Testing the role of nutrient input thresholds in governing microbial-mediated carbon sequestration for temperate peatlands

测试养分输入阈值在控制温带泥炭地微生物介导的碳封存中的作用

• 批准号: NE/X010635/1
• 负责人: Daniel Schillereff
• 金额: $ 7.75万
• 依托单位: King's College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX010635%2F1
• 关键词: Testing; role; nutrient; input; thresholds

Our research will shed new light on the ways nutrient input (primarily phosphorus and nitrogen) controls how efficiently temperate, ombrotrophic peatlands store carbon. Our recent synthesis of the few peatlands with well-dated and parallel core profiles of phosphorus, nitrogen and carbon underpinned a new conceptual model of long-term peatland carbon cycling (Schillereff et al. 2021). Ombrotrophic (rain-fed) peatlands derive nutrients primarily via atmospheric deposition, so nutrient input maintains the tight balance between primary productivity and the decomposition of organic matter by microbes. We therefore hypothesised that nutrient input thresholds govern how efficiently and how much carbon becomes sequestered in peatlands over decades, centuries and millennia. Our study highlighted two research gaps preventing our conceptual model being tested: i) measurements of the activity and diversity of microbial communities are strikingly absent from palaeoenvironmental peat research and (ii) surprisingly few peatlands have parallel measurements for all nodes of the peatland carbon cycle: climate, vegetation, nutrients, microbes and carbon. Our proposal will implement an innovative research design to test our conceptual model. Working at four carefully selected temperate, ombrotrophic peatlands in the UK and Sweden where we have established research portfolios, we will integrate some of the first DNA characterisation of down-core microbial dynamics with high-resolution reconstructions of each other node of the peatland carbon cycle spanning the last 2000 years. This will enable our hypothesis that nutrient input thresholds govern long-term peatland carbon sequestration to be empirically tested for the first time. To deliver these objectives, we will: (i) collect new peat cores from four sites and perform DNA characterisation of their microbial communities at regular depths; (ii) complete high-resolution measurements of each other node at King's College London, University of Liverpool, Stockholm University and the NERC Environmental Omics Facility; (iii) apply statistical modelling to quantify the role of and interplay between each driver of peatland carbon cycling. Site selection (Holcroft and May Moss, England; Store and Draftinge Mosse, Sweden) is guided by our extensive baseline data and strategically captures gradients of nutrient deposition, altitude and land-use. By combining in an innovate way cutting-edge metagenomic characterisation of microbial activity with conventional measurements of other drivers, we will produce a more complete picture of peatland carbon cycling. Globally, peatlands are a significant carbon store, containing one-third of the soil carbon pool. Peatlands sequester carbon efficiently because their waterlogged, nutrient impoverished conditions slow the decomposition of organic matter relative to the productivity of surface vegetation. This also means small changes in nutrient input can trigger significant shifts in carbon storage. Human activities have amplified P and N deposition in recent decades, which has changed the nutrient limitation status and carbon cycling in other terrestrial ecosystems. The implications for the future peatland carbon sink remain unclear. As well as establishing a testbed for our conceptual model, the findings should stimulate deeper integration between the peatland ecology, soil microbiology and global carbon cycling research communities. We intend our findings to underpin ambitious future research aimed at better understanding the resilience of temperate peatlands to both 21st-century climate and biogeochemical change. This will involve parameterising new numerical models of peatland development that encapsulate nodes for climate, vegetation, nutrients, microbes and carbon. Subsequent integration into Earth System models should produce more representative trajectories for peatland carbon through the 21st-century. Schillereff et al. 2021, Comms. Earth & Env. 2:1-10

我们的研究将揭示养分输入（主要是磷和氮）控制温带、营养型泥炭地储存碳的有效方式。我们最近合成了几个泥炭地，这些泥炭地具有年代久远且平行的磷、氮和碳核心剖面，为泥炭地长期碳循环的新概念模型奠定了基础（Schillereff et al. 2021）。营养型（雨养）泥炭地主要通过大气沉降获取养分，因此养分输入维持了初级生产力和微生物分解有机物之间的紧密平衡。因此，我们假设养分输入阈值决定了泥炭地在几十年、几个世纪和几千年里的碳封存效率和数量。我们的研究强调了阻止我们的概念模型得到验证的两个研究空白：1)在古环境泥炭研究中明显缺乏对微生物群落活动和多样性的测量；2)令人惊讶的是，很少有泥炭地对泥炭地碳循环的所有节点（气候、植被、营养物质、微生物和碳）进行平行测量。我们的提案将实施一个创新的研究设计来测试我们的概念模型。我们在英国和瑞典的四个精心挑选的温带、全养泥炭地工作，在那里我们建立了研究组合，我们将把一些下核微生物动力学的第一个DNA特征与过去2000年泥炭地碳循环的每个节点的高分辨率重建结合起来。这将使我们关于营养输入阈值控制泥炭地长期碳固存的假设首次得到实证检验。为了实现这些目标，我们将：(i)从四个地点收集新的泥炭岩心，并在常规深度对其微生物群落进行DNA表征；（ii）在伦敦国王学院、利物浦大学、斯德哥尔摩大学和NERC环境组学设施完成彼此节点的高分辨率测量；（iii）应用统计模型量化泥炭地碳循环各驱动因素的作用和相互作用。选址（Holcroft and May Moss，英格兰；Store and Draftinge Mosse，瑞典）以我们广泛的基线数据为指导，并策略性地捕捉养分沉积、海拔和土地利用的梯度。通过以一种创新的方式将微生物活动的尖端宏基因组特征与其他驱动因素的传统测量相结合，我们将产生更完整的泥炭地碳循环图像。在全球范围内，泥炭地是一个重要的碳库，含有三分之一的土壤碳库。泥炭地之所以能有效地吸收碳，是因为它们的水淹和营养贫乏的条件，相对于地表植被的生产力，减缓了有机质的分解。这也意味着养分输入的微小变化可以引发碳储存的重大变化。近几十年来，人类活动放大了P和N沉积，改变了其他陆地生态系统的营养限制状况和碳循环。这对未来泥炭地碳汇的影响尚不清楚。这一发现不仅为我们的概念模型建立了一个测试平台，还将促进泥炭地生态学、土壤微生物学和全球碳循环研究界之间更深层次的整合。我们希望我们的发现能够支持未来雄心勃勃的研究，旨在更好地了解温带泥炭地对21世纪气候和生物地球化学变化的适应能力。这将涉及泥炭地发展的新数值模型的参数化，这些模型包含了气候、植被、营养物质、微生物和碳的节点。随后与地球系统模型的整合将产生21世纪泥炭地碳的更具代表性的轨迹。Schillereff et al. 2021，通讯。地球与环境，2:1-10