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

土壤有机碳代表着地球上最大的积极循环的碳库，这突显了我们需要了解其转变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碳、能量和养分的最大储存库，这使得对其随气候变化的循环的预测性了解成为森林和水生资源战略管理的优先事项。这项研究将确定气候变化在调节土壤溶解有机质(DOM)和养分向下游水生生态系统输送方面对北方高地森林到水源的临界区的缓冲能力的影响。这一点尤其重要，因为预计下个世纪北方地带的气温和降水量将会上升。在北方森林流域提供土壤和地下水流动通道的基础设施将部署在(1)由成熟森林和在水文上表现出较大差异的采伐的再生林组成的试验场，以及(2)类似林场和相关源头溪流的气候样带。这些试验场将使我们能够确定增加的水文如何影响DOM的组成和输出，以及输送到水环境中的营养物质。气候样带将使我们能够评估气候变暖如何改变这些水文影响。人工操作实验将为检验水文和温度在调节土壤碳流失中的相互作用提供直接的手段。我们的工作结合了地球化学、同位素和生物学方法，以识别DOM和营养物质通量的变化与水文学、变暖及其相互作用，并阐明推动这些变化的生物和矿物学机制的影响。这项研究将通过提供对北方森林及其相关水生生态系统气候变化反应的预测性了解，使我们的支持组织受益，这些组织包括林业行业以及省和联邦林业局。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 soiland 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.