Effects of groundwater tables and salinity levels on soil organic carbon and total nitrogen accumulation in coastal wetlands with different plant cover types in a Chinese estuary

Abstract Groundwater tables and soil salinity can greatly affect the biogeochemical cycles of carbon and nitrogen by altering soil physicochemical properties. Coastal wetlands with different plant cover types (including bare land, Phragmites australis, and Suaeda salsa wetlands) and groundwater table wetlands (including low groundwater table, medium groundwater table, and high groundwater table wetlands) were investigated in 2012–2013 to characterize the spatial and temporal changes and the effects of groundwater tables on soil organic carbon (SOC) and total nitrogen (TN) in the Yellow River Estuary, China. The results showed that SOCs in 2012 was higher than that in 2013 regardless of the groundwater tables, while TNs was higher in 2013 than in 2012 except in the BL soil with low groundwater tables and the PA wetlands with middle groundwater tables. The SOCs and TNs were mainly concentrated in the top 20 cm soils. SOCc and TNc were fitted very well with soil depth by the general linear fit (p