The biogeochemistry of peatlands: linking nutrients, stoichiometry and greenhouse gases

泥炭地的生物地球化学：将养分、化学计量和温室气体联系起来

• 批准号: RGPIN-2019-04657
• 负责人: Moore, Tim
• 金额: $ 5.46万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=715093
• 关键词: biogeochemistry; peatlands; linking; nutrients; stoichiometry

The overall objective of my research program is to establish the relationships between soils and the environment, under natural and disturbed conditions. I have focused much of my attention on peatlands which cover over 1 million km2 in Canada and play an important role in the global carbon (C) cycle with feedbacks to climate change. This involves field and laboratory studies of key processes in peatlands, with a strong integration with the development and application of models. Many peatlands have developed under conditions of limited nutrient availability but there have been increases in the atmospheric deposition of N and P, enhancing nutrient availability. Part of my research here examines the effect of increased N and P availability on the functioning of peatlands, including changes in vegetation, hydrology, greenhouse gas exchange and C sequestration. Critical to this are the relationships between C, N, P and other nutrients, in vegetation and peat, as part of ecological stoichiometry. In this proposal, I outline three objectives to contribute to answering these issues. The effect of nutrient addition on the functioning of an ombrotrophic bog I plan to continue a long-term study of increased N addition, simulating increased atmospheric deposition, to the Mer Bleue peatland. As the longest running peatland nutrient addition experiment in North America, we have observed changes in plant and microbial communities, resulting in a weaker CO2 sink and increases in CH4 emission. Many of the changes did not appear for several years, highlighting the importance of long-term experiments. The bog will continue to be fertilized to 2024 and measurements will be made of CO2 exchange and CH4 and N2O emissions as well as using 13CO2 and 14CO2 to determine the proportion of root and peat respiration (one PhD student). The ecological stoichiometry of peatlands My work has identified differences in C:N:P nutrient maintenance among plant species, which may explain their relative ability to withstand nutrient addition and in a Redfield Ratio' in Canadian forests and peatlands. I will test whether these relationships are more broadly applicable, using a large data base of plant and peat nutrient content in New Zealand and deep peat cores, formed under different conditions than Canadian peatlands (one MSc student). CH4 emission by trees along dry-wet gradients Although much work has been done on exchange of CH4 between soils and the atmosphere, there is now evidence that trees can be significant contributors to CH4 emission. I propose to measure the role of tree stem emission of CH4 along two transects representing a sequence from well drained to peat soils at a bog and a swamp, with common tree species along the gradient. Fluxes of CH4 from tree stem and soil surface will be related to environmental variables and spatially extrapolated to test whether we need to take into account the role of trees (one PhD student).

我的研究计划的总体目标是在自然和干扰条件下建立土壤与环境之间的关系。我主要关注加拿大面积超过 100 万平方公里的泥炭地，它们在全球碳 (C) 循环中发挥着重要作用，并对气候变化产生反馈。这涉及对泥炭地关键过程的现场和实验室研究，并与模型的开发和应用紧密结合。许多泥炭地是在养分利用率有限的条件下发展起来的，但大气中氮和磷的沉积量有所增加，从而提高了养分利用率。我的部分研究研究了氮和磷可用性的增加对泥炭地功能的影响，包括植被、水文、温室气体交换和碳封存的变化。对此至关重要的是植被和泥炭中碳、氮、磷和其他养分之间的关​​系，作为生态化学计量的一部分。在本提案中，我概述了有助于回答这些问题的三个目标。 添加养分对反营养沼泽功能的影响 我计划继续对 Mer Bleue 泥炭地增加氮添加量进行长期研究，模拟增加的大气沉降。作为北美运行时间最长的泥炭地养分添加实验，我们观察到植物和微生物群落的变化，导致二氧化碳汇减弱和甲烷排放增加。许多变化几年后才出现，凸显了长期实验的重要性。该沼泽将继续施肥至 2024 年，测量二氧化碳交换、甲烷和氧化亚氮排放，并使用 13CO2 和 14CO2 确定根系和泥炭呼吸的比例（一名博士生）。 泥炭地的生态化学计量 我的工作已经确定了植物物种之间 C:N:P 养分维持的差异，这可以解释它们承受养分添加的相对能力以及加拿大森林和泥炭地的“雷德菲尔德比率”。我将使用新西兰植物和泥炭养分含量的大型数据库以及在与加拿大泥炭地（一名硕士生）不同条件下形成的深层泥炭核心来测试这些关系是否更广泛适用。 树木沿着干湿梯度排放甲烷 尽管在土壤和大气之间的甲烷交换方面已经做了很多工作，但现在有证据表明树木可能是甲烷排放的重要贡献者。我建议沿着两条横断面测量树木茎排放的 CH4 的作用，这两条横断面代表从沼泽和沼泽的排水良好到泥炭土的序列，以及沿梯度的常见树种。来自树干和土壤表面的 CH4 通量将与环境变量相关，并进行空间外推，以测试我们是否需要考虑树木的作用（一名博士生）。