Studies on the Composition and D iversity of the CanopyArthropod Commun ity of Moso Bamboo Forest

The survey of canopy arthropod community was conducted by netting from Ap ril to October in 1999 inChangning Bamboo Area, Yibing, Sichuan. The results indicated that there were 113 species ( group s) of canopy insects, which belonged to 13 orders and 54 families method. All sp iders were considered as one group because ofsimilar ecological functions. Homp tera and sp iders constituted the dominant group s in arthropod communities in thefour investigation areas. The relative abundance ranged from 30% to 51% for Homp tera and from19% to 43% forsp iders, respectively. Dominant concentration index of Simp son was in the order ofAreaⅡ >AreaⅢ >AreaⅣ >AreaⅠ. Em poasca sp. (Homp tera: Cicadellidae) was the a dominant species in four Areas. At p resent, it had already become one of the most important bamboo pests in China. The indices of dominant concentration and diversitywere used to analyze and compare the seasonal dynamics of arthropod community. The dynamics of dominant concentration started highly, then decreased to a low level, but finally increased to a relatively high level. The changetendencies of the dynamics of diversity (H′) were from low to high, then to low, and to high again, and to low finally. This trend was closely related to bionomics of arthropod and seasonal change, but there was difference in the four areas. The dynamics of the diversity in Area II was an excep tion as a result of the obvious dominance ofEm poasca sp. inMay. Its change tendencywas from high to low, then to high, and to low again, and to high again,and to low finally. The seasonal pattern of bamboo canopy arthropod communitywithin investigation period could bedivided into five stages by the op timal sorting. The five stageswere before earlyAp ril, from mid Ap ril to early June,from mid June to early Sep tember, from mid Sep tember to mid October, and after mid October, respectively. Thesecond stage forming the first peak was the most important and op timum time to monitor dynamics and control pestsbecause most pests appeared at this stage. At the third stage, the pests declined because of high temperature andoccasional strong wind. At the forth stage, temperature declined to a relatively suitable range. The second peak ofsome insect pests appeared and sp ider population also increased. Biological control should be emphasized at thisstage. The arthropod over-wintered between late October and next earlyAp ril. Forestmanagement should be emphasized to control the over-wintering pest populations.