Abstract: To clarify the spatial variations of soil carbon and nitrogen contents of different wetlands in Shanyutan of the Minjiang River estuary,Phragmites australismarsh (PM), Cyperus malaccensismarsh (CM) and their ecotonal marsh (P. australis-C. malaccensismarsh, PCM) were investigated. In the horizontal direction, the contents of soil total nitrogen (TN) and soilorganic carbon (SOC) in different marshes were in the order of PCM>PM>CM. At the verticaldirection, a decrease trend was observed in soil profiles of the three marshes. Compared with PM and CM, the contents ofNH₄⁺-N in surface soil of PCM decreased by 15.78% and 0.84%, while that of NO₃^--N decreased by 13.04% and 44.00%, respectively. In bottom soil layers, soil NH₄⁺-N increased by 30.00% and 6.06%, while soil NO₃^--N increased by 43.75% and 23.91%, respectively. The NH₄⁺-N contents of PM soils were mainly controlled by organic matter contents, while the contents of TN in CM soils were influenced by electric conductivity (salinity). Soil particle composition and moisture were the key driving factors for the contents of NH₄⁺-N and NO₃^--N in PCM soils. The competition of P. australisandC. malaccensis significantly increased the contents of SOC and TN and altered the spatial distributions of NH₄⁺-N and NO₃^--N in PCM soils, probably due to the alteration of fine particle composition and nitrogen mineralization and nitrification.

Key words: hydraulic characteristics, land use pattern, air transport