Study Questions Nature's Ability to 'Self-Correct' Global Warming

FLAGSTAFF, Ariz., Aug. 6, 2013 /PRNewswire/ -- Forests have a limited capacity to soak up atmospheric carbon dioxide (CO2), according to a new study from Northern Arizona University.

The study, available online in the journal New Phytologist, aimed to explore how rising atmospheric carbon dioxide could alter the carbon (C) and nitrogen (N) content of ecosystems.

By performing tests on subtropical woodland plots over an 11-year period, the researchers found that ecosystem carbon uptake was not significantly increased by the high CO2 treatment – in contrast to expectations. While plants did contain more carbon when CO2 levels were increased, soil actually lost carbon due to microbial decomposition; both factors essentially balanced one another out.

"Nature cannot 'self-correct' entirely against climate change, and the scientific community has been both overestimating the impact of plants and underestimating the impact of soil microorganisms in how they absorb CO2 and ultimately impact global warming," said Dr. Bruce Hungate, director of The Center for Ecosystem Science and Society, Northern Arizona University and lead author on the study. "Models of land ecosystems need to be revised to represent microbial responses explicitly. They're the carbon balance 'trump card,' reversing the effect of plants on total carbon storage."

The tests confirmed that although soil microorganisms are microscopic, they are just as important as plants in determining carbon storage by ecosystems.

In addition, the study results indicate that widely accepted carbon cycle models overestimate the role of ecosystems in absorbing carbon from the atmosphere because the models do not represent the responses of soil microorganisms correctly.

Additional co-authors for the study were Paul Dijkstra (Department of Biological Sciences and The Center for Ecosystem Science and Society, Northern Arizona University), Zhuoting Wu (Department of Biological Sciences and The Center for Ecosystem Science and Society, Northern Arizona University), Benjamin Duval (U.S. Dairy Forage Research Center, USDA-ARS), Frank Day (Department of Biological Sciences, Old Dominion University), Dale Johnson (Department of Natural Resources and Environmental Science, University of Nevada), Patrick Megonigal (Smithsonian Environmental Research Center), Alisha Brown (Department of Biological Sciences, Old Dominion University) and Jay Garland (Environmental Protection Agency, Microbiological and Chemical Exposure Assessment Research Division).

Funding was provided by the U.S. Department of Energy, the National Science Foundation, NASA, and the Smithsonian Institution.

About Northern Arizona University
Northern Arizona University is a four-year public research university in Flagstaff, Ariz., that offers more than 150 different bachelor's, master's, and doctoral degrees. NAU degree programs are also accessible at 35 statewide campuses and online. Learn more about Northern Arizona University at www.nau.edu.  

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SOURCE Northern Arizona University