Sources, pathways and fate of water in montane subarctic ecosystems

永冻土区极易受到全球气候变化的影响，这已成为一种逐渐形成的共识和日益增长的社会关切。例如，北极碳弹理论认为，通过从融化的永久冻土中大量释放有机碳，大气中的二氧化碳浓度将迅速上升，带来灾难性的后果。永久冻土的融化也为液态水的流动和化学物质的运输提供了新的途径，改变了河流的流量和水质。极地放大的变暖导致随着水文循环的加速，降雨变得更加主导，并为广泛的植被转移提供了合适的条件。这些变化引起了各级政府的极大关注，危及民用基础设施，并威胁到第一民族和因纽特人，他们的传统生计在变暖的世界中受到挑战。通过两个综合项目，这项研究将提高我们对北部集水区如何对综合环境变化作出水文反应的理解。第一个项目将利用育空地区9个流域的样带，这些流域有不同数量的永久冻土。同位素示踪剂和水文数据将用于评估冻土状况对水的储存、混合和释放的影响。新技术将用于评估水的“人口统计”，并评估冻土如何影响水在集水区停留的时间、如何储存和释放。这些信息将与高频水化学数据相结合，以探索这些流域中产生水流的地方以及冻土状况如何影响汇水径流。第二个项目将确定正在迅速发生的植被变化将如何影响水的分配和植物使用的水源。利用不同的生态带，以比较的方式评价乔木和灌木的水分利用动态。它们的蒸散动力学将被比较，并将使用示踪剂来评估植物正在使用的水源以及它们从哪里获得这些水。这将为植被变化如何影响储水和水流的可用性提供证据。寒冷地区正在迅速变化，而我们理解和预测变化的能力仍然有限。在接下来的五年里，这个拟议的项目将从根本上推进我们对永久冻土流域的水储存和循环以及环境变化的驱动因素的理解。需要改进信息和预测工具，以便政府机构和原住民能够更有信心地为北方水资源和基础设施制定准则和行为守则，并制定适应方法。

There is an emerging consensus and growing societal concern that permafrost regions are highly vulnerable to the effects of global climate change. For example, the arctic carbon bomb theory suggests that through a massive release of organic carbon from thawing permafrost soils, atmospheric CO2 concentrations will rapidly rise with catastrophic consequences. Thawing permafrost also provides new pathways for liquid water flow and chemical transport, altering river discharge and water quality. Polar-amplified warming results in rainfall becoming more dominant as the hydrological cycle accelerates, and provides suitable conditions for widespread vegetation shifts. These changes are of great concern for all levels of government, endanger civil infrastructure, and threaten First Nations and Inuit whose traditional livelihoods are challenged in a warmer world. Through two integrated projects, this research will improve our understanding of how northern catchments will respond hydrologically to integrated environmental changes. The first project will utilize a transect of 9 watersheds in Yukon Territory with varying amounts of permafrost. Isotope tracers and hydrological data will be used to assess the influence of frozen ground status on the storage, mixing and release of water. New techniques will be used to assess the 'demographics' of water, and evaluate how frozen ground influences how long water resides in a catchment, how it is stored, and then released. This information will be combined with high-frequency water chemistry data to explore where in these watersheds flows are being generated and how frozen ground status influences catchment runoff. A second project will determine how vegetation change, which his rapidly occurring, will affect the partitioning of water and the sources of water being used by plants. Using different ecozones, tree and shrub water use dynamics will be evaluated in a comparative manner. Their evapotranspiration dynamics will be compared, and tracers will be used to evaluate what sources of water the plants are using and where they are accessing this water from. This will provide evidence on how changes in vegetation will influence the availability of water for storage and streamflow. Cold regions are changing rapidly and our ability to understand and predict changes remains limited. In the next five years, this proposed program will fundamentally advance our understand of water storage and cycling in permafrost watersheds and the drivers of environmental change. Improved information and predictive tools are needed so that government agencies and First Nations can more confidently develop guidelines and codes of practice for northern water resources and infrastructure and develop methods of adaptation.