Plant diversity in the secondary forest in mountain of Youxi County

Plant community biodiversity has been counted on four plots in subtropical secondary forest in Xiwei Township of Youxi County,Fujian Province. It has been discovered that there are 21 arbor species with 155 trees,20 shrub species with 107 plants,4interlayer plant species with 40 plants,and only one herb species in the plots. Shannon values and Pielou values at the different layer in order is shrub arbor interlayer herb while the Simpson values show a total contrary trend compared with Shannon or Pielou values. Diversity difference between arbor and shrub layers is insignificant while plant diversity value in shrub layer is the highest and significantly higher than that in herb layer which only includes one species,this phenomenon may be related to heavy interference.