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

我的研究计划的总体目标是建立土壤和环境之间的关系，在自然和干扰条件下。我把大部分注意力集中在加拿大100多万平方公里的泥炭地上，这些泥炭地在全球碳（C）循环中发挥着重要作用，并对气候变化产生反馈。这涉及泥炭地关键过程的实地和实验室研究，与模型的开发和应用紧密结合。许多泥炭地是在养分有限的条件下发展起来的，但大气中氮和磷的沉积增加了，从而提高了养分的可用性。我的研究的一部分在这里检查的影响，增加氮和磷的供应对泥炭地的功能，包括植被，水文，温室气体交换和碳封存的变化。这方面的关键是C，N，P和其他营养素之间的关系，在植被和泥炭，作为生态化学计量的一部分。在本提案中，我概述了三个目标，以帮助回答这些问题。营养素添加对湿地沼泽功能的影响我计划继续增加氮的长期研究，模拟增加大气沉积，到Mer Bleue泥炭地。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CO2汇减弱和CH4排放增加。许多变化在几年后才出现，这凸显了长期实验的重要性。沼泽将继续施肥到2024年，并将测量CO2交换和CH4和N2O排放量，以及使用13CO2和14CO2来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不同植物物种之间的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"。我将测试这些关系是否更广泛地适用，在新西兰和深泥炭核心，在不同的条件下形成的植物和泥炭养分含量的大型数据库比加拿大泥炭地（一个硕士生）。树木沿着干湿梯度的CH 4排放尽管在土壤和大气之间的CH 4交换方面已经做了很多工作，但现在有证据表明树木可以成为CH 4排放的重要贡献者。我建议测量的作用，树干排放的CH 4沿着两个横断面代表一个序列，从排水良好的泥炭土在沼泽和沼泽，与常见的树种沿着梯度。来自树干和土壤表面的CH4通量将与环境变量相关，并在空间上进行外推，以测试我们是否需要考虑树木的作用（一名博士生）。

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).