How do mycorrhizal fungal traits influence ecosystem functioning?

菌根真菌（Mycorrhizal fungi， MF）与世界上大多数植物有关。它们接受植物光合作用产物的很大一部分，作为交换，它们为寄主植物提供更好的营养和对生物和非生物胁迫的耐受性。考虑到MF接收的大部分植物源碳(C)，它们极有可能影响碳循环的主要步骤。许多研究确实表明，MF可以通过改变凋落物分解或植物初级生产力来剧烈影响碳循环。然而，不同种类的MF在其特征上存在较大差异，这可能在更广泛的范围内转化为对C循环和生态系统功能的不同影响。为了更好地预测MF的特定特征如何影响生态系统过程，需要一个基于特征的框架。这是我研究项目的核心。我的重点是MF的一个特定群体，即丛枝菌根（AM）真菌，这是MF最广泛的群体。使用各种技术，我的研究将有助于回答以下问题：******1- AM真菌稳定土壤有机质吗？例如，我们将评估AM真菌对土壤团聚体中植物源性C整合的影响，并确定AM真菌是否会对其他土壤真菌的分解活性产生负面影响。******2-植物招募具有特定性状的AM真菌吗？这项工作将极大地促进我们对AM真菌生态学和植物生态学的理解：一些作者已经认识到植物的功能策略不仅整合了它们自身的特征或特征，而且还整合了它们的微生物共生体的特征，如AM真菌。因此，我们可以期望植物和AM真菌之间的性状相关性。这将有助于AM真菌在C循环模型中的整合，因为植物性状比真菌性状更容易测量：用前者来估计后者更方便。******3-植物源性C在AM真菌组织中的停留时间是多久？考虑到大量的C转移到AM真菌，我们必须更好地了解它在土壤中的命运。例如，如果快速生长的AM真菌迅速更换其组织并迅速将植物来源的C呼吸回大气中，那么在全球机会下增加的C分配给AM真菌可能不会转化为增加的土壤C储存。在这方面，我们迫切需要表征AM真菌组织中的C转换。******总的来说，我的研究计划将提供一个有凝聚力的尝试，以推进我们对AM真菌如何驱动土壤C循环的理解。使用基于性状的方法，这里提出的工作也将为研究AM真菌的功能策略铺平道路。这本身将是该领域的重大进步：植物生态学是一个很好的例子，说明基于性状的方法如何在科学学科中带来新的问题和见解。我的目标是促进AM真菌生态学的类似飞跃。

Mycorrhizal fungi (MF) associate with a majority of plants worldwide. They receive a significant portion of plant photosynthesis products, and in exchange they provide their host plants with an improved nutrition and tolerance to biotic and abiotic stresses. Given the large fraction of plant-derived carbon (C) that MF receive, they are highly likely to influence major steps of the C cycle. Many studies have indeed showed that MF can drastically influence C cycling through the alteration of litter decomposition or of plant primary productivity. However, different species of MF vary considerably in their traits, which may translate into different impacts on C cycling and ecosystem functioning more broadly. A trait-based framework is necessary to better predict how specific traits of MF influence ecosystem processes. This is the core of my research program. I focus on a specific group of MF, namely arbuscular mycorrhizal (AM) fungi, which are the most widespread group of MF. Using a variety of techniques, my research will contribute to answer the following questions:******1- Do AM fungi stabilize soil organic matter? We will assess, for example, the impact of AM fungi on the integration of plant-derived C within soil aggregates, and we will determine whether AM fungi negatively impact the decomposing activity of other soil fungi.******2- Do plants recruit AM fungi with specific traits? This work will significantly advance our understanding of AM fungal ecology, but also of plant ecology: it has been recognized by several authors that plant functional strategies not only integrate their own traits or characteristics, but also the traits of their microbial symbionts, such as AM fungi. We may thus expect trait correlations between plants and AM fungi. This would facilitate the integration of AM fungi in C cycling models, because plant traits are much easier to measure than fungal traits: it would be convenient to estimate the latter with the former. ******3- What is the residence time of plant-derived C in AM fungal tissues? Given the large amount of C transferred to AM fungi, we must better understand its fate in the soil. If fast-growing AM fungi quickly replace their tissues and rapidly respire back plant-derived C to the atmosphere, then an increased allocation of C to AM fungi under global chance might not translate into an increased soil C storage, for example. We urgently need to characterize C turnover in AM fungal tissue, in this regard.******Overall, my research program will offer a cohesive attempt to advance our understanding how AM fungi drive soil C cycling. Using a trait-based approach, the work presented here will also pave the way for studying functional strategies in AM fungi This, in itself, will be a major advancement of the field: plant ecology is an excellent example of how a trait-based approach can bring novel questions and insights in a scientific discipline. My aim is to promote a similar leap forward in AM fungai ecology.