丛枝菌根真菌群落响应植物种群密度的变化规律及构建机制

Studies on the driving mechanism of biological communities is within the core issue of ecology. The driving mechanism of arbuscular mycorrhizal fungal community has received much attention. There existed hot discussions about the effect of host plant on AMF community and AMF species competition. It has long been neglected that how the variation of plant population affects the AMF community and its construction process. Both previous domestic and foreign researches and our results support the hypothesis that `plant population density affects AMF communities through influencing AMF species competition `. In this project, we plan to construct plant population density gradient under natural and controlled conditions. We aimed to explore responses of AMF communities, AMF absorption function and species competition to plant population densities, with high-throughput sequencing, isotope addition experiments and designing of AMF interspecific competition experiment, calculating neighbor interaction intensity to reflect AMF interspecific competition intensities. The results will reveal how AMF community structure responds to variations in plant population density and driving mechanism, which is with academic value for deeper understanding of maintaining mechanism of AM symbiotic relationship, and constructing theory of biological community.

生物群落构建机制研究是生态学的核心议题。丛枝菌根真菌（Arbuscular Mycorrhizal Fungi, AMF）群落构建机制广受重视。宿主植物对AMF群落和AMF种间竞争影响的讨论十分热烈。植物种群水平的变异如何影响AMF群落及构建过程长期被忽视。国内外研究和申请者前期研究，均支持“植物种群密度通过影响AMF种间竞争而驱动AMF群落构建”的假说。本项目计划在自然和人工建立的植物种群密度梯度下，通过高通量测序、同位素添加实验以及设计AMF种间竞争实验，计算邻体相互作用强度以反映AMF种间竞争强度，研究AMF群落、AMF养分吸收功及种间竞争随植物种群密度变化规律。结果将揭示AMF群落结构响应植物种群密度变化规律及群落构建机制，对深化理解植物-AMF共生关系稳定维持机制和生物群落构建理论有重要学术价值。

宿主植物对AMF群落和AMF种间竞争影响的讨论十分热烈，植物种群水平的变异如何影响AMF群落及构建过程长期被忽视，本项目提出“植物种群密度通过影响AMF种间竞争而驱动AMF群落构建”的假说，并通过野外取样和室内受控实验进行了验证。AMF群落物种丰富度随宿主植物密度升高而增加，并且AMF群落变化与植物生物量显著相关、AMF物种丰富度与细根生物量显著相关。同位素添加实验以及AMF种间竞争实验表明，随植物密度升高，AMF优势种氮素吸收量降低，AMF非优势种氮素吸收量无显著变化。随植物密度增加，AMF优势种的丰度降低，对非优势种的竞争排斥效应降低，AMF总的物种丰富度增加。进一步拓展了相关研究 ，发现AMF可以同时促进细根凋落物分解和土壤团聚体形成，并且氮素吸收和稳定土壤团聚体间存在权衡关系。基于本项目研究，构建了3个合成微生物群落，并进行了相关推广应用。结果揭示了AMF群落结构响应植物种群密度变化规律 及群落构建机制，对深化理解植物-AMF共生关系稳定维持机制和生物群落构建理论有重要学术价值。