土壤细菌群落对纳帕海高原湿地退化的响应

Response of soil bacterial community to wetland degradation in the Napahai Plateau

【目的】探明高原退化湿地土壤细菌群落结构及多样性的时空动态特征,为理解土壤微生物群落对高原湿地退化的响应过程及机制提供关键数据支撑。【方法】以纳帕海高原不同湿地退化阶段(沼泽湿地、沼泽化草甸、草甸)为研究对象,采用Illumina高通量测序技术,探测土壤细菌群落组成及多样性的干湿季变化规律。【结果】①共检测到土壤细菌10门21属,其中变形菌门Proteobacteria和未分类菌属为优势门和属,相对丰度分别达35.92%和20.64%。②相较于原生沼泽湿地,沼泽化草甸的变形菌门和酸杆菌门Acidobacteria相对丰度分别增加14.06%和47.72%,绿弯菌门Chloroflexi相对丰度显著减少38.54%(P<0.05);草甸的酸杆菌门、放线菌门Actinobacteria、疣微菌门Verrucomicrobia和浮霉菌门Planctomycetes相对丰度分别增加了210.15%、231.37%、229.55%和315.22%。上述菌门相对丰度均为干季大于湿季。沼泽化草甸的厚壁菌门Firmicutes相对丰度在干季显著增加72.38%,在湿季显著减少73.17%(P<0.05);而拟杆菌门Bacteroidetes相对丰度在干季显著减少55.50%,在湿季显著增加223.54%(P<0.05)。③沼泽化草甸和草甸的Shannon指数较原生沼泽湿地显著增加(P<0.05),且沼泽湿地和沼泽化草甸表现为湿季大于干季,草甸则表现为干季大于湿季。④Mantel分析结果表明:干季细菌群落结构组成由土壤pH和氮、磷、钾质量分数调控,湿季则由含水量、有机质、氮磷及pH调控;Pearson相关性分析结果表明:含水量、有机质、氮和pH是影响干季土壤细菌多样性的主控因子;湿季则为磷、钾和碳氮比。【结论】高原湿地退化导致土壤含水量和pH减小,进而影响土壤碳、氮、磷和钾养分状况,最终调控土壤细菌群落组成和多样性的干湿季变化。

[Objective]This study aims to explore the spatiotemporal dynamic characteristics of soil bacterial structure and diversity in plateau degraded wetlands,so as to provide key data support for understanding the response process and mechanism of soil microbial communities to plateau wetland degradation.[Method]Illumina high-throughput sequencing technology was used to detect the dry and wet seasonal changes of soil bacterial community composition and diversity during different wetland degradation stages(swamp wetlands,swamp meadows,and meadows)in the Napahai Plateau.[Result](1)A total of 10 phyla and 21 genus of soil bacteria were detected,dominated by Proteobacteria and unclassified genera,with relative abundance of 35.92%and 20.64%,respectively.(2)Compared with native swamp wetlands,the relative abundance of Proteobacteria and Acidobacteria in swamp meadows increased by 14.06%and 47.72%,respectively,while that of Chloroflexi significantly decreased by 38.54%(P<0.05).The relative abundance of Acidobacteria,Actinobacteria,Verrucomicrobia and Planctomycetes in meadows increased by 210.15%,231.37%,229.55%and 315.22%,respectively.The relative abundance of above phyla was greater in the dry season than in the wet season.The relative abundance of Firmicutes in swamp meadows significantly increased by 72.38%in the dry season and decreased by 73.17%in the wet season(P<0.05).The relative abundance of Bacteroidetes in meadows significantly decreased by 55.50%in the dry season and increased by 223.54%in the wet season(P<0.05).(3)The Shannon index of swamp meadows and meadows significantly increased compared with native swamp wetlands(P<0.05).The Shannon indices in swamp wetlands and marsh meadows were higher in the wet season than in the dry season,while those in meadows showed an opposite pattern.(4)Mantel test indicated that the composition of bacterial community structure in the dry season was regulated by soil pH and the concentrations of nitrogen,phosphorus and potassium,while in wet season it was mainly regulated by soil water content,organic matter,nitrogen,phosphorus and pH.The Pearson correlation analysis showed that the controlling factors affecting bacterial diversity in the dry season were soil water content,organic matter,nitrogen and pH,while those in the wet season were soil phosphorus and potassium and carbon nitrogen ratio.[Conclusion]The degradation of plateau wetlands leads to a decrease in soil moisture and pH,which in turn affects the nutrient status of soil carbon,nitrogen,phosphorus,and potassium,ultimately regulating the dry and wet season changes in soil bacterial community composition and diversity.