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Research Highlight

FACE dig uncovers increased soil carbon storage under elevated carbon dioxide

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From the left, Joanne Childs, Colleen Iversen, and Rich Norby dig soil pits and excavate roots and soil at the Free-Air Carbon dioxide- Enrichment (FACE) site

Elevated carbon dioxide concentrations can increase carbon storage in the soil, according to results from a 12-year DOE-sponsored carbon dioxide–enrichment experiment led by the Environmental Science Division. The increased stor­age of carbon in soil could help to slow down rising atmo­spheric carbon dioxide concentrations.


In a paper published in Global Change Biology, ESD’s Colleen Iversen and colleagues quantified the effects of el­evated carbon dioxide concentrations on soil carbon by ex­cavating soil from large pits that were nearly 3 feet deep. The dig marked the final harvest of the Free-Air Carbon dioxide- Enrichment–or FACE–experiment that ended in 2009.

"Under elevated carbon dioxide, the trees were making more, deeper roots, which contributed to the accumulation of soil carbon," Iversen said.

She pointed out that processes such as microbial de­composition and root dynamics change with soil depth, and information on processes occurring in deeper soil will help to inform large-scale models that are projecting future cli­matic conditions.

Co-authors on the paper, "Soil carbon and nitrogen cy­cling and storage throughout the soil profile in a sweetgum plantation after 11 years of carbon dioxide-enrichment" are ESD's Charles Garten and Richard Norby, FACE project leader; and Chapman University's Jason Keller.

Reference:  Iversen et al. 2012. “Soil carbon and nitrogen cycling and storage throughout the soil profile in a sweetgum plantation after 11 years of CO2-enrichment,” Global Change Biology, 18, 1684–1697.