关键词: 冀北山区, 植被恢复, Illumina Miseq测序, 根际土, 细菌群落结构

Abstract: [Objective]This study aimed to investigate the influence of different vegetation restoration patterns in mountainous areas of northern Hebei on the structural characteristics and functional diversity of rhizosphere soil bacterial community, and to explore the mechanisms of natural and artificial restoration measures on soil microorganism, so as to provide theoretical foundation for vegetation restoration and management in the region.[Method]The rhizoplane, rhizosphere and non-rhizosphere soils of the natural restored scrub-grassland, shrubbery and secondary forest, as well as the artificial restored forest were targeted, and high-throughput sequencing of V3-V4 fragment of bacterial 16S rRNA was conducted by using the Illumina Miseq platform, to analyze the α, β and functional diversities of the soil bacteria, as well as the communities structure and their relationships with the environmental factors.[Result] 1) the α-diversity of soil bacteria among different restoration patterns was significantly different (P<0.05). The abundance and diversity of soil bacteria in secondary forest were all higher than those of artificial forest. To be specific, the scrub-grassland had higher diversity but the lowest abundance, while the shrubbery had higher abundance but the lowest diversity. There was no significant difference in the bacterial α-diversity among different rhizosphere ranges (P>0.05) The bacterial α-diversity in root surface and rhizosphere soils were relatively higher than that in non-rhizosphere soil. 2) There were certain similarities in soil bacterial community structure between secondary forests and artificial forests. However, there were big differences in soil bacterial community structure between secondary forests and scrub-grassland and shrubbery. Moreover, there was big difference in the soil bacterial community structure between root surface soil and rhizosphere and non-rhizosphere soils, while the bacterial community structure of rhizosphere soil was similar with that of non-rhizosphere soil. 3) Proteobacteria, Actinobacteria, Bacteroidetes, Acidobacteria, Gemmatimonadetes and Firmicutes were the dominant groups. Meanwhile, the abundance of bacterial communities (Proteobacteria, Actinobacteria, and Bacteroidetes) decomposing organic matter among all sample lands was significantly different; specifically, the abundance of scrub-grassland and secondary forest was remarkably higher than that in other vegetation types The abundance in root surface and rhizosphere soils was also markedly higher than that in the non-rhizosphere soil. Besides, the carbon-fixing and nitrogen-fixing bacteria (Gemmatimonadetes and Firmicutes) were relatively evenly distributed. 4) Soil field water holding capacity, organic matter and total phosphorus, vegetation distribution uniformity, Simpson diversity index and abundance index were the major factors affecting the soil bacterial communities. Typically, soil factors (including soil field water holding capacity, organic matter and total phosphorus) had distinct influence on the non-rhizosphere soil bacteria of shrubbery and scrub-grassland, but had little effect on the root surface and rhizosphere soil bacteria. Moreover, vegetation factors (vegetation distribution uniformity, Simpson diversity index and abundance index) had extremely significant influence on the soil bacterial communities within different rhizosphere ranges of arbor species (secondary forest and artificial forest). 5) The number of genes encoding metabolism function on KEGG was the largest, which was the dominant function of soil bacteria. There were significant differences in the number and diversity of KEGG functional gene sequences among all soil bacterial communities, suggesting that there were numerous bacterial species with unique functions in rhizosphere soils from all vegetation restoration patterns. However, soil and vegetation could not determine the functional diversity of soil bacteria.[Conclusion]Restoration modes, vegetation types and roots all can affect the soil bacterial community structure and diversity in mountainous areas of northern Hebei, among which, the restoration modes have more obvious effect on soil bacterial diversity, while vegetation types have more significant effect on soil bacterial community structure. The closer to the root system, the higher the diversity of soil bacteria, the greater the difference between soil bacterial community structure and non-rhizosphere soil. Moreover, environmental factors, such as soil nutrient, moisture content and vegetation distribution, are all related to the soil bacterial community structure and diversity.

Key words: mountainous areas of northern Hebei, vegetation restoration, Illumina Miseq sequencing, rhizosphere soil, bacterial structure