Preprints
https://doi.org/10.5194/egusphere-2025-2972
https://doi.org/10.5194/egusphere-2025-2972
13 Aug 2025
 | 13 Aug 2025
Status: this preprint is open for discussion and under review for Biogeosciences (BG).

Vegetation-mediated surface soil organic carbon formation and potential carbon loss risks in Dongting Lake floodplain, China

Liyan Wang, Zhengmiao Deng, Yonghong Xie, Tao Wang, Feng Li, Ye’ai Zou, Buqing Wang, Zhitao Huo, Cicheng Zhang, Changhui Peng, and Andrew Macrae

Abstract. Sources and stabilization mechanisms of soil organic carbon (SOC) fundamentally govern the carbon sequestration potential of wetland ecosystems. Nevertheless, systematic investigations regarding SOC sources and molecular stability remain scarce in floodplain wetland environments. This study employed dual analytical approaches (stable isotope analysis and 13C nuclear magnetic resonance spectroscopy) to characterize surface SOC composition across three dominant vegetation communities (Miscanthus, Carex, and mudflat) in Dongting Lake floodplain wetlands. Key findings revealed: (1) Significantly elevated SOC concentrations in vegetated communities (Miscanthus: 13.76 g kg-1; Carex: 12.98 g kg-1) compared to unvegetated mudflat (6.88 g kg-1); (2) Distinct δ13C signatures across communities, with the highest isotopic values in Miscanthus (−22.67 ‰), intermediate in mudflat (−26.01 ‰), and most depleted values in Carex (−28.25 ‰); (3) Bayesian mixing models identified autochthonous plant biomass as the primary SOC source (Miscanthus: 53.3±10.6 %, Carex: 52.4 %±11.6 %, Mudflat: 47.5±12.5 %); (4) Spatial heterogeneity in POM contributions across sub-lakes, showing descending contributions from South (highest) > West > East (lowest) Dongting Lake; (5) Molecular characterization revealed O-alkyl C dominance (27.3–46.8 %), followed by alkyl C and aromatic C. Notably, Miscanthus soils exhibited enhanced O-alkyl C content (Alip/Arom) and reduced aromaticity/hydrophobicity indices, suggesting comparatively lower biochemical stability of its SOC pool. These results highlight the critical role of vegetation-mediated SOC formation processes and warn against potential carbon loss risks in Miscanthus-dominated floodplain ecosystems, providing a scientific basis for carbon management of wetland soils.

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Liyan Wang, Zhengmiao Deng, Yonghong Xie, Tao Wang, Feng Li, Ye’ai Zou, Buqing Wang, Zhitao Huo, Cicheng Zhang, Changhui Peng, and Andrew Macrae

Status: open (until 11 Oct 2025)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-2972', Anonymous Referee #1, 28 Aug 2025 reply
    • AC1: 'Reply on RC1', Zhengmiao Deng, 03 Sep 2025 reply
Liyan Wang, Zhengmiao Deng, Yonghong Xie, Tao Wang, Feng Li, Ye’ai Zou, Buqing Wang, Zhitao Huo, Cicheng Zhang, Changhui Peng, and Andrew Macrae
Liyan Wang, Zhengmiao Deng, Yonghong Xie, Tao Wang, Feng Li, Ye’ai Zou, Buqing Wang, Zhitao Huo, Cicheng Zhang, Changhui Peng, and Andrew Macrae

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Short summary
We employed stable isotope and ¹³C nuclear magnetic resonance spectroscopy analyses to characterize soil organic carbon sources and stability in Dongting Lake wetlands. Our results revealed vegetation elevated soil organic carbon (Miscanthus: 13.76; Carex: 12.98 g kg-1 > mudflat: 6.88 g kg-1), with plant-derived carbon dominating (47.5–53.3 %). Miscanthus exhibited lower soil organic carbon stability (high O-alkyl C), suggesting a higher risk of organic carbon loss in its floodplain ecosystems.
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