摘要:采用高通量测序技术对天然次生林生态系统演替过程中先锋树种白桦的根际土壤细菌多样性及群落结构进行了分析。研究结果表明：白桦根际土壤细菌隶属于28门、90纲、126目、213科、286属，在3个采样地中排名前8的优势细菌门的相对丰度均大于1%，分别为变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）、放线菌门（Actinobacteria）、芽单胞菌门（Gemmatimonadetes）、绿弯菌门（Chloroflexi）、硝化螺旋菌门（Nitrospirae）、疣微菌门（Verrucomicrobia）和拟杆菌门（Bacteroidetes）。各样地中前3个门的相对丰度之和均在60%以上。对白桦根际土壤细菌的α多样性指数、门水平的聚类热图以及PCoA聚类结果的分析表明，3个采样地中，小井沟（B2）和哈达门森林公园（C2）白桦根际土壤细菌的物种组成更为接近，与井儿梁（A2）的物种组成有一定差异；且小井沟和哈达门森林公园的物种多样性及丰度（ACE指数）显著高于井儿梁，表明细菌对不同环境的适应能力有明显差异。对细菌群落结构与土壤理化性质的RDA分析及相关性分析表明，环境因子对白桦根际土壤细菌的影响顺序为：全氮TN > 酸碱度pH > 含水量WC > 速效钾AK > 硝态氮NN > 铵态氮AN > 有机质OM > 有效磷EP，其中，TN、pH和WC是白桦根际土壤优势细菌的主要影响因子。研究结果为深入认识森林生态系统中根际土壤细菌的群落结构和影响因子提供了理论依据。



Abstract:The bacterial diversity and community structure in rhizosphere soil of Betula platyphylla, a pioneer species in the succession of a natural secondary forest ecosystem, were studied using high-throughput sequencing technology. The results showed that bacteria from 28 phyla, 90 classes, 126 orders, 213 families, and 286 genera were detected in the rhizosphere soil samples. The relative abundances of the top 8 dominant bacterial phyla in all three sampling sites were greater than 1%; they were Proteobacteria, Acidobacteria, Actinobacteria, Gemmatimonadetes, Chloroflexi, Nitrospirae, Verrucomicrobia, and Bacteroidetes. The sum of the relative abundances of the first three phyla in each sampling site was above 60%. The analyses of the alpha diversity index, cluster heatmap at phylum level, and the PCoA of bacterial communities in rhizosphere soil of B. platyphylla showed that, among the three sampling sites, the species compositions of soil bacteria were similar in Xiaojinggou (B2) and Hadamen Forest Park (C2), which were different from Jingerliang (A2). The species diversity and abundance (ACE index) of Xiaojinggou and Hadamen Forest Park were significantly higher than those of Jingerliang, indicating there were significant differences in the ability of the bacteria to adapt to different environments. The RDA and correlation analysis of bacterial community structure with soil physical and chemical properties showed that the degree of influence of soil environmental factors was in the order of TN > pH > WC > AK > NN > AN > OM > EP. Of these, TN, pH, and WC were the main influencing factors for dominant bacteria in rhizosphere soil of B. platyphylla. The results of this study provide a theoretical basis for further understanding of the community structure and influencing factors of rhizosphere soil bacteria in forest ecosystems.





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