Document Type

Article

Publication Date

2013

DOI

10.1111/nph.12333

Publication Title

New Phytologist

Volume

200

Issue

3

Pages

753-766

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.

Rights

Published under an Attribution 3.0 Unported (CC BY 3.0) license.

https://creativecommons.org/licenses/by/3.0/

Original Publication Citation

Hungate, B. A., Dijkstra, P., Wu, Z. T., Duval, B. D., Day, F. P., Johnson, D. W., . . . Garland, J. L. (2013). Cumulative response of ecosystem carbon and nitrogen stocks to chronic CO2 exposure in a subtropical oak woodland. New Phytologist, 200(3), 753-766. doi:10.1111/nph.12333

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