MAIN CHARACTERISTICS OF LITTLEDALEA RACEMOSA ALPINE STEPPE IN QINGHAI XIZANG(TIBET)PLATEAU
青藏高原扇穗茅高寒草原的基本特点

Littledalea racemosa is one of the endemic grass species distributed only in the Qinghai- Xizang Plateau. and mainly within the alpine beIt between 4400- 4900m above sea level. The distribution area of the alpine steppe dominated or co- dominated by L. racemosa is delineated by the Kunlun Mountains in the north. the Tuotu- ohe river in the south. and the Hoh xil Mountains in the west.The steppe community is relatively poor in species. only 34 species being recorded in the 8 investigated plots.The 61.8%of the species are of Qinghai-Xizang Plateau geographic elements. and more than half (also 61.8%)of species belongs to the hemicryptophytes.Most of species are perennial with exceptions of 2 prostrate shrubs and I annual. Based on the species composition and structure of the investigated com- munities. at least 4 community- types of the alpine steppe were distingui- shed.they were the L. racemosa dominated steppe. the L. raccmosa and Carcx moorcrojtii co- dominated steppe. the L. racemosa and Astragalus conf- ertus(A. polycladus)c0-dominated steppe. and the L. racemosa and Stipa purpurea co- dominated steppe. The difference of soil texture and structure were the principal reason for formation of these community-types.