Species diversity of pasture community at different altitude levels in Qilian Mountains
祁连山区不同海拔草地群落的物种多样性

According to the occurring frequency and life form of plant species at different altitude levels, this paper studied the changing characteristics of the species a diversity of pasture community at the altitude from 2500 m to 3000 m in Qilian Mountains. The results showed that with increasing altitude, the Shannon-Wiener species diversity index increased from 1.432 to 1.832, and the variety of Simpson index was very complicated. An altitude of 2701-2800 m was an important turning point for species diversity. In pasture community of Qilian Mountains, the percentage of the poisonous and the less edible species exceeded 50%, and their biomass was more than 60% of the total biomass of the community. The biodiversity showed a degraded trend.