Critical evaluation of micrometeorological methods for measuring ecosystem–atmosphere isotopic exchange of CO₂

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• 作者：Bowling ; David R. ; Pataki ; Diane E. ; Ehleringer ; James R.
• 关键词：Net ecosystem exchange ; Isotopic fluxes ; Isoflux ; Photosynthesis ; Respiration ; Hyperbolic relaxed eddy accumulation
• 刊名：Agricultural and Forest Meteorology
• 出版年：2003
• 出版时间：May 31, 2003
• 年：2003
• 卷：116
• 期：3-4
• 页码：159-179
• 全文大小：349 K

文摘

Isotopic net ecosystem exchange (isofluxes, or flux densities of ¹³CO₂) can be combined with standard eddy covariance methods to partition net ecosystem exchange of carbon dioxide (F) into its component one-way fluxes, photosynthesis and respiration. At present, the approaches used to estimate isotopic fluxes are labor-intensive and dependent on several assumptions. To assess the relative utility of the available methods, we studied an ecosystem associated with large CO₂ fluxes and maximal isotopic exchange. Three independent techniques were used to measure isotopic flux densities over an irrigated alfalfa field: (1) a combination of standard eddy covariance and flask sampling; (2) the flux-gradient method; and (3) hyperbolic relaxed eddy accumulation (HREA). Consistent isotopic flux results were obtained via the three methods, with similar diurnal patterns and peak midday isotopic flux densities of 600–700μmolm⁻²s⁻¹‰.