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Chinese Journal of Applied Ecology ›› 2024, Vol. 35 ›› Issue (2): 415-423.doi: 10.13287/j.1001-9332.202402.031

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Effects of fresh-salt water interaction on spatial variations of soil organic carbon in reed wetland of Yellow River Estuary

YU Miao1, GUO Xuelian1*, LI Yunzhao2, ZHANG Kun1, DU Zhaohong2   

  1. 1National Plateau Wetlands Research Center, College of Wetland, Southwest Forestry University, Kunming 650224, China;
    2Institute for Advanced Study of Coastal Ecology, Ludong University, Yantai 264025, Shandong, China
  • Received:2023-07-22 Revised:2023-12-19 Online:2024-02-18 Published:2024-08-18

Abstract: Estuarine wetlands exhibit significant interaction between fresh and salt water, with long-term carbon sequestration capability. We set up 60 sampling sites in the reed wetlands of the fresh-salt water interaction zone of the Yellow River Estuary, covering four different zones of the weak-intensity fresh-salt water interaction zone (WIZ), medium-intensity fresh-salt water interaction zone (MIZ), high-intensity interaction fresh-salt water zone (HIZ) and strong-intensity fresh-salt water interaction zone (SIZ). We investigated how fresh-salt water interaction affected the spatial variation of soil organic carbon (SOC) storage. The results showed that the area of reed wetland accounted for 17.8% of the total area of the fresh-salt water interaction zone the Yellow River Estuary, which mainly distributed in the WIZ and MIZ. The SOC content of reed wetland in the fresh-salt water interaction zone ranged from 1.09 to 3.65 g·kg-1, the SOC density was between 1.85-5.84 kg·m-2, and the SOC storage was (17.32±3.64)×104 t. The SOC content and SOC density decreased with increasing fresh-salt water interaction. There were significant differences in surface SOC content between different subzones of the fresh-salt water interaction zone. The surface SOC content decreased significantly with the increases of fresh-salt water interaction intensity. SOC density was positively correlated with SOC, TN, NH4+-N, and biomass, but negatively correlated with salt ions, soil bulk density, pH, and EC. SOC storage in the 0-30 cm soil layer accounted for 50.9%-64.2% of that in the 0-60 cm soil layer, while SOC storage in the 0-60 cm soil layer occupied 19.1%-37.7% of that in the 0-400 cm soil layer. The results could provide a scientific basis for accurately evaluating SOC storage of estuarine wetlands, improving carbon sink function and wetland management.

Key words: Yellow River Estuary, fresh-salt water interaction, reed wetland, soil organic carbon storage, spatial differentiation