Major Types of Natural Forest Vegetation in Huangjiahe River Basin of Yunnan

In the Huangjiahe river basin of Yunnan,the natural forests cover an area of 185493 hm~(2),accounting for 66.18% of the total river basin area.Based on the rel ves collected four times in October to December,2001～2003,the natural forest vegetation in the river basin could be divided into 3 vegetation types,3 vegetation sub-types or 6 formations by the vegetation classification criteria from the book,Vegetation in Yunnan.These types of forest vegetation vary with the elevations,showing a distinct law of vertical distribution.From low to high elevation,they compose the subtropical montane vertical series of forest vegetation as follows: semihumid evergreen broad-leaved forest(Form.Lithocarpus dealbatus-Form.Cyclobalanopsis delavayi-Form.Castanopsis orthacantha),warm temperate coniferous forest(Form.Pinus yunnanensis),deciduous broad-leaved forest(Form.Populus bonatii)(alt.1 570 to 2 750 m)-middle montane humid evergreen broad-leaved forest(Form.Lithocarpus variolosus)(alt.2 650 to 3 320 m).The area of warm coniferous forest is the largest one and accounts for 60.50% of the total area of the natural forest in the river basin,that of evergreen broad-leaved forest for 36.69% and that of deciduous broad-leaved forest for 2.81%.And their general forest characteristics were described in detail.