| Desertification is one of the great environmental problems concerned by human society, which threatens natural environment of human existence and sustainable development of society and economy. Desertification means not only degradation of vegetation structure and function, but also soil degradation. Based on vegetation quantitative classification and Multi-variant analysis, the characteristics of vegetation and soil at different degradation steps were analyzed, the evaluation indicators of desertification were identified and the desertification degrees of Artemisia ordosica sandy land were evaluated. The major conclusions are as the following:(1) Species composition is rich in Artemisia ordosica communities, with Asteraceae, Gramineae, Leguminosae and Chenopodiaceae as the dominant families. The characteristics of ecological type and life form of plants in Artemisia ordosica community are the higher proportion of hemicryptophyte and vivacious herbage and the important role of xerophyte and psammophyte in the communities. Based on TWINSPAN classification, the Artemisia ordosica communities were divided into five communities: Artemisia ordosica+Agriophyllum pungens community, Artemisia ordosica+Agriophyllum pungens, Corispermum heptapotamicum community, Artemisia ordosica+ herbage layer dominated by psammophyte community, Artemisia ordosica+ forbs and grasses community and Artemisia ordosica+ herbage layer dominated by mesophyte community.(2) Allocation pattern of Artemisia ordosica individual biomass is that aboveground biomass is far higher than belowground biomass. T/R is 2.19. Artemisia ordosica individual biomass has greatly remarkable correlation with the coronal area, height, cubage and number of branches of plant individual. The prediction model of Artemisia ordosica individual biomass is W=202.9+11.29Cï¼0.0135C~2, in which C is a integrated variable calculated by cubage times number of branches.(3) Shifting sandy land, semi-fixed sandy land and fixed sandy land are different...
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