Abstract: This study selected four typical types of wetlands around Jiaozhou Bay including Spartina anglica wetland, the barren wetland, Suaeda glauca wetland and Phragmites australis wetland, to analyze and compare the contents of soil organic carbon (SOC) and their stock with seasonal and vertical variations. The results showed that the SOC contents of S. anglica wetland, S. glauca wetland and P. australis wetland all decreased with the increasing soil depth except that the concentration of SOC in the barren wetland showed a decreasing trend first, and then increased slightly along the soil profile. S. anglica wetland ranked first in SOC content, followed by the barren wetland, S. glauca wetland and P. australis wetland. Seasonally, the SOC contents in Jiaozhou Bay coastal wetlands were in an order of spring>summer>autumn>winter. Correlation analysis demonstrated that SOC content was positively correlated with soil salinity, moisture content, TN and C/N. Negative relationships were observed between SOC content and pH, and between SOC content and soil bulk density. The carbon densities of soil profile were in a decreasing order of the barren wetland, P. australis wetland and S. glauca wetland. There were some differences in the distributions of SOC and carbon density among the various types of wetlands. The barren wetland had a significant higher value for carbon stock per unit area than P. australis wetland and S. glauca wetland due to the differences in carbon density and thickness of carbon storage layer, playing a significant role in the carbon sink process of coastal wetlands.

Key words: temporal and spatial distribution, soil organic carbon, carbon storage., coastal wetland