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Aims <p>This study aimed to assess the effects of grazing exclusion on soil organic carbon (SOC) stabilization in alpine wetlands on the Qinghai-Tibet Plateau. We specifically focused on the roles of plant and microbial necromass in both particulate organic matter (POM) and mineral-associated organic matter (MAOM).</p> Methods <p>Field experiments were carried out in alpine wetlands comparing grazed sites with areas under grazing exclusion. Soil samples were collected and analyzed to quantify SOC fractions (POM and MAOM). Lignin phenols and amino sugars were used as biomarkers to distinguish between plant necromass C and microbial necromass C. Additionally, soil properties, microbial biomass, and exoenzyme activities were measured. PLS‑PM was employed to explore the relationships among soil properties, microbial necromass in POM and MAOM.</p> Results <p>Grazing exclusion did not significantly alter POM‑C but resulted in a 1.40‑fold increase in MAOM‑C. Although overall plant litter inputs did not change POM‑C, biomarkers indicated that microbial necromass increased in both POM and MAOM fractions under exclusion. PLS‑PM analysis revealed that microbial necromass in POM, while not directly affecting MAOM‑C, significantly promoted microbial necromass accumulation in MAOM, thereby indirectly enhancing MAOM‑C stability.</p> Conclusion <p>Grazing exclusion improves SOC storage in alpine wetlands primarily by enhancing microbial activity that drives MAOM formation and stabilization. The indirect influence of microbial necromass in POM on MAOM‑C underscores the importance of plant–soil–microbe interactions in SOC stabilization. These findings provide valuable insights for the restoration and conservation of degraded alpine wetlands.</p>

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Microbial necromass as a key driver of carbon stabilization: indirect pathways from POM to MAOM in grazing-excluded alpine wetlands

  • 期刊论文

  • 发表日期：

    2025年7月7日

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  • Hao Tang,
  • Hengxin Li,
  • Zihao Song,
  • Qian Bao,
  • Yang Ding,
  • Qian Li,
  • Linjing Ren,
  • Kun Li,
  • Lei Du

摘要

Aims

This study aimed to assess the effects of grazing exclusion on soil organic carbon (SOC) stabilization in alpine wetlands on the Qinghai-Tibet Plateau. We specifically focused on the roles of plant and microbial necromass in both particulate organic matter (POM) and mineral-associated organic matter (MAOM).

Methods

Field experiments were carried out in alpine wetlands comparing grazed sites with areas under grazing exclusion. Soil samples were collected and analyzed to quantify SOC fractions (POM and MAOM). Lignin phenols and amino sugars were used as biomarkers to distinguish between plant necromass C and microbial necromass C. Additionally, soil properties, microbial biomass, and exoenzyme activities were measured. PLS‑PM was employed to explore the relationships among soil properties, microbial necromass in POM and MAOM.

Results

Grazing exclusion did not significantly alter POM‑C but resulted in a 1.40‑fold increase in MAOM‑C. Although overall plant litter inputs did not change POM‑C, biomarkers indicated that microbial necromass increased in both POM and MAOM fractions under exclusion. PLS‑PM analysis revealed that microbial necromass in POM, while not directly affecting MAOM‑C, significantly promoted microbial necromass accumulation in MAOM, thereby indirectly enhancing MAOM‑C stability.

Conclusion

Grazing exclusion improves SOC storage in alpine wetlands primarily by enhancing microbial activity that drives MAOM formation and stabilization. The indirect influence of microbial necromass in POM on MAOM‑C underscores the importance of plant–soil–microbe interactions in SOC stabilization. These findings provide valuable insights for the restoration and conservation of degraded alpine wetlands.