Renewal application: How do ecological trade-offs drive ectomycorrhizal fungal community assembly? Fine- scale processes with large-scale implications

几乎所有的植物都与栖息在其根部的互利共生真菌有关。这些菌根真菌为植物提供营养源，作为交换，植物为真菌伴侣提供碳源。树木通常与外生菌根（ECM）真菌，这是至关重要的生态系统内的许多过程，包括分解和氮和碳循环。不同种类的ECM真菌在获得营养物质的能力或它们执行的功能套件方面可能有所不同。因此，了解影响ECM真菌物种组成的因素对于更好地全面了解土壤中的养分循环、森林健康、生产力和生物多样性至关重要。个别种类的ECM真菌争夺树根上的空间。一些真菌可能比其他真菌更好地竞争根空间，但最好的竞争对手可能在其他重要策略中表现不佳，如养分获取。这些“权衡”，这意味着在一个方面表现最佳的能力与另一个方面的表现下降有关，这是已知的一个根本原因，为什么这么多物种的大型生物体可以共同出现在一个单一的栖息地。然而，这些权衡在影响菌根群落中所起的作用却知之甚少，尽管它在确定这些生态上重要的真菌的物种组成方面可能很重要。我机械地测试了一个假设，即营养获取和营养摄入之间的权衡（氮的吸收宽度）和碳的使用（获得植物碳并在碳供应低时持续存在的能力）是驱动菌根真菌物种的关键过程，发生在个别植物的根部。这是在实验室里通过一系列实验完成的，这些实验使我能够追踪从植物供应到单个真菌物种的碳的数量，以及作为交换，有多少氮从真菌传递到植物。在这个奖学金的更新阶段，我将建立在所获得的知识和测试如何权衡证明在第一阶段可以帮助解释ECM真菌物种在该领域的分布和功能。我将通过访问欧洲各地受到密切监测的森林地块来做到这一点，在那里，关键的ECM真菌物种的发生是已知的，并且可以与环境条件（如氮的可用性）联系起来。英国的森林提供了重要的舒适性，碳捕获和木材价值，而全球树木形成了高度多样化的热带雨林，并在北方生态系统中储存了大量的碳。由于ECM真菌是所有以树木为主的生态系统的重要组成部分，该项目的成果将为我们自然环境的这一关键方面提供高质量的见解，并有助于在英国及其他地区发展未来的研究，政策和林业实践。

Nearly all plants are associated with mutualistic fungi which inhabit their roots. These mycorrhizal fungi provide the plants with a source of nutrients and in exchange, the plant provides the fungal partner with a source of carbon. Trees typically associate with ectomycorrhizal (ECM) fungi, which are critical to many processes within ecosystems including decomposition and nitrogen and carbon cycling. Different species of ECM fungi can differ in their ability to acquire nutrients or in the suite of functions that they carry out. Understanding what affects the species composition of ECM fungi is therefore important for a better overall understanding of nutrient cycling in soils, forest health, productivity and biodiversity. Individual species of ECM fungi compete for space on the roots of trees. Some fungi are likely to be better competitors for root space than others, but the best competitors are likely to perform less well in other important strategies, such as nutrient acquisition. These 'trade-offs', which mean the ability to perform optimally in one respect is associated with a decline in performance in another, are known to be a fundamental reason why so many species of macro-organisms can co-occur in a single habitat. However, the role that these trade-offs play in affecting mycorrhizal communities is poorly understood despite its probable importance in determining the species composition of these ecologically vital fungi.In the first part of this fellowship, I mechanistically tested the hypothesis that trade-offs between nutrient acquisition (the breadth of nitrogen that can be taken up) and carbon use (the ability to obtain plant carbon and persist when carbon supply is low) is a critical process driving the species of mycorrhizal fungi that can co-occur on individual plant roots. This was done using a series of experiments in the laboratory which allowed me to trace the quantities of carbon being supplied from the plant to individual specie of fungi, and in exchange how much nitrogen is being passed from the fungus to the plant. In the renewal phase of this fellowship, I will build upon the knowledge gained and test how the trade-offs demonstrated in the first phase can help explain the distribution and functioning of ECM fungal species in the field. I will do this by visiting intensively monitored forest plots across Europe, where the occurrence of key ECM fungal species is already known and can be linked to environmental conditions such as nitrogen availability. The UK's forests provide significant amenity, carbon-capture and timber value, whilst globally trees form hyper-diverse tropical rainforests, and hold significant stores of carbon in boreal ecosystems. As ECM fungi are a critical component of all tree-dominated ecosystems, the outputs from this project will provide high-quality insights into this key aspect of our natural environment, and help to develop future research, policy and forestry practice in the UK and beyond.