Diversity of natural vegetation at high belt (elevation over 1600m) at Hoanglien national park, Laocai province

The natural conditions of high belt of Hoanglien national park show both of subtropical and temperature characteristics. So the vegetation types are special in Vietnam . In this paper, base on UNESCO (after Phan Ke Loc, 1985), 3 classes including 9 formations with 14 supformations were described and arranged in a system. The characteristic species are: Huodendron tibeticum, Tsuga dumosa and species of families: Ericaceae, Cyperaceae, Symplocaceae, Fagaceae, Rosaceae and supfamily Bambusoideae (Poaceae). The woodland and forest distribute on valleys and elevation below 2200m alt., the dwarf forest (including mixed with Dumosa tsuga) is distributed at higher zones. The scrubs of grasses and shrubs distribute on the high peak (include Phanxipan peak) where the elevation is over 2600m alt., cold and strong windy but the moisture is high, the grasses and shrubs in this types includes poa-grass and others.