Abstract:

To study the impacts of secondary disasters induced by Wenchuan earthquake on soil fauna communities, two plots in previous debris flows and landslide regions and two plots in Cryptomeria fortunei forests, served as control, were set up in Yinchanggou, Pengzhou city. Soil fauna communities in the plots were investigated in November 2008. No soil macrofauna was found in the secondary geological disaster areas, but total 196 soil macrofauna, belonged to 3 phyla, 7 classes, 17 orders and 36 groups (families), were found in two control plots, with average density 65.34 ind.·m^-2. There were 232 soil meso-microfauna, belonged to 3 phyla, 4 classes, 6 orders and 26 groups (families) in two secondary geological disaster plots and 2 747 soil meso-microfauna, belonged to 3 phyla, 7 classes, 9 orders and 64 groups (families) in two control plots. The average densities of secondary geological disaster areas and coutrol areas were 3 222.22 ind.·m^-2 and 38 152.78 ind.·m^-2, respectively. The species group numbers, individual density, and the diversity index (H) and abundance index (D) of three diversity indexes of soil meso-microfauna communities in secondary geological disaster areas were significantly lower than those of the control areas (P<0.01), but the evenness index (E) was significantly higher than that of the control areas (P<0.01). Some scares group extinction and community density decrease were the main reasons for the soil meso-microfauna diversity's changes. Compared with the control areas, individual percent of the soil meso-microfauna species community living in wet environment of the secondary geological disaster areas was declined and that of the species living in drought and middle environment increased. The similarities of soil fauna community between the secondary geological disaster areas and control areas were lower than those within the same areas. The results demonstrated that the earthquake-induced geological disasters had strong disturbed effects on the structures and diversities of soil fauna communities, especially, soil macrofauna.

Key words: soil fauna, debris flows, landslide, Cryptomeria fortunei forest, Wenchuan earthquake