Abstract: By using Biolog-ECO technique, this paper studied the variations of the functional diversity of soil microbial communities in Stipa baicalensissteppe under effects of different land use patterns (grazing, mowing, and fencing). Different land use patterns changed the metabolic activities of the soil microbial communities significantly. The average well color development which directly reflected the microbial activities changed in the order of fencing > grazing > mowing. Under the effects of the land use patterns, the diversity indices of the microbial communities varied. The richness index (H), evenness index (E), and dominance index (D) were the highest under grazing, followed by under fencing and mowing. The principal component analysis (PCA) showed that the carbon source utilization mode and metabolic function of the microbial communities were similar under grazing and mowing, but differed from those under fencing. Carbohydrates, amino acids, intermediate metabolites, and secondary metabolites were the main carbon sources utilized by the microbial communities. This study showed that different land use patterns changed the functional diversity of the soil microbial communities in the Stipa baicalensis steppe in Inner Mongolia.

Key words: stable isotope, shark, trophic ecology, migration patterns, discrimination factor.