Species Composition and DCA Ordination of Natural Regeneration Communities at the Burned Area of Pinus yunnanensis Forest

Take the natural regeneration communities at the forestland burned in 1993, 2001 and 2008 in Xishan forest farm of Kunming city as research object, the species and flora composition under different succession gradients had been analyzed. Meanwhile, plant community distribution at different succession gradients and species diversity change had been analyzed and explained by DCA ordination. The result showed that there were 102 species belong to 50 families and 88 genera in the plot. Except for 5years natural succession communities, the 12years and 20years natural succession communities had been dominant by tree layer, and the dominant species was Pinus yunnanensis. The dominant species in the shrub layer were Rhododendron spiciferum and Lyonia ovalifolia, the herb layer was dominant by the species belong to the families of Compositae, Poaceae and Pteridiaceae. The fauna was dominant by the species belong to the genera of Temperate type, especially the North Temperate type; the regularly change of plant species in different succession stage indicated the gradient change trend of vegetation succession in burned area. The trend of forest community succession change from shrub to forest and the succession gradient change of vegetation with the time series could be found by DCA ordination; plant diversity was change regularly with the succession gradient. Gleason richness index, ShannonWeiner diversity index and Simpson diversity index of the 20years Pinus yunnanensis natural succession community were significantly higher than the 12years natural succession community. For shrub layer, richness index, diversity indices and evenness index of 12years natural succession community were the highest compared with the 5years and 20years natural succession community and the 5years was the lowest. For herb layer, these indices of the 5years natural succession community were significantly higher than the other two gradients and the 20years natural succession community was the lowest.