Effects of Human Disturbance on Species Diversity of Cyclobalanopsis glauca Community in Lotus Mountain in Ya'an

Using the Lotus Mountain as the study area,with typical plots methods,we investigated the species composition of different levels of stand structure,population structure and species diversity of Cyclobalanopsis glauca community under the slight,intermediate and severe human disturbances.The species richness index(S),Shannon-Wiener index(H),Simpson index(H′)and Pielou index(Jsw)were adoptedto comprehensively evaluate the level of species diversity in C.glaucacommunity.The results showed that:(1)a total of 161 vascular plant species belonging to 83 families and 134 genera were observed across the 9explored plots within an area of 3 600m2,and Gramineae,Lauraceae,Fagaceae,Theaceae are the dominant plant;(2)plant communities vary under different degrees of human disturbance effects.Trees are mainly in low diameter class(diameter at breast height8cm)and low height class(37m)in arborous layer under sight and intermediate disturbances,suggesting apotential capacity of natural regeneration.Trees in low diameter and low height classes are rare under serious disturbance,and the community structure is unstable with a low primary productivity;(3)the important values vary significantly under different degrees of human disturbances,while dominant species show insignificant differences under these disturbances with a simple species composition Machilus microcarpais the predominant species in shrub layer under severe disturbance,while herbaceous species are the dominant plants under intermediate disturbance;(4)S,H,H′,and Jswdecreased with the increases of human disturbance,indicating a decrease for plant biodiversity as a whole.