[Community characteristics in Qingyihe River basin of Xuchang section and their relationships with environmental factors.]

We took Xuchang section of Qingyihe River Basin as study object to explore biodiversity in Qingyihe River. On the basis of field survey and in-laboratory analysis, community characteristics of aquatic macrophytes, riparian zone plants and macrobenthos, with environmental characteristics of water and surface sediment were investigated. Results showed that a total of 12 species of aquatic macrophytes, 66 species of riparian zone plants, and 10 species of macrobenthos were found. The communities varied sharply with the changes in the environmental factors, such as NH ₄ ⁺ -N, TN, TP in the water and oxidation-reduction potential (ORP), TP, Cd, Hg, Zn in the surface sediment. The CCA ordination results indicated that COD, temperature, pH, DO, TP in the water were key factors influencing aquatic macrophytes, while ORP, pH in the water and Ni, Hg, TOC, Pb, Cd in the surface sediment were key factors for riparian zone plants. pH, temperature, ORP, As, Pb, Ni in the surface sediment and temperature in the water were the key factors influencing community characteristic of macrobenthos. In Qingyihe River basin of Xuchang section, the water had been polluted and the biodiversity of communities was low, so it is urgent to treat wastewater along the river as well as protect and recover communities.