This study investigated the effects of Spartina alterniflora invasion on soil carbon dynamics and tried to reveal the potential underlying mechanisms of these effects in wetlands of the Yangtze River estuary.Herein,each sampling transect was set up separately in the high and low tide zones of the Dongtan wetland in the Yangtze River estuary.Three sites were distributed evenly on each transect.A pair-wise experiment was designed between S.alterniflora(invasive plant) and Phragmites australis(native plant) stands in the high tide zone,and S.alterniflora and Scirpus mariqueter(native plant) stands in the low tide zone,which was used to minimize the potential effects of background heterogeneities.Compared with the native plant stands,the S.alterniflora invasion significantly increased the plant carbon,soil total carbon(TC),and soil organic carbon pools.There was no significant difference in the soil inorganic carbon(SIC) pool between plant stands or tide zones.The estimated SIC pool in the Dongtan wetland accounted for more than 60% of the soil TC pool in the soil profile to a depth of 100cm.The lack of difference in the SIC pool between the S.alterniflora and native plant stands demonstrated that the soil TC pool in coastal wetland soils did not reflect the effects of invasion.The mean soil respiration rates were(210.024.90) and(157.796.39)mg/(m~2·h) in the S.alterniflora and P.australis stands in the high tide zone,and(157.415.27) and(110.905.16)mg/(m~2·h) in the S.alterniflora and S.mariqueter stands in the low tide zone,respectively.This indicated that the S.alterniflora invasion significantly enhanced soil respiration in the Yangtze River estuary.These results showed that the S.alterniflora invasion simultaneously increased soil carbon input and carbon output,but the invasion also significantly increased the soil carbon pool,suggesting that the invasion-related increase in the soil carbon input was significantly higher than the invasion-related increase in the soil carbon output.As shown above,S.alterniflora invasion into the Yangtze River estuary could strengthen the soil carbon sequestration capacity and net carbon sink of wetlands in the background of global climate change.However,long-term systematic monitoring and study are still needed in order to comprehensively evaluate the ecological impacts of S.alterniflora invasion into China's coastal wetlands.