that the effects of the carbon cycle on atmospheric O2 are far less pronounced than on CO2.

6) net oxygen production of the amazon is effectively 0 (millions of years before a significant impact) because of 5) and 3)

In what way do any of these points contradict eachother?

The major reason (carbon cycle related, excluding biodiversity & global weather patterns & cooling etc) to care about about the amazon is to avoid releasing the CO2 already there. Purely in terms of net carbon sinking ecosystems, we should be paying more attention to our oceans as they do a much better job of sequestering that carbon into the ground.

Oxygen in the atmosphere is simply not an issue because we have so much of it.