Soil Animal Composition and Distribution in the Leymus chinensis Grassland Region in Central Part of North-East of China

Since 1990, we have investigated the soil animal composition and distribution in the Leymus chinensis (Aneuro chinensis) grassland region in central part of north-east of Chinn. Soil animals were studied in 20 plant communities in 4 habitats. A total of 15 797 soil animals belonging to 4 phyla, 6 classes, 28 orders and 86 families were obtained. Among them, 26 families and 22 species were new records in norlh-easl of China. The dominant groups were Formicidne, Actinedida, Oribatidn, lsotomidne, Rhnbditidae, Dorylainidae. Sparse woods of Ulmus, and the most animal groups (40) and Puccinellia chinapoesis and Heleochalis intersiIa communities the least (14). The biggest numbers of individuals were found in mixed grass communites and the smallest in Kochia sieversia11a and Puccinella chinampoesis communities. Both numbers of groups and of individuals decreased with increasing depth of soil. A number of environmental factors were used to compare data from different communities. In general 1-2 factors were dominant and varied from habitat to habitat.