[Relationship between soil bacterial community and environmental factors in the degraded alpine grassland of eastern Qilian Mountains, China].

To explore the distribution of bacterial community and its relationship with soil environmental factors in degraded alpine grasslands in the eastern Qilian Mountains, we analyzed the changes of bacterial community structure and diversity across lightly, moderately and severely degraded grasslands by using high-throughput sequencing technology. Redundancy analysis (RDA) was performed to analyze the relationship between soil bacterial communities and soil environmental factors by using CANOCO 4.5 software. The results showed that there were significant differences in soil physicochemical properties among different degraded alpine grasslands. There were 257125 effective sequences, 180826 high-quality sequences and 4790 OTUs. The Chao1 index was lightly degraded grassland > moderately degraded grassland > severely degraded grassland; Shannon index was lightly degraded grassland > severely degraded grassland > moderately degraded grassland. Phylogenetic analysis indicated that the soil bacterial groups of each plot belonged to 33 phyla, with Actinomycetes, Proteobacteria and Firmicutes being the dominant groups in the three grasslands. From analysis of the proportion of soil bacteria in different degraded grassland, we found that the Actinomycetes, Acidobacteria and Proteobacteria increased first and then decreased with the degree of degradation, and the Firmicutes showed an opposite trend. The results of RDA analysis showed that the dominant groups of bacteria were significantly correlated with invertase, cellulase, phosphatas, pH, electronic conductivity, available nitrogen and available potassium. It was concluded that there were significant differences in soil bacterial communities among different degraded alpine grasslands in the eastern Qilian Mountains, and the soil environmental factors were the important factors driving the distribution of soil bacterial communities.