Research On The Relationship Between Macrophyte Community And Hydro-environment In Beijing's Wetland

Our purpose was to explore the primary determinants of freshwater macrophyte(submerged plants) distribution in hydro-environmental.Factors include chemical,physical and hydrological parameters. The study investigated whether certain plant species and communities can be used as direct estimators of environmental parameters.Six rivers and four reservoirs in Beijing were visited and eighty-seven samples were collected.At each site,submerged plants were noted and their fresh weight recorded.At each location eleven environmental variables including velocity,Secchi depth,transparency, conductivity,temperature,pH,redox potential,concentration of total nitrogen and phosphorus,chemical oxygen demand were analyzed by LIVIBOND hydrolab in the field. Subsequently we ordinated samples and environmental variables by DCCA through the programme CANOCO 4.5,Using the ordination,the samples and species were rearranged in a 2-way table, bringing together repeating combinations of species.Using this method,fourteen submerged plants fell into 10 groups which were then examined according to the measured environmental variables. The species classification correlated strongly with velocity,which appeared to be the key dividing variable.The second important factor in still water determining submerged plant distribution was concentration of total nitrogen.While in the flowing water,environmental variables such as conductivity,COD,redox potential played significant role in plant community distribution.Different communities indicated responses to different environmental variables.The occurrence of Myriophyllum spicatum+ Potamongeton Association crispus is a indicator of hypertrophic state.And the Batrachium pekinens Association can be regarded as an indicator of excellent water quality because it was found only in water with low TN,good transparency and low temperatures.