Structure and Functional Diversity of Bacterial Community in Rhizosphere Soil of Typical Vegetation in the Riparian Zone Along the Downstream of Songhua River

Abstract

The aim of this study was to provide a reference for the riparian zone with protection and ecological restoration by analyzing the differences in typical vegetation (Phragmites communis, Populus tomentosa, Salix sungkianica, and Carex schmidtii) rhizosphere bacterial communities and their functions and identifying the potential of different types of vegetation to restore the damaged riparian zone in Songhua River. The 16S rRNA of rhizosphere soil bacteria in the four typical vegetation types of the riparian zone along the downstream of the Songhua River was sequenced using the Illumina MiSeq PE300 high-throughput sequencing platform. The community diversity, functional differences, and influencing factors of rhizosphere soil bacteria for different vegetation types were analyzed. The results showed that the Ace index, Chao1 index, and Shannon index of soil bacterial diversity in P.communis were significantly higher than those of P.tomentosa (P<0.05), and there was no significant difference between the above two types of vegetation and S. sungkianica and C.schmidtii. There were significant differences between the soil bacterial community structure of P. tomentosa and that of the three other vegetation types (P<0.05). The soil bacterial community structures of S.sungkianica, C.schmidtii, and P.communis were similar. Bacteria in the rhizosphere soil of the four typical vegetation types could be divided into 38 phyla. Acidobacteria, Actinobacteria, Chloroflexi, Verrucomicrobia, and Proteobacteria were the dominant phyla (relative abundance>5%), and the Nitrospirae, Gemmatimonadetes, Bacteroidetes, Firmicutes, and Rokubacteria of bacteria had a relative abundance greater than 1%. The bacterial community in the rhizosphere soil of the four typical vegetation types had 6 primary metabolic pathways and 43 secondary metabolic pathways, including 14 types of main secondary metabolic pathways (relative abundance>1%). Diversity in rhizosphere soil bacterial communities of different vegetation types was significantly influenced by the C/N ratio, soil pH, and moisture content. Hence, the effects of different vegetation types in repairing the degraded riparian zone were different, and wetland vegetation (S.sungkianica and C.schmidtii) was conducive to the improvement in soil bacterial diversity and soil ecosystem functions.