dc.identifier.citation |
Hungate, Bruce A., Dijkstra, Paul, Wu, Zhuoting, Duval, Benjamin D., Day, Frank P., Johnson, Dale W., Megonigal, J. Patrick, Brown, Alisha L. P., and Garland, Jay L. 2013. "<a href="https%3A%2F%2Frepository.si.edu%2Fhandle%2F10088%2F21648">Cumulative response of ecosystem carbon and nitrogen stocks to chronic CO2 exposure in a subtropical oak woodland</a>." <em>New Phytologist</em>. 200 (3):753–766. <a href="https://doi.org/10.1111/nph.12333">https://doi.org/10.1111/nph.12333</a> |
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dc.description.abstract |
* Rising atmospheric carbon dioxide (CO2) could alter the carbon (C) and nitrogen (N) content of ecosystems, yet the magnitude of these effects are not well known. We examined C and N budgets of a subtropical woodland after 11 yr of exposure to elevated CO2. * We used open-top chambers to manipulate CO2 during regrowth after fire, and measured C, N and tracer 15N in ecosystem components throughout the experiment. * Elevated CO2 increased plant C and tended to increase plant N but did not significantly increase whole-system C or N. Elevated CO2 increased soil microbial activity and labile soil C, but more slowly cycling soil C pools tended to decline. Recovery of a long-term 15N tracer indicated that CO2 exposure increased N losses and altered N distribution, with no effect on N inputs. * Increased plant C accrual was accompanied by higher soil microbial activity and increased C losses from soil, yielding no statistically detectable effect of elevated CO2 on net ecosystem C uptake. These findings challenge the treatment of terrestrial ecosystems responses to elevated CO2 in current biogeochemical models, where the effect of elevated CO2 on ecosystem C balance is described as enhanced photosynthesis and plant growth with decomposition as a first-order response. |
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