the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Conditional CO2 flux analysis of a managed grassland with the aid of stable isotopes
M. J. Zeeman
B. Tuzson
L. Emmenegger
A. Knohl
N. Buchmann
W. Eugster
Abstract. Short statured managed ecosystems, such as agricultural grasslands, exhibit high temporal changes in carbon dioxide assimilation and respiration fluxes for which measurements of the net CO2 flux, e.g. by using the eddy covariance (EC) method, give only limited insight. We have therefore adopted a recently proposed concept for conditional EC flux analysis of forest to grasslands, in order to identify and quantify daytime sub-canopy respiration fluxes. To validate the concept, high frequency (≈5 Hz) stable carbon isotope analyis of CO2 was used. We made eddy covariance measurements of CO2 and its isotopologues during four days in August 2007, using a novel quantum cascade laser absorption spectrometer, capable of high time resolution stable isotope analysis. The effects of a grass cut during the measurement period could be detected and resulted in a sub-canopy source conditional flux classification, for which the isotope composition of the CO2 could be confirmed to be of a respiration source. However, the conditional flux method did not work for an undisturbed grassland canopy. We attribute this to the flux measurement height that was chosen well above the roughness sublayer, where the natural isotopic tracer (δ13C) of respiration was too well mixed with background air.
M. J. Zeeman et al.
- RC C294: 'referee comment', Anonymous Referee #1, 05 May 2009
- RC C363: 'Review of 'Conditional Review of “Conditional CO2 flux analysis of a managed grassland with the aid of stable isotopes” by M. Zeeman et al.', Anonymous Referee #2, 08 May 2009
- SC C544: 'Response to RCs', Matthias J. Zeeman, 27 May 2009
- AC C1112: 'Final Response', Matthias J. Zeeman, 10 Jul 2009
- RC C294: 'referee comment', Anonymous Referee #1, 05 May 2009
- RC C363: 'Review of 'Conditional Review of “Conditional CO2 flux analysis of a managed grassland with the aid of stable isotopes” by M. Zeeman et al.', Anonymous Referee #2, 08 May 2009
- SC C544: 'Response to RCs', Matthias J. Zeeman, 27 May 2009
- AC C1112: 'Final Response', Matthias J. Zeeman, 10 Jul 2009
M. J. Zeeman et al.
M. J. Zeeman et al.
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Cited
5 citations as recorded by crossref.
- Summer drought reduces total and litter-derived soil CO<sub>2</sub> effluxes in temperate grassland – clues from a <sup>13</sup>C litter addition experiment O. Joos et al. 10.5194/bg-7-1031-2010
- Continuous isotopic composition measurements of tropospheric CO<sub>2</sub> at Jungfraujoch (3580 m a.s.l.), Switzerland: real-time observation of regional pollution events B. Tuzson et al. 10.5194/acp-11-1685-2011
- Eddy covariance measurements of CO2 isotopologues with a quantum cascade laser absorption spectrometer P. Sturm et al. 10.1016/j.agrformet.2011.09.007
- Contrasting response of grassland versus forest carbon and water fluxes to spring drought in Switzerland S. Wolf et al. 10.1088/1748-9326/8/3/035007
- Concurrency of Coherent Structures and Conditionally Sampled Daytime Sub-canopy Respiration M. Zeeman et al. 10.1007/s10546-012-9745-2