Reserch On Ecology Function And Population Establishment Machanism Of Stipagrostis Pennata In The Southern Edge Of Gurbantonggut Desert

Stipagrostis pennata is a pioneer plant in Gurbantonggut Desert in Northern Xinjiang. It can be look upon as the first chosen plant for migratory dune restoration. In order to find out the ability of Stipagrostis pennata population, and how the species population grow and how it promotes other species to settle, a plot of 25m×25m and a typical plot of 100m×100m were surveyed. And Geostatistics's method was applied to diagnose spatial patterns of S. pennata, Salsola collina; and Ripley's K(d) function were applied to diagnose spatial patterns of S. pennata and spatial associations between S. pennata and Calligonum leucocladum,and between S. pennata and Haloxylon persicum. The results show:(1) Appling the semi-variance analysis, the results of pattern indicated:the patterns of S. pennata population and their seedlings belonged to cluster distribution, and the ranges(a) were 1.84m and 0.57m respectively; the pattern of S. collina belonged to cluster distribution, the range was 8.12m.(2) Appling the Ripley's K(d)function of point pattern, the result showed:the small size and medium size class 1 of the S. pennata population are cluster distribution pattern below 38m,and show random distribution upon 38m; The medium size class 2 and class 3 and all S. pennata population are all cluster distribution pattern below 50m; The medium size class 4 are clusters distribution at 2～17m scale, and shows random distribution upon 17m; The large size are cluster distribution below 47m, and show random distribution at 47-50m scale. It shows all significantly positive correlation between mediun size and small size, large size and small size, medium size and large size of S. pennata population at 0-50m scale. S. pennata is both significantly positively associated to C. leucocladum and H.persicum at 0-50m scale. It shows:S. pennata has obvious facilitation effect on seed germination,ecesis and growth of C.leucocladum and H. persicum.(3)The low organic contents showed the soil of S. pennata plot had few nutrient; the electrical conductivity and CL-, SO42- contents were all very low, which showed the degree of soil salinization was very light; pH were signifiantly alkalescence.