五大连池火山土壤细菌多样性及其群落结构

火山熔岩生境孕育了独特的土壤微生物群落。为了解火山生态系统土壤细菌群落多样性和群落结构及其关键影响因子，选择五大连池新、老期火山为研究样点，非火山为对照，基于高通量测序方法，分析不同采样点土壤细菌群落结构和多样性，结合土壤理化指标，进一步分析影响火山生态系统土壤细菌群落多样性的环境因子。结果表明：细菌操作分类单元（OTUs）、Ace指数、Chao1指数和Simpson指数变化趋势一致，表现为非火山 > 新期火山 > 老期火山。三个样点土壤的共有OUTs数量为713个，各自特有的OTUs数量不尽相同。三个样点土壤中检测到共有细菌16个类群，其中变形菌门、酸杆菌门、放线菌门和绿弯菌门为优势菌群，老期火山土壤中酸杆菌门、疣微菌门、Rokubacteria相对丰度最大，而Patescibacteria相对丰度最小。三个样点的土壤细菌群落具有明显的空间关系，相似性差异较大，但不符合随地理距离的增加而降低的模型。土壤理化性质测定结果标明：老期火山土壤pH、有机质、全氮、全磷、铵态氮和硝态氮显著高于新期火山和非火山，新期火山土壤含水量和速效磷显著低于老期火山和非火山。喷发时间和火成岩基质等特性会导致不同火山土壤理化性质的差异，进而影响土壤细菌多样性和群落结构。Pearson相关性分析表明：土壤pH显著影响细菌的多样性指数。冗余分析（RDA）结果表明：土壤氮含量、pH和有机质是影响火山森林生态系统土壤细菌群落结构的主要因子。

Diversity and community structure of soil bacteria in different volcanoes, Wudalianchi

Volcanic lava habitats breed unique soil microbial communities. Soil bacterial diversity, community structure, and key factors influencing volcanic ecosystems were explored using soil microorganisms in new volcano soils and old volcano soils in Wudalianchi, Heilongjiang Provice. Non-volcano soils were used as the control. Using the Illumina high-throughput sequencing method, we analyzed soil bacterial community structure and diversity at three sampling sites. Combined with soil physical and chemical characteristics, environmental factors affecting the diversity of soil bacterial community in a volcanic ecosystem were analyzed. Results showed that the operational taxonomic units (OTUs) and the diversity index (the Ace index, the Chao 1 index, and the Simpson index) of bacteria presented the same trends and followed the order Non-volcano > new volcano > old volcano. The number of OTUs unique to new volcano soils, old volcano soils and Non-volcano soils were 852, 820, and 879 respectively, as well as the number of their common OTUs was 713. The three plots soils contained same 16 kinds of bacterial groups, and Proteobacteria, Acidobacteria, Actinobacteria, and Chloroflexi were the most dominant bacteria groups. Acidobacteria, Verrucomicrobia, and Rokubacteria had the highest relative abundances, whereas Patescibacteria had the lowest in the old volcanic soils. In the three plots, the soil bacterial communities had obvious spatial relationships, and their similarity in community structure varies greatly, It did not conform to the model of beta diversity, which similarity in bacterial composition gradually decreased with increasing geographical distance. We think it could be related to the volcanic eruption characteristics or magma composition. The obtained soil physicochemical properties indicated that soil pH, Soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), ammonium nitrogen (AN), and nitrate nitrogen (NN) in old volcanic soils were significantly higher than those in the new volcanic soils and non-volcanic soils, while water content and available phosphorus in the new volcanic soils were significantly lower than those in the old volcanic soils and non-volcanic soils. Volcanic eruption is a form of violent large-scale disturbance, the volcanic characteristics of eruption time and igneous rock led to differences among volcanic soils at different stages, and further led to differences among soil bacterial diversity and community structure. Pearson correlation analysis showed that soil pH significantly affected the Simpson index, the Ace index and the Chao 1 index of soil bacteria. The redundancy analysis (RDA) showed that soil nitrogen, soil pH, and SOM were the crucial factors affecting the bacterial community structure of the Wudalianchi volcanic ecosystem.