FLORISTICS AND VEGETATION OF THE GENUS CARAGANA IN ORDOS PLATEAU
ZHANG Ming-li 1 HUANG Yong-mei 2 KANG Yun 1 WANG Ying-wei 1(1 Institute of Botany, Chinese Academy of Sciences, Beijing 100093) (2 Institute of Resource Science, Beijing Normal University, Beijing 100875)
There are 9 species of the genus Caragana in the Ordos Plateau, which is a rich biodiversity region of the genus. Specially, Caragana korshinskii var. intermedia was treated as one of the most suitable species cultured to preserve soil and fix sand in the Maowusu sandland which located at eastern Ordos Plateau. There are two phytogeographical distribution elements, the Central Asia element and East Asia element of the genus in Ordos Plateau. The Central Asia element consists of Mongolia Plateau distribution, Alashan distribution, Gobi Mongolia distribution, and Inner Mongolia Plateau Loess Plateau distribution. The East Asia consists of North China distribution, North China Qinghai-Xizang (Tibet) Plateau distribution and southern Mongolia Plateau Qinghai-Xizang (Tibet) Plateau distribution. These elements showed the conjunction and transition between Ordos Plateau and the adjacent regions. The vicarism is illustrated by two typical species C. korshinskii and C. korshinskii var. intermedia. The former occurs in western Ordos Plateau and the latter in the east. The shrub communities are the dominant life form in the vegetation of Ordos Plateau. There are fourteen life forms, of four belong to Caragana community, i.e., Form. Caragana korshinskii var. intermedia , Form. Caragana stenophylla , Form. Caragana korshinskii , and Form. Caragana tibetica . Form. Caragana tibetica distributing in western Ordos Plateau and usually forming the small sand hill about 40～80 cm high, is one of the most typical natural landscapes in Ordos Plateau. These Caragana communities represent the characteristic of the vegetation zone, namely from eastern typical steppe and desert steppe to western steppe desert zones in Ordos Plateau.