Cumulative response of ecosystem carbon and nitrogen stocks to chronic CO2 exposure in a subtropical oak woodland
Article first published online: 30 MAY 2013
© 2013 The Authors. New Phytologist © 2013 New Phytologist Trust
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Volume 200, Issue 3, pages 753–766, November 2013
How to Cite
Hungate, B. A., Dijkstra, P., Wu, Z., Duval, B. D., Day, F. P., Johnson, D. W., Megonigal, J. P., Brown, A. L. P. and Garland, J. L. (2013), Cumulative response of ecosystem carbon and nitrogen stocks to chronic CO2 exposure in a subtropical oak woodland. New Phytologist, 200: 753–766. doi: 10.1111/nph.12333
- Issue published online: 11 OCT 2013
- Article first published online: 30 MAY 2013
- Manuscript Accepted: 10 APR 2013
- Manuscript Received: 24 JAN 2013
- US Department of Energy. Grant Number: DE-FG-02-95ER61993
- National Science Foundation. Grant Numbers: DEB 9873715, 0092642, 0445324
- carbon cycling;
- elevated CO2;
- global change;
- long-term experiment;
- nitrogen cycling;
- scrub oak;
- soil carbon;
- subtropical woodland
- 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.