Studies On The Arthropod Community Structure And Diversity In The Forest-steppe Ectone

The author has researched the composition and diversity of arthropod communities in the forest -steppe ecotone, including community structure, seasonal variation, vertical structure,nutrition structure,community diversity, community similarities, sub-communities niche and so on. The result is as follows:1 Through investigating the arthropod communities in the different habitats, we discovered that in the forest and forest-steppe region, the number of individual and species of mixed forest was apparently richer than that of pure forest, and that in meadow-steppe ecotone, the species of arthropod community, in which the natural enemy was predominated, was rich and the number of them was more than the other, dominative among them.2 Analyzing the nutrition structure, the result indicated that the species in forest was richer than that in forest-steppe, in which base species was outstanding and the number of intermediate species was as many as that of top species, and that nutritional structure of arthropod communities in forest zone was more complex than that of forest-meadow region. In addition, in Meadow-steppe region the number of species were more than that of forest zone and forest-meadow region, whose communities stability was higher than and forest-meadow region.From the vertical structure of different stand types, the number of individual, diversity, even index of arthropod communities in herbal layer was largest than the others and stability was stronger;but leaf litter layer was smaller than the others.3 With the time changing, the number of individuals, species, diversity index and even index of arthropod communities in different stand types varied as follows: August> July > September > May, and the rule of time changing was primarily caused by environmental factors.Analyzing the time dynamic of the various sub-communities of Arthropod communities in three different habitats, the result showed that the number of enemy and pest sub-community and their species was affected as the number of neutral arthropod sub-communities by three different habitats, and only the neutral arthropod species sub-communities of forest zone was impacted greater.4 With the comparison of arthropod communities similarities coefficient, it could be known that in three different habitat types, arthropod communities of forest zone was similar to forest-meadow region, and that of meadow-steppe region and forest-meadow region was dissimilar largely. The difference of arthropod sub-communities in three different habitats was caused by the difference of pest sub-communities species.5 In the time niche of groups in three different habitats, with the analysis of niche breath, we concluded that the composition of arthropod communities was affected greatly by the group of Parasitical natural enemy and the group of neutral arthropod. The analysis for niche overlap index showed that the group of neutral arthropod survive the other groups for a period of time and it also played a role in regulating food chain;In meadow-steppe region, the arthropod communities were greater dominated by predators than other groups.6 From the principal component analysis(PCA), in forest zone and forest-steppe region, intermediate arthropod have greater influence on the whole community, and in meadow-steppe region, the effect of predators was apparent. The result indicated that the function groups in the different habitats have different effects on arthropod community.It is concluded from the cluster analysis that the diversity of arthropod community is mainly affected by the vegetation types in addition to environment factors.