Ecohydrology in Permafrost Systems: The Impact of Watershed Heterogeneity on Stream Flow Dynamics and Hydrologic Pathways

本研究的总体目标是量化的植被用水和土壤储水动态与冻土的存在/不存在，在确定水的流动路径，机制，时间和幅度在亚北极寒带森林生态系统的相对作用。该生态系统位于不连续的多年冻土带，有两个主要的生态系统类型：无多年冻土，落叶为主和受多年冻土影响，针叶为主。这项研究将整合气候，生态，热量和水文过程，通过一个激烈的实地研究计划，使用水文建模。现场包括三个集水区，代表了不同的冻土范围和生态系统类型组成的梯度在驯鹿扑克溪流域研究（CPCRW）长期生态研究（LTER）网站。除了溪流观测外，还将沿沿着北向（受冻土影响）针叶为主的生态系统到南向（无冻土）落叶为主的生态系统收集植物用水、土壤湿度、季节性土壤解冻和气象变量的测量值。实地研究的数据将用于开发植被用水模型并设定参数，该模型将被纳入混合水文模型。这种半分布式的，基于过程的混合水文模型的发展将模拟北方森林生态系统的主要水文过程，强调水的储存和释放机制。 北方森林是阿拉斯加的重要资源？是淡水。这项研究将有助于更好地了解和预测淡水供应量，这将受到永久冻土和北方森林生态系统分布变化的影响。这项研究还将推进生态水文学领域，这是相对不足的探索，在北方系统。亚北极环境将是北极地区最先经历大多数当前或预期气候相关变化的环境。这种变化有可能改变向北冰洋输送淡水的规模和时间，预计这将导致海冰形成、温盐环流以及最终从地方到全球范围的气候系统发生变化。 外联是这项研究的一个重要方面。来自当地K-12学校的教师将参加以北方森林生态系统为重点的培训研讨会，该研讨会将与阿拉斯加大学费尔班克斯的全球学习和观察有益于环境计划（地球仪）项目一起进行。以往的经验表明，该项目将采用的方法是将该地区的自然科学纳入当地课堂的有效手段。

The overall objective of this study is to quantify the relative roles of vegetation water use and soil water storage dynamics associated with permafrost presence/absence in determining the water flow pathways, mechanisms, timing and magnitudes in the sub-Arctic boreal forest ecosystem. This ecosystem is located in the zone of discontinuous permafrost and has two primary ecosystem types: permafrost free, deciduous dominated and permafrost affected, coniferous dominated. This study will integrate climatic, ecologic, thermal, and hydrologic processes through an intense field study program using hydrologic modeling. The field site comprises three catchments that represent a gradient of varying permafrost extent and ecosystem-type composition at the Caribou Poker Creeks Research Watershed (CPCRW) Long Term Ecological Research (LTER) site. In addition to stream flow observations, measurements of plant water use, soil moisture, seasonal soil thaw, and meteorologic variables will be collected along a north-facing (permafrost affected) coniferous dominated ecosystem to a south-facing (permafrost free) deciduous dominated ecosystem. Data from the field study will be used to develop and parameterize a vegetation water use model, which in turn will be integrated into a hybrid hydrologic model. Development of this semi-distributed, process-based hybrid hydrologic model will simulate the major hydrologic processes of the boreal forest ecosystem, emphasizing the water storage and release mechanisms. The boreal forest is a critical source of Alaska?s freshwater. This study will contribute to improved understanding and prediction of freshwater availability that will be affected by changes in permafrost and ecosystem distributions in the boreal forest. This study will also advance the field of ecohydrology, which is relatively under-explored in northern systems. The sub-Arctic environment will be the first in the Arctic to experience most of the current or expected climate-associated changes. Such changes have the potential to shift the magnitude and timing of freshwater delivery to the Arctic Ocean which is anticipated to lead to changes in sea-ice formation, thermohaline circulation, and ultimately the climate system from local to global scales. Outreach is an important aspect of this study. Teachers from local K-12 schools will participate in training workshops focused on the boreal forest ecosystem that will be conducted in conjunction with the Global Learning and Observations to Benefit the Environment program (GLOBE) program at the University of Alaska Fairbanks. Prior experience shows that the approach that will be used in this project is an effective means to integrate the natural science of the region into local classrooms.