Abstract:In order to understand the succession dynamics and biodiversity maintenance mechanism of forest community in karst area, the species composition, flora characteristics, species diversity and population structure of Pinus armandii forest in Caohai National Nature Reserve by using sample-plot survey. The results showed that there were 81 species of seed plants, belonging to 21 families and 39 genera, including 11 species of trees, 32 species of shrubs and 38 species of herbs. The floristic type of families and genera was complex mainly composed by temperate element. The main life-form spectrum was dominated by phanerophytes (46.91%) and hemicryp-tophyte (27.16%). Pinus armandii was the single dominant species with importance value of 58%; the diameter structure was a skewed normal distribution (left-biased type), and the distribution of tree height was focused on 12-21 m, and the distribution of e crown was V type. There was a significant difference in the diversity between tree layer with shrub layer and herb layer. The species richness indexes, S and DM, and diversity indexes, H and DS, were in the order of herbaceous layer > shrub layer > tree layer, and the evenness index (J) was shrub layer > herb layer > tree layer. So, the characteristics of P. armandii community and species diversity in Caohai National Nature Reserve have obvious regional features.
