【作者】 李媛媛；

【导师】 马飞；

【作者基本信息】 宁夏大学 ， 自然地理学， 2022， 硕士

【摘要】 全球气候背景下,CO2浓度增加、气温升高和降水格局的改变将直接影响土壤营养状况,进而影响植被生长和土壤微生物群落多样性。干旱和半干旱地区生态系统脆弱,对气候变化极其敏感,建群植物作为干旱、半干旱生态系统的核心组成部分,这些植物如何响应和适应气候变化是当前亟需解决的重要问题,会直接影响生态系统结构和功能的稳定。根际土壤是植物与微生物相互作用的区域,根际土壤微生物对植物的生长和生态适应性具有重要影响,研究干旱和半干旱地区建群植物根际土壤微生物多样性和群落结构对环境变化的响应及其驱动因素,对理解未来气候变化下建群植物的生态适应机制具有重要意义。因此,本研究以中间锦鸡儿和小叶锦鸡儿为研究对象,通过分析2种锦鸡儿不同地理种群根际土壤细菌、真菌和古菌多样性及群落结构的变化特征,揭示半干旱地区影响锦鸡儿属植物根际土壤微生物多样性和群落构建的关键因子,探讨土壤微生物群落构建过程中确定性过程和随机过程的相对作用,从微生物学角度揭示锦鸡儿属植物对干旱环境的响应和适应机制,同时为荒漠植物土壤微生物多样性的研究、保护和开发提供相关的基础资料。主要结果如下:(1)中间锦鸡儿和小叶锦鸡儿根际土壤中共检测到细菌的22门62纲131目185科304属。变形菌门、酸杆菌门、拟杆菌门和放线菌门为优势菌门。纲水平上,α-变形菌纲、γ-变形菌纲和拟杆菌钢相对丰度较高。优势细菌属为根瘤菌属、鞘氨醇单胞菌属、RB41和芽孢杆菌属。主坐标分析和ANOSIM结果表明,2种锦鸡儿属植物根际土壤细菌群落结构差异显著。冗余分析结果发现,影响2种锦鸡儿属植物根际土壤细菌多样性的主要生态因子是海拔,土壤pH、电导率、海拔和干旱指数是影响细菌群落结构变化的关键因子。随着地理距离的增加,土壤细菌群落的β多样性显著降低。通过变差分解分析(VPA)和Mantel分析发现,环境因子(土壤pH、电导率、海拔和干旱指数)和空间变量共同影响着土壤细菌群落的构建。(2)中间锦鸡儿和小叶锦鸡儿根际土壤中共检测到真菌的7门20纲43目66科78属。子囊菌门、担子菌门和接合菌门为优势菌门。纲水平上,散囊菌纲、粪壳菌纲、伞菌纲和座囊菌纲相对丰度较高。优势真菌属为青霉菌属、Unclassified_f_Unidentified、地丝霉菌属和被孢霉菌属,且根内球囊霉菌和球囊霉菌也分布于土壤中。Chao1、ACE和Simpson指数在中间锦鸡儿根际土壤中显著低于小叶锦鸡儿。主坐标分析和ANOSIM结果表明,2种锦鸡儿属植物根际土壤真菌群落结构差异显著。冗余分析结果发现,影响2种锦鸡儿土壤真菌多样性的主要生态因子是土壤有机碳、全氮、电导率、速效钾、海拔、全磷和干旱指数,海拔、速效钾和全磷是影响真菌群落结构变化的关键因子。随着地理距离的增加,土壤真菌群落的β多样性显著降低。通过变差分解分析(VPA)和Mantel分析发现,环境因子(海拔、速效钾和全磷)和空间变量共同影响着土壤真菌群落的构建。(3)中间锦鸡儿和小叶锦鸡儿根际土壤中共检测到古菌的4门5纲5目6科7属。奇古菌门、未分类菌门、广古菌门和纳古菌门为优势菌门。纲水平上,亚硝基菌纲、未分类菌纲、热原体纲、Woesearchaeia、嗜盐杆菌纲和Nanohaloarchaeia相对丰度较高。优势古菌属为Nitrososphaeraceae科未分类的属、未分类的属、暂定Nitrocosmicus属氨氧化古菌和暂定Nitrososphaera属氨氧化古菌。Shannon和Simpson指数在小叶锦鸡儿根际土壤中显著高于中间锦鸡儿。主坐标分析和ANOSIM结果表明,2种锦鸡儿属植物根际土壤古菌群落结构差异显著。冗余分析表明土壤有机碳是影响2种锦鸡儿属植物根际土壤古菌群落结构变化的关键因子。随着地理距离的增加,土壤古菌群落的β多样性显著降低。通过变差分解分析(VPA)和Mantel分析发现,环境因子(土壤有机碳)和空间变量共同影响着土壤古菌群落的构建。综上所述,在半干旱区锦鸡儿属植物根际土壤中,环境因子是影响细菌、真菌和古菌群落结构变化的主要因子,且地理距离与土壤微生物群落结构存在显著相关性,即确定性过程和随机过程之间的权衡决定了土壤微生物群落的构建过程。更多还原

