I have been doing some research into the composition of the ancient
atmospheres. As part of that work, I ran into an intriguing line of
inquiry--what happens to plants if the levels of CO2 rises in the
atmosphere. Here is what one 1993 article said:
"In the longest carbon dioxide enrichment experiment ever conducted,
well-watered and adequately fertilized sour orange tree seedlings were
planted directly into the ground at Phoenix, Arizona, in July 1987 and
continuously exposed, from mid-November of that year, to either ambient air
or air enriched with an extra 300 ppmv of CO2 in clear-plastic wall open-top
enclosures. Only 18 months later, the CO2-enriched trees had grown 2.8 times
larger than the ambient-treated trees; and they have maintained that
productivity differential to the present day. This tremendous growth
advantage is due to two major factors: a CO2-induced increase in daytime net
photosynthesis and a CO2-induced reduction in nighttime dark respiration.
Measurements of these physiological processes in another experiment have
shown three Australian tree species to respond similarly, while an
independent study of the atmosphere's seasonal CO2 cycle suggests that all
earth's trees, in the mean, probably share this same response. A brief
review of the plant science literature outlines how such a large growth
response to atmospheric CO2 enrichment might possibly be maintained in light
of resource limitations existing in nature. Finally, it is noted that a CO2
'fertilization effect' of this magnitude should substantially slow the rate
at which anthropogenic carbon dioxide would otherwise accumulate in the
atmosphere." Sherwood B. Idso and Bruce A. Kimball, "Tree Growth in Carbon
Dioxide Enriched Air and Its Implications for Global Carbon Cycling and
Maximum Levels of Atmospheric CO2," Global Biogeochemical Cycles,
7(1993):3:537-555, p. 537
**
"Numerous experiments revealed this hypothesis to be robust. In reviewing
the results of hundreds of observations from the early 1900s through the
early 1980s, Kimball concluded that, in the mean, a 300 ppmv (parts per
million by volume) increase in the CO2 content of the air boosts the
productivity of crop and horticultural plants by about a third; and this
conclusion has been confirmed repeatedly by a number of subsequent reviews.
"But what about trees? Accounting for approximately 75% of terrestrial
photosynthesis, which comprises about 90% of the global total, woody plants
are the primary planetary players in the biological sequestration of carbon,
being responsible for fully two thirds (0.75 x 90% = 67.5%) of the planet's
net primary production." Sherwood B. Idso and Bruce A. Kimball, "Tree Growth
in Carbon Dioxide Enriched Air and Its Implications for Global Carbon
Cycling and Maximum Levels of Atmospheric CO2," Global Biogeochemical
Cycles, 7(1993):3:537-555, p. 537-538
**
"By this means we determined that at the end of two complete years of
differential CO2 exposure, the CO2-enriched trees had 2.79 times more
aboveground 'biovolume' than the ambient-treatment trees; while at the end
of three complete years of the experiment the ratio was 2.90." Sherwood B.
Idso and Bruce A. Kimball, "Tree Growth in Carbon Dioxide Enriched Air and
Its Implications for Global Carbon Cycling and Maximum Levels of Atmospheric
CO2," Global Biogeochemical Cycles, 7(1993):3:537-555, p. 539
**
The projected higher temperatures as CO2 rises will not hurt the ability of
plants to respond and act as a negative feedback:
".as Long has convincingly demonstrated that atmospheric CO2 enrichment
typically raises the optimum temperature for plant growth by several
degrees, which suggests that higher temperatures should not have hurt the
trees." Sherwood B. Idso and Bruce A. Kimball, "Tree Growth in Carbon
Dioxide Enriched Air and Its Implications for Global Carbon Cycling and
Maximum Levels of Atmospheric CO2," Global Biogeochemical Cycles,
7(1993):3:537-555, p. 545
**
"The implications of these observations are profound. They suggest, first
of all, that trees are currently operating far below their genetic potential
for growth. Other plants are obviously operating below their maximum growth
potential too: but trees may be operating far below. Hence Earth's 'global
forest' could benefit immensely from the rising CO2 content of the
atmosphere. In fact, if the air's CO2 productivity of the planet's trees may
possibly rise severalfold.
"The consequences of such a growth stimulation are staggering. Most obvious
is the equivalent severalfold enhancement of harvestable forest products
that would result from the magnified tree growth. Greater forest biomass
would also imply greater niche availability for animals that reside there,
so that both larger and more diverse populations of conceivably even more
species could possibly co-exist within smaller geographical areas.
"Perhaps most important of all, greatly enhanced tree growth would greatly
augment the biospheric removal of carbon dioxide from the atmosphere. In
fact, for the degree of growth stimulation identified in this review. Idso
has calculated that, for current anthropogenic CO@ emission rates and the
current size of earth's 'global forest,' the CO2 content of the atmosphere
could rise by only about another 170 ppmv. At that point, earth's vegetation
would have the capacity to yearly remove from the atmosphere all of the CO2
that man yearly puts into it that is not absorbed by the oceans. Indeed,
Marland (1988, p. 56) has stated that such a stimulation of forest growth
would in 18-36 years return to the biosphere all of the carbon that has been
released over the last 100 to 200 years,' citing Houghton et al. (1985) as a
basis for this statement." Sherwood B. Idso and Bruce A. Kimball, "Tree
Growth in Carbon Dioxide Enriched Air and Its Implications for Global Carbon
Cycling and Maximum Levels of Atmospheric CO2," Global Biogeochemical
Cycles, 7(1993):3:537-555, p. 550-551
**
God certainly has designed a marvelous place.
glenn
Foundation, Fall and Flood
Adam, Apes and Anthropology
http://www.flash.net/~mortongr/dmd.htm
Lots of information on creation/evolution
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