Study On Population Dynamic Of Arthropod In Phyllostchys Hetercycla Cv.pubescens Forest

The bamboo forest of Phyllostchys heterocycla cv. pubescens is one of the most importantnatural resources in South China. In recent years, many kinds of pest insects that damagedbamboo have outbreaked incessantly. And bamboo pest insects had become the vast obstaclesof bamboo industrial development, so it was important and imminent to find some sustainablecontrol methods. The structure and dynamics of arthropod community were importantparameters of the ecosystem stability, and the study on the dynamics of arthropod communitywas the key to understand the plant-herbivore-natural enemy interactions and the mechanismof outbreak. In this paper, the arthropod community in bamboo forest as research object wasstudied, and the arthropod group was divided into 3 functional groups, phytophagous group,the neutral group and natural enemy group based on the feeding characteristics. Thecomposition, the structure and the dynamics of arthropod community in the bamboo forestwere analyzed according to aboundant and systematic data of indoor and outdoor investigations.Structure and diversity of arthropod community that under the different level of disturbancewere compared; Effects on arthropod community by disturbance were analyzed with DiversityIndex, Eveness Index and Centralized Index, and so on. The difference of arthropodcommunity between the bamboo forest of growing bamboo shoots and the bamboo forest ofgrowing leaves was also analyzed. And the main results are showed as followings:1. 42,439 insect samples belonging to 17 orders, 126 families and 511species werecollected through the systematic investigation. The result indicated that the arthropodcommunity presented obvious seasonal pattern, as well as the parameters such as thecomposition, the diversity, the centralized index and so on. There were two peaks in thetime-trend, separately appeared in June and September. The phytophagous group was superiorsignificantly to other two groups according to analysis of species, families and the individuals,next was the natural enemy group and the neutral group was least.2. Based on the different level of disturbance of artificial management, bamboo forest wasdivided them into three kinds of system, the mixed bamboo forest, the weedy bamboo forestand the cleaned bamboo forest. Through systematic investigation, it was significantly differentin three arthropod groups in the orders, the families, the species, as well as the speciesindividuals. Comparison with the bamboo forest with little disturbance, with other two kinds ofmanagement disturbance the richness, the diversity, the eveness index and the individuals ofthe arthropod community reduced, and centralized index incread. The influence of fine management was the most significant, with which the diversity and eveness index of thephytophagous group, the neutral group and the natural enemy group reduced. In the process ofseasonal changes, along with the increasing of disturbance level, the species richness, thediversity and the eveness index kept at lower level in the majority stage, and centralized indexwas at higher level. The main performance was keeping the relative richness of the neutralgroup and natural enemy group at lower level, and phytophagous group was at higher level inthe whole year, so the control potential of the natural enemy became worse.3. In the bamboo forest of growing bamboo shoots and the bamboo forest of growingleaves, species composition, individuals, diversity index, and other aspects of the twoarthropod groups were almost the same. And there were some differences in arthropod groupswith seasonal changes. Before June, it was the time of leaf-exchanging in the bamboo forest ofgrowing leaves, the bamboo pest insects and other correlative species was low because of thefew quantity of bamboo shoots (or no bamboo shoots),. At the same time, the environment wasquite normal in the bamboo forest of growing bamboo shoots, and plenty of bamboo shootscould be found, so the diversity of arthropod was higher. At the end of leaf-exchanging period,,the environment in the bamboo forest of growing leaves changed, and the arthropod diversityincreased quickly because of the newly-growing leaves. The two groups return to the identicallevel in June. In later time, many species, such as Crocidophora evenoralis Walker, Algdoniacoclesalis Walker and Circobotys aurealis Leech moved to the bamboo forest of growingleaves, so the diversity of arthropod group in the bamboo forest of growing leaves started to behigher than the bamboo forest of growing bamboo shoots.