Keywords: 
• endangered medicinal plants /
• size class structure /
• static life table /
• survival curve /
• Changjiang County

Abstract: A field survey was made of the medicinal plants,especially endangered medicinal plants living in Changjiang County（ including the National Nature Reserve of Bawang Mountain）,Hainan Province,China to analyze their population dynamics. A quadrat with 4 subquadrats was made at each representative site in the field survey to record the species,number of trees,tree height,DBH and number of young trees,as well as the geological locations,vegetation and altitude. Four endangered medicinal plant species,Aquilaria sinensis,Dimocarpus longan,Dracaena cambodiana and Litchi chinensis,were selected to analyze their patterns of population size class structure,static life table and the survival curve based on the field survey. Population size class structure analysis showed that both A. sinensis and D. longan populations had an increasing size-class structure,while D. cambodiana and L. chinensis populations had a decreasing and a stable size-class structure,respectively. A. sinensis and L. chinensis populations showed a survival curve of Deevey’s type Ⅱ,and D. cambodiana and D. longan populations had respective survival curves of Deevey’s types Ⅰ and Ⅲ. Combined with the analysis of the static life table the results showed that the size class structure generally tended to increase in both A.sinensis and D. longan populations but decreased in D. cambodiana population and was stable in L. chinensis population. This indicates that these four species of the endangered medicinal plants live in a degraded habitat with a high frequency of human disturbance and are hence recommended for protection and conservation.