关键词: 荒漠草地, 种子植物, 植物区系, 地理成分, 锡林郭勒

Abstract: The local flora structure and the distribution characteristics of seed plants in the Xilingol desert steppe were studied based on wild vegetable survey by processing the data, analyzing the plant families, genera and species and applying the methods of botany and phytogeography. It is suggested to protect and utilize rationally the wild plant resources in the study area, and an important reference is provided as the scientific basis to protect the local plant species. The results show that the local plants belong to the desert steppe flora. So far 348 endemic species in 180 genera and 55 families in the Xilingol desert steppe were recorded. In which there were 4 species in 2 genera and 2 families of Gymnosperm and 344 species (including 31 varieties) in 178 genera and 53 families of Angiosperm. Composed by the families and genera, the plurimotypic families (including more than 10 species), monotypic genera and oligotypic genera were the main part of the local flora and the main sources of flora complexity and species diversity to be as the widely distributed local species. At family level, the proportion of Gramineae, Compositae, Leguminosae, Chenopodiaceae, Cruciferae and Polygonaceae was the highest, there was a trend that the floristic element laid in big families of spermatophyte, and the dominance of plurimotypic families was evident. The proportion of 45 families with less than 10 species was 81.83% of the total families in the region. At genus level, although plurimotypic genera and plurotypic genera were the dominant species of local plant communities and the typical components, but they were not the main part, they had an important influence on the structure of flora and vegetable composition. The single-species genera and few-species genera are the main part of the local flora and the main sources of the local flora complexity and species diversity to be as the widely distributed local species. After analyzing the floristic geographical element of genera and species, the results reveal that the temperate element genera and species were the main part of the local flora, the geographic element of the flora was the multiplicity, and the temperate element was the main part of local flora; the temperate element characteristics were the typical features of local flora. The main floristic feature was temperate, but it was affected by pantropical element to a certain extent. The comparison of similarity coefficients of various florae (including the Dalai Lake Nature Reserve, the Dalinor National Nature Reserve, Otindag Sandy Land and Alxa Desert) reveals that the flora had an affinitive relationship with Alxa desert, and the seed plant flora in the steppe had the obvious desertification characteristics. The analysis of floristic geographical element and distribution characteristics in Xilingol desert steppe also indicated that the climate and environmental conditions, ecological amplitude and adaptive capacity of plants affected determinatively the floristic geographic distribution.

Key words: desert steppe, spermatophyte, floristic element, geographical element, Xilingol