Study sites
In this study, 14 sampling sites of different climatic zones in East Asia were selected (Figure 1), and they were: the Tahe, Aershan, Changbaishan, Donglingshan, Baotianman, Badagongshan, Tiantongshan, Shimentai, Jianfengling, Xishuangbanna, Guanghwa, Sapporo, Hiroshima, and Yushan. The latitude of the site cross ranges from 18.50° to 52.33°, and the climatic zones include temperate, subtropical, and tropical zones. The vegetation types in the study areas include temperate coniferous and broad-leaved mixed forest temperate deciduous broad-leaved forest, temperate deciduous broad-leaved forests, subtropical evergreen broad-leaved forests, and tropical rain forests. Method of Tullgren was used for the isolation of the soil animals and then the soil animals were identified based on morphology using the same criteria in all samples (Yin et al., 1998; Yin, 2000).