Environmental Factors and Community Characteristics of Aquatic Macrophytes in Taizi River Tributaries of Liaoning Province

The community structure and biomass of aquatic macrophytes were investigated in three Taizi River tributaries of northeast China.The results indicated that Potamogeton pusillus,P.crispus and P.malaianus were the dominant species in the North Taizi Stream,where P.pusillus+P.crispus presented the main community type;P.crispus,P.malaianus and Hydrilla verticillata were the dominant species in the Xi Stream,where P.crispus+Hydrilla verticillata was the main community type;H.verticillata,P.pusillus,Ceratophyllum oryzetorum and P.crispus were the dominant species in the Haicheng Stream,where H.verticillata+P.pusillus+P.crispus was the main community type.Parvopotamids and magnopotamids were the main growth-form of quota growth-form spectrum in the North Taizi Stream and Xi Stream,respectively.The quota growth-form spectrum of Haicheng Stream was more complex with magnopo-tamids,parvopotamids,ceratophyllids and elodeids all dominant growth-forms.The submerged plants were the dominant life-form at all three streams.Based on cluster analysis,the aquatic macrophytes community differed significantly between the three streams.The longitudinal distribution pattern of aquatic macrophytes was highly patched at each stream and the vertical distribution pattern was not indentified along water depth.The aquatic macrophytes appeared from upstream to downstream at the North Taizi Stream,but were only found from middle stream to downstream in Haicheng Stream and downstream in Xi Stream.Average productivity(wet weight)of aquatic macrophytes showed that the highest value was at Haicheng Stream(644 g/m²),middle value was at the North Taizi Stream(586.8 g/m²),and the lowest value was at Xi Stream(151.1 g/m²).The correlation analyses of aquatic macrophytes and physico-chemical factors showed that species richness showed significant positive correlation with ammonium(NH₃-N),water temperature,pH,and conductivity(p<0.05),but showed significant negative correlation with dissolved oxygen,substrate index and altitude(p<0.01).The biomass of P.pusillus demonstrated significant positive correlation with water depth(p<0.01)but significant negative correlation with conductivity and total nitrogen(p<0.05).