Soil Organic Carbon along a Salinity Gradient in Phragmites australis Marsh in the Minjiang River Estuary
Wetlands are an important ecosystem for carbon storage, contributing 20% of continental carbon storages within 4%-5% of the continental areas. Carbon cycling has become an important ecosystem service set against a background of climate change. China has a coastline of 18 000 km along which there is an estimated 12 000 km2 of tidal estuarine wetlands. These tidal wetlands are generally rich in animal and plant biodiversity and appear to have an important biogeochemical role within the estuary ecosystem. Estuarine wetlands occur along salinity gradient as a result of tidal inundation and this influences carbon storages by regulating the inputs and outputs of dissolved carbon and the accumulation and erosion of carbon. Research in this area is conflicting. The Min River estuarine wetlands are an important tidal wetland ecosystem in south-east China, as it is located at the boundary between mid- and southern subtropical climate zones. This estuarine wetland is close to Fuzhou city where rapid economic development, building construction and expansion of the city scale has intensified the use of the wetland and over-exploitation of the wetland resources has occurred. As a result, the area of natural wetland is decreasing and the ecosystem services are reducing as its ecological functions are impaired. The Minjiang River estuary is a typical tidal estuary in the south-east of China; Phragmites aus-tralis is the dominant species and distributed from upper to lower reaches. Soil depth profiles (0-60 cm cores) were collected from three Phragmites australis communities spread across three wetlands distributed along a salinity gradient; these cores were divided in 10 cm layers and various soil properties were measured including soil organic carbon concentrations. Soil pH, bulk density, sand composition all decreased with soil salinity increased, but, soil clay and silt composition increased. Soil organic carbon concentrations (0-60 cm depths) ranged between 11.6-14.7 g/kg, 14.1-19.2 g/kg and 20.9-2.9 g/kg, respectively in the Phragmite australis marshes in the Youxizhou, Bianfuzhou and Shanyutan wetlands as salinity increased. The amount of carbon stores in each layer in the 3 communities also increased with salinity from 1 408-1 670 t/km2, 1 328-1 660 t/km2 and 1 320-1 678 t/km2, respectively with mean site values of 1 534 t/km2, 1 548 t/km2 and 1 569 t/km2, respectively. The total soil (0-60 cm) carbon storages were 9 204.79 t/km2,9 288.71 t/km2 and 9 415.35 t/km2, respectively. Soil organic carbon concentration and storage increased as soil salinity increased. Soil organic carbon concentration was influenced by many factors.
salinity gradientPhragmile australis marshsoil organic carbonMinjiang River estuary
NETL
NSTL
万方数据
维普
