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Background and aims <p>Elucidating mechanisms and quantifying relative contributions of plant versus microbial carbon to mineral-associated organic carbon (MAOC) are essential for managing and modelling soil carbon sequestration in the combat of climate change. Microbial biomarker analysis and two-pool stoichiometric ratio method, proposed as two mainstream methods for estimating the contribution of microbial necromass carbon (MNC) to MAOC, have been rarely compared at the same study site.</p> Methods <p>We conducted a field experiment to directly compare these two methods using surface mineral soils (0-20&#xa0;cm) from a coniferous forest, a mixed forest and a broad-leaved forest in southern China.</p> Results <p>The contribution of MNC to MAOC in the mixed forest was estimated to be comparable using stoichiometric ratio method (51.26 ± 2.29%) and microbial biomarker method (52.84 ± 3.54%). Nevertheless, the estimate employing stoichiometric ratio method was lower in the coniferous forest (25.54 ± 4.47% <i>vs.</i> 40.95 ± 3.16%) and higher in the broad-leaved forest (62.92 ± 4.89% <i>vs.</i> 47.52 ± 3.52%) than that using microbial biomarker method. These disparities were presumably ascribed to the direct mineral adsorption of higher C/N plant lignin in coniferous forest and lower C/N dissolved components in broad-leaved forest, relative to particulate organic matter.</p> Conclusions <p>Our results revealed significant disparities in estimating the MNC contribution to MAOC by stoichiometric ratio method and microbial biomarker method, and underscore the complexity and variability of specific plant compound interactions with soil minerals across diverse forest types. These findings advance our understanding of MAOC formation pathways and mechanisms, enabling us to better estimate the contribution of plant versus microbial carbon to MAOC.</p>

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Estimating microbial necromass contribution to mineral-associated organic matter: comparison of stoichiometric and biomarker methods

  • 期刊论文

  • 发表日期：

    2025年10月1日

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  • Yiren Zhu,
  • Yuanliu Hu,
  • Xianyu Yao,
  • Guoyin Chen,
  • Junbing Bai,
  • Jianling Li,
  • Deqiang Zhang,
  • Qi Deng

摘要

Background and aims

Elucidating mechanisms and quantifying relative contributions of plant versus microbial carbon to mineral-associated organic carbon (MAOC) are essential for managing and modelling soil carbon sequestration in the combat of climate change. Microbial biomarker analysis and two-pool stoichiometric ratio method, proposed as two mainstream methods for estimating the contribution of microbial necromass carbon (MNC) to MAOC, have been rarely compared at the same study site.

Methods

We conducted a field experiment to directly compare these two methods using surface mineral soils (0-20 cm) from a coniferous forest, a mixed forest and a broad-leaved forest in southern China.

Results

The contribution of MNC to MAOC in the mixed forest was estimated to be comparable using stoichiometric ratio method (51.26 ± 2.29%) and microbial biomarker method (52.84 ± 3.54%). Nevertheless, the estimate employing stoichiometric ratio method was lower in the coniferous forest (25.54 ± 4.47% vs. 40.95 ± 3.16%) and higher in the broad-leaved forest (62.92 ± 4.89% vs. 47.52 ± 3.52%) than that using microbial biomarker method. These disparities were presumably ascribed to the direct mineral adsorption of higher C/N plant lignin in coniferous forest and lower C/N dissolved components in broad-leaved forest, relative to particulate organic matter.

Conclusions

Our results revealed significant disparities in estimating the MNC contribution to MAOC by stoichiometric ratio method and microbial biomarker method, and underscore the complexity and variability of specific plant compound interactions with soil minerals across diverse forest types. These findings advance our understanding of MAOC formation pathways and mechanisms, enabling us to better estimate the contribution of plant versus microbial carbon to MAOC.