Analysis on Species Diversity of Oxytropis in Xinjiang

There are 98 species and 2 varieties in the genus of Oxytropis in Xinjiang,and they account for 67.1% of the total in China.Among them 7 species are endemic in Xinjiang,58 ones are distributed only in Xinjiang in China,and about 65% species belongs to the two of them.Species are all distributed in 11 floristic regions in Xinjiang.The Junggar Basin and the Tianshan Mountains,especially the Tianshan Mountains,are regarded as the areas with the most abundant species of Oxytropis in Xinjiang.So it is concluded that the Junggar Basin and the Tianshan Mountains may be the central areas of modern distribution and origin differentiation of Oxytropis DC.Most species(about 99%) are distributed in the mountainous areas with an altitude range from 1 001 m to 5 000 m a.s.l.,especially in an altitude range from 1 001 m to 4 000 m,and the richest species are distributed in an altitude range from 2 001 m to 3 000 m.There are two kinds of life-forms,hemicryptophyte and chamaephyte,the proportion of the former is as high 96%,but that of the latter is 4% only.The relations of flora in Xinjiang are the closest with that in adjacent Qinghai Province and Tibet Autonomous Region(their similarity coefficients are 28.8% and 28.6% respectively),but not so close with that in Inner Mongolica and Gansu Province.The relations of flora in Xinjiang are the closest with that in Kazakhstan(the similarity coefficient is as high as 65.2%),then with that in west Siberia and Kyrghizstan(the similarity coefficients are 41.8% and 41.0% respectively),and the weakest with that in Mongolica,Tajikistan and Pakistan(their similarity coefficients are 29.2%,22.8% and 11.6% respectively).