Understanding the contribution of pools to boreal peatland carbon exchange

泥炭地在调节气候系统方面发挥着重要作用，因为它们是二氧化碳（CO2）的长期净汇。然而，这些生态系统也是大气中甲烷（CH4）的净来源。虽然研究表明，当考虑到CO2和CH4时，泥炭地仍然是碳(C)的净汇，但短期交换率及其方向是单个泥炭地上空间可变微形态所经历的环境条件的函数。迄今为止，在生态系统尺度上的研究绝大多数排除了池对净交换的贡献。由于库是CO2和CH4的净源，具有库的泥炭地生态系统的净汇可能比以前认为的要弱。为了更好地定义池在泥炭地碳交换中的作用，在研究的第一阶段，将在代表深度和大小分布的多个仪器池上探索对CO2和CH4交换的控制。沸腾（冒泡）可贡献湖泊和海狸池塘总CH4通量的50%以上，但通常不进行常规测量。沸腾对整个池气交换的贡献将被量化，并确定对气泡产生的控制。这项研究将调查在湖泊中发现的关系是否可以扩展到北方泥炭地固有的许多浅池和小池。在相同的池中，将在无冰期间进行近乎连续的溶解二氧化碳浓度测量，以量化扩散通量。剖面测量将提供关于无冰季节池内可能的分层和翻转的信息，而冬季数据将提供浓度，以计算在寒冷季节结束时冰融化期间释放的气体。将评估沉降速率和水柱生产力。利用底部沉积物/有机层的孵育，将根据温度和氧含量来确定CO2和CH4的产生速率。在研究的第二阶段，对北方泥炭地进行为期多年的调查，将使用双通量塔来确定一个有池和一个没有池的地区的连续生态系统尺度的CO2和CH4通量，以确定池的贡献。在第一阶段建立的关系将结合遥感分类和塔通量足迹模型用于确定通量的比例。这项研究计划将提供信息，以减少泥炭地净碳交换目前估计的不确定性，并将为这些敏感生态系统的未来气候模拟建模人员提供有用的关系。该项目将培养博士、硕士和本科生。

Peatlands play an important role in regulating the climate system as they are a net long-term sink for carbon dioxide (CO2). However, these ecosystems are also a net source of methane (CH4) to the atmosphere. While studies have shown that peatlands remain net sinks of carbon (C) when both CO2 and CH4 are accounted for, the short-term rates of exchange and their direction are functions of the environmental conditions experienced by the spatially variable microforms on an individual peatland. To date, studies at the ecosystem scale have overwhelmingly excluded the contribution of pools to the net exchange. Since pools are net sources of both CO2 and CH4, a peatland ecosystem with pools may be a weaker net sink than previously considered. To begin to better define the role that pools play in peatland carbon exchange, in the first phase of the research, the controls on exchanges of CO2 and CH4 will be explored on multiple instrumented pools representing a distribution of depth and size. Ebullition (bubbling) can contribute greater than 50% of the total CH4 flux from lakes and beaver ponds and yet is not often measured routinely. The contribution of ebullition to the overall pool gas exchange will be quantified and the controls on the production of bubbles determined. This study will investigate if relationships found in lakes can be extended to the numerous shallow and small pools inherent in boreal peatlands. In the same pools, near continuous dissolved CO2 concentration measurements will be made during the ice-free period to quantify diffusive flux. Profile measurements will provide information on possible stratification and turn-over within the pools during the ice free season while winter data will provide concentrations to calculate gas release during the ice melt at the end of the cold season. Sedimentation rates and water column productivity will be evaluated. Rates of CO2 and CH4 production will be determined in relation to temperature and oxygen content using incubations of bottom sediments/organic layer. In the second phase of the research, a multi-year investigation in a boreal peatland will use dual flux towers to determine continuous ecosystem scale fluxes of CO2 and CH4 from an area with pools and one without pools to identify the contribution from the pools. Relationships developed in the first phase will be used to scale fluxes in combination with remote sensing classification and tower flux footprint models. This research program will provide information to reduce uncertainty around current estimates of peatland net C exchange and will produce relationships useful to modellers for future climate simulations of these sensitive ecosystems. The program will train PhD, MSc and undergraduate students.