Microorganisms play an important role in the formation and turnover of soil organic matter, and microbial residues (necromass) represent an important pool of soil organic nitrogen. To date, however, the mechanism controlling the production, turnover and stabilization of soil microbial necromass is still unclear. In addition, it remains unclear whether global warming affects soil organic matter turnover via affecting microbial necromass dynamics.
To address this issue, researchers from the Biogeochemistry Group of the Institute of Applied Ecology (IAE), Chinese Academy of Sciences (CAS), isolated a number of strains of bacteria and fungi from soils in a temperate forest in Changbai Mountain National Nature Reserve using the classical microbial culturing method.
The researchers incubated microbial necromass using a medium containing enriched nitrogen isotopes, and then determined microbial necromass decomposition rates under different temperature conditions.
Despite the differences in chemical composition, the mineralization rates of bacterial and fungal necromass nitrogen were not significantly different. Under higher temperature conditions, the formation rate of microbial necromass was higher than its decomposition rate, resulting in the accumulation of necromass nitrogen in soil.
Most microbial necromass 15N (nitrogen) was recovered in the mineral‐associated organic matter, indicating that the stabilization of necromass nitrogen is mainly controlled by mineral protection rather than by necromass quality.
This research reveals the effects of elevated temperature on decomposition and stabilization process of microbial necromass nitrogen. The finding provides data support and theoretical basis for more accurately predicting the response of soil organic matter under global climate change scenarios.
The study has been published in the journal Global Change Biology WITH the title of "Elevated temperature increases the accumulation of microbial necromass nitrogen in soil via increasing microbial turnover."
This work was financially supported by the Original Innovation Program of CAS, the Key Program of the National Natural Science Foundation of China, the Youth Innovation Promotion Association of CAS and the National Science Fund for Distinguished Young Scholars.
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