Distribution,community characteristics and classification of Stipa tianschanica var. gobica steppe in China

Aims Stipa tianschanicavar. gobica steppe is mainly distributed on the rocky slopes or rocky hills of desert steppe region, and can also be found in rocky hills or mountains of the typical steppe area eastwardly and some rocky slopes of the desert region westwardly. The main vegetation types of S. tianschanicavar. gobica steppe in China were investigated in this paper, and based on the 115 plot samples, the characteristics of the main desert steppe plant communities from the main vegetation types were quantitatively described. And the results showed that: according to the quadrat data, 272 seed plants belonging to 38 families and 127 genera (including the subspecies, varieties and forms) were recorded in the S. tianschanicavar. gobica steppe of China, among which there were 3 gymnosperm species belonging to 1 families and 1 genera, and 269 angiosperm species belonging to 37 families and 126 genera. The families having more than 10 species were Compositae, Poaceae, Leguminosae, Rosaceae, Liliaceae, Chenopodiaceae and Caryophyllaceae respectively. Hemicryptophyte, with a total of 178 species is the dominant life form in S. tianschanicavar. gobica steppe, which accounted for 65.44% of the total species. As for the ecological type of water, xerophytes was the dominant plants, with a total of 120 species, accounting for 44.12% of all species. East Palaeo-North element areal-type (including 82 species) and Middle Asia element (included the variants) areal-type (including 80 species) were the major floristic elements, containing 30.14% and 29.41% of the total species. The coverage of 0.1%-1% was the dominant level in the cover class distribution of the species, including 63.97% of the total species. The constancy degree of I (0-20%) was the dominant level in the constancy degree distribution of the species in S. tianschanicavar. gobica steppe, containing 94.85% of all the species. In accordance with the classification principle of community-appearance, Form. S. tianschanicavar. gobica was divided into 8 S. tianschanicavar. gobica steppe association groups, and 106 associations were divided from these 8 association groups based on community survey data.