Dynamics of isotopic exchange of carbon dioxide in a tennessee deciduous forest

David R. Bowling, Dennis D. Baldocchi, Russell Monson

Research output: Contribution to journalArticle

67 Citations (Scopus)

Abstract

The combination of isotopic measurements and micrometeorological flux measurements is a powerful new approach that will likely lead to new insight into the dynamics of CO2 exchange between terrestrial ecosystems and the atmosphere. Since the biological processes of photosynthesis and respiration modify the stable isotopic signature of atmospheric CO2 in different ways, measurements of the net fluxes of CO2, 13CO2, and C18OO can be used to investigate the relative contribution of each process to net ecosystem CO2 exchange. We used two independent approaches to measure isotopic fluxes of CO2 over a Tennessee oak-maple-hickory forest in summer 1998. These approaches involved (1) a combination of standard eddy covariance with intensive flask sampling, and (2) a modification to the relaxed eddy accumulation technique. Strong isotopic signals associated with photosynthesis and respiration were observed and persisted in forest air despite the potential for mixing due to atmospheric turbulence. Calm nights allowed a buildup of respiratory CO2 below the canopy and were associated with isotopically depleted forest air in the morning. Windy nights were followed by a relatively more enriched early-morning isotopic signal. Entrainment of air from above the decaying nocturnal boundary layer during daytime mixed layer growth exerted strong control on isotopic composition of forest air, resulting in similar isotope ratios in the late afternoon despite different isotopic starting points following calm or windy nights. The influences of the convective boundary layer and turbulent mixing within the forest cannot be ignored when using isotopes of CO2 to investigate biological processes.

Original languageEnglish (US)
Pages (from-to)903-922
Number of pages20
JournalGlobal Biogeochemical Cycles
Volume13
Issue number4
DOIs
StatePublished - 1999
Externally publishedYes

Fingerprint

deciduous forest
Carbon Dioxide
carbon dioxide
Photosynthesis
Fluxes
Air
Isotopes
Ecosystems
air
Boundary layers
biological processes
photosynthesis
respiration
Air entrainment
Atmospheric turbulence
isotope
nocturnal boundary layer
convective boundary layer
turbulent mixing
eddy covariance

ASJC Scopus subject areas

  • Global and Planetary Change
  • Atmospheric Science
  • Environmental Science(all)
  • Environmental Chemistry

Cite this

Dynamics of isotopic exchange of carbon dioxide in a tennessee deciduous forest. / Bowling, David R.; Baldocchi, Dennis D.; Monson, Russell.

In: Global Biogeochemical Cycles, Vol. 13, No. 4, 1999, p. 903-922.

Research output: Contribution to journalArticle

Bowling, David R. ; Baldocchi, Dennis D. ; Monson, Russell. / Dynamics of isotopic exchange of carbon dioxide in a tennessee deciduous forest. In: Global Biogeochemical Cycles. 1999 ; Vol. 13, No. 4. pp. 903-922.
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