The Ecology Study On The Estuary Wetland Vegetation Of Shiwuli River In Chaohu Lake

Chaohu lake is one of the five largest freshwater lakes in China, and it is also the important freshwater resources to Hefei city and Chaohu city. However, increasingly serious eutrophication restricts the sustainable development of the local economy and society. Consequently, the treatment for lake pollution and protection for lake freshwater resources are being put into practice without delay.The rivers are the first zone of the point pollutants and non-point pollutants, and are also the main channels of pollutants into the lake. Esturary wetlands are the transitionary zone between lake and land ecosystem, which can trape and remove the pollutants by adsorption, sedimentation, assimilation, and microbe decomposition of wetlands. So the study on the esturary wetland plants' eco-characteristics and its water purification function is considered as very important significance.The esturary wetland plants of Shiwuli River in Chaohu, including the floristic diversity, the interspecific relationship of plant communities, the relationships between plant communities and environments, the capacity of uptake nutrients and heavy metals of some plants are studied, respectively. The major results are summarized as follows:1. The plants composition and distribution in the esturary wetlandThe lake water level is regarded as the main factor that affected the plants composition of the esturary wetland. The species composition are not varied greatly in the same time, but varied greatly in different time. The species richness is higher and the community composition is more complex in the low water level period than in the high water level period. The results of DCA ordination indicate that there are obvious relationships between the distribution pattern of associations and soil water content, soil texture.2. The plants interspecies associations in the esturary wetlandA series of techniques including the analysis of variance, X~2 and Ochiai are used together with a 2×2 contingency table in order to analyze the interspeciesassociations of the plants species in the esturary wetland. The results indicate that the community structure is stable in the low water level period, and is instable in the high water level period. The environment of the esturary wetland is more and more not suit for the plants grow.3. The species diversity variation in the esturary wetlandThe diversity index, the evenness index and the richness index are used to analyze the plants communities diversity of the esturary wetland in different period. The results indicate that the plant diversity index in the low water level period is higher than that in the high water level period, but its evenness index is lower than that in high water level period;The lake level, water quality and human activity are the main factors that cause the plant diversity changes in the estuary wetland.4. The assimilation ability of N> P and heavy metals by hydrophyte and prevention of the secondary pollutionN-. P and heavy metals contents of the plants in the estuary wetland are measured. The results indicate that different kinds of aquatic plants in the estuary wetland had different enrichment by the N> P and heavy metals, and advanced that reap of the estuary wetland plants is the best way to prevention of the secondary pollution.