permaculture

["Kirby Fry" <peace@totalaccess.net>]

Hey John,

How right you are.  I didn't even look at who or what they were... Darn!

I did find another article though saying the free ride is over, attached
below, that soils under present circumstance will soon absorb all the carbon
they can hold and increases in carbon will then sky rocket as soon as soils
are saturated.

It's scarry, all of these "organisations" out their generating information
with an alterior motive in mind.  It just reinforces my theory that it's
really up to the permaculture community to round out the picture.  Of
course, we have our motives too! ;^>

* * * * *

Contact: Dennis Meredith
dennis.meredith@duke.edu
919-681-8054
Duke University

End of 'free ride' on ecosystem CO2 absorption
DURHAM, N.C. -- According to a new study, the world may soon see the end of
the "free ride," in which carbon absorption by natural ecosystems
ameliorates the rise in atmospheric CO2 due to fossil fuel burning and loss
of forest.

The precise ecosystem study of the reaction of a Texas grassland to a range
of carbon dioxide levels has shown that soil nitrogen availability may limit
the capacity of ecosystems to absorb expected increases in atmospheric CO2.
The researchers said their study emphasizes the urgency with which the U.S.
and other nations should adopt stringent limitations on CO2 emissions, as
outlined in the international Kyoto accord on climate change.

The researchers, led by Duke University ecologist Robert Jackson and USDA
Agricultural Research Service researchers Wayne Polley, and Hyrum Johnson,
published their findings in the May 16, 2002, Nature. First author of the
study is Richard Gill, a former Duke postdoctoral associate, now a faculty
member at Washington State University. The research was supported by the
Department of Energy and the U.S. Department of Agriculture.

"Based on fossil fuel emissions, the carbon dioxide concentration in the
atmosphere should be going up twice as fast as it currently is," said
Jackson. "However, natural systems such as the regrowing Eastern forests are
currently taking up that extra carbon dioxide, so we're really getting a
free ride now.

"Many of us, myself included, believe that this free ride won't continue to
the same extent that it has, because the incremental benefits of the extra
CO2 get smaller and smaller relative to other nutrient constraints," he
said. The policy implications of their findings are apparent, said Jackson.

"Considering the expected population increase, greater resource use per
capita and the inability of natural systems to take up CO2, we may well be
looking at increases per year that are double what they are now, with
atmospheric CO2 concentrations as high as 800 parts per million in this
century," he said. "This means that the current lack of interest by the U.S.
in participating in the Kyoto accords is especially unfortunate." According
to Jackson, the study offered a new approach to studying the ecological
effects of increased CO2.

"The study is unique in enabling us to study the effects of CO2
concentrations ranging from those before the Industrial Revolution to those
projected for the next century," said Jackson. "It is also unique in
providing a continuous gradient of CO2 in the field, allowing us to examine
nonlinear and threshold responses and limitations of the system. Nitrogen
availability appears to be one such limitation on the ability of plants to
absorb CO2."

The researchers chose a section of north Texas prairie as the site for their
experimental apparatus, which began operation in May 1997. The apparatus
consists of two 60-meter-long long plastic-covered chambers -- resembling
giant segmented worms -- erected over the grassland. The chambers measured
about a meter wide and a meter high.

In one chamber, the scientists expose the grasses to a smooth gradient of
CO2 concentrations ranging, from the current 365 parts per million (ppm)
level down to the 200 ppm present at the end of the last ice age. The
scientists achieve this concentration gradient by blowing ambient air into
one end of the chamber, and as the air flows the length of the chamber, CO2
uptake by the grasses reduces CO2 concentrations down to 200 ppm.

In the other chamber, the scientists pump into one end air enriched to a CO2
concentration of 550 ppm -- the expected level over the next century -- and
the plants' CO2 absorption reduces this to 350 ppm at the opposite end. The
chamber also includes controls to ensure that moisture and temperature
levels match those outside.

"There have been few experiments, even in growth chambers, that could
explore the effects of changes since before the Industrial Revolution, but
our design enables us to do just that," said Jackson. "Thus, it gives us
insights into what changes occurred in the past and improves our
understanding about will happen in the future." Operating the apparatus over
multiple growing seasons, the scientists conducted detailed biochemical and
biological analyses of the grass plants as well as the soil. They also
measured how the species composition of the plant community changed.

"We found that many of the plants' physiological processes responded fairly
linearly to increases in carbon dioxide, and plant production went up," said
Jackson. "However, production and soil carbon storage basically saturated
above 400 parts per million, a CO2 concentration very close to the current
one.

"For me, this was the most interesting part of the study, because it
indicates that we are now right at a threshold where the benefits of extra
CO2 may not be all that great." Particularly important, said Jackson, were
the measures of soil nitrogen availability. Soil bacteria metabolize organic
matter, mobilizing nitrogen as ammonia and nitrate, which serves as the
plants' nitrogen nutrient source

"Our measurements showed that soil nitrogen decreased about threefold in a
nonlinear way, such that as CO2 went up, available nitrogen went down," said
Jackson. "So that's where the fundamental nutrient limitation of the system
occurred. The decrease in nitrogen availability apparently constrains the
ability of the plants to use extra CO2. "

According to Jackson, the findings by him and his colleagues agree with
tentative findings by the Forest-Atmosphere Carbon Transfer Storage
(FACTS-1) facility at Duke (http://www.env.duke.edu/forest/FACTSI.htm). In
that facility, sections of open forest are maintained at high CO2 levels, to
study their effects. Data from a prototype FACTS-1 facility indicated that
the forest section under study had stopped responding to high CO2 levels
with enhanced growth.

The researchers plan future studies using the apparatus to examine another
potential limitation, water availability, said Jackson.