Study on dynamics succession pattern of secondary forest in Hanquangou valley of Gansu Province

Based on the investigation on the composition of plant species, plant diversity and important value of species in the secondary plant community in Hanquangou valley of Gansu Province, the community was classified by using twoway indicator species analysis, the spatial distribution pattern of plant populations and the succession tendency of tree species was studied. The results showed that 1) the plant community could be classified into 7 types;2) their restoration degrees ranged from PhaseⅠto Phase Ⅶ with similar Simpson dominance index of tree layer, shrub layer and herb layer; as for the ShannonWiener diversity index, it was tree layershrub layerherb layer; as for the Pielou evenness index, it was tree layerherb layershrub layer, and the species richness gradually increased from PhaseⅠto Phase Ⅶ. The species composition and the spatial structure of the community gradually become complication and stable;3) the succession sequence was from aspen, birch to Qinghai spruce.