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Purpose <p>Litter quality plays critical roles in regulating soil organic carbon (SOC) dynamics. However, it remains unclear how the input of above- and below-ground plant litter (e.g., leaf, stem and root) with contrasting chemistry influences SOC mineralization, formation and stability.</p> Methods <p>In this study, <sup>13</sup>C-labeled high-quality litter (leaves) and low-quality litter (stems and roots) from a coniferous tree (<i>Cunninghamia lanceolata</i>) and a broadleaved tree (<i>Phoebe Bournei</i>) were added to subtropical forest soils, and then priming effects, litter-derived C incorporated into SOC fractions (i.e., particulate organic carbon (POC) and mineral-associated organic carbon (MAOC)), and net C balance were measured.</p> Results <p>After 180&#xa0;days of incubation, SOC mineralization decelerated by 9% and 7% following <i>C. lanceolata</i> stem and root addition, respectively. This was because their input decreased phenol oxidase and peroxidase activities. However, <i>C. lanceolata</i> leaf input accelerated SOC mineralization by 12% due to increased microbial biomass and abundance of fungi and actinomycetes. Contrastingly, native SOC mineralization decelerated by 11% after <i>P. Bournei</i> leaf litter input, which may have favored soil microbes to preferentially utilize the added substrate rather than the native SOC. However, native SOC mineralization neither decelerated nor accelerated following <i>P. Bournei</i> stem or root input. Moreover, the litter-derived new SOC (i.e., the sum of POC and MAOC) from stem and root litter accounted for 39–48% of the added litter C, which were greater than those from leaf litter (29–31%). The newly formed SOC was 2–11 times greater than the primed C loss, with this effect being more pronounced in soil enriched with stem and root litter than in soil enriched with leaf litter. Therefore, stem and root litter input caused greater positive net C balance than leaf litter input. In this study, the initial litter lignin content was negatively correlated with the priming effect (for <i>C. lanceolata</i>), but positively correlated with the new SOC formation. This suggests that litter lignin content is the key factor in regulating SOC mineralization and formation.</p> Conclusion <p>Our results indicate that low-quality stem and root litter rather than high-quality leaf litter promote net SOC accrual by suppressing priming effect and enhancing new SOC formation.</p>

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Low-quality litter promotes soil organic carbon accumulation by inhibiting priming effects and stimulating mineral-associated organic carbon formation

  • 期刊论文

  • 发表日期：

    2025年8月8日

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  • Qingyan Qiu,
  • Zixi Mao,
  • Ziying Gan,
  • Abubakari Said Mgelwa,
  • Sebastian Leuzinger,
  • Yalin Hu

摘要

Purpose

Litter quality plays critical roles in regulating soil organic carbon (SOC) dynamics. However, it remains unclear how the input of above- and below-ground plant litter (e.g., leaf, stem and root) with contrasting chemistry influences SOC mineralization, formation and stability.

Methods

In this study, 13C-labeled high-quality litter (leaves) and low-quality litter (stems and roots) from a coniferous tree (Cunninghamia lanceolata) and a broadleaved tree (Phoebe Bournei) were added to subtropical forest soils, and then priming effects, litter-derived C incorporated into SOC fractions (i.e., particulate organic carbon (POC) and mineral-associated organic carbon (MAOC)), and net C balance were measured.

Results

After 180 days of incubation, SOC mineralization decelerated by 9% and 7% following C. lanceolata stem and root addition, respectively. This was because their input decreased phenol oxidase and peroxidase activities. However, C. lanceolata leaf input accelerated SOC mineralization by 12% due to increased microbial biomass and abundance of fungi and actinomycetes. Contrastingly, native SOC mineralization decelerated by 11% after P. Bournei leaf litter input, which may have favored soil microbes to preferentially utilize the added substrate rather than the native SOC. However, native SOC mineralization neither decelerated nor accelerated following P. Bournei stem or root input. Moreover, the litter-derived new SOC (i.e., the sum of POC and MAOC) from stem and root litter accounted for 39–48% of the added litter C, which were greater than those from leaf litter (29–31%). The newly formed SOC was 2–11 times greater than the primed C loss, with this effect being more pronounced in soil enriched with stem and root litter than in soil enriched with leaf litter. Therefore, stem and root litter input caused greater positive net C balance than leaf litter input. In this study, the initial litter lignin content was negatively correlated with the priming effect (for C. lanceolata), but positively correlated with the new SOC formation. This suggests that litter lignin content is the key factor in regulating SOC mineralization and formation.

Conclusion

Our results indicate that low-quality stem and root litter rather than high-quality leaf litter promote net SOC accrual by suppressing priming effect and enhancing new SOC formation.