The Composition and Species Diversity of Herb Plants of Xihu Wetland of Dunhuang

Taking the Xihu wetland in Dunhuang of Gansu Province for an example,we selected 4 type wetlands as the plots: Meadow bog,Reed swamp,Salt marsh and Saline land,and used the ways of field investigation and laboratory analysis and studied on the composition and species diversity of herb plants Xihu wetland in Dunhuang.The results show that: a total of 43 species belonging to 17 families are found in the 4 type wetlands,of which,Gramineae and Compositae species making up to 46.5%.Meadow bog has the largest number of species in the 4 type wetlands.It has 29 species,but Salt marsh only has 8 species.Meadow bog is an equal dominant community,so the Shannon-Wiener diversity index and Pielou evenness index are high and Simpson index is low.Reed swamp is a single structure community,reed(Phragmites australis)is the dominant species,Shannon-Wiener diversity index and Pielou evenness index are low,while Simpson index was high.Salt marsh and Saline land growth halophyte and xerophyte plants,these plants are dominant species in the community,Pielou evenness index is high and Simpson index is low.Meadow bog,Reed swamp,Salt marsh and Saline land plots distribute as step because of the different elevation,this distribution pattern can effect the flow direction and hydrops,so it is one of main reasons for the 4 type wetlands form significant difference on composition and species diversity.