COMMUNITY CHARACTERISTICS OF STIPA PURPUREA STEPPE IN SOURCE REGIONS OF CHANGJIANG AND HUANGHE RIVERS, CHINA

Aims Stipa purpurea steppe is one of the most important ecosystems in source regions of Changjiang (Yangtse) and Huanghe (Yellow) Rivers. Our objective was to determine Stipa purpurea community characteristics. Methods Typical Stipa purpurea communities distributed in Maduo, Qumalai and Tongde of Qinghai Province were selected as three sampling locations and sampled using 33 sampling lines for a total of 330 samples. Analyses used PCORD, SPSS and EXCEL software. Important findings Species composition of the investigated community was simple, with 96 species grouped into 58 genera and 23 families. North Temperate genera were dominant. We identified three associations: Stipa purpurea+Potentilla bifurca association (Ⅰ), Stipa purpurea + Carex parva association (Ⅱ), and Stipa purpurea+Poa indattenuata association (Ⅲ). These associations have different characteristics that are analyzed in this paper. Comparability analysis show that association Ⅰ is much more similar to association Ⅱ than Ⅲ, but the importance value of S. purpurea is much higher than any other species in all associations. The community distribution of S. purpurea steppe is heterogeneous at coarse scale and regionally homogeneous at fine scale. The correlations are all significant among evenness, Simpson, Shannon-Wiener indices and latitude. The curves of evenness, Simpson and Shannon-Wiener indices changed similarly in samples. Species diversity for the associations was Ⅱ>Ⅲ>Ⅰ.