Objective  Wetlands play the important roles in regulating soil carbon cycling. The objective of this study was to explore how soil physicochemical properties, soil inorganic carbon (SIC) content, and SIC stocks of 0-100 cm responded to degraded-natural wetlands, and to clarify the interaction of SIC stocks with soil and plant parameters in the Yellow River Delta.

  Method  In this study, a typical saline halophytes of Tamarix chinensis was selected. SIC content was measured using Automatic Soil Inorganic Carbon Analyzer. The SIC stocks were evaluated based on soil bulk density, SIC content, and soil depth.

  Result  Compared with natural wetlands, degraded wetlands hold lower soil cation (i.e., Ca^{2 +} and Mg^{2 +} ) content, relative content of carbonate, whereas no change in soil pH. Wetland degradation significantly reduced SIC content and stocks, indicating that degraded wetlands showed negative effects on the retention and storage of inorganic carbon in soil. Linear regression analyses demonstrated that SIC stocks were positively related with soil bulk density, water content, cation (Ca^{2 +} and Mg^{2 +} ) content, carbonate, SIC content, and aboveground biomass, while negatively related with soil electrical conductivity. Multiple regression analysis showed that soil bulk density, soil water content, and cation content were mainly driving factors to change SIC stocks of 0 ~ 100 cm. Additionally, the deep soil of 40-100 cm contributed about 60% of SIC stocks, indicating that deep soil plays an important role in SIC storage.

  Conclusion  The results demonstrated that wetland degradation increased SIC loss, whereas the protection and recovery of wetlands could promote SIC storage. Therefore, clarifying the changes in SIC stocks under degraded and natural wetlands in the Yellow River Delta, can provide scientific basis for improving soil carbon sink of wetlands and achieving carbon neutrality in terms of inorganic carbon.