Soil organic carbon accumulation and influencing factors at the saltmarsh of Yangtze Estuary

Soil organic carbon sequestration in the coastal saltmarsh is considered to be an important part of “blue carbon” because of its high carbon accumulation rate and low greenhouse gas emission. However, the factors influencing the carbon accumulation ability is not yet fully revealed yet due to lack of knowledge about underground biomass and root zone soil processes. Based on the field investigation at the young salt marsh of the East Chongming Headland, Yangtze Estuary, we tried to link the spatial and vertical distribution of soil organic carbon with key influencing factors such as above ground and underground biomass, surface elevation, salinity, and sediment particle size, through ArcGIS Kriging interpolation, SPSS correlation and path analyses. We found that: 1) The spatial distribution of soil organic carbon was relatively high in the northern part and high tidal zone of East Chongming Headland, with soil salinity, biomass and elevation as main influencing factors; 2) The vertical distribution of soil organic carbon was closely related to soil salinity, biomass, and 0-31 μm soil particles; 3) The carbon sequestration rate showed a decrease trend with time of vegetation establishment. To promote carbon sequestration in coastal wetlands for mitigating climate change, protection of “old marsh” and creating “new marsh” are both needed in the future management.