Abstract:

The community characteristics of Asterothamnus centrali-asiaticus and Gymnocarpos przewalskii in the north Subei of Gansu Province were investigated from 2006 to 2009. The results showed that A. centrali-asiaticus and G. przewalskii mainly distributed over piedmont alluvial fan, proluvial fan, gravel gobi and dry river bed regions. They distributed at a range from about 1 500 to 1 600 m a.s.l.in the northern mountain region of Subei, and at a range from about 1 900 to 2 900 m a.s.l. in the southern mountain region of Subei. G. przewalskii, as companion species, emerged in A. centrali-asiaticus community on West gobi of Subei, while A. centrali-asiaticus and G. przewalskii, as constructive or dominant species, formed plant community in Hongliu Gap region. The species composition of A. centrali-asiaticus and G. przewalskii community consisted of 44 species, which belong to 31 genera of 13 families. The flora of the ancient Mediterranean and the West Asia to Central Asia accounts for 54.8%; The flora of the north temperate distribution pattern accounts for 19.4%, and world-distributed species constitute 9.7%. There was close relation among the floras of A. centrali-asiaticus, G. przewalskii desert communities and those of the ancient Mediterranean. The species diversity indexes of A. centrali-asiaticus and G. przewalskii community were all high, However, evenness index was very low in Hongliu Gap region, although species were abundant. Species distribution was not uneven in the community, and the number of old age plants of G. przewalskii was more than that of young age plants in all communities which implied that G. przewalskii population was inclining to recession.

Key words: Subei, Asterothamnus centrali-asiaticus, Gymnocarpos przewalskii, community characteristics