Biological and landscape controls on the net greenhouse gas balance of High Arctic ecosystems

自20世纪50年代的S以来，北极大陆的年气温上升了2摄氏度到3摄氏度，而冬季的气温上升了4摄氏度。这些变暖的温度可能会引起北极陆地生态系统的级联变化，例如：由于降水增加而改变了水文循环，改变了植物群落的分布，改变了地表属性，如地表反照率降低，以及增加了永久冻土融化。冻土含有全球土壤碳库的大约一半，因此，由于冻土融化而导致的碳流失速度增加，可能会加速未来的气候变化。与此同时，永久冻土融化可以释放植物养分，提高植物生产力和碳储量，对未来变暖产生负面反馈。为了预测北极生态系统未来对气候变化的响应，我们需要在一系列时空尺度上了解北极高地生态系统中关键的温室气体(GHG)循环过程。我将在梅尔维尔岛的邦蒂角北极分水岭观测站(CBAWO)探索植被分布和气候变化之间的相互作用如何改变北极高地生态系统的温室气体净平衡。具体地说，我将研究1)苔藓对温室气体净通量的贡献，以及苔藓与土壤水分之间的相互作用；2)极地半荒漠群落对北极高海拔地区甲烷净平衡的贡献；3)温度、湿度、活动层深度、太阳辐射和基于卫星的植被属性估计如何相互作用来控制整个北极景观的温室气体净平衡。我将使用现场和实验室测量相结合的方法来探索这些问题，包括以高时间频率测量二氧化碳通量的最先进的自动化室，以及表征负责甲烷生产和消费的细菌的土壤分子技术。我和我在这个地点工作的同事的结果将被整合到最先进的分水岭尺度生物地球化学模型中，该模型将为该地区未来可能如何改变以应对气候变化提供见解。我的研究将帮助培训下一代北极科学家，为4名硕士、1名博士和5名本科生提供跨学科培训-培训还为许多环境职位提供关键技能。我的研究结果将为陆地生态系统如何应对气候变化提供洞察力，并有助于开发预测北极生态系统对未来气候的贡献的改进模型。

Since the 1950's, annual air temperatures over Arctic landmasses have risen between 2C and 3C, while winter temperatures have increased as much as 4C. These warmer temperatures could induce cascading changes to terrestrial Arctic ecosystems, such as: altered hydrological cycles from increasing precipitation, shifting distribution of plant communities, altered surface properties such as decreased surface albedo, and increased permafrost thawing. Permafrost soils contain approximately half of the global soil carbon reservoir, so an increased rate of carbon loss due to permafrost thawing could accelerate future climate change. At the same time, permafrost thawing could liberate plant nutrients, increasing plant productivity and carbon storage, creating a negative feedback on future warming. To predict the future response of arctic ecosystems to changes in climate, we need to understand key greenhouse gas (GHG) cycling processes in high Arctic ecosystems at a range of spatial and temporal scales.*******At the Cape Bounty Arctic Watershed Observatory (CBAWO) on Melville Island, I will explore how the interactions between vegetation distribution and climate change alters the net GHG balance of high Arctic ecosystems. Specifically, I will examine 1) the contribution of mosses to net GHG fluxes, and the interaction between mosses and soil moisture 2) the contribution of polar semi-desert communities to the net methane balance of the high Arctic, and 3) how temperature, moisture, active layer depth, solar radiation, and satellite-based estimates of vegetation properties interact to control the net GHG balance across Arctic landscapes. I will explore these questions using a combination of field and laboratory measurements, including state-of-the-art automated chambers to measure carbon dioxide fluxes at high temporal frequencies and soil molecular techniques to characterize the bacteria responsible for methane production and consumption. My results, along with those of my colleagues working at this site, will be integrated into a state-of-the art watershed scale biogeochemistry model that will provide insights into how the region might change in the future in response to changes in climate. My research will help train the next generation of Arctic scientists by providing interdisciplinary training to 4 MSc, 1 PhD, and 5 undergraduate students - the training also provides key skills for many environmental positions. Results from my research will provide insights into how terrestrial ecosystems will respond to climate change, and help develop improved models that predict the contribution of Arctic ecosystems to future climate.******