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.

科学家们越来越意识到，土壤中高度多样化的微生物群落在驱动地球功能所依赖的生物地球化学循环方面发挥着重要作用。人们越来越清楚，这种地下微生物多样性对土地利用和气候变化高度敏感，但人们对这种现象对生物地球化学循环的影响却知之甚少。这就是该提案的目的：了解土地利用和气候变化如何共同影响土壤微生物群落及其功能，并通过实验测试其对主要生物地球化学循环的影响。独一无二的是，我们在高山生态系统中做到了这一点，该生态系统覆盖了地球陆地表面的很大一部分，并为人类提供了大量的服务，包括储存大量的碳、养分和水。此外，山区还受到气候和土地利用变化的巨大威胁，但这对生物地球化学循环的影响在很大程度上尚不清楚。例如，山区发生的气候变化速度几乎是北半球平均速度的两倍。此外，人们非常担心土地利用的变化，特别是传统农业的崩溃，将对山区生态系统的功能产生重大影响。鉴于这一切，再加上山区生态系统养分循环依赖于土壤微生物和植物群落之间的紧密耦合的新知识，更令人惊讶的是，全球变化对土壤微生物多样性和山区生态系统功能的影响在很大程度上仍未得到探索。气候变化对山区最显着的影响之一是降雪减少，尤其是在春季。降雪量正在以惊人的速度发生，人们担心未来几年降雪量还会加速，到本世纪末积雪量可能会减少约 50%。除了气候变化之外，山区的耕作方式也在发生变化，世界许多山区放弃了传统的放牧方式。其后果是矮灌木侵入高山地区，再加上气候变化，情况更加复杂。新的研究表明，这两种变化，即积雪的减少和矮灌木的侵占，都会对山区生态系统的运作方式产生巨大影响。但令人担忧的是，当它们同时发生时，影响会被放大。该提案正面解决了这个问题，测试灌木侵蚀和积雪减少如何同时影响土壤微生物群落的多样性和活性，以及​​对这些未充分研究的生态系统中生物地球化学循环的影响。我们将解决以下迄今为止尚未探索的问题。积雪的减少是否会扰乱全年土壤微生物群落的生长和活动，无论是夏季还是冬季，这是否会改变碳和养分的循环以及植物养分的供应？土壤微生物群落的这些变化是否会在未来产生遗留影响，降低它们应对气候变化其他影响的能力，例如在高山地区也日益加剧的夏季干旱？最后，灌木的侵占是否会通过改变小气候并促进土壤中更有弹性的真菌的生长来抑制或放大积雪减少对生态系统过程的影响？通过测试这些问题，我们不仅将对微生物群落的结构、功能和动态及其与生物地球化学循环的联系产生新颖的、变革性的理解，而且我们将在一个未经充分研究和脆弱的自然生态系统中，在持续和快速的环境变化的背景下进行实地研究。我们的研究还将为政策制定者和土地管理者提供指导，帮助他们了解如何最好地管理山区生态系统，以在气候和土地利用快速变化的情况下保持其完整性。