Scientists Have Series of Discoveries on Soil Microbial Carbon Pump and Carbon Storage Mechanism
The mechanism of soil carbon turnover and sequestration is a hot and difficult point in carbon biogeochemical cycling research. The improvement of soil carbon sink function is closely related to key issues such as food security, water body quality, biodiversity maintenance, land health conservation (e.g., the black soil protection in particular), the international development strategy of Carbon Neutrality, and global climate crisis.
Soil organic carbon (SOC) mainly exists in the form of soil organic matter (SOM) in terrestrial ecosystems. Nowadays, the academic community’s enthusiasm for SOM-related topics has shifted to the soil microbial metabolism and regulation theory, and there has been a consensus on the contribution of soil microbes to the formation of SOM and to the storage and stability of soil carbon pools.
The concept of "soil Microbial Carbon Pump (sMCP)" was proposed for the first time in 2017 by scientists from the Ecosystem Microbiology Research Team of the Institute of Applied Ecology, Chinese Academy of Sciences. The concept of "sMCP," in combination with "soil microbial dual metabolic pathways" and "continuous burial effect," are the three core concepts of a new theory of soil carbon sequestration. Focusing on anabolism and dead residues of soil microorganisms and their connections with soil carbon pool, the theory clarified the regulation mechanism of soil microbes on soil carbon capture, and provided a new way to study soil carbon biogeochemical cycling. The findings were published as Perspective in Nature Microbiology under the title of "The importance of anabolism in microbial control over soil carbon storage." Then, the research team followed up with a series of theoretical explorations and experimental studies around the concept of sMCP.
Following the sMCP theory and other methodologies such as model simulation and carbon & nitrogen stoichiometry, members of the research team quantified the contribution of soil microbes to soil organic carbon (SOC) pool in 2019 for the first time and discussed the systematic errors in the estimation. According to their estimation, dead microbial residues accounts for more than 50% of topsoil SOC stocks in temperate farmlands and grasslands, and also a significant proportion to forest topsoil SOC. These results were published as Opinion in Global Change Biology entitled "Quantitative assessment of microbial necromass contribution to soil organic matter."
In 2020, in a study on bioenergy croplands, the researchers of the team proposed a method to calculate parameters influencing the function of sMCP, and validated the method by quantifying sMCP in situ in the field. The results were published as Opinion in Global Change Biology entitled "the soil microbial carbon pump: from conceptual insights to empirical assessments." In addition, they published a review article in Soil Ecology Letters in 2020 under the title of "Soil microbial carbon pump: Mechanism and appraisal," in which the researchers explained in detail the mechanism and influencing factors of the sMCP-mediated carbon capture process, and discussed the methodological shortcomings of the biomarkers used for quantifying sMCP. In the same year, members of the team wrote an editorial, "Microbial necromass on the rise: the growing focus on its role in soil organic matter development," for Soil Biology and Biochemistry, reviewing the research on microbe-mediated soil carbon storage and development and discussing the problems and challenges in the research area.
In 2021, members of the research team published a review paper titled "The soil microbial carbon pump as a new concept for terrestrial carbon sequestration" in the top Chinese journal "China Science: Earth Sciences", detailing the concept, influencing factors and application prospects of sMCP, and fully expounding the role of microbial carbon source in the theoretical system of sMCP, which has important significance for promoting the research on soil carbon sink in China.
In addition, through a series of studies conducted in farmland and forest ecosystems (see the list of papers below), members of the research team revealed the effects of forest succession and farmland conservation tillage on the dynamic relationship between soil microbes and SOC, supporting the sMCP theory with a lot of first-hand (field and indoor) experimental data.
Institute of Applied Ecology, Chinese Academy of Sciences