Comparisons of diversity of grasshopper community in fragmentary forest of Nanniwan
南泥湾片段森林蝗虫群落多样性比较

Forest fragmentation is a key factor affecting the insect. The study had principally been carried out in tropical area in China. The paper studies the grasshopper community structures of north china's Nanniwan fragmentary forest using principal component analysis(PCA) and stepwise regression analysis. The results show that there are 12 species of grasshopper in both edge forest and inner forest of the region, which belong to 5 families,12 genuses. When forest vegetation structure doesn't change drastically, the species, diversity index ,dominant index and evenness index of grasshoppers change slightly in forest edge grasses, whereas the density, diversity index and evenness index of grasshoppers in grasses of inner forest decrease with area of forest reducing. In severely damaged forest, in comparison with slightly damaged forest, the vegetation undergoes obvious changes, the species, density, diversity index and evenness index of grasshoppers in grasses of inner forest show signs of obvious increase, the density, dominant index of grasshoppers in grasses of edge forests increase, the diversity index and evenness index decrease. Using principal component analysis(PCA),the grasshopper community structures of fragmentary forest can be divided into two types: the slightly damaged forest and the severely damaged forest. It shows, by stepwise regression analysis,that the area of fragmentary forest and the structure of vegetation and food are important factors, which affect the structure and diversity of grasshopper community.