Abstract: Exploring the phylogenetic structure of understory community in different development stages of artificial forest can provide theoretical basis for explaining the mechanism of forest community assembly and ecological restoration. In this study, we examined the phylogenetic structure of shrub layer and herb layer in pure Cupressus funebris forest with three different stand ages (15-24 years, 25-34 years and above 35 years) in the hilly region of central Sichuan. We calculated two phylogenetic diversity indices (NRI: net relatedness index; NTI: nearest taxon index) based on the phylogenetic framework of angiosperms Ⅲ. The results showed that species composition of shrub layer and herb layer in the early development period (15-24 years) showed phylogenetic dispersion (NRI<0, NTI<0), with coexisting species being estranged from each other. The phylogenetic structure of the shrub layer and herb layer in 25-34 years old plantation tended to be random. For the plantation over 35 years old, the phylogenetic structure of the shrub layer and herb layer was clustered (NRI>0, NTI>0). The phylogenetic diversity index between shrub layer and herb layer in different development stages had significant positive correlation. There were significant differences across different development stages with respect to NRI index of shrub layer and NTI index of herb layer. There was no difference between the latter two stages for NRI in the herb layer and for NTI in the shrub layer. There were significant differences in NRI and NTI between the first stage and the latter two stages in shrub and herb layers. The phylogenetic structure index of shrub layer was significantly different from that of herb layer. There was no correlation between NRI, NTI in shrub and herb layers and Shannon diversity index in different development stages.

Key words: hilly area of central Sichuan, Cupressus funebris plantation, phylogenetic structure, species diversity.