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Background <p>Vegetation restoration enhances soil carbon sequestration, yet the mechanisms linking soil organic matter accumulation to rhizosphere microbial dynamics remain unclear.</p> Methods <p>This study examined rhizosphere DOM and microbial communities of <i>Pinus massoniana</i> across a restoration chronosequence in Changting County, a typical red soil-eroded region in southeastern China. Using FT-ICR-MS (Fourier transform ion cyclotron resonance mass spectrometry) and high-throughput sequencing, we characterized root-associated DOM composition and rhizosphere microbial diversity.</p> Results <p>Results showed that vegetation restoration was associated with increased DOM molecular diversity and Shannon index, alongside rising O/C ratios, NOSC (average nominal oxidation state of carbon), AI<sub>mod</sub> (modified aromaticity index), and CHO indices, and declining H/C ratios and MLB<sub>L</sub> percentage. The abundance of lignin/CRAM-like (lignin/carboxyl-rich alicyclic-like) and tannin compounds increased, accompanied by a shift toward larger DOM molecules (mass-to-charge ratio (m/z) &gt; 450) and a reduction in smaller ones (m/z &lt; 300). Rhizosphere bacterial and fungal alpha diversity increased across the chronosequence, with the abundance of&#xa0;oligotrophic taxa (Alphaproteobacteria, Acidobacteria, Solibacteres) also increasing and&#xa0;potentially contributing to nutrient cycling and recalcitrant SOM decomposition in the plant rhizosphere. PICRUSt2 (phylogenetic investigation of communities by reconstruction of unobserved states) suggested a functional shift from inorganic phosphate transport in early stages to phosphate solubilization and mineralization in later stages. Correlations between DOM properties and microbial assembly were consistent with substrate preference and life-history strategies influencing rhizosphere DOM stability.</p> Conclusion <p>This study reveals an association between vegetation restoration and a successional shift from labile to recalcitrant rhizosphere DOM states, patterns consistent with root-associated microbial restructuring toward oligotrophy. These findings improve understanding of rhizosphere biogeochemical cycling under vegetation restoration, providing a basis for understanding root-mediated carbon persistence mechanisms in degraded red soils.</p>

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Microbe-mediated changes of soil dissolved organic matter in the rhizosphere of Pinus massoniana during vegetation restoration in a typical red soil erosion region of southern China

  • 期刊论文

  • 发表日期：

    2026年5月13日

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  • Chuifan Zhou,
  • Yilin Fan,
  • Shuzhen Wang,
  • Yanlin Zhang,
  • Weijuan Qiu,
  • Yuanchun Yu,
  • Lei Chen

摘要

Background

Vegetation restoration enhances soil carbon sequestration, yet the mechanisms linking soil organic matter accumulation to rhizosphere microbial dynamics remain unclear.

Methods

This study examined rhizosphere DOM and microbial communities of Pinus massoniana across a restoration chronosequence in Changting County, a typical red soil-eroded region in southeastern China. Using FT-ICR-MS (Fourier transform ion cyclotron resonance mass spectrometry) and high-throughput sequencing, we characterized root-associated DOM composition and rhizosphere microbial diversity.

Results

Results showed that vegetation restoration was associated with increased DOM molecular diversity and Shannon index, alongside rising O/C ratios, NOSC (average nominal oxidation state of carbon), AImod (modified aromaticity index), and CHO indices, and declining H/C ratios and MLBL percentage. The abundance of lignin/CRAM-like (lignin/carboxyl-rich alicyclic-like) and tannin compounds increased, accompanied by a shift toward larger DOM molecules (mass-to-charge ratio (m/z) > 450) and a reduction in smaller ones (m/z < 300). Rhizosphere bacterial and fungal alpha diversity increased across the chronosequence, with the abundance of oligotrophic taxa (Alphaproteobacteria, Acidobacteria, Solibacteres) also increasing and potentially contributing to nutrient cycling and recalcitrant SOM decomposition in the plant rhizosphere. PICRUSt2 (phylogenetic investigation of communities by reconstruction of unobserved states) suggested a functional shift from inorganic phosphate transport in early stages to phosphate solubilization and mineralization in later stages. Correlations between DOM properties and microbial assembly were consistent with substrate preference and life-history strategies influencing rhizosphere DOM stability.

Conclusion

This study reveals an association between vegetation restoration and a successional shift from labile to recalcitrant rhizosphere DOM states, patterns consistent with root-associated microbial restructuring toward oligotrophy. These findings improve understanding of rhizosphere biogeochemical cycling under vegetation restoration, providing a basis for understanding root-mediated carbon persistence mechanisms in degraded red soils.