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From an advertisement for turf / rolled sod by a German company:

250 m² Rollrasen produzieren etwa so viel Sauerstoff wie 10.000 m² Kiefernwald oder etwa so viel, wie eine vierköpfige Familie zum atmen braucht. 

translation:

250 m² rolled sod produces approximately as much oxygen as 10000 m² pine forest or as much as a family of 4 needs to breathe

Does rolled sod / turf really release significantly (factor 40?) more oxygen than a pine forest?

Philipp
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Daniel Jour
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    [For the unit-challenged] 10000 square meters is about 2.5 acres. – GEdgar Apr 20 '20 at 13:32
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    It doesn't actually seem that implausible to me. Plants generate oxygen by growing (photosynthesis means over-simplified that carbon-dioxide gets turned into oxygen and carbon, and that carbon becomes more plant). And grass grows pretty quick under the right conditions. But the problem is that you are going to cut the grass sooner or later. And the cut grass in then burnt or composted, which uses up oxygen and releases carbon. – Philipp Apr 20 '20 at 14:26
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    @GEdgar, the unit is the same in both numbers, thus it can safely be - and actually is in the last paragraph of the question - cancelled out. - In the official German unit for area it is "2 Fußballplätze", though. (1 football field - or soccer field, for the sports-challenged - is about 5.000 m² ;) ) – I'm with Monica Apr 20 '20 at 17:39
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    10000 sq m is exactly **one hectare**. – Weather Vane Apr 20 '20 at 18:51
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    Important context: whatever the relative oxygen emissions are doesn't really matter, because the broader implication (that sod is good because oxygen production is good) is moot. At least half the oxygen emissions of the world come from plankton, and the ocean more generally. Pine forests and sod gardens are comparatively irrelevant – Alexander Apr 20 '20 at 19:15
  • This kind of claim is just plain dumb, no need to delve too much. They are probably looking at the current rate of O2 production in some mature pine forests which has a monstrous pool of dead OM continuously decomposing. A fair comparison would be both starting from seed/baby plants on the same type of soil capable of sustaining both (identical starting properties). On a per-area basis, pine trees would win by-far in terms of the overall net amount of O2 produced in the long-run. – y chung Apr 22 '20 at 06:31

1 Answers1

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As the top answer to this related question states, plants in general are oxygen neutral. In other words, whatever oxygen is emitted today will be emitted as CO2 later. So what really matters from a climate perspective is CO2 storage, not oxygen emission.

That said, short-term oxygen emission is apparently difficult to measure, but it is largely a function of leaf surface area. This extension site from the University of California states:

Assignment levels of oxygen emission are not precise and different methods can give different results. That said, it is well documented that oxygen release is proportional to the overall leaf mass, also known technically as Leaf Area Index.

There is general agreement that:

  • Pines are at the bottom of the list in terms of oxygen release because they have a low Leaf Area Index.

I can find lots of sod companies promoting the oxygen producing properties of their product, but no independent research supporting their claims. It is possible that immediate oxygen emission by sod is higher than pine forest, but as far as I can tell, the 10.000 m² is just a made-up and meaningless figure.

