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Purpose <p>Soil organic carbon (SOC) is crucial for ecosystem functioning and global carbon cycling, with vegetation restoration playing a vital role in enhancing SOC sequestration and stability. However, in the karst regions of southwest China, how vegetation restoration regulates SOC sequestration potential and underlying mechanisms remains poorly understood. This study aims to quantify changes in SOC fractions and microbial necromass (MNC, FNC, BNC) under different vegetation restoration types in karst ecosystems, identify key regulating factors, and provide mechanistic insights to enhance SOC stabilization and guide sustainable land use strategies.</p> Methods <p>We examined the impacts of vegetation restoration, including maize and soybean rotation (MS, as the control), natural restoration after being abandoned from cropland (RC), pure forest restoration (PF), forage grass restoration (RG), forest-grass mixed restoration (FG), and mixed forest restoration (MF), on soil POC, MAOC, microbial necromass and its contribution to SOC in karst ecosystems.</p> Results <p>Vegetation restoration enhanced microbial necromass, particularly FNC, which accounted for 78.9–85.3% of MNC and contributed significantly to SOC stabilization. Compared to cropland, vegetation restoration significantly increased soil MNC and its contribution to SOC, which may be attributed to greater plant residues inputs and reduced soil disturbance. MAOC (8.24–12.01&#xa0;g kg⁻¹) dominated SOC pool, accounting for 58.1–77.9% of total SOC. All restoration treatments significantly increased MAOC content by 19.4–45.7% compared to cropland, potentially driven by increased microbial necromass accumulation, elevated dissolved organic carbon, and improved soil moisture as indicated by correlation analysis and PLSPM results. Among all restoration types, MF exhibited the highest MAOC, MNC, and FNC levels, likely due to improved nutrient availability (e.g., greater total nitrogen content and lower C: N ratio) and richer plant diversity, suggesting a greater contribution to SOC stability and long-term persistence.</p> Conclusions <p>These findings highlight the crucial role of vegetation restoration, particularly mixed forest systems, in enhancing SOC sequestration and stability through the promotion of microbial necromass formation and mineral association mechanisms, offering valuable insights for sustainable land management in karst regions.</p>

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Vegetation restoration promotes soil carbon stability by enhancing mineral-associated organic carbon and microbial necromass accumulation in karst ecosystems

  • 期刊论文

  • 发表日期：

    2025年10月7日

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  • Ziyue Feng,
  • Dan Chen,
  • Tongqing Su,
  • Lifen Xie,
  • Zhenchuan Wang,
  • Cong Wang,
  • Jianbing Zhang,
  • Xiaoyong Bai,
  • Baoqing Hu

摘要

Purpose

Soil organic carbon (SOC) is crucial for ecosystem functioning and global carbon cycling, with vegetation restoration playing a vital role in enhancing SOC sequestration and stability. However, in the karst regions of southwest China, how vegetation restoration regulates SOC sequestration potential and underlying mechanisms remains poorly understood. This study aims to quantify changes in SOC fractions and microbial necromass (MNC, FNC, BNC) under different vegetation restoration types in karst ecosystems, identify key regulating factors, and provide mechanistic insights to enhance SOC stabilization and guide sustainable land use strategies.

Methods

We examined the impacts of vegetation restoration, including maize and soybean rotation (MS, as the control), natural restoration after being abandoned from cropland (RC), pure forest restoration (PF), forage grass restoration (RG), forest-grass mixed restoration (FG), and mixed forest restoration (MF), on soil POC, MAOC, microbial necromass and its contribution to SOC in karst ecosystems.

Results

Vegetation restoration enhanced microbial necromass, particularly FNC, which accounted for 78.9–85.3% of MNC and contributed significantly to SOC stabilization. Compared to cropland, vegetation restoration significantly increased soil MNC and its contribution to SOC, which may be attributed to greater plant residues inputs and reduced soil disturbance. MAOC (8.24–12.01 g kg⁻¹) dominated SOC pool, accounting for 58.1–77.9% of total SOC. All restoration treatments significantly increased MAOC content by 19.4–45.7% compared to cropland, potentially driven by increased microbial necromass accumulation, elevated dissolved organic carbon, and improved soil moisture as indicated by correlation analysis and PLSPM results. Among all restoration types, MF exhibited the highest MAOC, MNC, and FNC levels, likely due to improved nutrient availability (e.g., greater total nitrogen content and lower C: N ratio) and richer plant diversity, suggesting a greater contribution to SOC stability and long-term persistence.

Conclusions

These findings highlight the crucial role of vegetation restoration, particularly mixed forest systems, in enhancing SOC sequestration and stability through the promotion of microbial necromass formation and mineral association mechanisms, offering valuable insights for sustainable land management in karst regions.