为探究白桦林地上层土壤与下层土壤细菌群落结构差异及细菌对上、下层土壤功能的驱动作用,采用 16S rRNA基因高通量测序和土壤养分测定方法,对苏木山 40 a白桦林地 0~20 cm和 20~40 cm土层进行分析.结果表明,白桦林地上层土壤有机质含量和多酚氧化酶活性较下层土壤显著提高 75.25%和 120.45%;上层土壤细菌Shannon多样性指数(5.83)较下层土壤Shannon多样性指数(5.74)显著提高;放线菌门、变形菌门和酸杆菌门(相对丰度>15%)、黄杆菌科(相对丰度>7%)、慢生根瘤菌属、鞘氨醇单胞菌属、土微菌属以及放线菌门的分枝杆菌属、类诺卡氏属、土壤红杆菌属和Gaiella属(相对丰度>1%)是白桦林地的优势细菌类群;疣微菌门(线性判别分析LDA值为 4.07)和拟杆菌门(LDA值为 3.80)以及放线菌门的类诺卡氏属(LDA值为3.72)和土壤菌属(LDA值为3.48)是白桦林地上层和下层土壤差异贡献度最大细菌门和属;多酚氧化酶活性、碱性蛋白酶活性和有机质含量是影响林地细菌群落结构的主要环境因子,并且显著影响放线菌门细菌类群.综上,白桦林地上层和下层土壤细菌多样性存在显著差异,放线菌门作为白桦林地重要的细菌类群,通过促进土壤碳循环的方式提高林地肥力水平,促进白桦林地土壤生态系统健康稳定发展.
In order to investigate the difference of bacterial community structure between upper soil and lower soil and the driving effect of bacteria on the function of soil,16S rRNA gene high-throughput sequencing and soil nutrient determination methods were used to analyze the 0-20 cm and 20-40 cm soil layers of Betula platyphylla forest at 40 ages in Sumushan Mountain.The results showed that the content of organic matter and the activity of polyphenol oxidase in the upper soil of Betula platyphylla forest significantly in-creased by 75.25%and 120.45%compared with the lower soil.Shannon diversity(5.83)of bacteria in upper soil was significantly higher than that in lower soil(5.74).Actinobacteria,Proteobacteria and Acidobacteria(relative abundance>15%),Xanthobacter-aceae(relative abundance>7%),Bradyrhizobium,Sphingomonas,Pedomicrobium,and Mycobacterium,Nocardioides,Solirubrobacter and Gaiella(relative abundance>1%)belonged to Actinobacteria were the dominant bacterial groups in Betula platyphylla forest.Ver-rucobacteria(Linear Discriminate Analysis,LDA 4.07),Bacteroides(LDA 3.80),and Nocardioides(LDA 3.72)and Oryzihumus(LDA 3.48)belonged to Actinobacteria were the main bacterial phylum and genus contributing to the difference between the upper and lower soil of Betula platyphylla forest.Polyphenol oxidase activity,alkaline protease activity and organic matter content were the main environmental factors affecting the bacterial community structure of Betula platyphylla forest,and significantly affected the Actinobacte-ria bacteria.In conclusion,there were significant differences in bacterial diversity between the upper and lower layers of soil in Betula platyphylla forest.Actinobacteria improved the fertility level of forest land as an important bacterial group by promoting soil carbon cyc-ling in Betula platyphylla forest,and promoted the healthy and stable development of soil ecosystem in Betula platyphylla forest.