Soil microbial community dynamics and biogeochemical cycles under global change: effects of climate and vegetation change in alpine ecosystems

全球变化下的土壤微生物群落动态和生物地球化学循环：气候和植被变化对高山生态系统的影响

• 批准号: NE/N009452/1
• 负责人: Richard Bardgett
• 金额: $ 73.07万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FN009452%2F1
• 关键词: Soil; microbial; community; dynamics; biogeochemical

Scientists are becoming increasingly aware that that highly diverse microbial communities in soil play major roles in driving the biogeochemical cycles on which the functioning of Earth depends. It is also becoming clear that this belowground microbial diversity is highly sensitive to land use and climate change, but the consequences of this for biogeochemical cycling are poorly understood. This is what this proposal is about: understanding how both land use and climate change work together to influence soil microbial communities and their functioning, and to experimentally test the consequences of this for major biogeochemical cycles. Uniquely, we do this in high mountain ecosystems, which cover a large part of the Earth's land surface and provide a host of services for mankind, including the storage of vast amounts of carbon, nutrients and water. Moreover, mountains are under considerable threat from climate and land use change, but the consequences of this for biogeochemical cycles is largely unknown. Climate change, for example, has been taking place in the mountains at almost double the rate of the northern hemisphere average. Also, there is considerable concern that land use change, especially the collapse of traditional farming, will have major impacts on how mountain ecosystems function. Given all this, coupled with new knowledge nutrient cycles of mountain ecosystems rely on tight coupling between soil microbial and plant communities, it is all the more surprising that the consequences of global change for soil microbial diversity and the functioning of mountain ecosystems remains largely unexplored. One of the most noticeable impacts of climate change in mountain areas is less snow, especially in spring. This reduction in snow is happening at an alarming rate, and there is concern that it will accelerate in future years, potentially reducing snow cover by around 50% at the end of this century. On top of climate change, the way that mountains are farmed is also changing, with traditional grazing practices being abandoned in many mountains areas of the world. A consequence of this, which is compounded by climate change, is the encroachment of dwarf shrubs into the alpine zone. New research shows that both of these changes, namely reductions in snow cover and the encroachment of dwarf shrubs, can have dramatic affects on the way that mountain ecosystems function. But the concern is that when they happen together, the impacts are magnified. This proposal tackles this issue head on, testing how shrub encroachment and reduced snow cover simultaneously affect the diversity and activity of soil microbial communities and the consequences for biogeochemical cycles in these understudied ecosystems. We will tackle the following so far unexplored questions. Do reductions in snow cover disrupt the growth and activity of soil microbial communities across the year, both in summer and winter, and does this alter the cycling of carbon and nutrients, and supply of nutrients to plants? Do these changes in soil microbial communities have legacy effects in the future, reducing their ability to deal with other affects of climate change, such as summer drought, which is also increasing in alpine areas? Finally, does the encroachment of shrubs dampen, or amplify, the effects of reduced snow cover on ecosystem processes by altering microclimate and promoting the growth of more resilient fungi in soil? By testing these questions, we will not only yield novel, transformative understanding of the structure, function, and dynamics of microbial communities, and how this links to biogeochemical cycling, but we will do so in situ in the context of ongoing and rapid environment change in an understudied and vulnerable natural ecosystem. Our studies will also provide policy makers and land managers with guidance on how best to manage mountain ecosystems to maintain their integrity in the face of rapid climate and land use change.

科学家越来越意识到，土壤中高度多样化的微生物群落在推动地球功能所依赖的生物地球化学周期中起着重要作用。同样清楚的是，这种地下微生物多样性对土地使用和气候变化高度敏感，但是对生物地球化学循环的后果知之甚少。这就是该建议的目的：了解土地使用和气候变化如何共同影响土壤微生物群落及其功能，并在实验中测试这对主要生物地球化学周期的后果。独特的是，我们在高山生态系统中这样做，覆盖了地球地面的很大一部分，并为人类提供了许多服务，包括存储大量的碳，营养和水。此外，山区受到气候和土地使用变化的巨大威胁，但是生物地球化学周期的后果在很大程度上是未知的。例如，气候变化在山区发生，几乎是北半球平均水平的两倍。同样，人们非常担心土地利用变化，尤其是传统农业的崩溃，将对山区生态系统的运作方式产生重大影响。鉴于所有这些，再加上新知识的山地生态系统营养周期依赖于土壤微生物和植物群落之间的紧密耦合，更令人惊讶的是，全球变化对土壤微生物多样性的后果以及山生态系统的功能仍然很大程度上。山区气候变化最明显的影响之一是降雪，尤其是在春季。下雪的减少以惊人的速度发生，并且令人担忧的是，它将在未来的几年中加速，在本世纪末可能将雪覆盖量减少约50％。除了气候变化之外，山区的耕种方式也在发生变化，传统的放牧做法在世界许多山区被放弃。由于气候变化而加剧了这种情况的结果是矮灌木对高山区的侵占。新的研究表明，这两种变化，即雪覆盖的减少和矮灌木的侵占，都会对山地生态系统功能的方式产生巨大影响。但是担心的是，当它们一起发生时，影响会放大。该提议解决了这一问题，测试了灌木侵占和减少的雪覆盖如何同时影响土壤微生物群落的多样性和活动，以及这些研究研究的生态系统中生物地球化学周期的后果。到目前为止，我们将解决以下问题。在夏季和冬季，雪覆盖的减少是否破坏了一年中土壤微生物群落的生长和活动，这是否会改变碳和养分的循环，并为植物供应营养素吗？土壤微生物群落中的这些变化是否在将来会产生遗产影响，从而降低了它们应对其他气候变化影响的能力，例如夏季干旱，阿尔卑斯山地区也在增加？最后，通过改变微气候并促进土壤中更弹性的真菌的生长，灌木的侵占降低或放大了雪覆盖对生态系统过程的影响吗？通过测试这些问题，我们不仅将对微生物群落的结构，功能和动力学产生新颖的，变革性的理解，以及这如何与生物地球化学循环联系在一起，而且我们将在不断被忽视且易受伤害的自然生态系统中持续和快速环境的情况下这样做。我们的研究还将为政策制定者和土地经理提供有关如何最好地管理山区生态系统以保持其诚信的指导，以面对快速的气候和土地利用变化。