What are the large-scale diversity, distributions and fates of forest mycorrhizal communities?

森林里隐藏着一个令人惊讶的秘密。尽管树木主导着这些生态系统，创造了一个复杂的栖息地，保护了许多物种，同时遮蔽了许多其他物种，但这种优势依赖于与真菌的隐藏关系。这些真菌很少看到，但它们被称为菌丝的丝状细丝交织在树木的根部，形成了一种紧密的共生关系，有助于树木和真菌的生长--一种互惠互利的相互作用。这两种生物都需要碳水化合物和矿物质才能生长，树木擅长从空气中捕捉和储存碳，而微小的真菌菌丝则擅长从土壤中提取水分和营养物质，如氮和磷。树木和真菌之间的交换量非常高：真菌中的所有碳都可以直接从其伙伴树获得，而树中的大部分氮直接来自其伙伴真菌。涉及的不同种类的真菌称为外生菌根(或ECM)真菌，以改良的细根或外生菌根命名，树木和真菌相互连接。这种共生关系非常常见：大多数欧洲树木依赖外生菌根真菌，有许多不同的真菌形成了这些关系。其中一些真菌以其有性子实体而闻名，例如有毒的苍蝇蘑菇和可食用的松露和小圆面包蘑菇。然而，令人担忧的是，我们对外生菌根真菌的多样性知之甚少。虽然一些真菌可能与各种各样的树木和其他植物一起生长，但另一些真菌可能是仅限于密切相关的树种的专家。虽然已经描述了大约8000种ECM真菌，但可能还有更多未被发现的物种。此外，我们在很大程度上忽略了这些真菌的地理范围。有些可能分布广泛，但另一些可能局限于少数几个小地点。我们确实知道，至少有一些物种可以入侵其他大陆，而另一些物种可能在当地灭绝。最令人担忧的是，我们知道外生菌根真菌对环境变化非常敏感，特别是污染以及降雨和温度的变化。但我们不知道这些观察如何转化为大规模的地理范围的变化。在这里，我们建议填补我们对树木-真菌共生体更广泛的多样性和分布的理解的空白，并帮助我们集中精力选择实验和遗传模型。为了做到这一点，我们提出使用地球上最广泛的生物监测小区网络之一，在该网络中，污染的影响和森林土壤质量的变化得到了密切的监测。我们的目标是利用这些地块对欧洲三种主要森林类型：山毛榉、苏格兰松和挪威云杉的菌根真菌进行第一次精确的测绘。在150个密集监测的地块中，我们将使用优化的分子生态学技术从外生菌根中获取DNA序列。一旦我们知道了谁和哪里是欧洲的优势真菌，我们打算使用从地块监测到的数据以及最新的环境变化预测来了解控制这些隐藏的共生环境的过程，以及它们在不断变化的世界中可能的命运。

Forests harbour a surprising secret. Although trees dominate these ecosystems, creating a complex habitat that shelters many species while shading out many others, this dominance relies on a hidden relationship with fungi. These fungi are rarely seen but their thread-like filaments, called hyphae, are intertwined among the roots of trees, forming a close symbiosis that helps both tree and fungus grow - a mutualistic interaction. Both organisms need carbohydrates and minerals to grow and, while trees excel at capturing and storing carbon from the air, the tiny hyphae of fungi excel at extracting water and nutrients, like nitrogen and phosphorus, from the soil. The amounts exchanged between trees and fungi is extremely high: all of the carbon in a fungus can be obtained directly from its partner trees, while most of the nitrogen in a tree comes directly from its partner fungi. The diverse groups of fungi involved are called ectomycorrhizal (or ECM) fungi, after the modified fine roots, or ectomycorrhizas, where the tree and fungus join each other.These symbiotic relationships are remarkably common: the majority of European trees depend on ECM fungi and there are many different fungi that form these relationships. Some of these fungi are well known for their sexual fruiting bodies, for example the poisonous fly agaric toadstools and the edible truffles and penny bun mushrooms. However, we know worryingly little about the diversity of ectomycorrhizal fungi. While some fungi may grow with a wide variety of trees and other plants, others may be specialists restricted to closely related tree species. And while around 8,000 species of ECM fungi have been described, there may be many more undiscovered. In addition, we largely ignore the geographic ranges of these fungi. Some may be widely distributed, but others may be restricted to a handful of small locations. We do know that at least some can invade in other continents and that others may be locally extinct. Most worryingly of all, we know that ectomycorrhizal fungi are sensitive to environmental change, particularly pollution and changes in rainfall and temperature. But we do not know how these observations translate to changes at large geographical scales.Here we propose to fill the gap in our understanding of the wider diversity and distribution of tree-fungi symbioses, and help focus our selection of experimental and genetic models. In order to do this, we put forward the use of one of the most extensive biomonitoring plot networks on Earth in which the effects of pollution and changes in forest soil quality have been closely monitored. We aim to use these plots to carry out the first precise mapping of mycorrhizal fungi across Europe's three major forest types: beech, Scots pine and Norway spruce. At each of 150 intensively-monitored plots, we will use optimised molecular ecology techniques to obtain DNA sequences from ectomycorrhizas. Once we know who and where are the dominant fungi in Europe, we intend to use the monitored data from the plots along with the latest environmental change predictions to understand the processes that control these hidden symbioses and their likely fate in our changing world.