Climate controls on terrestrial-to-aquatic biogeochemical fluxes in boreal forest watersheds

土壤有机碳是地球上最大的活跃循环碳库，强调我们需要了解其转化的驱动因素及其对气候变化的敏感性。土壤有机质也是森林生态系统中最大的碳、能量和养分储存库，因此预测了解其随气候变化的循环是我国森林和水产资源战略管理的优先事项。这项研究将确定气候变化对缓冲能力的影响，在调节土壤溶解有机质（DOM）和营养物质的下游水生生态系统的山地北方森林的源头流的关键区。考虑到预测的未来世纪北方地区气温和降水量的增加，这一点尤其重要。基础设施提供土壤 北方森林流域的地下水和地下水流路径将在以下两个地点部署：（1）由成熟森林和收获的再生林组成的实验地点，这些森林和再生林在水文方面表现出很大的差异;（2）类似森林地点和相关源头河流的气候横断面。实验地点将使我们能够确定水文的增加如何影响DOM的组成和输出以及输送到水生环境的营养物质。气候样带站点将使我们能够评估气候变暖如何改变这些水文影响。人工实验将提供一种直接的手段来测试水文和温度在调节土壤碳损失的相互作用。我们的工作结合了地球化学，同位素和生物学的方法来识别DOM和营养物质的流量与水文，变暖及其相互作用的变化，并阐明生物和矿物学机制驱动这些变化的影响。这项研究将有利于我们的支持组织，其中包括林业行业和省级和联邦森林服务，通过提供对北方森林及其相关水生生态系统的气候变化响应的预测性理解。研究结果将为旨在减少气候变化和采伐的潜在负面互动影响的林业管理做法提供信息。

Soil organic carbon represents Earth's largest actively cycling reservoir of carbon, underscoring our need to understand the drivers of its transformation and their sensitivity to climate change. Soil organic matter is also the largest reservoir of carbon, energy and nutrients in forest ecosystems, making the predictive understanding of its cycling with changing climate a priority for strategic management of our forest and aquatic resources. This research will determine the impacts of climate change on the buffering capacity of the upland boreal forest-to-headwater stream critical zone in regulating the delivery of soil dissolved organic matter (DOM) and nutrients to downstream aquatic ecosystems. This is particularly important given the predicted increases in temperature and precipitation for the boreal zone in the coming century. Infrastructure providing access to soil and groundwater flowpaths in boreal forest watersheds will be deployed across (1) an experimental site consisting of mature forest and harvested regenerating stands that exhibit large differences in hydrology, and (2) a climate transect of similar forest sites and associated headwater streams. The experimental sites will allow us to determine how increased hydrology impacts composition and export of DOM and nutrients delivered to the aquatic environment. The climate transect sites will allow us to assess how climate warming modifies these hydrological impacts. Manipulative experiments will provide a direct means to test the interaction of hydrology and temperature in regulating soil carbon losses. Our work combines geochemical, isotopic, and biological approaches to discern changes in the flux of DOM and nutrients with hydrology, warming and their interaction, and to elucidate the influence of biological and mineralogical mechanisms driving these changes. This research will benefit our supporting organizations, which include the forestry industry and both provincial and federal forest services, by providing a predictive understanding of climate change responses in boreal forests and their associated aquatic ecosystems. Results will inform forestry management practices aimed at reducing the potential negative interactive effects of climate change and harvesting.