Abstract: [Objective]This study aimed to investigate the variation in insect community structure and dynamics in larch plantations under different soil conditions, so as to provide fundamental basis for the forest management and biodiversity conservation.[Method]This experiment was conducted at Liangshui Nature Reserve, in Xiaoxing’anling Mountains, China. The 60-year-old larch plantation, which was in the condition of close hillsides, was used for this. According to the terrain soil conditions 4 habitats were chosen in the forest, and the 4 habitats are buried-gley dark brown soil-larch plantation forest(A), thick buried dark brown soil-larch plantation forest(B), dark brown loam soil-larch plantation forest (C), typical dark brown soil-larch plantation forest(D). Three 20 m×20 m plots were established in each habitat. Insect community was investigated by sweeping net method, the tin pot trap method, shaking-off method and high branch cutting standard branch method.[Result]A total of 5 204 insects were collected, belonging to 250 species, 77 families, and 10 orders. Diptera and Hymenoptera were the dominant taxa in each habitat, but the proportion had great difference. There was great difference in seasonal dynamics of the dominant family of insect communities over the four habitats. Cluster analysis showed that insect communities of the 4 habitats were classified into two categories, habitat A and habitat B were classified into one category, habitat C and habitat D were classified into the other category. Species diversity index and evenness index of insect communities in different habitats showed C > A > B > D, richness index showed B > D > A > C, dominant index showed D > B > A > C. In time series, the species diversity index of the B habitat and the D habitat was significantly positively correlated with the evenness index and richness index, but the former correlation coefficient was significantly higher than that of the latter. In all habitats, species number order of different trophic groups showed plant feeding taxa > neutral group > predators group > parasitic taxa, but the proportion of different trophic groups had significant difference. The relative stability of the insect communities in different habitats was B > D > C > A. Principal component analysis showed that the factors that played a dominant role in affecting the insect community change were different in different habitats.[Conclusion]The structure dynamics of the insect communities in larch plantations were significantly different under different soil conditions. The higher the positive correlation coefficient of species diversity index and richness index of insect community, the stronger the community stability. At the same time, neutral insects played a significant role in regulating the relative stability of insect communities. Environment conditions of thick buried dark brown soil-larch plantation were most suitable for the occurrence and development of insect community in the 4 habitats.

Key words: insect community, stability, principal component analysis, larch plantation, Liangshui Nature Reserve