Abstract: In order to analyze the influence of environmental factors on distribution of plant communities and composition of species in alpine grassland, 9 plots (10m×10m) were established from west to east, basic 2460m, along an altitude gradients at 100m intervals in Bayinbulak alpine grassland on the southern slope of Tianshan Mountain. Data were analyzed by using the quantitative classification method (Two-way Indicator Species Analysis) and the ordination technique (Canonical Correspondence Analysis and Detrended Canonical Correspondence). The results showed that: 1) Alpine steppe types mainly distributed from 2460 to 2760m, with the average temperature about 10.8℃ in July and August. Alpine steppe-meadow distributed at altitude of 2860m. Alpine meadow distributed about over altitude of 2960m. The average relative humidity and soil water content were 77.77% and 42.95% respectively in July and August. 2) Available soil potassium content gradually decreased from alpine steppe, alpine steppe-meadow to alpine meadow, but organic matters and available soil nitrogen content gradually increased. 3) CCA and DCA ordination showed that environmental factors, such as temperature, available soil potassium and organic matters played a very important role in the community distribution and species composition. 4) The TWINSPAN cluster analysis also indicated that the nine plots were divided into three types, alpine steppe, alpine steppe-meadow and alpine meadow, and it was completely approved by the result of ordination.

Key words: Alpine grassland, Alpine grassland, CCA ordination, TWINSPAN quantitative classification, Environmental factors