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Design and Operation of a Continuous <sup>13</sup>C and <sup>15</sup>N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling

Tracing rare stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes ...

Colorado State University

Soil C decomposition is sensitive to changes in temperature, and even small increases in temperature may prompt large releases of C from soils. But much of what we know about soil C responses to global change is based on short-term incubation data and model output that implicitly assumes soil C pools are composed of organic matter fractions with uniform temperature sensitivities. In contrast, kinetic theory based on chemical reactions suggests that older, more-resistant C fractions may be more temperature sensitive. Recent research on the subject is inconclusive, indicating that the temperature sensitivity of labile soil organic matter (OM) decomposition could either be greater than, less than, or equivalent to that of resistant soil OM. We incubated soils at constant temperature to deplete them of labile soil OM and then successively assessed the CO2-C efflux in response to warming. We found that the decomposition response to experimental warming early during soil incubation (when more labile C remained) was less than that later when labile C was depleted. These results suggest that the temperature sensitivity of resistant soil OM pools is greater than that for labile soil OM and that global change-driven soil C losses may be greater than previously estimated.

Michelle L Haddix

Natural Resource Ecology Laboratory

Colorado State University

Design and Operation of a Continuous ¹³C and ¹⁵N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling

Michelle L Haddix

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Colorado State University

Design and Operation of a Continuous 13C and 15N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling

Natural Resource Ecology Laboratory

Design and Operation of a Continuous ¹³C and ¹⁵N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling