Influence of changing active-layer thickness on PERmafrost PeatLand trace gas EXchanges and carbonbalance (PERPLEX)

几千年来，北方和亚北极泥炭地一直充当长期的碳（C）汇，因为每年的净初级生产量超过了二氧化碳（CO2）和甲烷（CH 4）的呼吸损失和横向C损失。加拿大北方泥炭地的很大一部分是永久冻土（永久冻土），在短暂的生长季节内，顶部会季节性地融化。由于持续的气候变化，这种渗透性和地球化学活性顶层的厚度增加，将对泥炭地的生态生理和地球化学过程产生严重后果，使更多的有机碳暴露于微生物分解和改变泥炭地水文。一个不断加深的活动层对永久冻土泥炭地的CO2和CH 4汇源强度的影响在很大程度上是未知的。拟议的研究项目将阐明泥炭地-大气相互作用如何受到增加活动层厚度的影响（当它通过泥炭剖面下降时，最大深度到霜冻表）。使用两套相同的仪器安装在两个站点在加拿大西部的不连续的永久冻土区，净交换的CO2，CH 4，水和能量将被测量超过永久冻土泥炭高原和附近的永久冻土无泥炭地与涡度相关技术。测量技术的最新前沿发展导致了新的强大的传感器和分析仪，旨在在偏远地区的恶劣条件下使用这种技术。辅助水文和光谱测量结合定期调查植被组成和结构，积雪，表面和霜冻表地形将有助于建立持续的永久冻土退化和泥炭地的CO2和CH 4汇源强度和碳平衡之间的联系。这方面的知识是迫切需要包括加拿大的巨大泥炭地C存储在该国的温室气体清单。

For millennia, boreal and subarctic peatlands have been acting as long-term carbon (C) sink because annually net primary production has been exceeding respiratory losses of carbon dioxide (CO2) and methane (CH4) and lateral C losses. A large portion of Canada's northern peatlands is underlain by permanently frozen ground (permafrost) that thaws seasonally at the top over a short growing season. Increases in the thickness of this permeable and biogeochemically active top layer due to ongoing climate change will have severe consequences for peatland ecophysiological and biogeochemical processes by exposing additional organic C to microbial decomposition and by altered peatland hydrology. The impact of a deepening active layer on the fate of permafrost peatlands' CO2 and CH4 sink-source strengths is largely unknown. The proposed research project will shed light on how peatland-atmosphere interactions are affected by increasing active-layer thickness (maximum depth to frost table as it descends through the peat profile). Using two identical sets of instrumentation installed at two sites in the discontinuous permafrost zone of western Canada, the net exchanges of CO2, CH4, water and energy will be measured over a permafrost peat plateau and a nearby permafrost-free peatland with the eddy covariance technique. Recent cutting-edge developments in measurement technology resulted in new robust sensors and analyzers designed for use of this technique under harsh conditions in remote locations. Ancillary hydrological and spectral measurements in combination with regular surveys of vegetation composition and structure, snow pack, and surface and frost table topography will aid in establishing the link between continued permafrost degradation and peatlands' CO2 and CH4 sink-source strengths and C balance. This knowledge is urgently needed for including Canada's vast peatland C store in the country's greenhouse gas inventory.