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

自20世纪50年代以来，北极大陆的年气温上升了2°C至3°C，而冬季气温上升了4°C。这些温暖的温度可能会导致陆地北极生态系统发生级联变化，例如：降水量增加导致水文循环改变，植物群落分布变化，表面特性改变，例如表面水分减少，以及永久冻土融化增加。永久冻土含有全球土壤碳库的大约一半，因此永久冻土融化导致的碳损失率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营养，增加植物生产力和碳储存，对未来变暖产生负反馈。为了预测北极生态系统对气候变化的未来响应，我们需要在一系列空间和时间尺度上了解北极生态系统中的关键温室气体（GHG）循环过程。在梅尔维尔岛的邦蒂角北极流域观测站（CBAWO），我将探讨植被分布和气候变化之间的相互作用如何改变北极高纬度生态系统的净温室气体平衡。具体来说，我将研究1）苔藓对净温室气体通量的贡献，以及苔藓和土壤水分之间的相互作用2）极地半沙漠社区对北极高纬度地区净甲烷平衡的贡献，以及3）温度，水分，活动层深度，太阳辐射和基于卫星的植被特性估计如何相互作用，以控制整个北极景观的净温室气体平衡。我将使用现场和实验室测量的组合来探索这些问题，包括最先进的自动化室来测量高时间频率下的二氧化碳通量，以及土壤分子技术来表征负责甲烷生产和消耗的细菌。我的研究结果，沿着我的同事在这个地点工作，将被整合到一个国家的最先进的流域尺度地球化学模型，将提供洞察该地区如何可能在未来变化，以应对气候变化。 我的研究将通过为4名硕士，1名博士和5名本科生提供跨学科培训来帮助培养下一代北极科学家-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见解，并有助于开发改进的模型，预测北极生态系统对未来气候的贡献。

Since the 1950's, annual air temperatures over Arctic landmasses have risen between 2°C and 3°C, while winter temperatures have increased as much as 4°C. 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.******