Synergistic global change impacts on belowground biodiversity and carbon stocks in mountain ecosystems

土壤是地球上最复杂、最重要的资源之一。它拥有巨大的生物多样性，支撑着一系列生态系统功能。土壤储存的碳(C)也比地球大气和植被的总和还要多。然而，在全球范围内，土壤正面临着多种挑战，这些挑战可能导致土壤生物多样性丧失，降低生态系统功能，并削弱土壤储存碳的能力。了解土壤生物多样性和土壤碳储量将如何应对全球环境变化的综合影响仍然是极具挑战性的。我们过去的理解大多是基于对单一因素的研究，而没有考虑到系统的复杂性及其组成部分之间的相互作用。目前我们对协同效应知之甚少。当两个或两个以上因素共同作用的影响不能从单个影响中预测时，就会产生协同效应。这些不可预见的影响可能导致生物多样性和土壤c的突然和灾难性损失。山地生态系统存在于所有纬度，是生物多样性的热点，并储存了大量的土壤c。然而，它们非常容易受到全球环境变化的影响。它们的变暖速度是全球平均速度的两倍，导致植被向上移动，以及极端干旱和洪水的增加。与此同时，农业和工业污染使脆弱的山地生态系统超载，产生过多的氮(N)，这可能对生态系统过程产生负面影响。在山地生态系统中，协同效应是一个特别紧迫的知识缺口，在山地生态系统中，甚至缺乏关于土壤微生物多样性、功能和土壤C储量的基本数据。在此期间，我将解决山地土壤地下生物多样性的知识差距，以及这如何关键地支撑碳循环过程。我将确定土壤生物多样性和功能如何响应全球变化的多种驱动因素，确定是否存在协同效应，以及这些协同效应对全球山地生态系统中土壤C储量的影响。为此，我将使用三种强大的实验方法。1)我将创建一个全球分布的实验，利用新的和现有的合作来评估气候、氮沉积速率和植被变化如何控制山地生态系统中的土壤C储量。参与者将把从不同山脉不同植被类型地区收集的土壤寄给我，我将测量所有样本的土壤C储量。我将使用开放访问的全球数据库和3D模型来获取每个特定地点的气候和氮沉降数据。2)我将在北极和高山山脉设置实验操作，明确测试在现实条件下，变暖、n添加和植被变化如何影响土壤生物多样性和碳循环速率。这将为土壤生物多样性丧失与环境变化后土壤碳流失之间的生态机制提供急需的知识。我将测量细菌、真菌和无脊椎动物的多样性，以及土壤中的一套c循环过程。3)我将测试多重环境变化的遗留是否会放大干旱和洪水对山地土壤温室气体排放的影响。为此，我将使用从田间实验中收集的土壤进行精心设计的受控环境实验。我的发现将开启一种范式转变，从单一因素的全球变化研究转向关注全球变化因素之间的协同效应。我还将对土壤生物多样性如何在不同的全球变化情景下促进山地生态系统的功能产生重要见解。这一新知识可以用来告知土地管理者和政策制定者如何最好地保护土壤生物多样性，并改善英国和国外山地生态系统的自然碳储存。

Soil is one of the most complex and important resources on earth. It harbours vast biodiversity that underpins an array of ecosystem functions. Soil also stores more carbon (C) than the Earth's atmosphere and vegetation combined. However, soils are facing multiple challenges globally that threaten to cause soil biodiversity loss, reduce ecosystem functioning, and diminish the capacity of soils to store C. Understanding how soil biodiversity and soil C stocks will respond to the combined effects of global environmental changes remains extremely challenging. Much of our past understanding is based on studies of single factors that fail to incorporate the complexity of the system and interactions of its component parts. Currently we know little about synergistic effects. Synergistic effects arise when the impact of two or more factors acting together cannot be predicted from their individual impacts. These unforeseen effects can lead to sudden and catastrophic losses in biodiversity and soil C. Mountain ecosystems occur at all latitudes, are hotspots of biodiversity, and store significant amounts of soil C. However, they are very vulnerable to global environmental change. They are warming twice as fast as the global average, leading to upward shifts in vegetation, and increased extremes of drought and flooding. At the same time, agricultural and industrial pollution are overloading fragile mountain ecosystems with too much nitrogen (N), which can have negative effects on ecosystem processes. Synergistic effects are a particularly pressing knowledge gap in mountain ecosystems, where even fundamental data on soil microbial diversity, functioning, and soil C stocks are lacking.During this fellowship, I will address the knowledge gap on belowground biodiversity in mountain soils and how this critically underpins C-cycling processes. I will determine how soil biodiversity and functioning respond to multiple drivers of global change, establish if there are synergistic effects, and what the consequences of these synergistic effects are for soil C stocks in mountain ecosystems worldwide. To do this, I will use three powerful experimental approaches. 1) I will create a globally distributed experiment using both new and existing collaborations to assess how climate, N-deposition rates, and shifts in vegetation control soil C stocks in mountain ecosystems. Participants will send me soil collected from areas with different vegetation types in various mountain ranges and I will measure soil C stocks on all samples. I will use open-access global databases and 3D models to acquire climatic and N-deposition data for each specific location.2) I will set up experimental manipulations in arctic and alpine mountain ranges to explicitly test how warming, N-addition, and vegetation shifts affect soil biodiversity and C-cycling rates under real-world conditions. This will provide much needed knowledge of the ecological mechanisms by which soil biodiversity loss is connected to C losses from soil following environmental change. I will measure the bacterial, fungal, and invertebrate diversity, along with a suite of C-cycle processes in the soil. 3) I will test whether a legacy of multiple environmental changes amplifies the effects of drought and flooding on greenhouse gas emissions from mountain soils. To do this, I will conduct carefully designed controlled environment experiments using soil collected from the field experiments. My findings will initiate a paradigm shift away from single factor global change studies, towards a focus on synergistic effects between global change factors. I will also generate important insights on how soil biodiversity contributes to the functioning of mountain ecosystems under different global change scenarios. This new knowledge could be used to inform land managers and policy makers on how best to preserve soil biodiversity and improve natural C storage in mountain ecosystems in the UK and abroad.