Nitrogen inputs and losses in response to chronic CO2 exposure in a subtropical oak woodland

Bruce A Hungate, B. D. Duval, Paul Dijkstra, D. W. Johnson, Michael E Ketterer, P. Stiling, W. Cheng, J. Millman, A. Hartley, D. B. Stover

Research output: Contribution to journalArticle

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Abstract

Rising atmospheric CO2 concentrations may alter the nitrogen (N) content of ecosystems by changing N inputs and N losses, but responses vary in field experiments, possibly because multiple mechanisms are at play. We measured N fixation and N losses in a subtropical oak woodland exposed to 11 years of elevated atmospheric CO2 concentrations. We also explored the role of herbivory, carbon limitation, and competition for light or nutrients in shaping the response of N fixation to elevated CO2. Elevated CO2 did not significantly alter gaseous N losses, but lower recovery and deeper distribution in the soil of a long-term 15N tracer indicated that elevated CO2 increased leaching losses. Elevated CO2 had no effect on nonsymbiotic N fixation, and had a transient effect on symbiotic N fixation by the dominant legume. Elevated CO2 tended to reduce soil and plant concentrations of iron, molybdenum, phosphorus, and vanadium, nutrients essential for N fixation. Competition for nutrients and herbivory likely contributed to the declining response of N fixation to elevated CO2. These results indicate that positive responses of N fixation to elevated CO 2 may be transient and that chronic exposure to elevated CO 2 can increase N leaching. Models that assume increased fixation or reduced N losses with elevated CO2 may overestimate future N accumulation in the biosphere.

Original languageEnglish (US)
Pages (from-to)3323-3337
Number of pages15
JournalBiogeosciences
Volume11
Issue number12
DOIs
StatePublished - Jun 23 2014

Fingerprint

fixation
woodlands
woodland
Quercus
nitrogen
leaching
nutrients
herbivores
vanadium
molybdenum
chronic exposure
tracer techniques
soil
legumes
herbivory
iron
nutrient
phosphorus
ecosystems
carbon

ASJC Scopus subject areas

  • Earth-Surface Processes
  • Ecology, Evolution, Behavior and Systematics

Cite this

Nitrogen inputs and losses in response to chronic CO2 exposure in a subtropical oak woodland. / Hungate, Bruce A; Duval, B. D.; Dijkstra, Paul; Johnson, D. W.; Ketterer, Michael E; Stiling, P.; Cheng, W.; Millman, J.; Hartley, A.; Stover, D. B.

In: Biogeosciences, Vol. 11, No. 12, 23.06.2014, p. 3323-3337.

Research output: Contribution to journalArticle

Hungate, BA, Duval, BD, Dijkstra, P, Johnson, DW, Ketterer, ME, Stiling, P, Cheng, W, Millman, J, Hartley, A & Stover, DB 2014, 'Nitrogen inputs and losses in response to chronic CO2 exposure in a subtropical oak woodland', Biogeosciences, vol. 11, no. 12, pp. 3323-3337. https://doi.org/10.5194/bg-11-3323-2014
Hungate, Bruce A ; Duval, B. D. ; Dijkstra, Paul ; Johnson, D. W. ; Ketterer, Michael E ; Stiling, P. ; Cheng, W. ; Millman, J. ; Hartley, A. ; Stover, D. B. / Nitrogen inputs and losses in response to chronic CO2 exposure in a subtropical oak woodland. In: Biogeosciences. 2014 ; Vol. 11, No. 12. pp. 3323-3337.
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