Abstract: Tetraena mongolica Maxim. is a relict and endangered monotypic genus species from the ancient Mediterranean flora and a second-degree endangered species in China. It is one of the dominant species in plant community in arid and semiarid regions of Northwest China, and thus plays an important role in maintaining ecosystem structure and function. Based on field investigation of natural T. mongolica community in Northwest China, we analyzed species composition, species diversity, and the correlation between species diversity and soil physicochemical properties. The results showed that: (1) T. mongolica community features simple composition structure and low species diversity. With a total of 64 species, 42 genera and 15 families recorded, most species are subshrubs and perennial herbs from Asteraceae, Poaceae and Chenopodiaceae. There were significant differences in species diversity among different T. mongolica plant communities (P<0.05). Plant species richness, Shannon index and Simpson index of Qianligou community were the highest (24.00, 2.92 and 0.93, respectively). The Pielou index in Qianlishan community was the highest (0.98). (2) There were significant differences in soil nutrient contents among different T. mongolica plant communities (P<0.01). Soil available nutrients (available nitrogen, available phosphorus, available potassium) of Haibowanqu and Hainanqu were higher than that of other communities. Soil organic content in Qianlishan was the highest, whereas soil moisture was the highest in Qianligou. Species diversity ofT. mongolica community was significantly positively correlated with soil available phosphorus (P<0.05). Our results provide scientific support for understanding the T. mongolica plant community and theoretical basis for protecting the germplasm of relic T. mongolica.

Key words: Tetraena mongolica Maxim., plant community structure, plant species diversity, soil nutrient, soil moisture.