| Based on the investigation and testing data of grassland on the northeast slope ofQue'er Mountain, according to the principles that reliability, practicability, operationalization ofindex, selected 17 valuating indexes by frequency statistical method and Delphi method,established evaluation architecture based on the indexes such as total coverage ofphytocommunity, height of undergrowth, species richness indices, biomass on the ground, theratio of poisonous weeds in community, thick of available soil layer, (0.02～2.00 mm) sandconten,(＜0.002 mm)clay conten, soil bulk density, pH, organic matter, total nitrogen, totalphosphorus, total potassium, alkali-dispelled nitrogen, available phosphorus and availablepotassium. Evaluated the degradation degree of the grassland on the northeast slope of Que'erMountain using main component analysis method and cluster analysis method, studied on thephytocommunity and Physical and Chemical Properties of Soil under different degradationdegrees, discussed the factors of degradation, came up with some sustainable measures, theresults were as follows:(1) Screened 7 new indexes which were biomass on the ground, height of undergrowth,organic matter, species richness indices, thick of available soil layer, available phosphorus andsoil bulk density on the base of main component analysis method, and classified the degradationinto 4 degrees that no-degradation (ND), light-degradation (LD), middle-degradation (MD) andhevay-degradation (HD) by quick cluster and discriminant analysis on SPSS13.0. Of which,there were 4 sample plots of ND, accounted for 9.3% of the total; while there were 9 sampleplots of LD, 21 sample plots of MD, 9 of sample plots of HD, accounted for 20.9%, 48.8% and20.9%, respectively.(2) Through soil physical-chemical signature analysis on four different degraded soil,no-degradation(ND),light-degradation(LD),middle-degradation(MD),and hevay-degradation(HD),the results showed that, while the degradation of grassland was strengthened(from ND to HD), thebulk density of soil surface gradually increased, the average contents were 1.08 g cm-3, 1.28 gcm-3, 1.31 g cm-3和1.34 g cm-3 respectively; the sand contents and pH values of sod layer(As),organic layer(A) and sediment horizon(B) increased with degradation, clay contents decreased atthe same time; except total nitrogen content was middle in the research areas, the contents oforganic matter, total phosphorus and potassium were abundant, soil organic matter content andtotal nitrogen decreased with degradation, total phosphorus and potassium contents changed little; besides alkali-hydrolysable nitrogen decreased with degradation as total nitrogen, itseemed other available nutrients like phosphorus and potassium had no relation withdegradation.(3) Study on the characteristics of plant community under different degradation degreegrassland, the results suggested, vegetation community got a converse succession asGramineae-Moraceae,Polygonaceae,Leguminosae-Compositae,Ranunculaceae-Rosaceae,Thymelaeaceae,Scrophulariaceae, we could also said that with the strengthened of degradation,vegetation gradually evaluated from Gramineae to Thymelaeaceae, Scrophulariaceae and thosekinds of poisonous and harmful plants, vegetation community became simpler; the quantity ofplant species got a trend as ND＞LD＞MD＞HD; coverage, total biomass decreased withdegradation.(4) The analysis of influence factor showed that the degradation of grassland was causedby the combined action of natural and human factors, in addition, the pests and rats aggravatedthe deterioration of the regional ecological environment. So, this paper advised to determinelivestock carrying capacity according to grass, develop seasonal animal husbandry, carry out theeffect and experience of grassland paying for contract, in order to achieve the sustainabledevelopment of animal agriculture and the restoration of the regional ecological environment.
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