Spatial Distribution Traits of Soil Organic Matter and Total Nitrogen in the Wetland of Poyang Lake, China

摘要

Contents of soil organic matter (SOM) and total nitrogen (TN) were measured in Nanjishan wetland of Poyang Lake, China, in 2009. Three types of soil from Ass. Triarrhera lutarioriparia, Ass. Carex cinerascens and Ass. Eleocharis valleculosa were analyzed along water gradients. Results showed that spatial distributions of both SOM and TN were very similar in soil profiles (0-100 cm) of the three areas, decreasing gradually from the top layer to the down, but kept stable under 20cm depth. The horizontal distributions of SOM and TN in surface soils (0-20 cm) were distinctly different in the three areas. The SOM content in Ass. Carex cinerascens was highest, intermediate in Ass. Triarrhera lutarioriparia, and the least was in Ass. Eleocharis valleculosa. However, the TN contents followed the order of Ass. Triarrhera lutarioriparia > Ass. Carex cinerascens > Ass. Eleocharis valleculosa. The ratios of carbon to nitrogen were relatively low indicating that the degree of humification of marsh soils was higher in the Nanjishan wetland. Our results further infer that the spatial distributions of SOM and TN were influenced by the capacities of plant uptake, characteristics of vegetation growth and eco-hydrological process of wetland.