Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.
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Primary Research Article
Soil carbon and nitrogen cycling and storage throughout the soil profile in a sweetgum plantation after 11 years of CO2-enrichment
Article first published online: 2 MAR 2012
DOI: 10.1111/j.1365-2486.2012.02643.x
Published 2012 This article is a U.S. Government work and is in the public domain in the USA
Additional Information
How to Cite
Iversen, C. M., Keller, J. K., Garten, C. T. and Norby, R. J. (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. doi: 10.1111/j.1365-2486.2012.02643.x
Publication History
- Issue published online: 9 APR 2012
- Article first published online: 2 MAR 2012
- Accepted manuscript online: 23 JAN 2012 06:28AM EST
- Manuscript Accepted: 11 DEC 2011
- Manuscript Received: 25 OCT 2011
Funded by
- Biological and Environmental Research. Grant Number: DE-AC05-00OR22725
Keywords:
- 13C;
- carbon mineralization;
- elevated [CO2];
- fine roots;
- Liquidambar styraciflua;
- mineral-associated organic matter;
- net nitrogen mineralization;
- particulate organic matter;
- soil carbon;
- soil depth
Abstract
Increased partitioning of carbon (C) to fine roots under elevated [CO2], especially deep in the soil profile, could alter soil C and nitrogen (N) cycling in forests. After more than 11 years of free-air CO2 enrichment in a Liquidambar styraciflua L. (sweetgum) plantation in Oak Ridge, TN, USA, greater inputs of fine roots resulted in the incorporation of new C (i.e., C with a depleted δ13C) into root-derived particulate organic matter (POM) pools to 90-cm depth. Even though production in the sweetgum stand was limited by soil N availability, soil C and N contents were greater throughout the soil profile under elevated [CO2] at the conclusion of the experiment. Greater C inputs from fine-root detritus under elevated [CO2] did not result in increased net N immobilization or C mineralization rates in long-term laboratory incubations, possibly because microbial biomass was lower in the CO2-enriched plots. Furthermore, the δ13CO2 of the C mineralized from the incubated soil closely tracked the δ13C of the labile POM pool in the elevated [CO2] treatment, especially in shallower soil, and did not indicate significant priming of the decomposition of pre-experiment soil organic matter (SOM). Although potential C mineralization rates were positively and linearly related to total SOM C content in the top 30 cm of soil, this relationship did not hold in deeper soil. Taken together with an increased mean residence time of C in deeper soil pools, these findings indicate that C inputs from relatively deep roots under elevated [CO2] may increase the potential for long-term soil C storage. However, C in deeper soil is likely to take many years to accrue to a significant fraction of total soil C given relatively smaller root inputs at depth. Expanded representation of biogeochemical cycling throughout the soil profile may improve model projections of future forest responses to rising atmospheric [CO2].