Air cleaning... by trees

Discussion in 'Plants: Science and Cultivation' started by Anne Taylor, Apr 23, 2007.

  1. Anne Taylor

    Anne Taylor Active Member 10 Years

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    This small but important inquiry came from my cub pack.... ( re earth day and planting trees and such like...) What kind of tree would put the most oxygen back into the air and "clean" the best?.... decidious or evergreen and which species?.... and can we grow them here?...
    I'm not sure how to research this for them but I'm confident someone here will have an information source.
    Thanks....
    Anne Taylor...
    Akela with the 14th Juan de Fuca Cub Pack, in Metchosin (Victoria B.C.)
     
  2. jimmyq

    jimmyq Well-Known Member 10 Years

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    good question Anne. I know that NASA did some research regarding tropical or house plants and their efficiency at 'cleaning' the air. I think Spathiphyllum was one of the top ones. Not sure about trees, I would suggest perhaps it would have to do with growth rate. theory: The faster it grows, the more bulk of minerals and gases it would use and release.
    If you research carbon sequestering of trees you may get on the right track and find some info.
     
  3. Dixie

    Dixie Active Member

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    Last edited: Apr 26, 2007
  4. TonyR

    TonyR Active Member

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    A simple generalisation would be that it is the tree with greatest net rate of photosynthesis, which translates to the greatest accumulation of photosynthetic products (direct and indirect), i.e. sugars, starches, cellulose, lignin etc. The more photosynthesis, the more carbon dioxide in, and oxygen out. Some of the sugars and starches are converted back to carbon dioxide by respiration, so it is really the locked-in forms of carbon in the tree's tissues that we need to consider.

    Since these carbon-based structural materials make up, I would guess, over 95% (possibly over 99%) of a tree's dry weight, you would be looking for the tree that adds dry weight at the greatest rate. Then you need to decide if you want to look at this on an hourly, daily or yearly basis, or over the lifetime of the tree. Things get complicated!

    So basically it's the fastest-growing trees that are likely to be most effective at absorbing carbon dioxide, the most abundant greenhouse gas though not the most potent. And by fastest-growing we mean not just in height but in total (dry) mass. Some cottonwoods, for example, have shown amazingly fast height growth in their first 10-15 years, and their rate of trunk diameter increase is pretty respectable too. Against this, their wood is of low density and so contains less dry matter. Foresters would have the best statistics about rates of addition of wood volume, which I suspect is approximately proportional to total dry matter.

    The whole question of carbon dioxide absorption by trees and other vegetation is incredibly complex. In a completely stable, mature forest there are old trees falling and decaying at the same rate younger trees are growing, and the decaying wood gives most of its carbon back to the atmosphere. But consider, if vigorously growing trees are converted to lumber which is then used to build houses, that carbon is locked away for as long as the houses last before themselves decaying (though what about the energy, mainly from coal and petroleum, consumed in harvesting the trees and building the houses?). You can go through endless possible scenarios, all complex, about the fate of atmospheric carbon.
     
  5. joecat

    joecat Active Member

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    Tony, don't scare the kids away from planting trees at all! LOL!

    Besides converting carbon dioxide to oxygen (at least until the tree itself decomposes), trees might also clean the air and provide shade, food or shelter for animals.

    You've brought up very good points, and I've wondered these things for myself -- and besides nuclear reactions, and ejecting things into space, we aren't changing the composition of the earth at all, just rearranging it, but we can rearrange things in bad ways (release greenhouse gases to the atmosphere) and good ways (plant trees).

    I admire the kids for asking such questions -- perhaps they will become scientists and answer the question definitively for themselves and for us.
     
  6. vuduchicken

    vuduchicken Member

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    Would it be possible to grow a high carbon plant such as castor beans, on the surface of the ocean (floating farms)? If it were possible would that provide a partial solution to the CO2 problem?

    Solar distilled H2O would be a cheap source of fresh water for irrigation, solar electric would be a cheap source of power for pumps for an irrigation system on a floating farm.

    That being said, if it were possible, could we then use the oil & any other carbon that would be produced for raw materials in manufacturing instead of fuel, so as not to introduce that carbon back into the atmosphere, think of it as carbon "farming" or "mining"?

    Is this crazy or do you think the idea has any merit?
     

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