Characters of Community Diversity in the Oasis-desert Transition Zone in Lower Reaches of Tarim River

Based on the data obtained from 29 plots of natural plant communities in the lower reaches of Tarim River,the paper analyzed the community structure and species diversity.The results showed that ①there are only 12 families,18 genera and 20 species in ten sections of Tieganlike transition zone between oasis and desert.Among those 20 species,Tamarix hispida and Tamarix ramosissima are the main families.The dominant plant species are Arbors Tamarix hispida,Shrubbery Lycium ruthenicum,H.caspica.and Herbage Phragmites communis,Glycyrrhiza inflata,Karelinia caspic etc.②The paper used Simpson and Shannon-wiener indices,Menhinick and Margalef indices,and JSW and JSI indices to calculate the species diversity index.The ecosystem is deteriorating,with Simpson index changed from 0.517 to 0.830,Shannon-wiener from 0.851 to 1.974;Menhinick index changed from 0.977 to 3.784,Margalef from1.517 to 8.496;JSW index changed from 0.719 to 0.908,JSI from 0.729 to 0.949.The amount of species changed from 13 to 8,and the vegetation coverage changed from 0.035 to 1.001.The results suggested that we should pay attention to the ecosystem of the lower Trim River and give a good protection to the standing plant.