松花江下游沿江湿地土地利用变化对土壤细菌群落多样性的影响

本研究旨在明确生境质量变化对土壤细菌群落的影响，为松花江退化湿地选择科学的修复方法提供参考依据.于2018年使用Illumina MiSeq PE300第二代高通量测序平台对松花江下游的5种土地利用类型湿地（天然湿地、稻田地、玉米田、采砂迹地及恢复湿地）土壤细菌16S rDNA进行测序，分析不同土地利用类型土壤细菌群落多样性和功能的差异.结果表明：沿江湿地开垦为玉米田造成土壤细菌的Ace、Chao1和Shannon指数显著降低（P<0.05），采砂迹地的仿湿地修复使土壤细菌的Ace、Chao1和Shannon指数显著提高（P<0.05）.天然湿地、稻田、玉米田和采砂迹地的土壤细菌群落结构差异显著（P<0.05），采砂迹地与恢复湿地的土壤细菌群落结构相似.沿江湿地土壤细菌划分为40门、105纲、258目、421科、802属和1673种，变形菌门、放线菌门、酸杆菌门、绿弯菌门、拟杆菌门、疣微菌门、厚壁菌门和芽单胞菌门为各样地共有的优势菌门（相对丰度>1%）.相比之下，拟杆菌门偏好稻田土壤环境，变形菌门和芽单胞菌门偏好玉米田土壤环境，放线菌门偏好采砂迹地土壤环境.湿地土壤细菌具有新陈代谢、环境信息处理、遗传信息处理、细胞过程、人类疾病和有机系统这6类一级代谢通路、46类二级代谢通路和19类主要二级代谢通路（相对丰度>1%）.土壤pH、含水量、碱解氮和碳氮比是沿江湿地土壤细菌群落多样性的主要影响因子.由此可见，改变沿江湿地土地用途降低了土壤生态系统稳定性，增加了湿地退化的潜在生态风险.

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

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.