TY - JOUR
T1 - Long-term measurements in a mixed-grass prairie reveal a change in soil organic carbon recalcitrance and its environmental sensitivity under warming
AU - Jung, Chang Gyo
AU - Du, Zhenggang
AU - Hararuk, Oleksandra
AU - Xu, Xia
AU - Liang, Junyi
AU - Zhou, Xuhui
AU - Li, Dejun
AU - Jiang, Lifen
AU - Luo, Yiqi
N1 - Funding Information:
This manuscript is to be published as part of a Special Issue honoring Dr. Russell Monson. We appreciate particularly Dr. Monson’s contributions to ecophysiology. The authors thank many members of Dr. Yiqi Luo’s lab for their help with field measurements. This work was financially supported by National Science Foundation Grant DEB 1655499, US Department of Energy (DOE), Terrestrial Ecosystem Sciences Grant DE-SC0020227 and the subcontracts 4000158404 from Oak Ridge National Laboratory (ORNL) to Northern Arizona University. ORNL’s work was supported by the DOE, Office of Science, Office of Biological and Environmental Research. ORNL is managed by UT-Battelle, LLC, for DOE under contract DE-AC05-00OR22725.
Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.
PY - 2021/12
Y1 - 2021/12
N2 - Soil respiration, the major pathway for ecosystem carbon (C) loss, has the potential to enter a positive feedback loop with the atmospheric CO2 due to climate warming. For reliable projections of climate-carbon feedbacks, accurate quantification of soil respiration and identification of mechanisms that control its variability are essential. Process-based models simulate soil respiration as functions of belowground C input, organic matter quality, and sensitivity to environmental conditions. However, evaluation and calibration of process-based models against the long-term in situ measurements are rare. Here, we evaluate the performance of the Terrestrial ECOsystem (TECO) model in simulating total and heterotrophic soil respiration measured during a 16-year warming experiment in a mixed-grass prairie; calibrate model parameters against these and other measurements collected during the experiment; and explore whether the mechanisms of C dynamics have changed over the years. Calibrating model parameters against observations of individual years substantially improved model performance in comparison to pre-calibration simulations, explaining 79–86% of variability in observed soil respiration. Interannual variation of the calibrated model parameters indicated increasing recalcitrance of soil C and changing environmental sensitivity of microbes. Overall, we found that (1) soil organic C became more recalcitrant in intact soil compared to root-free soil; (2) warming offset the effects of increasing C recalcitrance in intact soil and changed microbial sensitivity to moisture conditions. These findings indicate that soil respiration may decrease in the future due to C quality, but this decrease may be offset by warming-induced changes in C cycling mechanisms and their responses to moisture conditions.
AB - Soil respiration, the major pathway for ecosystem carbon (C) loss, has the potential to enter a positive feedback loop with the atmospheric CO2 due to climate warming. For reliable projections of climate-carbon feedbacks, accurate quantification of soil respiration and identification of mechanisms that control its variability are essential. Process-based models simulate soil respiration as functions of belowground C input, organic matter quality, and sensitivity to environmental conditions. However, evaluation and calibration of process-based models against the long-term in situ measurements are rare. Here, we evaluate the performance of the Terrestrial ECOsystem (TECO) model in simulating total and heterotrophic soil respiration measured during a 16-year warming experiment in a mixed-grass prairie; calibrate model parameters against these and other measurements collected during the experiment; and explore whether the mechanisms of C dynamics have changed over the years. Calibrating model parameters against observations of individual years substantially improved model performance in comparison to pre-calibration simulations, explaining 79–86% of variability in observed soil respiration. Interannual variation of the calibrated model parameters indicated increasing recalcitrance of soil C and changing environmental sensitivity of microbes. Overall, we found that (1) soil organic C became more recalcitrant in intact soil compared to root-free soil; (2) warming offset the effects of increasing C recalcitrance in intact soil and changed microbial sensitivity to moisture conditions. These findings indicate that soil respiration may decrease in the future due to C quality, but this decrease may be offset by warming-induced changes in C cycling mechanisms and their responses to moisture conditions.
KW - Data-assimilation
KW - Environmental sensitivity
KW - Long-term warming experiment
KW - Soil organic recalcitrance
KW - Soil respiration
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U2 - 10.1007/s00442-021-04875-1
DO - 10.1007/s00442-021-04875-1
M3 - Article
C2 - 33661403
AN - SCOPUS:85102192133
SN - 0029-8549
VL - 197
SP - 989
EP - 1002
JO - Oecologia
JF - Oecologia
IS - 4
ER -