东祁连山退化高寒草地土壤细菌群落与土壤环境因子间的相互关系

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

为探究东祁连山不同退化高寒草地细菌群落分布特征与土壤环境因子间的相互关系,采用高通量测序技术对轻度、中度和重度退化草地的土壤细菌群落结构变化及其多样性进行分析,运用CANOCO 4.5软件对土壤细菌群落与土壤环境因子间关系进行冗余分析(RDA).结果表明:不同退化高寒草地土壤理化性质间均差异显著,高通量测序共得到257125条有效序列,180826条优质序列,4790个OTUs.细菌群落Chao1指数依次为轻度>中度>重度;Shannon指数依次为轻度>重度>中度.系统发育分析表明,各样地土壤细菌类群分属于33个门,其中放线菌门、变形菌门和厚壁菌门是3种不同退化草地土壤中的优势类群.对不同退化草地土壤细菌各门所占比例分析发现,放线菌门、酸杆菌门和变形菌门随着退化程度加剧先减少后增加,厚壁菌门反之.RDA分析结果显示,细菌优势类群与蔗糖酶、纤维素酶和磷酸酶呈极显著相关,与pH、电导率、速效氮、速效钾呈显著相关.说明东祁连山不同退化高寒草地土壤细菌群落间差异明显,土壤环境因子是影响土壤细菌群落分布的重要因素.

To explore the distribution of bacterial community and its relatlonship with sou enwroH- mental factors in degraded alpine grasslands in the eastern Qilian Mountains, we analyzed the chan- ges of bacterial community structure and diversity across lightly, moderately and severely degraded grasslands by using high-throughput sequencing technology. Redundancy analysis （RDA） was per- formed 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 Chaol 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 belonzed to 33 phyla, with Actinomvce-tes, Proteobacteria and Firmicutes being the dominant of the proportion of soil bacteria in different degraded groups in the three grasslands. From analysis 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 distribu- tion of soil bacterial communities.