Effects of Land Use Changes on Soil Bacterial Community Diversity in the Riparian Wetland Along the Downstream of Songhua River

Abstract

The aim of this study was to provide a theoretical basis for the restoration of degraded wetlands in the Songhua River by determining the effect of habitat quality changes on the soil bacterial community. The 16S rDNA of soil bacteria in five land use types (natural wetland, paddy field, corn field, sand mining slash, restoration wetland) of the riparian wetland along the downstream of the Songhua River was sequenced using the Illumina MiSeq PE300 high-throughput sequencing platform. The differences in the community diversity and functions of soil bacteria for different land use types were analyzed. ACE, Chao1, and Shannon indices of soil bacterial diversity were significantly reduced by reclaiming the wetland into the corn field (P<0.05), and they were significantly improved by wetland restoration in the sand mining slash (P<0.05). The differences in the soil bacterial community structure were significant among natural wetlands, paddy fields, corn fields, and sand mines (P<0.05). Similar bacterial community structures were found in sand mining slash and restoration wetlands. Soil bacteria in the riparian wetland can be divided into 40 phyla, 105 classes, 258 orders, 421 families, 802 genera, and 1673 species. Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, Bacteroidetes, Verrucomicrobia, Firmicutes, and Gemmatimonadetes were the dominant phyla (relative abundance>1%). In contrast, Bacteroidetes preferred the soil under the paddy environment, Proteobacteria and Gemmatimonadales preferred the soil environment of corn, and Actinobacteria preferred the soil environment of sand mining slash. Wetland soil bacteria have six primary metabolic pathways (metabolism, environmental information processing, genetic information processing, cellular processes, human disease, and organismal systems) and 46 secondary metabolic pathways including 19 types of main secondary metabolic pathways (relative abundance>1%). Diversity of the soil fungal community was significantly influenced by soil pH, moisture content, available nitrogen, and the C/N ratio. Hence, potential ecological risks increased and ecosystem stability decreased because of the resource development activities in natural wetlands. Diversity of the soil fungal community plays a critical role in protecting the ecological security and supplying considerable amounts of undeveloped resources.