[Terrapreta] CO2 rising

[lou gold]

Hi Everyone,

The relationships between forests and global warming are quite complex and
function differently at different points in the life-cycle of a forest.

For example, while it is true that young fast growing forests draw more
carbon from the atmosphere than do old-growth forests, the latter is a much
bigger sink (long-term but temporary) of sequestered carbon. Put
simplistically, a young fast-growing tree will have to grow for 500 years in
order to store as much carbon as an existing 500 year old tree. But this is
a as an overly simplistic way to look at a forest which is an extremely
complex ecosystem.

The study referenced may have been the one about the "albedo effect" or the
extent to which forests absorb or reflect heat and it works quite
differently in temperate forests than in the tropics. Forest may contribute
to warming in the colder climates whereas they are cooling forces in the
tropics.

Truly significant carbon emissions from forests do occur another part of
nature's cycle -- forest fires. As temperatures and droughts increase, so do
fires creating a positive feedback loop. Under some models of global
warming, forests become so stressed and fires become so prevalent that
forests become not only net emitters, but huge 'tipping-point' emitters of
CO2. At present, tropical deforestation for logging and agriculture uses
fire as a clearing or 'management' tool. It's approximated 70% of Brazil's
significant greenhouse gas pollution is from forest fires. The important
thing to appreciate is that most of nature's carbon sinks are temporary and
function in long-term equilibrium only if left undisturbed.

We should not get caught up in thinking about trees separate from the
"biosphere" of atmosphere, plants, water and soil. The main reason to
preserve old-growth or primary forest ecosystems is that they have attained
a mature order (equilibrium) that maximizes internal recycling, increased
soil fertility, water retention, a complex biodiversity AND retention of
sequestered carbon. When the system is disturbed all kinds of things are
released in a chaotic and potentially catastrophic fashion. It's all
connected.

Here's a good article: http://www.conbio.org/CIP/article82sin.cfm

Hope this helps.

lou



On 9/20/07, Sean K. Barry <sean.barry at juno.com> wrote:
>
>  Hi Dave,
>
> I have read something like this too, but it was in regard to "old growth"
> or mature forests.  Mature forests have more decaying matter in them than
> younger, faster growing forests.  Also, "old growth" forests grow slower,
> taking in less CO2.  On balance an "old growth" forests may become a "net
> emitter" of CO2 into the atmosphere.
>
> I think there are some questions remaining, though.  Jon Frank just said
> this eloquently, that even though CO2 emissions might increase, the ecology
> may still be storing more carbon into the soil, than is emitted as CO2.  I
> think too, that there is a possibility that environmental temperatures could
> play an important part in regulating the fluxes of carbon from/to the biome
> and to/from the atmosphere.
>
> Frank Teuton, Tom Miles, and/or Lou Gold might be able to shed more light
> on this subject for you.  I believe that they all have had substantial
> experience in forestry.  Please forgive me, Frank, Tom, or Lou, if I am
> wrong about that.
>
>
> Regards,
>
> SKB
>
> ----- Original Message -----
> *From:* code suidae <codesuidae at gmail.com>
> *To:* terrapreta at bioenergylists.org
> *Sent:* Thursday, September 20, 2007 11:16 AM
> *Subject:* Re: [Terrapreta] CO2 rising
>
> I read an article sometime in the past year or so that described how
> forest can become net carbon emitters as global temperatures rise. I
> have been unable to find the article again, but IIRC they were
> describing research done on European forests.
>
> Unfortunately I don't recall the description of how the rising
> temperatures caused the forests to become net emitters.
>
> Anyone familiar with this idea?
>
> Dave K
> --
> "Our ignorance is not so vast as our failure to use what we know." -
> M. King Hubbert
>
> On 9/20/07, Sean K. Barry <sean.barry at juno.com> wrote:
> > The ever increasing rate of increase is what is called an "exponential
> > growth curve".  Exponential growth curves are very common in natural
> > systems.
> >
> > From: David Yarrow
> > > not only is CO2 rising, but the rate of increase is increasing.  the
> CO2
> > > graph is an upturning curve, not a flat line.  and we have entered the
> phase
> > > when the vertical component of the curve exceeds the horizontal -- the
> > > "knee" of the curve.
>
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-- 
http://lougold.blogspot.com/
http://www.flickr.com/photos/visionshare/sets/
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