Knowledge Resource Center for Ecological Environment in Arid Area
| 我国北方草地土壤微生物群落的空间格局及其驱动机制 | |
| 其他题名 | The spatial patterns of soil microbial communities and its drive mechanisms in the grassland of Northern China |
| 王晓波 | |
| 出版年 | 2016 |
| 学位类型 | 博士 |
| 导师 | 韩兴国 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 确定生物的空间分布格局及其驱动力是生态学研究的核心问题，也是揭示地球上生物多样性产生和维持机制的必要前提。作为地球上最丰富的生物类群之一，土壤微生物在生态系统中发挥至关重要的作用，调控生物地球化学循环等许多关键的生态系统过程。尽管人们已经认识到微生物的重要性，但是相对动植物而言，人们对于微生物多样性的空间分布及其驱动机制的认知仍然缺乏，甚至对其是否存在与大型生物相似的生物地理分布格局还尚存争论。究其原因，主要是因为技术手段的限制，人们很难对微生物群落多样性进行准确的评估，正是于此，使得很多学者认为微生物多样性的空间分异是微生物生态学研究的“噪音”。然而，近年来分子技术和生物信息分析技术的迅速发展，为人们更好的描述微生物群落物种和系统发育多样性提供了前所未有的机会。我们现在可以通过在不同生态系统和更大空间梯度下的系统取样，对土壤微生物多样性进行细致的比较研究，全面的理解土壤微生物多样性的空间格局及其控制机理。草地作为我国最大的生态系统类型，其地域广阔、不同草地类型气候差异显著，植被和土壤类型也各不相同，这都会导致土壤微生物群落在地理空间上的显著差异。本研究将以我国北方干旱和半干旱草原为研究对象，通过样带调查的方式，综合运用高通量测序和GeoChip技术，对土壤微生物群落结构和多样性进行系统的比较研究；通过与气候因子、土壤理化性质、植物群落以及空间距离等参数的耦合分析，解析区域尺度下驱动微生物群落空间分布的关键因子，阐明我国北方草地生态系统土壤微生物群落的空间分布特征及其驱动机制。本研究对于微生物资源的有效利用，提升我国草地生态系统管理水平有着重要的科学意义，为深入理解生态系统的结构和功能，预测生态系统对环境变化的响应提供科学依据。通过我们的研究主要发现：（1）在我国北方干旱和半干旱草原，放线菌门、酸杆菌门、α-变形菌门、δ-变形菌门、拟杆菌门和浮霉菌门是细菌主要的6个优势类群。干燥度是影响细菌群落多样性和群落组成最显著的环境因子。在越干旱的地区，细菌多样性越低，但是多样性存在较大的空间变异。干燥度也是影响细菌优势类群丰度最重要的环境因子，细菌优势门相对丰度随干燥度梯度的变化呈现不同的响应趋势。（2）细菌群落相似性随地理距离和环境距离显著降低，相对于环境因子，地理距离也是影响微生物群落空间聚集的另一重要因素。随着研究尺度的加大，地理距离对微生物群落空间分布的影响可能会更为明显。微生物群落组成和多样性的格局由历史因素（如扩散限制）和当代环境异质性两者共同驱动。（3）微生物alpha多样性在四个不同草地类型之间存在显著差异。荒漠地区的微生物多样性显著低于高寒草原、荒漠草原和典型草原。高寒草原的微生物多样性也显著低于荒漠草原和典型草原。从荒漠草原到典型草原，细菌多样性无显著变化，但是真菌多样性显著递增。（4）在属的水平上，细菌在不同草地类型的丰度特征也具有明显差异。在荒漠地区分布的属主要有：Aciditerrimonas，GP16，Blastococcus，Sphingomonas，lamia等。在荒漠草原分布的属主要有：Fervidicoccus，Solirubrobacter，Conexibacter，Rubrobacter，Microvirga，Steptomyces。在高寒草原和典型草原分布的属主要有：GP3，GP4，GP6，GP7，Gemmatimonas，Sphingosinicella，Bradyrhizobium。（5）不同草地类型的土壤微生物（细菌、古菌和真菌）群落具有不同的距离衰减格局，尽管群落相似性都随地理距离的增加而减小，但是微生物群落在不同草地类型中的距离衰减率（z 值）明显不同，在同一草地类型中，不同微生物群落的距离衰减率也不相同。 |
| 英文摘要 | A central goal in ecological research is to understand the spatial patterns of biodiversity and identify the factors that drive the spatial diversification. Soil microorganisms are the most diverse and abundant type of soil biota on Earth, which play vital roles in ecosystems and mediate a number of critical processes such as biogeochemical cycling. Despite their ubiquity and importance, our current knowledge about the spatial patterns of soil microbial diversity and its key determinants is still limited compared to what is known about macroorganisms. This gap in knowledge is primarily due to a lack of techniques for measuring the true diversity of microbial communities which has led many microbial ecologists to believe that any spatial variation observed in the diversity of soil microbial communities is “noise”. However, the rapid development of molecular techniques and bioinformatics techniques are now offering unprecedented opportunities for microbial ecologists to characterize the taxonomic and phylogenetic diversity of soil microbial communities. We can now conduct detailed comparative studies of soils across a wide range of ecosystems and broader spatial gradients in order to gain a comprehensive understanding of the spatial patterns of soil biodiversity and the underlying mechanisms that regulate biodiversity.Grassland ecosystems are the most important terrestrial ecosystem types in China. There has distinct differences in climate, soil and vegetation types in different grassland types which will in turn lead to a significant difference of microbial communities across space. In this study, we collected soil samples across a broad transect in arid and semi-arid grassland ecosystems including desert steppe, typical steppe and meadow steppe, quantified the microbial community diversity and the effect of spatial gradient of climate, edaphic and vegetation parameters, and geographic