Study On The Floristic Of Seed Plants In Alashan Desert District

This thesis applied the methodology and principles of the floristic geography, also based on the composition and phytogeographic elements of the species, genera and families is to Alashan Desert District, to comparative study among the flora of West-North Desert of China. The results are as follows: The plant diversity is abundant in this area. There are 1091 species of seed plants in Alashan Desert District, which belong to 377 genera and 87 families (exclusion from cultivated plants). Then wild seed plants included 1068 species, 371 genera, 84 families. Among them are about 18 species, 7 genera, 3 families, in Gymnospermeae; 1050 species, 364 genera and 81 families, in Angiosperm, which demonstrates to distribution of plants in Alashan Desert District in adaptation to this climate zone in the area.The 371 genera are devided into 15 types and 17 subtypes of geographical elements. Analysis of the floristic composition and the geographical elements shows that the flora has a complex composition.Temperate floristic elements which belong to 824 species and 221 genera make significant dominant in this area, in which the percentage of North Temperate genera is the highest, making up 30.8% in the total number of genera in this area. It is indicated that this area showes the typical temperate characteristics of the flora.The endemic elements are unbalanced. There are 149 species Chinese endemic species of seed plants in Alashan Desert District, making up 13.9% in the total number of species in this area. While there are only 13 genera Chinese endemic genera of seed plants in Allah Desert District, among them,8 genera are single species genera or genera axe with only a few species. There are obvious permeation, intersection, transition and frangibility of the flora.Quantitative comparison and analysis on flora in the Alashan Desert District and in related area such as Hexi Corridor ,the Tarim Basin ,the Zhungeer Basin and the Tsaidam Basin indicates that Alashan Desert District and Hexi Corridor is most closed, is significantly different with the Zhungeer Basin. Desert flora in Northwestern China is an unity according to their composition and evolution way.