黄河三角洲滨海湿地微生物多样性及其驱动因子

Analysis of microbial diversity and driving factors in coastal wetlands of the Yellow River Delta

微生物在湿地的生物地球化学循环和生态功能调节中发挥着重要作用,对全球气候变化具有重大影响,对维持全球生态系统的健康至关重要。以黄河三角洲滨海湿地为研究对象,通过采集代表性植被群落的土壤表层和部分植物根系,探究土壤微生物群落组成、根际微生物、环境因子及其内在的关联性和影响机制。研究结果表明不同植被覆盖地区微生物多样性存在差异,芦苇区和柽柳区微生物丰度高于泥滩区、碱蓬区和棉田,海漫滩微生物丰度高于河漫滩地和泥滩。土壤微生物菌群结构和多样性显著高于根际:土壤细菌的香农指数约为4—5.5,根际微生物的香农指数约为0—4。土壤细菌主要为厚壁菌门、变形菌门、拟杆菌门和放线菌门,占样品总数的90%以上;而根际细菌主要是蓝藻门、变形菌门和放线菌门,二者在属水平上的菌群结构差异更加明显。环境因子的含量与生境类型有关,SO^(2-)_(4)和NO_(-)^(3)的相关性最高,植被覆盖区土壤中Mn^(4+)、Fe^(3+)和水解氮的含量低于滩涂裸地。冗余分析(RDA)表明,pH值在小空间尺度上对湿地土壤中细菌群落的影响较小,环境因子在门和属水平的解释率分别为89.7%和86.8%,其中K(23.4%)、NO_(-)^(2)(11.8%)、Mn^(4+)(9.8%)和Na(8.0%)是解释门水平微生物区系结构变化和组成的主要因子。研究为理解湿地微生物多样性与湿地生态系统功能之间的影响机制提供了一个生态学视角,有助于了解黄河三角洲滨海湿地土壤和植物根际的细菌分布特征,对黄河三角洲退化滨海湿地的生物修复具有重要的指导意义。

Microorganisms play an important role in the biogeochemical cycle and ecological function regulation of wetlands.They have a major impact on global climate change and are critical for maintaining the health of the global ecosystem.Taking the coastal wetland of the Yellow River delta as the research object,this study explored the composition of the soil microbial community,rhizosphere microorganisms,environmental factors and their internal correlations and influencing mechanisms by collecting the soil surface layer of representative vegetation communities and part of plant roots.Research results showed that there were differences in microbial diversity among areas with different vegetation covers.The microbial abundance in Phragmites australis and Tamarix chinensis areas was higher than that in mudflat,Suaeda glauca and cotton field.Moreover,the microbial abundance in mudflat was significantly higher than that in washland and floodplain.The structure and diversity of soil flora were significantly higher than those of rhizosphere microorganism:the Shannon index of soil bacteria was about 4—5.5,while that of rhizosphere microorganism was about 0—4.The soil bacteria were mainly Firmicutes,Proteobacteria,Bacteroidetes and Actinobacteria,accounting for more than 90%in all samples,while rhizosphere bacteria were mainly Cyanobacteria,Proteobacteria and Actinomycetes,and the differences of flora structure at the genus level were more obvious.The species composition of bacteria in different habitat types and the microbial composition of different sampling sites in the same habitat type were different.The content of environmental factors was related to the habitat type,SO^(2-)_(4)and NO_(-)^(3)had the highest significance.The content of Mn^(4+),Fe^(3+)and hydrolyzed nitrogen in vegetation-covered areas in wetland soil was lower than that in bare mudflats.Redundancy analysis(RDA)showed that pH value had little influence on the bacterial community in wetland soil on a small spatial scale.The explanatory rates of environmental factors at the phylum and genus levels were 89.7%and 86.8%,respectively.K(23.4%),NO_(-)^(2)(11.8%),Mn^(4+)(9.8%)and Na(8.0%)were the main factors explaining the structural changes and composition of microbial flora at the phylum level.This study provides an ecological perspective for understanding the influence mechanism between wetland microbial diversity and wetland ecosystem function,and help us to understand the distribution and structure of bacteria in the soil and plant rhizosphere of coastal wetlands in the Yellow River delta,which has important guiding significance for the bioremediation of the degraded coastal wetlands in the Yellow River delta.