Maybe the answer would be more meaningful if:

1. We first determine the size of the average tree
2. Add how many square meters of sea are also needed to supply an average human's oxygen intake

The marine production of oxygen is estimated at 12x10^15 moles per year. Surface area is 360 million square kilometers.

An average human needs about 2000 calories per day, times ~0.25L per calorie = 500L per day at STP, divided by 22.4L/mole equals roughly 20 moles per day or 8000 per year.

So sq meters of ocean per human is a math problem. Not sure how to define an average tree. Maybe trees per acre, and then oxygen per acre of forrest? Those numbers are probably out there. Too late to search for them now!

 

OK, this looks easier in the morning light. A km^2 is 10^6 m^2, right? So 12x10^15 moles per 360x10^12 m^2 is 33.3 moles/m^2/yr. This means a human needs about 8000 moles per year/(33.3 moles/m^2/yr)=240 square meters of sea surface to produce the oxygen.

That's a patch only 15 meters on a side for average sea surface, which sounds small to me. A lot of the sea's surface is cold and unproductive, so the right patch could be a lot smaller. Surprising.

There are some sources here that suggest a tree, in as little as 1/12th acre (~3600ft^2 = 340m^2) can support roughly one human's oxygen needs.

Now, what can we do with that bit of trivia?

 

Now, what can we do with that bit of trivia?

Well, we could also add animal life requirements, and then calculate what's the minimum amount of trees needed on earth to sustain life as we know it...

kind of a scary thought experiment, don't you think?

 

Not so bad. In finding the data I reported above, I also found a source that estimated it would take 5000 years to run out of oxygen if photosynthesis stopped completely today. Of course we'd disappear in half that time, but it's still a surprisingly long buffer.

Most of the planet's oxygen is tied up in mineral oxides near the surface.

 

Most interesting. I would have to disagree with the 5000 yr. figure.

Oxygen is much to reactive.

 

That depends on concentration. Once it has declined by half, fires will cease and every other reaction involving oxygen will slow down dramatically. Cut it half again and, well, you get the idea.

 

I heard somewhere that trees(etc) actually use up oxygen at night, so what hey produce during the day may be partially consumed.
Also in your usage calculations in anyone factor in O2 used by animals and insect and other O2 breathing life forms.
Or is that why we are gradually making animals species extinct so they don't use up our O2.

 

I heard somewhere that trees(etc) actually use up oxygen at night, so what hey produce during the day may be partially consumed.

Absolutely true. The reported production rates are, I assume, net rates.

Also in your usage calculations in anyone factor in O2 used by animals and insect and other O2 breathing life forms.

The original question was about a human, not the entire biome, so no.

Or is that why we are gradually making animals species extinct so they don't use up our O2.

I'm not aware of anyone suggesting such a strategy. I think we raise far more animals in farming than we kill in the wild.

 

Wayneh,
points taken.
Re farming and wild. I realise thats true. i was just wondering about the loss of biodiversity and its long term effects on the whole planet including humans. The more we learn about our planet the more we seem to find a very intricate web of relationships between plants and animals( insects too). I wonder how long we can continue to upset habitats and lose species before it affects us directly. (off topic a bit , I know).

 

It's already affecting us and we will continue to ignore the problems until it gets to critical levels.

 

It's already affecting us and we will continue to ignore the problems until it gets to critical levels.

You're right on the first part... as for the second part, I sincerely hope you're wrong. Although history normally has proved otherwise.

 

peepal tree give 24Hours Oxygen i give them water daily morning.

 

How many trees are needed to provide enough oxygen for one person?

Most of the oxygen generation on this planet come from algae in the waters of northern canada, and rest come from pine trees in northern canada.

Trees in the rest of the world, collectively, account for little (net) oxygen generation.

 

Most of the oxygen generation on this planet come from algae in the waters of northern canada, and rest come from pine trees in northern canada.

Trees in the rest of the world, collectively, account for little (net) oxygen generation.

Interesting... don't take this wrong, but I'd really like to take a look at your source.

 

and rest come from pine trees in northern canada.

Trees in the rest of the world, collectively, account for little (net) oxygen generation.

I find that difficult to credit inasmuch as the forests of, for instance, Brazil, cover more area and are active year-round with Ca. 50% daylight -- And why should algae in North American waters liberate most of the world's elemental oxygen? -- Am I missing a joke? Or just missing "it"

As always - maintaining an open mind
HP

 

None of the sources I found identified Canada as an exceptional source of global oxygen. As noted, oxygen production happens in proportion to photosynthetic activity. Not a lot of that going on right now in northern Canada.

 

None of the sources I found identified Canada as an exceptional source of global oxygen. As noted, oxygen production happens in proportion to photosynthetic activity. Not a lot of that going on right now in northern Canada.

Indeed! I can but assume equatorial regions would be most 'productive' in this regard --- But let us not discount that 'old black magic' that is Hudson Bay algae!

With benevolent intent
HP

 

AHHhhhhhhhhh, I will need to go dig out the paper!!! Biology like my dad is my main love, I read a recent paper that put forward the case that chloroplasts were actually bacteria originally that were absorbed over millions of years into plants.

They have some fabulous symbiotic relationships, many of which we use to our advantage. Hairy root virus is one that springs to mind and its use in micro cell culture. We have plants to thank for the vast majority of our modern drugs, some we still use 'neat' like whitch hazel for bruises. Some women still use Raspberry leaf tea to induce labour.

Plants are very cool indeed

 

Gillyweed lets you breathe under water for up to one hour!

 

And Conium stops you breathing!