大兴安岭森林火烧后不同演替阶段土壤细菌多样性动态

Impact of forest succession on soil microbial diversity after fire in Greater Khingan Mountains

摘要:

【目的】研究我国最大的林区之一——大兴安岭森林火烧后不同演替阶段土壤细菌多样性动态，为天然林保护工程对于生物多样性的影响增添新的认识。【方法】以空间替代时间的方法分析大兴安岭森林演替对于土壤细菌多样性动态的影响。大兴安岭森林火烧后典型的自然演替序列为火烧迹地(LG-BA)、灌丛(SHR)、白桦林(BP)、白桦落叶松混交林(BP-LG)、落叶松林(LG-OM)。在演替序列的每个典型样地上采集0?10 cm土样，采用Illumina MiSeq高通量测序技术测定土壤细菌群落组成及其多样性。【结果】细菌操作分类单位(OTU)数量从少到多的顺序为火烧迹地<落叶松白桦混交林<灌丛<落叶松林<白桦林。随着森林演替，多样性指数Simpson先增高后降低；Shannon指数先增加后减少再增加；OTU的丰度变化比较平缓，表明物种变化较小。在各演替阶段中，土壤细菌种类主要有变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、放线菌门(Actinobacteria)和浮霉菌门(Planctomycetes)，4个门的种类含量随演替顺序都呈现先增加后减少的趋势。主成分分析表明不同演替阶段土壤细菌群落存在一定的差异性。冗余分析表明有机质(SOM)、全氮(TN)、全磷(TP)和pH对于土壤细菌群落变化有影响。【结论】随着森林演替，大兴安岭地区土壤细菌种类和生物多样性会发生变化，其变化与土壤化学成分和pH有关。

Abstract:

[Objective] Greater Khingan forest is one of the largest forest areas in China. There are many studies on plant diversity along forest succession in this area, but few studies on microbes. This research studied the impact of forest succession on soil microorganism diversity in Greater Khingan Mountains, which could provide a more comprehensive understanding of the impact of the natural forest protection project on biodiversity. [Methods] Effects of forest succession on soil bacterial diversity were analyzed by a space-trade-for-time experiment. The typical natural successional sequence after fire in Greater Khingan forest is fire-burned land (LG-BA), shrub (SHR), birch forest (BP), mixed forest of larch and birch (BP-LG), and larch forest (LG-OM). 0?10 cm top mineral soil samples were collected on forest plots and the bacterial community structure and diversity were determined with Illumina MiSeq high-throughput sequencing technique. [Results] The number of bacterial species from low to high was in the sequence of the larch and birch mixed forest, shrub forest, larch forest, and birch forest. Following forest succession, the Simpson diversity index firstly increased and then decreased. The Shannon index followed the dynamic trend of increase, decrease and increase pattern. The change of OTU (Operational taxonomic unit) abundance was relatively gentle in the succession processes, indicating that the species change was small. The phyla of soil bacteria were mainly Proteobacteria, Acidobacteria, Actinobacteria and Planctomycetes in all of the successional stages, all of them followed the change trend of increase in the first succession stage and decrease in the later stage. PCA analysis showed that bacterial communities were different in the varied successional stages. RDA analysis showed that organic matter, total nitrogen, total phosphorus and pH impacted soil bacterial community. [Conclusion] Following forest succession, the species of soil bacteria was changed in Greater Khingan forest. The most common soil bacteria communities differed across natural succession, varying as a function of soil SOM, total potassium, total phosphorus, and pH.