Trees' use of nitrogen has climate impact

Aug. 31, 2011 at 8:14 PM

DAVIS, Calif., Aug. 31 (UPI) -- Trees' ability to draw nitrogen from bedrock to boost growth increases their ability to absorb carbon dioxide and buffer climate change, a U.S. study found.

Nitrogen is necessary for all life and is the nutrient that most often limits plant growth in natural ecosystems, researchers at the University of California, Davis, said. If trees can access more nitrogen than previously thought, it could lead to more storage of carbon on land and less carbon remaining in the atmosphere, they said.

It was previously believed nitrogen could only enter ecosystems from the atmosphere.

"We were really shocked; everything we've ever thought about the nitrogen cycle and all of the textbook theories have been turned on their heads by these data," Benjamin Houlton, a biogeochemist and one of the study's co-authors, said. "Findings from this study suggest that our climate-change models should not only consider the importance of nitrogen from the atmosphere, but now we also have to start thinking about how rocks may affect climate change."

The UC Davis study found that rocks enriched in nitrogen have a profound effect on the fertility of forests.

"To put it in perspective, there is enough nitrogen contained in one inch of the rocks at our study site to completely support the growth of a typical coniferous forest for about 25 years," biogeochemist and study-coauthor Randy Dahlgren said.

The productivity of forests growing on nitrogen-rich rock was approximately 50 percent higher than the productivity of forests growing on nitrogen-poor rocks throughout Northern California and into Oregon, the study found.

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