Abstract: The artificially constructed wetland of Shatianhu River is a complex wetland system used for treating the surface flow and horizontal undercurrent of aquaculture wastewater. Taking this wetland as test object, this paper studied the seasonal variations of organic carbon concentration in plant organs, surface soil (0-10 cm), and rhizosphere soil, and assessed the carbon sequestration potential of the plant organs and surface soil. The fixed carbon in the aboveground parts of the wetland plants increased rapidly during growth period, being higher in August and kept stable at mature stage (November), and with significant difference between May and August and but less difference between August and November. The carbon fixed in underground parts of the plants was lower than that in aboveground parts, but its seasonal variation pattern was similar, being the lowest in May, relatively higher in August, and less difference between August and November. During the growth period of the plants, surface soil organic carbon content was significantly higher than that in the period with no plants in the wetland. The organic carbon content in surface soil was lower than that in rhizosphere soil, but less difference was observed (except for water lily). The surface soil organic carbon density was in the range of 0.96-1.67 kg·m^-2, which was affected by the plant species, plant growth season, and others. Based on the wetland area (surface flow part was 3592 m²) and surface soil organic carbon content, it was estimated that the wetland surface soil organic carbon stock was 5.61 t, and the annual plant carbon sequestration was 10.34 t.

Key words: Gongga Mountains, Dark coniferous forest, Abies fabri, Community structure