The Response Of Wetland Plant Diversity And Functional Trait To The Soil Moisture

Plant functional traits can reflect the ability to adapt to the environment changes of plants. In this study, the method of sample combined with quadrat was adopted to investigate the vascular plants in Beijing wetlands. The survey involved 10 wetlands, including 4 river wetlands and 6 reservoir wetlands. 11 plant functional traits which related with plant morphology and physiology were selected, such as shoot biomass, root biomass, total biomass, specific leaf area, leaf nitrogen (N) concentration, leaf phosphorous (P) concentration, specific stem weight, root nitrogen (N) concentration, root phosphorous (P) concentration, root tensile strength and specific root length were determined. Using multivariate statistical methods such as two-factor variance analysis and linear regression analysis respectively to study the differences in species richness, the frequency distribution of species and the correlation between the plasticity of plant functional traits and the distribution pattern index (DPI) in different wetland types (river wetland, reservoir wetland) and soil moisture gradient. The results showed that:(1) There are significant differences (p=0.001) in species richness of samples between the river wetlands and reservoir wetlands. And this suggests that the wetland types have an impact on species richness. In different soil moisture gradient (high soil moisture zone, moderate soil moisture zone, low soil moisture zone), there are no significant differences (p=0.472) in species richness of samples. Also the same result (p=0.093) under the interaction between wetland types and the soil moisture gradient.(2) In the river wetlands, Polygonum lapathifolium, Typha angustifolia, Bidens pilosa, Scirpus planiculmis and Phragmites australis have the highest frequency in the high soil moisture zone; Bidens pilosa, Polygonum lapathifolium, Carex neurocarpa, Xanthium sibiricum and Cirsium setosum have the highest frequency in the moderate soil moisture zone; Polygonum lapathifolium, Cirsium setosum, Xanthium sibiricum, Lactuca indica and Potentilla chinensis have the highest frequency in the low soil moisture zone. And in the reservoir wetlands, Typha angustifolia, Scirpus triqueter, Scirpus planiculmis, Acorus calamus and Phragmites australis have the highest frequency in the high soil moisture zone; Xanthium sibiricum, Inula japonica, Artemisia mongolica, Bidens pilosa and Glycine soja have the highest frequency in the moderate soil moisture zone; Xanthium sibiricum, Polygonum lapathifolium, Artemisia mongolica, Glycine soja and Inula japonica have the highest frequency in the low soil moisture zone.(3) In the river wetlands, the plasticity of shoot biomass and total biomass respectively has correlation (shoot biomass:p=0.017; total biomass:p=0.009) with the distribution pattern index, and they are negative correlation. The other plasticity of functional traits (root biomass, specific leaf area, leaf nitrogen (N) concentration, leaf phosphorous (P) concentration, specific stem weight, root nitrogen (N) concentration, root phosphorous (P) concentration, root tensile strength and specific root length) has no correlation (p>0.05) with the distribution pattern index. And in the reservoir wetlands, the plasticity of shoot biomass and total biomass respectively has correlation (shoot biomass:p=0.038; total biomass: p=0.033) with the distribution pattern index, and they are negative correlation. The other plasticity of functional traits (root biomass, specific leaf area, leaf nitrogen (N) concentration, leaf phosphorous (P) concentration, specific stem weight, root nitrogen (N) concentration, root phosphorous (P) concentration, root tensile strength and specific root length) has no correlation (p>0.05) with the distribution pattern index.In conclusion, due to the heterogeneity of soil water, habitat diversity and moderate anthropogenic interference, species richness in the reservoir wetlands is significantly higher than in the river wetlands. The ecological amplitude of Polygonum lapathifolium is relatively wide in the river wetlands; it has strong ability to adapt to the soil moisture changes. The demand for soil moisture content of Xanthium sibiricum, Inula japonica, Artemisia mongolica and Glycine soja under the aquatic plants such as Typha angustifolia, Phragmites australis and Acorus calamus in the reservoir wetlands. When the shoot biomass plasticity of species is reduced, it showed that the ability to adapt to the soil moisture changes of species shoot biomass is weak, and its preference for soil moisture is more obvious.