Ground-Level Ozone Blocks Trees' Carbon Absorption

Ozone May Offset Capacity of Trees to Sop Up Carbon
By Andrew C. Revkin
New York Times

"Scientists have long identified forests as a potential buffer against rising concentrations of carbon dioxide, the main smokestack and tailpipe emissions linked by most scientists to global warming. Trees sop up the heat-trapping greenhouse gas through photosynthesis and stash it in soil. The more carbon dioxide there is in air, the more that forests, in theory, can lock up in the earth.

But a new experiment has shown that fairly common concentrations of ozone, the eye-stinging ingredient in smog, can sharply impede this process. Thus, one kind of air pollution common in the Northern Hemisphere appears to hamper natural absorption of another, said the researchers, who report their findings in today's issue of the journal Nature.

"If we're increasing carbon in the atmosphere and we expect forests to be able to keep up, ozone could make it difficult for trees to compensate," said Dr. Wendy M. Loya, the lead author of the study and a research scientist at Michigan Technological University.

In the study, some experimental plots of trees were exposed to elevated levels of carbon dioxide and ozone, while others were exposed to higher levels of carbon dioxide alone. The trees exposed to ozone stored only half as much carbon in soil as the other trees."

EDIT

http://www.nytimes.com/2003/10/16/science/16SMOG.html

in either validated models or the real world.

Try these references.

Volin, J.C., Reich, P.B. and Givnish, T.J. 1998. Elevated carbon dioxide ameliorates the effects of ozone on photosynthesis and growth: species respond similarly regardless of photosynthetic pathway or plant functional group. New Phytologist 138: 315-325.

Wolf, J. and van Oijen, M. 2003. Model simulation of effects of changes in climate and atmospheric CO2 and O3 on tuber yield potential of potato (cv. Bintje) in the European Union. Agriculture, Ecosystems and Environment 94: 141-157.

Vilhena-Cardoso, J. and Barnes, J. 2001. Does nitrogen supply affect the response of wheat (Triticum aestivum cv. Hanno) to the combination of elevated CO2 and O3? Journal of Experimental Botany 52: 1901-1911.

Heagle, A.S., Miller, J.E. and Pursley, W.A. 2000. Growth and yield responses of winter wheat to mixtures of ozone and carbon dioxide. Crop Science 40: 1656-1664.