Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 13, 887-902, 2016
https://doi.org/10.5194/bg-13-887-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
18 Feb 2016
Responses of two nonlinear microbial models to warming and increased carbon input
Y. P. Wang1, J. Jiang2, B. Chen-Charpentier3, F. B. Agusto4, A. Hastings5, F. Hoffman6, M. Rasmussen7, M. J. Smith8, K. Todd-Brown9,11, Y. Wang10, X. Xu9, and Y. Q. Luo9 1CSIRO Ocean and Atmosphere, PMB 1, Aspendale, Victoria 3195, Australia
2Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996, USA
3Department of Mathematics, University of Texas, Arlington, TX, USA
4Department of Mathematics and Statistics, Austin Peay State University, Clarksville TN 37044, USA
5Department of Environmental Science and Policy, University of California, One Shields Avenue, Davis, CA 95616, USA
6Oak Ridge National Laboratory, Computational Earth Sciences Group, P.O. Box 2008, Oak Ridge, TN 37831, USA
7Department of Mathematics, Imperial College, London, UK
8Computational Science Laboratory, Microsoft Research, Cambridge, UK
9Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, USA
10Department of Mathematics, University of Oklahoma, Norman, OK, USA
11Pacific Northwest National Laboratory, Richland, WA, USA
Abstract. A number of nonlinear microbial models of soil carbon decomposition have been developed. Some of them have been applied globally but have yet to be shown to realistically represent soil carbon dynamics in the field. A thorough analysis of their key differences is needed to inform future model developments. Here we compare two nonlinear microbial models of soil carbon decomposition: one based on reverse Michaelis–Menten kinetics (model A) and the other on regular Michaelis–Menten kinetics (model B). Using analytic approximations and numerical solutions, we find that the oscillatory responses of carbon pools to a small perturbation in their initial pool sizes dampen faster in model A than in model B. Soil warming always decreases carbon storage in model A, but in model B it predominantly decreases carbon storage in cool regions and increases carbon storage in warm regions. For both models, the CO2 efflux from soil carbon decomposition reaches a maximum value some time after increased carbon input (as in priming experiments). This maximum CO2 efflux (Fmax) decreases with an increase in soil temperature in both models. However, the sensitivity of Fmax to the increased amount of carbon input increases with soil temperature in model A but decreases monotonically with an increase in soil temperature in model B. These differences in the responses to soil warming and carbon input between the two nonlinear models can be used to discern which model is more realistic when compared to results from field or laboratory experiments. These insights will contribute to an improved understanding of the significance of soil microbial processes in soil carbon responses to future climate change.

Citation: Wang, Y. P., Jiang, J., Chen-Charpentier, B., Agusto, F. B., Hastings, A., Hoffman, F., Rasmussen, M., Smith, M. J., Todd-Brown, K., Wang, Y., Xu, X., and Luo, Y. Q.: Responses of two nonlinear microbial models to warming and increased carbon input, Biogeosciences, 13, 887-902, https://doi.org/10.5194/bg-13-887-2016, 2016.
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Short summary
Comparing two nonlinear microbial models, we found that, in response to warming, soil C decreases in one model but can increase or decrease in the other model, and sensitivity of priming response to carbon input increases with soil T in one model but decreases in the other model Significance: these differences in the responses can be used to discern which model is more realistic, which will improve our understanding of the significance of soil microbial processes in the terrestrial C cycle.
Comparing two nonlinear microbial models, we found that, in response to warming, soil C...
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