Publication Abstracts

Randerson et al. 1996

Randerson, J.T., M.V. Thompson, C.M. Malmstrom, C.B. Field, and I.Y. Fung, 1996: Substrate limitations for heterotrophs: Implications for models that estimate the seasonal cycle of atmospheric CO2. Glob. Biogeochem. Cycles, 10, 585-602, doi:10.1029/96GB01981.

We examine the sensitivity of the seasonal cycle of heterotropic respiration to model estimates of litterfall seasonality, herbivory, plant allocation, tissue chemistry, and land use. As a part of this amalysis, we compare heterotropic respiration models based solely on temperature and soil moisture controls (zero-order models) with models that depend on available substrate as well (first-order models). As indicators of regional and global CO2 exchange, we use maps of monthly CO2 concentrations from an atmospheric tracer transport model. In one first-order model, CASA, variations on the representation of the seasonal flow of organic matter from plants to heterotrophs can increase global GSNF as much as 60% (5.7 Pg C /yr) above estimates obtained from a zero-order model. Under a new first-order scheme that includes separate seasonal dynamics for leaf litterfall, fine root mortality, coarse woody debris, and herbicory, we observe an increase in GNSNF of 8% (0.7 Pg C / yr) over that predicted by the zero-order model. The increase in seasonality of CO2 exchange in first-order models reflects the dynamics of labile litter fractions; specifically, the rapid decomposition of a pulse of labile leaf and fine root litter that enters the heterotrophic community primarily from the middle to the end of the growing season shifts respiration outside the growing season. From the perspective of a first-order model, we then explore the consequences of land use change and winter temperature anomalies on the amplitude of the seasonal cycle of atmospheric CO2. Agricultural practices that accelerate decomposition may drive a long-term increase in the amplitude, independent of human impacts on plant production. Consideration of first-order litter decomposition dynamics may also help explain year-to-year variation in the amplitude.

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BibTeX Citation

@article{ra08200o,
  author={Randerson, J. T. and Thompson, M. V. and Malmstrom, C. M. and Field, C. B. and Fung, I. Y.},
  title={Substrate limitations for heterotrophs: Implications for models that estimate the seasonal cycle of atmospheric CO2},
  year={1996},
  journal={Glob. Biogeochem. Cycles},
  volume={10},
  pages={585--602},
  doi={10.1029/96GB01981},
}

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RIS Citation

TY  - JOUR
ID  - ra08200o
AU  - Randerson, J. T.
AU  - Thompson, M. V.
AU  - Malmstrom, C. M.
AU  - Field, C. B.
AU  - Fung, I. Y.
PY  - 1996
TI  - Substrate limitations for heterotrophs: Implications for models that estimate the seasonal cycle of atmospheric CO2
JA  - Glob. Biogeochem. Cycles
VL  - 10
SP  - 585
EP  - 602
DO  - 10.1029/96GB01981
ER  -

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