Cross-season legacy effects of climate extremes on alpine soil microbial communities: resilience, regimes shifts and biogeochemical cycles

极端气候对高山土壤微生物群落的跨季节遗留影响：恢复力、政权转变和生物地球化学循环

• 批准号: NE/T007222/1
• 负责人: Richard Bardgett
• 金额: $ 73.14万
• 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: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FT007222%2F1
• 关键词: Cross; season; legacy; effects; climate

Soil contains a vast diversity of microbial that is an important driver of the biogeochemical cycles on which the functioning of earth depends. These soil microbial communities are vulnerable to environmental changes caused by human actions, including land use and climate change. However, our understanding of how shifts in microbial communities resulting from environmental change influences the global biogeochemical cycles they support is poor. This lack of knowledge is exacerbated by most studies investigating only one facet of environmental change: in the real world, human actions are causing multiple and simultaneous changes to the environment, including climate extremes that are expected to become more intense and frequent with on-going climate change. This is what this proposal is about: understanding how seasonally distinct climate extremes combine to impact soil microbial communities and the crucial biogeochemical cycles that they support. We do this in high mountain ecosystems, which cover a large part of the Earth's land surface, support high levels of biodiversity, and provide a host of services for humankind, including the storage of vast amounts of carbon, nutrients and water. Moreover, mountains are under considerable threat from climate and land use change. Climate change, for example, has been taking place in the mountains at almost double the rate of the northern hemisphere average, leading to less snow in winter, which reduces insulation of the ground and increases freeze-thaw activity, and less rain in summer, which causes prolonged drought. Yet, how these two factors combine to affect soil microbial communities, and is poorly understood. Furthermore, farming in mountains is also changing, with traditional grazing practices being abandoned in many mountains areas, which is causing encroachment of dwarf shrubs into the alpine zone. Put simply, mountain areas are at the front line of global change, but the consequences for microbial communities and the biogeochemical processes that they perform remain poorly understood. Whilst soil microbes can often resist or recover from individual environmental perturbations, they may not be able to withstand multiple shocks happening in quick succession. Reduced snow in winter, followed immediately by severe summer droughts may tip soil microbial communities, and the nutrient cycling functions they perform, into alternative states. When such a shift occurs, the structure of the soil microbial community, and its capacity to cycle key nutrients will be permanently altered. Alarmingly, we do not know under which conditions such regimes shifts in microbial communities will occur, or whether changes in land-use practices will affect the outcome. Nor do we know what it will mean for global biogeochemical cycles, which is surprising considering the vast amounts of carbon stored in alpine soils, and the importance of nitrogen cycling for agricultural activities. This proposal tackles this issue head on, testing how reduced snow cover and summer drought affects the diversity and function of soil microbial communities and the consequences for biogeochemical cycles in these understudied ecosystems. We will tackle the following so far unexplored questions. Does one type of climate extreme impair the ability of soil microbial communities, and the biogeochemical cycles they support, to resist and recover from further perturbations? At what frequencies and severities of summer drought do microbial communities tip into an alternative state? Does encroachment of shrubs dampen the combined effect of seasonally distinct climate extremes on soil microbial communities? By testing these questions, we will gain novel, transformative understanding of the structure, function, and dynamics of microbial communities, and how this links to biogeochemical cycling, and we will do so in situ in the context of ongoing and rapid environment change in an understudied and vulnerable natural ecosystem.

土壤包含大量的微生物，这是地球功能所依赖的生物地球化学周期的重要驱动力。这些土壤微生物群落容易受到人类行动所引起的环境变化的影响，包括土地利用和气候变化。但是，我们对环境变化导致微生物群落的转变的理解会影响他们支持的全球生物地球化学周期。大多数研究仅研究环境变化的一个方面，这种知识的缺乏加剧了：在现实世界中，人类的行动正在引起多种和同时改变环境的变化，包括极端的气候，预计会变得更加激烈和频繁。气候变化。这就是该提议的目的：了解季节性不同的气候极端是如何影响土壤微生物群落和它们支持的关键生物地球化学周期的结合。我们在高山生态系统中这样做，覆盖地球地面的很大一部分，支持高水平的生物多样性，并为人类提供大量服务，包括存储大量的碳，养分和水。此外，山区受到气候和土地利用变化的巨大威胁。例如，气候变化在山区发生了几乎是北半球平均水平的两倍，导致冬季降雪较少，从而减少了地面的隔热效果，增加了冻融活动，夏季降雨较小，夏季的降雨较小，这会造成长时间的干旱。然而，这两个因素如何结合起来影响土壤微生物群落，并且对土壤微生物群落的了解很少。此外，山区的耕种也在发生变化，传统的放牧做法在许多山区被遗弃，这导致矮灌木侵占高山区。简而言之，山区处于全球变化的前线，但是对微生物社区和他们所执行的生物地球化学过程的后果仍然很众所周知。尽管土壤微生物通常可以抵抗或从单个环境扰动中恢复，但它们可能无法快速连续地承受多次冲击。冬季的降雪减少，然后立即发生严重的夏季干旱，可能会使土壤微生物群落以及它们执行的营养循环功能变成替代状态。当发生这种转变时，土壤微生物群落的结构以及其循环关键营养素的能力将被永久改变。令人震惊的是，我们不知道在哪些条件下将发生微生物社区的这种状况转变，或者土地使用实践的变化是否会影响结果。我们也不知道这对全球生物地球化学循环意味着什么，考虑到高山土壤中存储的大量碳以及氮循环对农业活动的重要性，这令人惊讶。该提案解决了这一问题，测试了雪覆盖和夏季干旱的减少如何影响土壤微生物群落的多样性和功能，以及这些正在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。一种类型的气候是否会损害土壤微生物群落的能力以及它们支持的生物地球化学周期，以抵抗和从进一步的扰动中恢复？在夏季干旱的频率和严重性下，微生物群落会变成另一种状态？灌木的侵占是否会抑制季节性不同的极端气候对土壤微生物群落的综合作用？通过测试这些问题，我们将获得对微生物群落的结构，功能和动态的新颖，变革性的理解，以及这如何与生物地球化学循环联系起来，在持续和快速的环境中，我们将在持续和快速的环境中发生这种情况。研究且脆弱的自然生态系统。