【作者】 马璐雯；

【导师】 张健；

【作者基本信息】 华东师范大学 ， 生态学， 2022， 硕士

【摘要】 作为土壤中“看不见的大多数”,土壤微生物多样性在生态系统过程与功能中发挥着至关重要作用。探究其海拔梯度格局和影响因素对于理解生物多样性维持机制具有重要意义,但综合山地微气候对微生物群落的分析仍然缺乏。江西官山自然保护区以其特殊的气候、植被特性蕴藏了丰富的微生物资源。为了厘清沿海拔梯度微生物多样性格局及其主要影响因素,本论文以江西官山亚热带森林为研究对象,沿320-1350 m海拔采集土壤样品,利用Illumina Mi Seq高通量测序技术,并结合土壤、植被和微气候等,对土壤细菌和真菌分类学多样性(taxonomic diveristy)和系统发育多样性进行了综合研究。主要结果如下:(1)土壤细菌OTU丰富度和Shannon-Wiener指数均随海拔升高呈线性下降,但独立于丰富度的系统发育多样性指数PSV(Phylogenetic Species Variability)无明显规律;土壤温度和p H是细菌多样性的主要限制因素,PSV与土壤含水量和总磷显著相关;不同海拔梯度的土壤细菌群落结构均存在差异,并与土壤温度、p H密切相关;优势细菌门酸杆菌门(Acidobacteria)相对多度与植物多样性、均匀度呈正相关,而厚壁菌门(Firmicutes)相对多度与土壤温度、p H呈负相关。(2)土壤真菌OTU丰富度和Faith系统发育多样性沿海拔梯度均无明显趋势,而Shannon-Wiener指数和PSV随海拔单调递增;环境变量与土壤真菌α多样性相关性总体较弱;不同海拔梯度的土壤真菌群落结构均存在差异,并与土壤温度和硝态N含量密切相关;优势真菌门子囊菌门(Ascomycota)的相对多度与海拔呈正相关,而担子菌门(Basidiomycota)的相对多度与总钾、灌木比例呈负相关。综上所述,本论文详细阐述了土壤细菌和真菌、分类学多样性和系统发育多样性之间的特有格局,分析了微气候以及土壤、植被因子对地下生物多样性的显著影响,强调了微气候在调节土壤微生物多样性过程中的重要性,为理解山地生态系统中土壤微生物群落的驱动机制提供科学依据。更多还原

【Abstract】 As the“unseen majority”in soil environments,soil microbial diversity plays a crucial role in ecosystem processes and functions.Investigating soil microbial diversity patterns along elevations and the influencing factors can help us understand the maintenance mechanisms of biodiversity.Yet,we still lack the analysis of the influence of mountain microclimates on soil microbes.Guanshan National Nature Reserve has rich microbial resources due to its special climate and vegetation characteristics.In this study,using the Illumina Mi Seq high-throughput sequencing technique,I systematically examined the taxonomic diversity and phylogenetic diversity of soil bacteria and fungi along a 320-1350 m elevational gradient in subtropical forests in Mt.Guanshan,China.Meanwhile,soil physicochemical properties,plant proporties,and fine-scale monitoring data of microclimates were obtained to disentangle the underlying mechanisms of diversity patterns.The main results included:（1）Soil bacterial OTU richness and Shannon diversity decreased linearly with elevation,while phylogenetic species variability（PSV）showed no obvious trend.Soil temperature and p H were two main factors mediating bacterial diversity and PSV was mostly related to soil water content and total phosphorus.Bacterial community structure was taxonomically and phylogenetically different among elevational sites,closely related to soil temperature and p H.In addition,the relative abundance of Acidobacteria was positively correlated with plant diversity and evenness,while the relative abundance of dominant bacterial phylum Firmicutes was negatively correlated with soil temperature and p H.（2）Soil fungal OTU richness and Faith’s phylogenetic diversity showed no significant trend,while Shannon diversity and PSV increased monotonically with elevation.The correlation between fungalαdiversity and environmental variables was overall weak.Fungal community structure was taxonomically and phylogenetically different among elevations,closely related to soil temperature and NO₃^--N content.In addition,the relative abundance of the dominant fungal phylum Ascomycota was positively correlated with elevation,while the relative abundance of Basidiomycota was negatively associated with total Potassium and shrub porportion.In conclusion,this study demonstrates the contrasting elevational diversity patterns of soil bacterial and fungal communities,and the inconsistent patterns between taxonomic diversity and richness-independent phylogenetic diversity.These results indicate the unique elevational patterns of soil microbial diversity in subtropical forests,mediating by significant factors such as microclimates,soil and plant properties.We highlighted the importance of microclimates in regulating soil microbial diversity and provided a basis for the mechanistic understanding of microbial community assembly.更多还原