Abstract:

The eco-geographic distribution and coenologly characteristics of Cupressus gigantea were systematically studied. The results show that the barred and discrete distribution of C. gigantean is narrow only along the riversides of Yalutsangpo; Habitats of four C. gigantea populatiors overed three horizontal distributions zone of the humid, the sub-humid and the semi-arid. The communities of C. gigantea consist of 130 species of diodophyte plants originating from 106 genera and 43 families with significantly ancient and complex characteristics; Many plants in these communities with typical properties Tibet or Himalayas specific. C. gigantea is a uni-predominant species in the arbor layer, microphyll and simple leaf hemicryptophytes are dominated in the shrub and grass layers. The structure of plant communities tends toward simple and the plant composition ture to sparse from the sub-humid to the semi-arid zone .

Key words: Yalutsangpo River, Cupressus gigantea populations, geographic distribution, floristic element, community physiognomy, population structure