[Addition effects of co-expansion of two bamboos on plant diversity in broad-leaved forests].

The effects of Phyllostachys edulis and Oligostachyum oedogonatum expansion on species diversity of broad-leaved forests were investigated in Wuyishan National Nature Reserve, Jiangxi Province, China. Ph. edulis and/or O. oedogonatum expansion changed community structure and species composition. The co expansion of the two bamboos in high intensity (Ph. edulis was 30-50 ind·100 m, O. oedogonatum was 300-500 ind·100 m) changed the density ratio of arbor and shrub from 2:8 to 1:9, and density ratio of bamboo and tree from 0:10 to 9:1. The main effects of Ph. edulis and O. oedogonatum on the species diversity were significant. Ph. edulis mainly influe-nced arbor layer, while O. oedogonatum influenced shrub layer more, and the interaction effect of two bamboos was not remarkable. There existed addition effects between Ph. edulis and O. oedogonatum on species diversity. The co-occurrence of two bamboos in high intensity decreased the Shannon index of community by 91.3%. Ph. edulis and O. oedogonatum did not compete obviously unless in high density. It was addition effect rather than interaction effect that changed the community structure and reduced species diversity when broad leaved forest suffered invasion by Ph. edulis and O. oedogonatum.