大兴安岭落叶松林不同演替阶段土壤细菌群落结构与功能潜势

采用土壤细菌16S rDNA高通量测序方法研究了大兴安岭汗马自然保护区落叶松林不同演替阶段的土壤细菌群落结构和功能.结果表明: 不同演替阶段落叶松林土壤细菌优势门为变形菌门、酸杆菌门、疣微菌门、拟杆菌门、放线菌门、浮霉菌门和绿弯菌门,随着演替的进行,酸杆菌门相对丰度逐渐增加,绿弯菌门相对丰度逐渐减少,优势门相对丰度在不同演替阶段不同.细菌群落α多样性在不同演替阶段间无显著差异,但其群落结构分别在落叶松幼龄林与中龄林、幼龄林与过熟林、近熟林与成熟林之间存在显著差异.土壤氧化还原电位、土壤pH和有效磷是影响细菌群落结构的主要环境因素,其中土壤氧化还原电位对微生物群落结构影响最大.随着演替的进行,细菌参与的固氮作用、反硝化作用、氨氧化作用、木质素降解作用呈逐渐减弱的趋势,硫酸盐异化还原作用呈先降后升的趋势,碳固定作用呈先升后降的趋势,碱性磷酸酶没有明显的变化规律,影响土壤功能的主要因素有土壤有效磷和氧化还原电位等.

Soil bacterial community structure and predicted functions in the larch forest during succession at the Greater Khingan Mountains of Northeast China

To reveal soil bacterial community structure and potential functions in larch forest during succession at Greater Khingan Mountains (Hanma National Nature Reserve), 16S rDNA was sequencing by Illumina Miseq. The results showed that the Proteobacteria, Acidobacteria, Verrucomicrobia, Bacteroidetes, Actinobacteria, Planctomycetes and Chloroflexi were the most dominant phyla in soils of larch forests at various successional stages. Along forest succession, Acidobacteria increased, while Chloroflexi decreased. Relative abundance of dominant phyla was different at various successional stages. The α diversity, Chao1, Shannon index and Simpson index of soil bacterial community had no significant difference among five succession stages, while significant differences in soil bacterial community structure were observed between young and medium larch, between young and over mature larch, and between near mature and mature larch. Bacterial community structure was mainly influenced by redox potential, pH and available phosphorus. The redox potential was the most important factor influencing soil bacterial community structure. Along the succession of larch forest, N-fixation, denitrification, ammonia oxidation and lignin breakdown decreased, dissimilatory sulfate reduction had down-up trend, carbon fixation had up-down trend, and alkaline phosphatase had no apparent trend. Bacterial community potential function was mainly influenced by redox potential and available phosphorus.