A particularly resilient type of carbon from the first plants to regrow after the last ice age and that same type of carbon from all the plants since appears to have been accumulating for 11,000 years in the forests of British Columbia, Canada.

It's as if the carbon, which comes from the waxy material plants generate to protect their foliage from sun and weather, has been going into a bank account where only deposits are being made and virtually no withdrawals.

Modelers of the Earth's carbon cycle, who've worked on the assumption that this type of carbon remains in the soils only 1,000 to 10,000 years before microorganisms return it to the atmosphere as carbon dioxide, will need to revise their thinking if findings reported in the Nov. 24 issue of Science are typical of other northern forests.

"Our results about the resilience of this particular kind of carbon suggest that the turnover time of this carbon pool may be 10,000 to 100,000 years," says Rienk Smittenberg, a research associate with the University of Washington School of Oceanography and lead author of the paper. He did the work while at the Royal Netherlands Institute of Sea Research.

Soils harbor the third-largest pool of carbon in the world behind the carbon locked deep in the Earth as fossil fuel oils and coal and the carbon that is dissolved in the world's oceans.

In soils, the more edible kinds of carbon from plants are quickly digested by bacteria and turned back into carbon dioxide. But about half the organic carbon in soils is less edible or protected from the bacteria, making it ultimately responsible for long-term carbon storage on land, the authors say.

This carbon pool is not likely to have a role in offsetting increased greenhouse carbon dioxide in the atmosphere any time soon because of the very slow processes at work, Smittenberg says. Instead a better estimate of how long that carbon persists in soils is important for modelers interested in carbon rese
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Contact: Sandra Hines
shines@u.washington.edu
206-543-2580
University of Washington
23-Nov-2006