【Abstract】 In the context of global climate changes,the increase of carbon dioxide(CO2)concentration,temperature and shift in precipitation will directly affect soil nutritional status,thereby affecting vegetation growth and soil microbial community diversity.The ecological environment in arid and semi-arid areas is fragile and extremely sensitive to climate change.As the core component of arid and semi-arid ecosystems,how these plants respond to and adapt to climate change is an important problem to be solved,which will directly affect the stability of ecosystem structure and function.Rhizosphere soil is an area of plant-microorganism interaction.And rhizosphere soil microorganisms have important effects on plant growth and ecological adaptability.Studying the response of rhizosphere soil microbial diversity and community structure to environmental change and its driving factors in arid and semi-arid areas is of great significance for understanding the ecological adaptation mechanism of constructive plants under future climate change.Therefore,this study took Caragana liouana and C.microphylla as the research objects,analyzed the diversity and community structure characteristics of bacteria,fungi and archaea in rhizosphere soil of two different geographic populations of Caragana,clarified the main driving factors affecting soil microbial diversity and community structure,explored the relative roles of the deterministic and stochastic processes in the assembly of soil microbial community,revealed the response and adaptation mechanism of Caragana to drought environment,and also provided basic data for the research,protection and development of soil microbial diversity of desert plants.The main finding are as follows:(1)22 phyla,62 classes,131 orders,185 families,and 304 genera were identified from all rhizosphere soil of C.liouana and C.microphylla.At the phylum level,Proteobacteria,Acidobacteria,Bacteroidetes and Actinobacteria were the most abundant phyla.And the abundance of Alphaproteobacteria,Gemmaproteobacteria and Bacteroidia were higher at the class levels.At genus level,Rhizobium,Sphingomonas,RB41 and Bacillus were dominant.The principal coordinate analysis and ANOSIM demonstrated that there were significant differences between them in the bacterial community structure.Based on the redundancy analysis,altitude were the main ecological factors associated with soil bacterial diversity,and pH,electrical conductivity,altitude and aridity index were the dominant factors associated with changes in the rhizosphere bacterial community structure.With the increase of geographical distance,the β-diversity of soil bacteria community decreased significantly.Variance partitioning analysis(VPA)and Mantel analysis showed that both environmental factors(pH,EC,ALT and AI)and spatial variables played roles in the assembly of soil bacterial community.(2)7 phyla,20 classes,43 orders,66 families,and 78 genera were identified from all rhizosphere soil of C.liouana and C.microphylla.At the phylum level,Ascomycota,Basidiomycota and Zygomycota were the most abundant phyla.And the abundance of Eurotiomycetes,Sordariomycetes,Agaricomycetes and Dothideomycetes were higher at the class levels.At genus level,Penicillium,Unclassified_f_Unidentified,Geomyces and Mortierella were dominant,and we also found Rhizophagus and Glomus in rhizosphere soil.Soil fungi Chao1 index,ACE index and Simpson index were lower in the rhizosphere of C.liouana.The principal coordinate analysis and ANOSIM demonstrated that there were significant differences between them in the fungal community structure.Based on the redundancy analysis,soil organic carbon,total nitrogen,electrical conductivity,available potassium,altitude,total phosphorus and aridity index were the main ecological factors associated with soil fungal diversity,and altitude,available potassium and total phosphorus were the dominant factors associated with changes in the rhizosphere fungal community structure.With the increase of geographical distance,the β-diversity of soil fungi community decreased significantly.Variance partitioning analysis(VPA)and Mantel analysis showed that both environmental factors(ALT,AK and TP)and spatial variables played roles in the assembly of soil fungal community.(3)4 phyla,5 classes,5 orders,6 families,and 7 genera were identified from all rhizosphere soil of C.liouana and C.microphylla.At the phylum level,Thaumarchaeota,Unclassified,Euryarchaeota and Nanoarchaeota were the most abundant phyla.And the abundance of Nitrososphaeria,Unclassified,Thermoplasmata,Woesearchaeia,Halobacteria and Nanohaloarchaeia were higher at the class levels.At genus level,Unclassified_f_Nitrososphaeraceae,Unclassified,Candidatus Nitrocosmicus and Candidatus Nitrososphaera were dominant.The archaeal Shannon index and Simpson index of C.microphylla were significantly higher than those of C.liouana.The principal coordinate analysis and ANOSIM demonstrated that there were significant differences between them in the archaeal community structure.Redundancy analysis showed that soil organic carbon were the dominant factors associated with changes in the rhizosphere archaeal community structure.With the increase of geographical distance,the β-diversity of soil archaea community decreased significantly.Variance partitioning analysis(VPA)and Mantel analysis showed that both environmental factors(SOC)and spatial variables played roles in the assembly of soil archaeal community.In conclusion,environmental factors predominantly determined the structural of bacterial,fungal and archaeal community structure in the rhizosphere soil of Caragana species in semi-arid regions.And there was a significant negative relationship between geographical distance and microbial community structure.The result indicated that the deterministic versus stochastic processes jointly drive the assembly microbial communities of Caragana species.更多还原