Response Of Phragmites Australis Community And Leaf Traits To Typical Human Disturbance In The Yellow River Delta

The Yellow River Delta, one of China’s three major river deltas, has recently been the subject of numerous important research projects. Sixty-seven vegetation quadrats were selected in June,2010, and nine soil characteristics were analyzed, including soil moisture content (MC), soil electrical conductivity (EC), soil pH (pH), total carbon (TC), total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), available phosphorus (AP) and available potassium (AK). Vegetative analysis of the quadrants found52species, belonging to nineteen families and forty-six genera. Canonical Correspondence Analysis (CCA) was performed to analyze the relationships between the vegetation quadrats and the nine soil factors. The CCA results show the first two axes explained46.4%of the variance within the species-environmental relationships, and electrical conductivity and moisture content most heavily influenced the community distribution. Using TWINSPAN, we classified the quadrats into seven communities. The seven communities were classified into three groups along the first axis of the CCA:Com. Suaeda salsa, Com. Phragmites australis-Suaeda salsa and other meadow communities. The results indicate the succession series of coastal meadow in the Yellow River Delta develops along the salinity gradient. The Shannon-Wiener (H’) and Simpson (D) indices were calculated. Correlation analysis shows species diversity had a highly significant negative correlation with EC, AP and AK (P<0.01), and a significant positive correlation with pH (P0.05).Plant functional traits not only adapt to the environment but also reflect the pattern and process of plant communities and ecosystems. In2012, we selected Yellow River Delta as the study area, and investigated the plant functional traits, the pattern of community dynamics and environmental factors in the field plots under the typical human disturbance factors (ecological water diversion and sea wall) by the methods of ecological surveys, data mining and simulation tools. The results showed ecological water diversion and sea wall both significantly influenced the moisture and salinity characteristics of plant communities. The sea wall significantly influenced the leaf traits and community traits of Phragmites australis, and by the method of one-way ANOVA, Specific Leaf Area (SLA), Blade thickness, Leaf Nitrogen Content (LNC) and Leaf Phosphorus Content (LPC) were selected as leaf traits reflecting disturbance degree of sea wall. At community level, the community composition and the dominant position of Phragmites australis reflected the influence of ecological water diversion, while at the individual level, the height and leaf size of Phragmites australis reflected that influence.Through correlation analysis and regression analysis, significant correlation existed between some traits, which can be simulated by regression model, In our study, there was a significant negative correlation between SLA and Blade Thickness, as well as between the important value (IV) of Phragmites australis and SLA. There was a significant positive correlation between LNC and LCC, as well as between LPC and the average height of Phragmites australis. Regression analysis showed that all these significant correlation could be simulated by linear model, and significance test showed that all these models are significant.