天然阔叶林土壤微生物多样性的纬度分布格局和形成机制

Understanding spatial distribution patterns of biological diversity and their driving factors is indispensable to gaining a comprehensive understanding of the response of ecosystems to environmental change, aid in determining the broad scale distributions of species, and in the development ecological theories. In the past, most studies have focused on plants and animals, although soil microbes are abundant and play important roles in forest ecosystem as decomposers, primary producers and drive many important biogeochemical cycles. Because traditional methods fail to allow researchers to adequately classify microbial communities, little information is available related to the patterns of diversity in soil microbes along differential environment gradients. Recently, the development of techniques related to molecular biology which use the extraction of DNA from environmental samples has allowed researchers to classify soil microbes in different environments and has promoted an understanding of how soil microbial diversity changes along environmental gradients. Our understanding on the phylogenetic and taxonomic structure of soil microbial communities continues to expand, and much of the recent work documented how soil bacterial communities are affected by specific environmental changes or disturbances. However, due to the highly diverse, complexity and plasticity of environmental microorganism and methods limited, it is very difficult to understanding the detailed ecosystem processes mediated to microorganisms. Therefore, we currently know little regarding the distribution of microbial functional traits in nature. In this study, we will set up sampling sites in natural and mature broadleaf forest types along altitude gradient from North (N40o, E110o) to South (N18o, E110o) in national natural reserve in China, and study soil bacterial and fungal community composition, potential function key diversity and environmental conditions by using the Illumina 16S rRNA sequencing and GeoChip technologies. We will understand the distribution patterns of soil microbial diversity and key functional gene and their generate mechanism along the latitudinal gradient in forest; and the effect of climate change on soil microbial community and functional potentials. These research will help understand and know the biogeochemical cycling process mediated in soil microbe in forest ecosystems; and predict the effect of climate change.

生物多样性的分布格局及其对环境变化的响应是生物学研究的核心问题之一，土壤微生物在森林生态系统中具有重要作用，但其空间分布格局研究长期滞后于大型动植物，特别是土壤微生物功能类群的研究还较少。本项目以我国E110o为中心，沿N40o -N18o的天然阔叶林为研究对象，从区域尺度上研究土壤微生物的物种和主要功能基因类群的纬度分布格局和形成机制，包括：利用微生物功能基因芯片技术，研究天然阔叶林土壤中与碳、氮、磷、硫等循环密切相关的微生物功能基因类群的纬度分布格局；利用Illumina高通量测序技术研究土壤微生物物种（细菌、真菌）的纬度分布格局；结合地理距离、气候、植被和土壤养分等历史进化和环境因素，阐明土壤微生物多样性的形成机制；利用空间替代时间的方法，探讨气候变化对土壤微生物群落和潜在功能的影响。项目的实施对深入认识森林土壤微生物介导的生物地球化学循环过程和预测全球气候变化的影响具有重要意义。

生物多样性的分布格局及其对环境变化的响应是生物学研究的核心问题，土壤微生物的相关研究长期滞后于大型动植物，特别是土壤微生物功能类群等研究。本项目以我国E110o为中心，沿N40o -N18o的天然阔叶林为研究对象，利用Illumina高通量测序技术和微生物功能基因芯片技术等宏基因组学方法，从区域尺度上研究了森林土壤微生物的物种和主要功能基因类群的纬度分布格局和形成机制，探讨了气候变化对土壤微生物群落和潜在功能的影响。项目提出和建立了E110(±2)°为中心的天然阔叶林纬度梯度样带，完成了300个植物样方的调查和样品采集，建立了纬度梯度样带样方数据库（包括植物多样性、微生物物种和功能基因类群、土壤理化性质、气候数据等）。项目研究揭示了纬度梯度样带的土壤微生物及其主要功能基因类群的分布特征，其区域分布主要受气候和地理距离等环境因素影响；而土壤微生物的主要功能基因类群在纬度样带上具有明显的功能冗余现象，可能主要受到土壤理化性质等影响。项目分析了区域尺度上森林生态系统中植物-土壤微生物的耦合关系，表明纬度梯度样带森林土壤微生物和植物的alpha多样性没有显著的相互关系，而其beta多样性呈现显著的正相关关系；同时，土壤pH和年均降水量是影响土壤微生物beta多样性的主要环境因素。项目采用生态位宽度计算方法，分析了气候变化对植物和土壤微生物多样性的影响分析，结果表明，温度的上升和土壤pH接近中性的环境，均有利于植物群落和微生物群落生态位变宽；高年均温和年降水区域，植物物种生态位宽度较宽且植物群落的α多样性较高，而微生物群落则是在接近pH中性环境区域，物种生态位宽度变宽和α多样性升高。项目在GenBank数据库提交了一批基因序列，完善了相关数据库。项目累计撰写学术论文11篇，已经正式发表和接收10篇，其中在Science of the Total Environment, Molecular Ecology, Plant and Soil等发表SCI论文8篇。培养硕士研究生2名。

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