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)的净长期汇。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，当同时考虑二氧化碳和甲烷时，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的微型体所经历的环境条件的函数。到目前为止，生态系统规模的研究压倒性地排除了池子对净交换的贡献。由于池塘是二氧化碳和甲烷的净源，有池塘的泥炭地生态系统可能比之前认为的更弱的净汇。为了更好地确定池在泥炭地碳交换中所起的作用，在研究的第一阶段，将在代表深度和大小分布的多个仪表池上探索对二氧化碳和甲烷交换的控制。沸腾(冒泡)可以贡献来自湖泊和河狸池塘的CH4总通量的50%以上，但通常不是常规测量。将量化沸腾对整个池气交换的贡献，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部泥炭地固有的无数浅水池和小水池。在相同的水池中，将在无冰期间进行几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期间水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的气体释放。将对沉淀率和水柱生产力进行评估。二氧化碳和甲烷的产生率将通过底部沉积物/有机层的孵化来确定与温度和氧气含量的关系。在研究的第二阶段，一项在北部泥炭地进行的多年调查将使用双通量塔来确定有池子和没有池子的区域的持续生态系统尺度的二氧化碳和CH4通量，以确定池子的贡献。在第一阶段建立的关系将用于结合遥感分类和塔通量足迹模型来衡量通量。这项研究计划将提供信息，以减少围绕泥炭地净碳交换的当前估计的不确定性，并将为建模人员提供有用的关系，用于未来对这些敏感生态系统的气候模拟。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.