The vertical distribution and control of microbial necromass carbon in forest soils

Aim: Forest soils contain large amounts of terrestrial organic carbon (C), but the formation pathway of soil organic C (SOC) remains unclear. Recent evidence suggests that microbial necromass is a significant source of SOC, yet a global quantitative assessment across the whole-soil profile is lacking. We aimed to assess the vertical distribution and control of microbial-derived SOC in forest soils.

Location: Global forests.

Time period: 1996-2019.

Major taxa studied: Soil microbial necromass carbon.

Methods: We evaluated the proportions of fungal and bacterial necromass C in total SOC in the litter layer, O horizon soil, and various depths of mineral soil in forests using microbial biomarker (glucosamine and muramic acid) data.

Results: The total microbial necromass C increased significantly with soil depth, ranging from 30% of SOC in O horizon soil to 62% of SOC in mineral soils below 50 cm. However, only bacterial necromass C followed this increasing trend with soil dep...

目标：森林土壤蕴含大量陆地有机碳（terrestrial organic carbon, C），但土壤有机碳（soil organic C, SOC）的形成路径仍不明确。近期研究证据表明，微生物残体（microbial necromass）是SOC的重要来源，然而目前缺乏针对全土壤剖面的全球定量评估。本研究旨在评估森林土壤中微生物源SOC的垂直分布特征及其控制因素。

地点：全球森林。

时间范围：1996-2019年。

主要研究对象：土壤微生物残体碳（soil microbial necromass carbon）。

方法：我们利用微生物生物标志物（microbial biomarker）数据（氨基葡萄糖与胞壁酸），分析了森林凋落物层、O层土壤及不同深度矿质土壤中真菌与细菌残体碳占总SOC的比例。

结果：总微生物残体碳随土壤深度显著增加，占比范围从O层土壤SOC的30%至50 cm以下矿质土壤SOC的62%。然而，仅有细菌残体碳呈现出这种随土壤深度增加的趋势……