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.
河口湿地具有显著的咸淡水交互特征和长期持续的固碳能力。本研究以黄河口咸淡水交互区芦苇湿地作为研究对象,在弱强度交互区、中等强度交互区、较高强度交互区和高强度交互区布设60个研究点位,分析咸淡水交互作用对土壤有机碳空间分异的影响。结果表明: 黄河口咸淡水交互区芦苇湿地面积占比为17.8%,主要分布在弱强度交互区和中等强度交互区。咸淡水交互区芦苇湿地0～60 cm土层有机碳含量在1.09～3.65 g·kg-1,有机碳密度在1.85～5.84 kg·m-2,有机碳总储量为(17.32±3.64)×104 t,有机碳含量与密度均随着咸淡水交互作用的增强而降低。咸淡水交互区分区间表层土壤有机碳含量差异显著,随着咸淡水交互强度的增大,表层土壤有机碳含量明显减低。有机碳密度与土壤有机碳、总氮、铵态氮及生物量呈显著正相关,而与盐离子、土壤容重、pH及电导率呈显著负相关。0～30 cm土层有机碳储量占0～60 cm土层有机碳储量的50.9%～64.2%,0～60 cm土层有机碳储量占0～400 cm土层有机碳总储量的19.1%～37.7%。研究结果可为准确评估河口湿地碳储量、提升碳汇功能及湿地管理提供科学依据。.
Keywords: Yellow River Estuary; fresh-salt water interaction; reed wetland; soil organic carbon storage; spatial differentiation.