Peter Mortensen
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Brian Z
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    The important thing to take away here is, the whole "how much does this plant sequester vs. this plant" is a strawman argument. The answer is always "not enough to make a difference". Plant biomass is at best a *buffer*, not a *deposit* or counterweight to fossil CO2 emission. – DevSolar Apr 20 '20 at 16:50
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    @DevSolar, well, fossil carbon comes from such a buffer, too, albeit one that has been cut off from the atmosphere for millions of years. – I'm with Monica Apr 20 '20 at 17:43
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    "Damaged peatlands are a major source of greenhouse gas emissions, annually releasing almost 6% of global anthropogenic CO2 emissions." ([source](https://www.iucn.org/resources/issues-briefs/peatlands-and-climate-change)). Call that a buffer or a deposit, whatever that means... it's small but not insignificant. – Brian Z Apr 20 '20 at 18:05
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    @I'mwithMonica Which means that the fossil carbon will overwhelm the buffer, which had evolved to buffer the *current* natural emissions, not those reintroduced from those millions of years ago. As I said, strawman. You can introduce acid into a pH buffer as well, with no ill effects at first. Until that buffer is saturated... – DevSolar Apr 20 '20 at 18:13
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    This question is asking about oxygen production not carbon capture. Why do you spend your first paragraph answering a question that wasnt asked and is unrelated to what was asked? – Matt Apr 20 '20 at 20:47
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    But the description (in the source) did not say anything about C02 or carbon sequestration, only oxygen. The closest was about the environment, but that was about the absence of plastic and metal in the product. – Peter Mortensen Apr 20 '20 at 22:03
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    @Matt Because oxygen *production* effectively *means* carbon capture. If a plant doesn't capture carbon, it doesn't produce oxygen. – DevSolar Apr 21 '20 at 05:37
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    @Matt Re "This question is asking about oxygen production not carbon capture:" This is the same thing. The bad guy is CO2, a compound of oxygen and carbon. Plants split that when they grow. The oxygen is released. The carbon is used to build their cells. That's the "sequestering carbon while "producing" oxygen". When the dead plant eventually decomposes the carbon is eaten by micro-organisms, consuming the same amount of oxygen which was originally released. That is why a stationary forest is carbon (and oxygen) neutral. To permanently "sequester" the carbon you have to bury the plant. – Peter - Reinstate Monica Apr 21 '20 at 06:27
  • I'd go even stronger - most ecosystems in general are oxygen neutral, not just plants (depending on the environment, plants can both produce or consume net oxygen). Plants capture carbon dioxide in e.g. sugars and release oxygen; fungi and animals consume the sugar and oxygen, and release carbon dioxide. And that's the trick - an individual tree is an infinite carbon sink (and oxygen producer) - but a forest _isn't_. Trees live and die, and they are consumed and turned back into carbon dioxide and water. Unless you somehow remove the consumers, you quickly get a mostly closed loop. – Luaan Apr 21 '20 at 11:01
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    @Peter "so what really matters from a climate perpective is CO2 storage, not oxygen emission", "The bad guy is CO2" The question isnt about climate. There are no good or bad guys. This question isnt about CO2. It is quite short and asks about oxygen production. Its a simple yes or no question. Sure, plant O2 production is related to CO2 consumption. But we are discussing how fast a pine tree forrest does that vs a bunch of grass. Where that CO2 goes years down the road is not the question. We need O2 in the atmosphere. It isnt all about CO2. – Matt Apr 21 '20 at 11:29
  • @Matt Because oxygen production is irrelevant. We don't have a shortage of oxygen. No one seriously claims that we are going to have a shortage of oxygen in the future.The claim is designed to distract, and it seems to have successfully distracted you. There are other wrong/misleading statements in your comment, but it would be a further distraction to adress them. – Nobody Apr 21 '20 at 17:54
  • @DevSolar Current climate science says planting tree is an important pillar of fighting climate change. It won't save us alone, but the amount of captured and then stored (respectively released and recaptured again and again) CO2 does make a difference. It's much more realistic than synthesizing oil and pumping it back into the ground (which is currently extremely unrealistic, even though some people do work on it). – Nobody Apr 21 '20 at 17:56
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    @Nobody But... the question is literally asking about oxygen production, how can you claim its irrelevant? I couldnt care less if we have a shortage of it or not. The question isnt about the climate. Its about how fast object A does activity 1 and how fast object B does activity 1. You are reading into the question a lot of stuff that wasnt asked or even implied. If I asked how quickly an ice cream plant produced ice cream would the ice cream be irrelevant because we dont have a shortage of ice cream? Of course not. It is literally the question. The question cant be irrelevant to itself. – Matt Apr 21 '20 at 17:59
  • @Matt The stuff was certainly implied, that's the point. Sometimes a question has some context which implies that you should answer a slightly different question. Basically the question asks "Is A->B true?" and implies that C is true because B->C. The answer explains that A->C is false and why and includes the answer to the question as asked literally. – Nobody Apr 21 '20 at 18:04
  • @Nobody Of course it helps to ensure there *is* a buffer, to avoid utter catastrophe when the buffer "suddenly" saturates. But it is and remains a *buffer*, not a sink, so if you keep adding acid (carbon), you will just delay the logical and inevitable result by a little bit, if that much -- as, all in all, we are *reducing* the buffer, unless deforestation e.g. in Brazil and global desertification has ceased without me noticing... – DevSolar Apr 21 '20 at 18:30
  • @DevSolar Yes of course, but we are currently very much lagging behind in stopping climate change, i.e. a buffer than can give us an extra 10, 20 years is exactly what we need to prevent so much heating that it triggers all kinds of undesirable events. A forest that is being replanted is a sink for a few decades I would expect, before it becomes merely a store (reaches steady state). – Nobody Apr 21 '20 at 19:16
  • @DevSolar Here is a source: https://en-roads.climateinteractive.org/scenario.html Deforestation reduction and maximum afforestation gives us 0.2C improvement in 2100, 0.1C each. For single and relatively inexpensive methods that's quite a lot I would say. – Nobody Apr 21 '20 at 19:27
  • @Nobody A forest being replanted, to offset about 100 million barrels of oil used **every day**? – DevSolar Apr 21 '20 at 19:43
  • @DevSolar Check the source. It's from MIT and is not just a pretty toy, it has a huge amount of information including sources. – Nobody Apr 21 '20 at 19:48
  • @Nobody: What makes you think I haven't? Again. A forest being replanted by well-meaning people, *once*, versus 100 million barrels oil per day (that's not even counting gas and coal)? How many forests can you plant per day, for how long? We've been at this for a while, you know... – DevSolar Apr 22 '20 at 04:35
  • Plant biomass is certainly quite relevant. If you add plant biomass, animal biomass, fossile carbon and atmospheric carbon - you get all there is. An increase in one of these states necessitates a decrease in others. Thus, if your aim is a lower mass of carbon in the atmosphere, you have to increase it in one of the others. – Stian Apr 22 '20 at 07:58
  • @DevSolar I can just refer you to the existing calculations that show it's useful, I won't do them myself. – Nobody Apr 22 '20 at 08:42
  • @Nobody: I never challenged "useful". I challenged "sufficient", or "sustainable". – DevSolar Apr 22 '20 at 09:40
  • @DevSolar I never intended to claim the latter two. Possibly the whole disagreement was just a misunderstanding. – Nobody Apr 22 '20 at 09:46