How many trees do I need?

Main Question or Discussion Point

I am, for some reason, unable to post in the "earth" board, so here I am.

How many trees does it take to provide enough oxygen for one human? How large would these trees be?

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nautica
Why not show us what you have so far? As I am sure you would not want us to tell you the answer.

Nautica

You can't say how many trees of what size would make a sufficient amount of o2 for a human, since the size of a tree does not automatically give it a set o2 output. A better question would be how many photosynthetic cells with how many chloroplast acting how quickly would be needed to supply a human with oxygen.

Also, human oxygen needs vary depending on the mass of the person, how strong their heart is, how healthy their lungs are and many other factors, so you'd need to state how much oxygen your human intakes, or give some sort of description of the person for anyone to be able to figure it out beyond a rough estimate.

Staff Emeritus
Gold Member
Dearly Missed
Here's where it would be useful to do averages. How much does oxygen does the average tree (or generalize to large plant) produce, and how much does the average human consume? After you pin that down you can go to distributions on both sides.

Do you think a bonsai tree, japanese maple, and redwood have anywhere near the same o2 output?

But yeah, you could average human o2 needs.

3
But if you have a car (hint:ask on engineering forum)....

I'm thinking: wouldn't it also vary greatly with the amount of the CO2 supply to the tree?

Evo
Mentor
There are *many* factors that impact the oxygen production of a tree. Older trees can actually be higher net "users" of oxygen, not net "producers". The ocean produces much more oxygen than all of the trees combined.

LURCH
Originally posted by selfAdjoint
"Here's where it would be useful to do averages." "...how much does the average human consume?"
Exactly my thinking, but I went a-searchin' and couldn't find that information. Giot pretty furstrating, actually; there are all kinds of reference to "VO2-MAX" ( the amount of O2 consumed during maximum exrtion) in the medical science sites, but none of them used a resting rate of consumtion for a baseline.

NASA.Gov has an entire tutorial about provisions for space travel, and they talk about the need for "enough Oxygen for each crew member", but never mention how much that is.

Can anybody else find an average number?

I remember once that Chroot (I think it was him at least) said that a rough estimate for an o2 supply/concentration was, assuming the pressure of the air is the same as it is at sea-level, you'd need the air to be composed of 16% oxygen.

Evo
Mentor
Originally posted by wasteofo2
I remember once that Chroot (I think it was him at least) said that a rough estimate for an o2 supply/concentration was, assuming the pressure of the air is the same as it is at sea-level, you'd need the air to be composed of 16% oxygen.
Are you referring to the article I posted? "Now, on an average, cool,
clear day, only 21% of that air is oxygen." Or does no one read my posts? [b(]

No, it was in that thread I made asking if deforestation could lead to the lack of ability to light fires. People said we'd all be dead before we couldn't light fires, so I needn't worry about it and chroot said that due to his scuba-diving experience he's learned that a safe amount of o2 is 16 atmospheres partial pressue, meaning that you need 16% o2 concentration and the same pressure that is found at sea-level to stay concious. Though he said that was playing it safe, and some can survive with only 10 atmospheres partial pressure.

Well I see no one took my post seriously, but I wasn’t kidding with that 3 number :)
I remembered it from some elementary school book (it’s probably 3 assumption)……

cheers

russ_watters
Mentor
Originally posted by eagleone
Well I see no one took my post seriously, but I wasn’t kidding with that 3 number :)
I remembered it from some elementary school book (it’s probably 3 assumption)
Dubious. Looking at the issue from another angle, you guys remember the Biosphere project and why it failed...?