Abstract
Seasonality is a key feature of the biosphere and the seasonal dynamics of soil carbon (C) emissions represent a fundamental mechanism regulating the terrestrial–climate interaction. We applied a microbial explicit model—CLM-Microbe—to evaluate the impacts of microbial seasonality on soil C cycling in terrestrial ecosystems. The CLM-Microbe model was validated in simulating belowground respiratory fluxes, that is, microbial respiration, root respiration, and soil respiration at the site level. On average, the CLM-Microbe model explained 72% (n = 19, p < 0.0001), 65% (n = 19, p < 0.0001), and 71% (n = 18, p < 0.0001) of the variation in microbial respiration, root respiration, and soil respiration, respectively. We then compared the model simulations of soil respiratory fluxes and soil organic C content in top 1 m between the CLM-Microbe model with (CLM-Microbe) and without (CLM-Microbe_wos) seasonal dynamics of soil microbial biomass in natural biomes. Removing soil microbial seasonality reduced model performance in simulating microbial respiration and soil respiration, but led to slight differences in simulating root respiration. Compared with the CLM-Microbe, the CLM-Microbe_wos underestimated the annual flux of microbial respiration by 0.6%–32% and annual flux of soil respiration by 0.4%–29% in natural biomes. Correspondingly, the CLM-Microbe_wos estimated higher soil organic C content in top 1 m (0.2%–7%) except for the sites in Arctic and boreal regions. Our findings suggest that soil microbial seasonality enhances soil respiratory C emissions, leading to a decline in SOC storage. An explicit representation of soil microbial seasonality represents a critical improvement for projecting soil C decomposition and reducing the uncertainties in global C cycle projection under the changing climate.
| Original language | English |
|---|---|
| Pages (from-to) | 3035-3051 |
| Number of pages | 17 |
| Journal | Global Change Biology |
| Volume | 27 |
| Issue number | 13 |
| DOIs | |
| State | Published - Jul 2021 |
Funding
We are grateful to the editor and two anonymous reviewers for their constructive comments that have substantially improved the manuscript. The authors thank Drs. Hayley Peter-Contesse and Kate Lajtha from Oregon State University and Dr. Alejandro Cueva from University of California, Riverside for providing sampling time of respiration fluxes. This study is supported by San Diego State University and the CSU Program for Education & Research in Biotechnology. Partial support for this work was provided by an Early Career Award through the U.S. Department of Energy (DOE) Biological and Environmental Research Program. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the U.S. DOE. The data used for model parameterization and validation are obtained in published literature that have been clearly cited in the Table 1 of the manuscript. This study is also supported partly by JSPS KAKENHI Grant Numbers JP18H03365, JP19H01975 and JP19H03301. We are grateful to the editor and two anonymous reviewers for their constructive comments that have substantially improved the manuscript. The authors thank Drs. Hayley Peter\u2010Contesse and Kate Lajtha from Oregon State University and Dr. Alejandro Cueva from University of California, Riverside for providing sampling time of respiration fluxes. This study is supported by San Diego State University and the CSU Program for Education & Research in Biotechnology. Partial support for this work was provided by an Early Career Award through the U.S. Department of Energy (DOE) Biological and Environmental Research Program. Oak Ridge National Laboratory is managed by UT\u2010Battelle, LLC, under contract DE\u2010AC05\u201000OR22725 with the U.S. DOE. The data used for model parameterization and validation are obtained in published literature that have been clearly cited in the Table 1 of the manuscript. This study is also supported partly by JSPS KAKENHI Grant Numbers JP18H03365, JP19H01975 and JP19H03301.
Keywords
- microbial respiration
- microbial seasonality
- root respiration
- soil respiration