Microbial transitions in soil ecosystems under land use and climate change

土地利用和气候变化下土壤生态系统的微生物转变

• 批准号: 2594515
• 金额: --
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Studentship
• 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=studentship-2594515
• 关键词: Microbial; transitions; soil; ecosystems; under

Background: The soil microbiome, which encompasses a vast diversity of microbial life, plays a crucial role in regulating biogeochemical cycles and plant growth. Yet, our understanding of the factors that regulate the dynamics and functioning of the soil microbiome, and its capacity to resist and recover from perturbations, such as those associated with intensive land use and climate change, remains poor2. Added to this, remarkably little is also known about the vulnerability of the soil microbiome to transitions to alternative states, with potentially deleterious consequences for soil functioning and plant growth. Abrupt transitions to alternative states have been widely documented in other ecosystems in response to perturbations, including the human gut; but studies of transitions to alternative stable states, and the factors that trigger them, are lacking in soil microbial communities. This represents an important gap in knowledge given that soil microbial communities are increasingly challenged by multiple co-occurring perturbations associated with land use and climate change, and emerging evidence that: (a) discrete perturbations, such as severe drought, can trigger abrupt transitions to alternative microbial states with consequences for soil functioning; and (b) land use history can modify the response of soil microbial communities to drought, being more vulnerable to transitions to alternative states in soils previously under intensive agriculture. This studentship will tackle these gaps in knowledge and deliver an integrated understanding of the capacity of repeated drought to trigger transitions in the taxonomic and functional state of soil microbiomes and how thresholds for these transitions are modified by land use history. The studentship will focus on drought because the risk of drought is globally pervasive, with increases in drought frequency and intensity expected in most parts of the world, and on grassland soils, given our past BBSRC funded work showing that their microbial communities are highly sensitive to land use change4. Objectives: This studentship seeks to understand what makes soil microbiomes vulnerable to transitions to alternative states and determine consequences for soil functioning and plant growth. Specifically, the student will test the hypotheses that: (a) repeated drought triggers shifts in soil microbiomes to alternative states with negative consequences for soil nutrient cycling and plant performance; and (b) soil microbiomes shaped intensive land use are more vulnerable to transitions to alternative states than those with a history of sustainable management. By testing these hypotheses, this studentship will not advance understanding of the factors that make the soil microbiome vulnerable to transitions to alternative taxonomic and functional states, but also it will inform on how this vulnerability is modified by land use history, which is key to sustainable management. Methods and approach: The student will test these hypotheses using a series of highly integrated controlled-environment and field-based experiments and will use state-of-the-art genomic and biogeochemical technologies to interrogate taxonomic and functional attributes of the soil microbiome and quantify nutrient transfers through the soil system in response to perturbations. Specifically, this will include integrated use of amplicon and metagenomics sequencing, in combination with novel experimental manipulation of drought intensity and frequency, to test the vulnerability of microbial communities to transitions to alternative states and to identify critical thresholds for these transitions, and how they are modified by land use history. Experiments will be done using soils taken from well characterized, long-term grassland experiments with treatments reflecting different land use histories, as used in past BBSRC funded research.

背景：土壤微生物群包含了广泛的微生物生命，在调节生物地球化学循环和植物生长中起着至关重要的作用。然而，我们对调节土壤微生物群落动态和功能的因素，以及其抵抗和从扰动中恢复的能力（如与土地集约利用和气候变化有关的扰动）的理解仍然很差。除此之外，人们对土壤微生物群向替代状态过渡的脆弱性也知之甚少，这可能会对土壤功能和植物生长造成有害后果。在其他生态系统中，为了响应扰动，包括人类肠道，已经广泛记录了向替代状态的突然转变；但是，在土壤微生物群落中，缺乏对过渡到另一种稳定状态以及触发它们的因素的研究。鉴于土壤微生物群落正日益受到与土地利用和气候变化相关的多重共同发生的扰动的挑战，并且新出现的证据表明：(a)离散扰动，如严重干旱，可能引发向替代微生物状态的突然转变，从而对土壤功能产生影响，因此这代表了一个重要的知识缺口；(b)土地利用历史可以改变土壤微生物群落对干旱的反应，在以前的集约化农业土壤中更容易过渡到替代状态。该研究将解决这些知识空白，并提供对反复干旱触发土壤微生物组分类和功能状态转变的能力的综合理解，以及这些转变的阈值如何被土地利用历史修改。由于干旱的风险在全球范围内普遍存在，预计在世界大部分地区干旱的频率和强度都会增加，因此该奖学金将侧重于干旱，并且考虑到我们过去由BBSRC资助的研究表明，草原土壤的微生物群落对土地利用变化高度敏感，因此将侧重于干旱。目的：本研究旨在了解是什么使土壤微生物群易受过渡到其他状态的影响，并确定土壤功能和植物生长的后果。具体来说，学生将测试以下假设：(a)反复干旱会触发土壤微生物组向其他状态的转变，对土壤养分循环和植物性能产生负面影响；(b)与具有可持续管理历史的土壤微生物组相比，集约化土地利用的土壤微生物组更容易向替代状态过渡。通过测试这些假设，本研究将不会促进对土壤微生物群易受其他分类和功能状态影响的因素的理解，但它也将告知这种脆弱性如何被土地利用历史所改变，这是可持续管理的关键。方法和途径：学生将使用一系列高度集成的受控环境和基于现场的实验来测试这些假设，并将使用最先进的基因组和生物地球化学技术来询问土壤微生物组的分类和功能属性，并量化通过土壤系统响应扰动的养分转移。具体来说，这将包括综合使用扩增子和宏基因组测序，结合干旱强度和频率的新实验操作，来测试微生物群落向替代状态过渡的脆弱性，并确定这些过渡的关键阈值，以及它们如何被土地利用历史所改变。实验将使用从特征良好的长期草地试验中提取的土壤，并采用反映不同土地利用历史的处理方法，就像过去BBSRC资助的研究中使用的那样。