AMF促进土壤有机碳固持的机理会随其多样性改变吗？

Arbuscular mycorrhizal fungi (AMF) is widely considered as an important regulator for soil carbon (C) pool. However, due to lack of researches on the coupling of AMF diversity and its ecological multifunction, the knowledge gap still exists on whether the role of AMF in mediating soil C storage will be altered by changes in AMF diversity. Based on our previous studies of mycorrhizae resources in evergreen broadleaf forests, we propose a hypothesis that AMF diversity affects its regulation on soil organic carbon (SOC) accumulation. Specifically, AMF diversity will be altered by the succession stages in evergreen broadleaf forests and the mechanism underlying the regulation of AMF on SOC accumulation will shift from biochemical driving to chemical and physical protection during forest succession. To test this hypothesis, we examine AMF diversity along succession stages in evergreen broadleaf forests and the possible ways of regulation of AMF on SOC accumulation, including biochemical, chemical, and physical paths. The ultimate goal of this project is to illuminate the tendency of AMF diversity along the process of succession in evergreen broadleaf forests, to reveal the relationship between AMF diversity and plant diversity, to establish theoretical model for the regulation of AMF on SOC accumulation. This project will provide synthetical methods for evaluating the influence of AMF on soil C cycling; it will also provide first hand data for understanding the above- and belowground relationship in evergreen broadleaf forests. In addition, it will provide information to refine current knowledge on ecological multifunction in evergreen broadleaf forests under global change.

丛枝菌根真菌（AMF）是土壤碳库重要的调节者。AMF多样性研究近年来取得重要进展，然而对其多样性和生态系统功能的耦合研究十分有限，学术界关于AMF多样性变化是否引起其生态功能改变尚无定论。本项目基于对常绿阔叶林菌根资源的研究基础，提出AMF促进土壤有机碳固持的机理随其多样性变化的假设：AMF多样性随植物多样性变化而变化，在群落演替过程中AMF对土壤有机碳固持的影响机理存在由生物化学过程主导向化学、物理过程为主的方式变迁。为验证该假设，项目以常绿阔叶林及其演替系列为研究对象，以AMF多样性为切入点，从生物化学、化学、物理途径定量研究AMF对土壤有机碳累积的影响，阐明AMF多样性的变化及其与植物物种多样性的关系，分析AMF促进土壤有机碳累积的机制，解答AMF促进土壤有机碳固持的机理是否会随其多样性而改变的问题。研究结果可为评估常绿阔叶林地上地下多样性关联和探讨AMF对碳循环的影响提供科学依据。

土壤碳动态及其对环境因子变化的响应一直是全球变化相关领域研究的热点。由于对土壤生物学过程的认识相对薄弱，大量模型将土壤作为“黑箱”，因而不同模型对气候变化条件下全球土壤碳库的预测误差巨大。越来越多的宏观生态学研究强调土壤生物多样性对土壤碳动态的影响不容忽视。有研究表示，相对于其他微生物，丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF）具有分布范围广、多样性较低、在土壤碳循环中起重要调节作用等优势，值得深入研究。以AMF 作为切入点，研究其多样性与植物多样性的关系和 AMF 对土壤有机碳固持的影响，可以为了解生态系统地下、地上多样性的关系，探讨土壤生物多样性对生物地球化学循环过程的影响提供新的视点。热带、亚热带地区，群落结构随森林恢复或演替阶段而存在差异，群落结构变化过程中AMF多样性或功能类群是否发生变化？AMF多样性的变化是否导致其促进土壤有机碳固持的机理发生改变？围绕上述问题，项目选择热带亚热带的常绿阔叶林自然演替系列、退化丘陵恢复系列、沿海台地恢复系列，构建植物群落多样性存在差异的研究对象，围绕“AMF促进土壤有机碳固持的机理会随其多样性改变吗”这一核心问题，从生态系统水平对丛枝菌根真菌多样性进行了评估，利用磷脂脂肪酸、高通量测序、13C核磁共振等方法定量研究AMF对土壤有机碳固持的影响，并从直接和间接两个途径分析AMF对土壤有机碳的贡献。项目从宏观生态学角度出发，评估了AMF多样性随植物群落多样性的变化规律，为探讨地上-地下生物多样性关系提供了新思路；将AMF特征磷脂含量与代谢产物相结合，从直接和间接两个途径辨析了AMF促进土壤有机碳固持的机理；辨析了热带亚热带森林生态系统AMF多样性对土壤碳累积的影响因素；阐明了亚热带森林演替过程中AMF对土壤有机碳固持的影响机制的变化。项目执行期间发表论文（含接受待刊）论文4篇，含SCI收录期刊论文1篇，培养研究生6名。