Community characteristics and species diversity of wetland plants in middle reaches of Heihe River, Northwest China

By using the methods of botany and phytogeography, in combining with field investigation, this paper studied the wetland flora composition, geographical elements, ecological characteristics, and species diversity in the middle reaches of Heihe River, Northwest China. A total of 84 plant species were recorded, belonging to 70 genera and 32 families. The species of Compositae and Gramineae were dominant, occupying 29.8% of the total. The geographic elements of the flora were of multiplicity, most of which embodied the feature of temperate zone. Herbs had the numerical advantage, and perennial herbs were the main component. By using two-way indicator species analysis (TWINSPAN), the vegetation in 42 sampling plots could be classified into 10 communities. The species diversity indices of the communities were relatively low, but had large differences among each other. According to the importance value, the Margalef richness index (Rm) ranged from 0.344 to 1.202, Simpson diversity index (D) was between 0 and 0.840, Shannon diversity index (H) ranged from 0 to 1.999, and Pielou evenness index (J) was within the range of 0.712-1.0, indicating that the structure of the wetland plant communities in the middle reaches of Heihe River was relatively simple.