Distribution and diversity patterns of soil fauna in different salinization habitats of Songnen Grasslands, China

The soil fauna communities were studied in the Songnen Grassland, which is located at the easternmost Eurasian steppe of northeast China. We sampled sites from May to October with different alkaline contents to investigate the salinization process on soil fauna. We found that the dominant groups were Prostigmata, Oribatida, and Gamasina mites and the collembolan families Isotomidae and Entomobryidae. Results showed that the composition of the soil fauna communities differed significantly among the habitats with different salinity. Number and density of taxa were lower in communities with high salinity. The highest number of taxa (66) was found on the Artemisia anethifolia sites, the lowest number (47) on the Alkali patches. The Shannon-Wiener index was the lowest on the Alkali patches, whereas the Simpson-dominance index was the highest in these habitats. The number and density of taxa changed during the seasons. The soil fauna tended to gather on soil's surface. According to the Redundancy analysis, the soil organic matter positively affected the density of the soil fauna and soil fauna decreased with increasing degree of salinization in Songnen Grasslands.