Abstract:Wetland plants and soils are essential for ecological functions of wetlands and have strong interactions, e.g. wetland soils affect the distribution and abundance of plants species, especially the quantity, growth, development and morphology, as well as the distribution of plant communities. On the other hand, wetland vegetation also affects the distribution,dynamics and variation of chemical elements within the soil. The diversity of wetland plant communities and wetland soil in the Poyang Lake wetland and the resultant habitat for migratory birds are dependent on plant-soil interactions and Lake water-level fluctuations of varying frequency and amplitude. Much qualitative research had described the response of vegetation to alternating high and low lake levels in Poyang lake wetland, but few quantitative studies have documented the changes that occur. In response to recent concerns over the relationship among the lake water level, wetland vegetation and the habitat for migratory birds, we collected a quantitative data set from Poyang lake wetland and do some analyzes. Aimed to (1) study the characteristics of plant communities and (2)study the characteristics of wetland soil organic matter, total nitrogen, total phosphorus and total potassium, and (3) infer some hypotheses about the relationships between all of these variables in Poyang Lake wetland, we did monthly continued vegetation survey from October 2010 to October 2011 in 57 fixed quadrats in the Phragmites australis (Cav.) Trin.ex Steub.),Triarrhera lutarioriparia L. Liu,C. cinerascens Kükenth.,Phalaris arundinacea Linn and E. vallecuIosa Ohwi communities along different water level gradients,and did laboratory analysis of 135 soil samples under the 5 dominant plant communities in Poyang Lake wetland. The results showed that, the distribution of plant communities present cluster distribution in population, present banded or arc-shaped distribution along the water level and elevation gradient in communities, and some species present mosaic distributions; plant community composition and characteristics also changed with the seasons and hydrological fluctuations. These characteristics may be due to the combined effects of the distribution of soil elements, Lake Water Level Fluctuations and the plant growth characteristics. There were relatively similar distribution patterns of organic matter and total nitrogen,the concentrations of soil organic matter and total nitrogen in the 0-20cm layer were significantly higher than those in the 30-90cm layers, and the content of nutrients in the soil decreased slowly with the soil depth and kept stable below 30 cm. Obviously, there are strong correlations between plant communities and soil characteristics,e.g. the content and change of soil organic matter, total nitrogen, total phosphorus and total potassium, for there are large significant differences with the chemical elements content and diversification between different plant communities. There was a significant negative correlation between Plant weight and soil SOC, TN and TP content, however, a strong positive correlation with TK content. Meanwhile, the plant's weight and height have a weak negative correlation with depth of groundwater. This study provided quantitative evidence that lake-level fluctuations drive vegetative change and soils' changes in Poyang Lake wetlands and it may assist in making decisions regarding Poyang lake management for government.