distance on bacterial community structure using advanced techniques including GeoChip-based analysis of the functional genes and high-throughput sequencing of the 16S rRNA and ITS2 genes. This study will contribute greatly to identify the main factors that structure spatial distribution of microbial diversity and reveal the underlying mechanisms at regional scales, to understand the relationship between soil microbial communities and ecological function, and facilitate the scientific management and functional regulation of grassland ecosystems. Furthermore, results from this study will have great implications for the conservation, development and utilization of microbial resources, providing scientific evidence for predicting the responses of ecosystems to environmental change.(1) In this study, all bacterial communities were dominated by six major groups, Actinobacteria, Acidobacteria, Alphaproteobacteria, Deltaproteobacteria, Bacteroidetes and Planctomycetes. The major environmental factor that influenced bacterial community composition and diversity was aridity in the grassland of Northern China. The communities from more arid soils (lower AI) harbored lower diversity but with drastic variation being found at more arid area. We observed that the relative abundance of the dominant phyla were also strongly correlated with aridity and changes in the abundance of these dominant phyla varied across the AI gradient.(2) Bacterial community similarity significantly declined with environmental distance and geographic distance. Compared to environmental factors examined in our study, geographical distance was also an important factor influencing bacterial community assemblage over space. As a result, the factors operating at large spatial scales, like dispersal limitation, may become apparent only in studies of spatial structure rather than over smaller scales or site-specific habitats. The spatial variation of biodiversity and composition in bacterial communities across a large-scale gradient may reflect concurrent influences of contemporary environmental heterogeneity and historical contingencies (e.g. dispersal limitation).(3) The alpha diversity of soil microorganisms changed significantly across different grassland types in Northern China. Lower diversity was found in desert area than that of in alpine grassland, desert grassland and typical grassland. In addition, There was not significant changes of bacterial diversity from desert grassland to typical grassland, but fungal diversity increased significantly.(4) The abundance of bacterial dominant groups (at genus level) across all soils changed in different grassland types. Aciditerrimonas, GP16, Blastococcus, Sphingomonas and lamia were dominant genus in alpine grassland. Fervidicoccus, Solirubrobacter, Conexibacter, Rubrobacter, Microvirga and Steptomyces were dominant genus in desert area. GP3, GP4, GP6, GP7, Gemmatimonas, Sphingosinicella and Bradyrhizobium were dominant genus in desert grassland and typical grassland.(5) Different distance-decay pattern of soil microbial communities was observed in different grassland types. Although community similarity declined with increasing geographic distance, the slope of distance-decay changed across different grassland types or microbial groups. |
| 中文关键词 | 土壤微生物 ; 微生物生物地理 ; 空间格局 ; 扩散限制 ; 群落多样性 ; 距离-衰减关系 ; 功能基因 ; 干燥度 ; 草原 |
| 英文关键词 | soil microorganisms microbial biogeography spatial patterns dispersal limitation community diveristy distance-decay relationship functional genes aridity grassland. |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院沈阳应用生态研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287743 |
| 推荐引用方式 GB/T 7714 | 王晓波. 我国北方草地土壤微生物群落的空间格局及其驱动机制[D]. 中国科学院大学,2016. |
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