Long-term measurements in a mixed-grass prairie reveal a change in soil organic carbon recalcitrance and its environmental sensitivity under warming

Chang Gyo Jung, Zhenggang Du, Oleksandra Hararuk, Xia Xu, Junyi Liang, Xuhui Zhou, Dejun Li, Lifen Jiang, Yiqi Luo

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)989-1002
Number of pages14
JournalOecologia
Volume197
Issue number4
DOIs
StatePublished - Dec 2021
Externally publishedYes

Keywords

  • Data-assimilation
  • Environmental sensitivity
  • Long-term warming experiment
  • Soil organic recalcitrance
  • Soil respiration

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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