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Purpose <p>In order to understand the spatiotemporal dynamics and regulatory mechanisms of soil organic carbon (SOC) fractions in reclaimed opencast coal mine dumps, this study investigated the composition, vertical distribution, key drivers of nine SOC fractions, and seasonal evolution under differential vegetation reclamation modes in a semi-arid mining ecosystem.</p> Methods <p>Soil samples (0–50&#xa0;cm depth) were collected from five sites: <i>Robinia pseudoacacia monoculture</i> (RM), <i>Robinia pseudoacacia</i> × Elm × <i>Ailanthus altissima</i> mixed forest (REA), <i>Pinus tabuliformis</i> × Elm mixed forest (PE), an unreclaimed area (UR), and an undisturbed native forest (UD). The content of SOC and its nine fractions (DOC, WSOC, MBC, EOC, IOC, LFOC, HFOC, POC, MAOC), soil physicochemical properties and enzyme activities were analyzed. Seasonal dynamics were assessed for surface layers (0–15&#xa0;cm, 15–30&#xa0;cm). Statistical analyses included ANOVA, structural equation modeling, and redundancy analysis.</p> Results <p>Across sites and depths, SOC ranged from 1.85 to 35.45&#xa0;g kg⁻¹, overall SOC ranked REA &gt; RM &gt; PE &gt; UD &gt; UR. Mixed forests outperformed monocultures in restoring SOC and its fractions. Among the different forest types, PE exhibited the most significant effect on the recovery of labile fractions. Additionally, the recovery of stable fractions was particularly remarkable in the REA mixed forest. Stable carbon fractions dominated SOC pools (&gt; 80% of SOC), with IOC being the largest component. Soil depth exerted the strongest direct influence on SOC dynamics, followed by physicochemical properties and enzyme activities. Surface SOC exhibited a distinct seasonal “decline-rise” pattern, peaking in November. Labile fractions showed significant seasonal fluctuations in surface soil.</p> Conclusion <p>Vegetation configuration critically regulates SOC allocation: mixed forests enhance functional redundancy via synergistic root systems and litter inputs, while monoculture limits deep carbon sequestration. Prioritizing species with complementary root architectures and recalcitrant litter optimizes multi-layered carbon pool restoration.</p>

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Characteristics and mechanisms of soil organic carbon fraction d]1lloopx/ynamics in opencast coal mine dumps under differential reclamation

  • 期刊论文

  • 发表日期：

    2026年2月5日

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  • Fangzheng Wang,
  • Zhanjun Xu,
  • Jinxin Miao,
  • Yangna Wang,
  • Yuan Xi

摘要

Purpose

In order to understand the spatiotemporal dynamics and regulatory mechanisms of soil organic carbon (SOC) fractions in reclaimed opencast coal mine dumps, this study investigated the composition, vertical distribution, key drivers of nine SOC fractions, and seasonal evolution under differential vegetation reclamation modes in a semi-arid mining ecosystem.

Methods

Soil samples (0–50 cm depth) were collected from five sites: Robinia pseudoacacia monoculture (RM), Robinia pseudoacacia × Elm × Ailanthus altissima mixed forest (REA), Pinus tabuliformis × Elm mixed forest (PE), an unreclaimed area (UR), and an undisturbed native forest (UD). The content of SOC and its nine fractions (DOC, WSOC, MBC, EOC, IOC, LFOC, HFOC, POC, MAOC), soil physicochemical properties and enzyme activities were analyzed. Seasonal dynamics were assessed for surface layers (0–15 cm, 15–30 cm). Statistical analyses included ANOVA, structural equation modeling, and redundancy analysis.

Results

Across sites and depths, SOC ranged from 1.85 to 35.45 g kg⁻¹, overall SOC ranked REA > RM > PE > UD > UR. Mixed forests outperformed monocultures in restoring SOC and its fractions. Among the different forest types, PE exhibited the most significant effect on the recovery of labile fractions. Additionally, the recovery of stable fractions was particularly remarkable in the REA mixed forest. Stable carbon fractions dominated SOC pools (> 80% of SOC), with IOC being the largest component. Soil depth exerted the strongest direct influence on SOC dynamics, followed by physicochemical properties and enzyme activities. Surface SOC exhibited a distinct seasonal “decline-rise” pattern, peaking in November. Labile fractions showed significant seasonal fluctuations in surface soil.

Conclusion

Vegetation configuration critically regulates SOC allocation: mixed forests enhance functional redundancy via synergistic root systems and litter inputs, while monoculture limits deep carbon sequestration. Prioritizing species with complementary root architectures and recalcitrant litter optimizes multi-layered carbon pool restoration.