Abstract: This study aimed to investigate the species composition, species diversity of shrub communities under “mountaindesertoasis” landscape configuration in an arid region of Xinjiang. According to quadrat sampling, shrub communities were classified by TWINSPAN classification method, and the community diversity indexes were calculated. A total of 185 species were identified, including 44 shrub species and 141 herb species, belonging to 123 genera and 33 families. Most of plants belonged to Rosaceae, Compositae and Chenopodiaceae, which were the dominant families in arid regions of northwest China. The flora of shrub species was dominated by the North temperate, the ancient Mediterranean and West Asia to Central Asia components. Shrub communities could be divided into 9 types of shrub community or shrub landscape, including plain and valley shrub, montane scrub and plain desert type. The Shannon diversity index, Pielou evenness index and species richness index showed a similar pattern, being opposite to the dominance index. Moreover, with the increase of the altitude, the Shannon diversity index, Pielou evenness index and species richness index showed a single peak distribution pattern. Our results indicated that the shrub community structure in the study area was relatively simple, the compositional species were relatively few, and the species distribution was not uniform, which may be related to the geographical background and the habitat conditions of shrub plants in arid areas.

Key words: biological soil crusts, drought process, nitrate nitrogen, net nitrification rate.