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（CH 4）的净来源。虽然研究表明，当CO2和CH 4都被考虑在内时，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形态所经历的环境条件的函数。迄今为止，在生态系统规模的研究绝大多数排除了池的净交换的贡献。由于池是CO2和CH 4的净源，因此具有池的泥炭地生态系统可能是比先前考虑的更弱的净汇。为了开始更好地定义池在泥炭地碳交换中发挥的作用，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CH 4交换的控制。沸腾（冒泡）可以贡献50%以上的总CH 4通量从湖泊和海狸池塘，但并不经常定期测量。将量化沸腾对整个池气体交换的贡献，并确定对气泡产生的控制。这项研究将调查，如果在湖泊中发现的关系可以扩展到许多浅和小池固有的北方泥炭地。在相同的水池中，将在无冰期进行近连续的溶解CO2浓度测量，以量化扩散通量。剖面测量将提供有关无冰季节期间池内可能的分层和翻转的信息，而冬季数据将提供浓度，以计算寒冷季节结束时冰融化期间的气体释放。将对沉积速率和水柱生产力进行评估。CO2和CH 4的产生率将通过对底部沉积物/有机层的培养，根据温度和氧含量来确定。在研究的第二阶段，在北方泥炭地的多年调查将使用双通量塔，以确定连续的生态系统规模的CO2和CH 4通量从一个地区的池和一个没有池，以确定从池的贡献。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确定通量的比例。这项研究计划将提供信息，以减少目前的泥炭地净碳交换估计的不确定性，并将产生有用的建模这些敏感的生态系统的未来气候模拟的关系。该计划将培养博士，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.