微生物介导的土壤有机碳动态研究进展

Advances on Soil Organic Carbon Dynamics Mediated by Microorganisms

土壤有机碳因其储量大、驻留时间长而成为陆地生态系统碳库的主要组分,其微小变化将对陆地碳通量和全球气候变化产生重大影响。土壤有机碳的组成、转化和稳定性机制主要受土壤微生物调控。综述了微生物介导的土壤有机碳形成、转化和稳定等方面的研究进展。土壤有机碳包括植物源碳和微生物源碳两部分:植物碳是土壤有机碳的主要来源,而土壤微生物活性是土壤有机碳形成、转化和稳定的主要驱动力。土壤微生物通过“体外修饰”途径将植物碳分解形成易周转的土壤颗粒态有机碳;微生物通过“体内周转”途径形成的微生物残体碳,与土壤黏土矿物相互作用形成的矿物结合态有机碳均贡献于土壤有机碳稳定组分。激发效应和续埋效应之间的平衡,调控土壤有机碳库的储量和稳定。全球尺度上,介导土壤有机碳变化的微生物活性受制于年降水量和土壤环境要素(如土壤有机碳、总氮和p H等)。响应于全球变化,将来应关注植物凋落物—微生物活性—土壤基质耦合调控的土壤有机碳数量与质量变化机制研究以及微生物碳利用效率的环境依赖性探究,以揭示土壤微生物对土壤有机碳周转及稳定性维持的调控机制。

Soil Organic Carbon(SOC)is a crucial component of the carbon pool in terrestrial ecosystems because of its high storage capacity and long residence time.Slight changes in the SOC pool have a remarkable impact on terrestrial carbon flux and global climate change.The mechanisms of composition,transformation,and stability of SOC are primarily controlled by soil microbial properties.Therefore,the research results on the formation,transformation,and stabilization of SOC mediated by microorganisms are reviewed here,with the aim to further understand the function of soil carbon sequestration.SOC consists of plant-and microorganisms-driven carbons.Plant carbon is the major source of SOC.Soil microbial activity is the primary driving force of SOC formation,transformation,and stabilization.Soil microorganisms decompose plant carbon to form easy turnover soil particulate organic carbon through the“ex vivo modification”pathway.Microbial Residual Carbon(MRC)produced by soil microorganisms through the“in vivo turnover”pathway and Mineral-Associated Organic Carbon(MAOC)formed by the interaction with soil clay minerals contribute to stable SOC components,of which the contribution rate of MRC to stable SOC has been reported to be 38.74%.The equilibrium between the“priming and ongoing burial effects”regulates the storage and stability of SOC.On a global scale,the microbial activity mediating SOC changes is subject to annual precipitation and soil environmental factors(SOC,TN and pH).In response to global changes,the mechanism of SOC quantity and quality control by coupling plant litter,microbial activity,and soil matrix should be given more attention.In addition,environmental dependence of microbial carbon use efficiency should be focused to improve our understanding of the carbon sequestration effect of soil microorganisms.