Abstract: There is growing interest in whether plant species composition can affect the composition of soil microbial communities or soil fauna communities. In the present study, the effects of three dominant grass species (Stipa grandis, Stipa krylovii and Leymus chinensis) and one companion species (Agropyron cristatum) on the composition and function of nematode communities were studied in a 10month potexperiment with soil from the Inner Mongolian steppe. Our results revealed the following patterns: (1) Nematode compositions, including abundance, diversity and trophic group structure, and nematode maturity index were significantly different among different plant species. Nematode maturity index was lowest in soil conditioned by A. cristatum. (2) Nematode communities could be separated by plant species identity by discriminant analysis. (3) Based on the similarity coefficients, the result of cluster analysis indicated that these samples were clustered into three subgroups: samples conditioned by S. grandis and S. krylovii as the first subgroup, then samples conditioned by A. cristatum as the second subgroup, samples conditioned by L. chinensis as the third subgroup. This ordination closely resembles the phylogenetic structure of the grasses that were used in this study.

Key words: alpine forest, simulated warming, altitude gradient, DOC, DON