HR: 16:15h
AN: B14B-02    [Abstracts]
TI: High-resolution stable-isotope partitioning of net ecosystem exchange into respiration and photosynthesis
AU: * Zobitz, J M
EM: zobitz@math.utah.edu
AF: University of Utah, Department of Mathematics 155 South 1400 East, Salt Lake City, UT 84112-0090 United States
AU: Ogée, J
EM: ogee@pierroton.inra.fr
AF: Institut National de la Recherche Agronomique, 71 Avenue Edouard Bourlaux BP81, Bordeaux, 33883 France
AU: Monson, R K
EM: Russell.Monson@colorado.edu
AF: University of Colorado, Department of Ecology and Evolutionary Biology, Campus Box 334 University of Colorado, Boulder, CO 80309-0334 United States
AU: Bowling, D R
EM: bowling@biology.utah.edu
AF: University of Utah, Department of Biology 257 S 1400 E, Salt Lake City, UT 84112 United States
AB: We estimated ecosystem-scale photosynthesis and respiration in a subalpine forest (Niwot Ridge, CO AmeriFlux site) via a Bayesian technique in conjunction with high-resolution [CO₂] and δ¹³C stable isotope ratio measurements taken with a tunable diode laser (TDL) spectrometer during the summer of 2003. Isotope-derived half-hourly estimates of photosynthesis and respiration were obtained with <1 μmol m^-2 s^-1 uncertainty, as well as estimates of δ¹³C_r, the isotopic signature of respiration and Δ, the carbon isotope discrimination of net photosynthesis. Estimates of δ¹³C_r range from -25 to -28‰ with uncertainty <1‰, even when the range of [CO₂] measurements were small (<20 ppm). Estimates of Δ are 16-19‰, in agreement with past studies at the Niwot Ridge site. Isotope-derived estimates of photosynthesis and respiration from this study have correlations to environmental drivers (e.g. light, vapor pressure deficit, and temperature) even though no a priori relationship was assumed, suggesting the possibility of using stable-isotope partitioning to derive meaningful ecosystem-scale physiological relationships.
DE: 0428 Carbon cycling (4806)
DE: 0434 Data sets
DE: 0438 Diel, seasonal, and annual cycles (4227)
DE: 0466 Modeling
DE: 0476 Plant ecology (1851)
SC: Biogeosciences [B]
MN: Fall Meeting 2005