Soil microorganisms play an important role in carbon cycling. In addition to microbes take up the liable carbon for growth, their residue carbon also makes a high contribution to soil stable carbon pool. In recent years, the relationship between soil organic carbon (SOC) and microbial necromass has been extensively explored, however, whether microbial physiological traits affect microbial necromass and how to link among microbial biomass, microbial necromass and SOC are less studies.  

In August 2018, Associate Prof. WANG Chao and Ph.D student QU Lingrui from the Institute of Applied Ecology (IAE) of the Chinese Academy of Sciences (CAS) conducted a laboratory incubation experiment with soil samples collected from 16 forest sites along a north-south transect in eastern China. 

The researchers measured SOC, microbial physiological parameters (microbial biomass carbon, carbon use efficiency, turnover rate) and residue index (amino sugar) and found that SOC was positively correlated with microbial biomass carbon and amino sugar, and negatively correlated with mean annual temperature and precipitation.

In addition, the general linear model with physiological parameters and residue index was more effective in simulating SOC content. 

Subsequently, structural equation model analyses showed that microbial biomass carbon pool and necromass carbon pool were regulated mainly by climate and soil factors, which indirectly controlled SOC pool.  

Results provide a novel platform for developing the effects of microbial community structure, physiological parameters and necromass on SOC content on a large-scale. 

The results were published in an article in Global Change Biology entitled "Large-scale importance of microbial carbon use efficiency and necromass to soil organic carbon".  

This study was supported by the National Natural Science Foundation of China, the key Research Program of Frontier Sciences of CAS, the Youth Promotion Association of CAS and the National Program of Support of Top-notch Young Professionals.