Homestead mailing list

[Clansgian AT wmconnect.com]

In a message dated 1/31/2008 12:55:37 PM Eastern Standard Time, 
don.bowen AT earthlink.net writes:


> That would be true is plant growth were restricted by CO2 availability.  I 
> have looked for information on that but have found little.  One quick 
> thought is that if it were true, plant growth near busy highways would be 
> significantly greater.  It makes sense at a certain level but no 
> observations support it.
> 

The CO2 near highways is not a concentration.  Auto exhaust contains water 
too, but we don't look on proximity to highways as being a concentration of 
water.  Atmospheric gases difuse very quickly and completely.  That's why you 
can't suffocate at night sleeping in a tiny bedroom.  No matter how small the 
cracks and fissures in the room, they are enough for the gases to exchange 
enough 
to keep the oxygen in your personal atmosphere the same level.

It is not availability that is the question, it's concentration.  A plant can 
take in and use C02 only so fast *partially* due to concentration levels.  
The very same thing is true of humans and 02.  We don't absorb all the O2 out 
of 
the atmosphere but depend on a certain concentration (20% or the like isn't 
it?) to give a certain parts per million dissolved in the blood.  If we 
enrich 
the oxygen in the air we breathe, we absorb more (much to our harm).  Just 
like that, plants aren't using all the C02 in their vicinity, only dissolving 
it 
at a certain rate which is proportional to atmospheric  concentration.

Higher rates of C02 means the plants absorb it differently and yield more 
growth.  It's slight, but in time it would sequester the carbon back into the 
biosphere.   </HTML>