The Study On Community Characteristics And Soil Ecological Stoichiometry At Stipa Glareosa Community In Inner Mongolia Desert Steppe

In this study, enclosure is used in Stipa glareosa community for a period of four years. The vegetation composition,dynamic productivity characteristics and soil ecological stoichiometry were studied in both fenced and freely grazed plots.The results indicated:1、The species composition of Stipa glareosa community is relatively poor which f our years without a markedly change. The number of species between6-8kinds The community is mainly compose of perennial xerophytic pasture-based, including five functional groups:Bunch grass, Carex, Shrub, Perennial forbs, A biennale forbs。2、The change of community biomass on the ground in four years has significantly posit ive correlation with precipitation.(R2=0.97, P<0.05) The density and variation of aboveground biomass of salsola in the community produced great influence on the community total density and biomass on the ground.3、After four years of fencing, Margarlef index,Shannon-Wiener index, Simpson index, Pielou index showed a slight rise. And diversity index (with the important value of parameter calculation) positively correlated with evenness index showed, with the major species dominance was negatively correlated. 4、With the soil depth, soil nutrient of Stipa glareosa community increase.Phosphorus content in soil below the average content (0.56g/kg) in our country.There is no surface aggregation effect of Stipa glareosa communities (0-30cm).5、Species composition after fence treatment with no significant difference in communities outside the fence. But community density, ground biomass are more than the community which outside the fence6、Shannon-Wiener index, Pielou index were higher than the fencing Stipa glareosa communities。7、After four years of fencing, the soil nutrients content(organic matter, total nitrogen, total phosphorus) have risen than the community before treatment. Soil C: N less than the previous enclosure, and there were significant differences.There is no significant difference (P>0.05)of soil N:P between enclosure and free Stipa glareosa communities。N:P of soil is significantly higher than the Community before treatment.But it still lower than the N:P threshold of leaf.During four year of fencing the community is still in a state of nitrogen deficiency.