Abstract:

The two resource axes are composed by community types and stand altitude, which can reflect various ecological factors. The paper deals with the niche measurement of the dominant species of desert gobi shrub community in Jiuquan, Gansu province. The ability in utilizing resources and occupying ecological spaces by different species is important for maintaining, self-improvement, scientific conservation and managing the diversity of desert gobi shrub communities.The results showed that: (1) Across the community types and altitude gradient, important values and niche breadth were major in Reaumuria songarica, Nitraria sphaerocarpa and Sympegma regelii. Thus，these species had high adaptability，broad habitats，and inclined to be generalist species which played an important role in the communities due to strong ecological adaptability in desert gobi shrub communities.(2) Most shrub species’ niche overlap values were minor, of which 62.63% and 77.89% shrub species were lower than 0.5 across the two resource axes. The species with higher niche breadth had relatively larger niche overlap, due to species had strong ability to utilize resources and were competitive in shrub communities. However, the species with higher niche breadth or species with lower niche breadth had relatively small niche overlap, due to different species complement each other in their environmental resource needs and can coexist in harmony. The species with lower niche breadth had larger niche overlap，because of the habitat patch of species distribution. It suggested that there was no signi?cant correlation between niche overlap and niche breadth. (3)Macro-association was significantly positively correlated among 20 dominant species，this result indicated that the plant community was in a relatively stable status.

Key words: desert gobi, dominant species of shrub communities, niche breadth, niche overlap