A STUDY ON DEVELOPMENT AND UTILIZATION OF MOUNTAINOUS VEGETATION IN YIMEN COUNTY, YUNNAN PROVINCE

Yimen county is situated in the central part of Yunnan plateau, occuping 2427'-2457'N, 10154'-10218'E, with the natural condition of subtropical semi-humid forest climate. It is a mountainous county, 97% of which are mountainous areas. The forest coverage occupies only 19.7% and the zonal vegetation(evergreen broad-leaved forest) has been destroyed because of the unreas onable utilization and exploitation in the bygone historical period. Now most remains of the vegetation has become secondary and less valuable. Based on the existing status of vegetation there, its economic value, habitat factors, scientific mangement and reasonable utilization of plant resources, the main vegetation types are mainly divided into three groups as follow:the first one is the vegetation which has been slightly damaged and still maintain its higher economic value, such as Pinus armandii forest, Pinus yunnanensis forest karst evergreen broad-leaved forest etc., the second one is the vegetation which has been destroyed at middle level with lower economic value, but still remains the forest sites such as shooting shrubs of evergreen broad-leaved trees, Pinus yunnanensis woodland, etc., the last one is the vegetation which have been destroyed very seriously while the plant resources tend to be exhausted, biomass becomes lower and the ecological environment has become very poor for the forest of dry-hot valley vegetation, karst shrub-grasslands, monntinous shrub-grasslands on the sandsoil, etc. According to the characteristics of various plant communities, the relationship between wegetation and environment and their effective functions, the author has offered some preliminary proposals about the reasonable utiliztion of the mountainous vegetation in Yimen county which can be taken as reference to many other mountainous counties of the central part of Yunnan plateau.