Species diversity and spatial variation of ephemeral community In the southern part of the Gurbantunggut Desert

The southern part of Gurbantunggut Desert is the concentrated distribution area of ephemerals which are important in reducing wind, stabilizing sand and keeping the desert stable. However, little research has been done so far on the community diversity and ecosystem function of ephemerals. This study provides an inspection and analysis of the diversity feature of ephemerals in 35 sites which cover a total area of 3.86 × 10⁴ m² in the southern part of the Gurbantunggut Desert, using stratified sampling techniques. A total of 93 species belonging to 18 families and 48 genera are found, of which families like Chenopodiaceae, Compositae, Cruciferae and Leguminosae are dominant, taking up 19.35%, 17.20%, 11.83% and 9.68%, of the total species respectively. In terms of life forms, ephemerals make up 53.76%, herbage plant with long period of nourishment account for 22.58% and arbor and shrub mahe up 16.13%. In terms of important value, arbor and shrubs account to 30.93% and ephemerals acount for 45.73%. The spatial variation of ephemerals are distinct: in longitude, the species number and important value of ephemerals increase significantly with the increase of longitude(from west to east), while the important value of herbage plant with long period of nourishment and arbor and shrub decreases with the increase of longitude; in latitude, the species number and important value of ephemerals decrease with the increase of latitude(from south to north), while the important value of herbage plant with long period of nourishment and arbor and shrub increases with the increase of latitude and there are no distinct change in species number. Species distribution is found to be greatly influenced by slope positions, longitude and latitude, annual precipitation and precipitation from March to May through detrended canonical correspondence analysis(DCCA). We use two-way indicator species analysis(TWINSPAN) and divided the ephemerals living in the southern- - part of the Gurbantunggut Desert into 7 communities. In conclusion, we think the important value and species number of the ephemeral plants would increase with the increase of the precipitation in the Gurbantunggut Desert but the density of the constructive species of Haloxylon persicum would decline gradually.