The carbon cycling of eastern Quebec boreal forests in the context of climate change and hydropower production

水电是魁北克人和加拿大人的主要电力来源，也是对美国越来越重要的出口产品。为水力发电而进行的水库注水会排放二氧化碳和甲烷，这是两种重要的温室气体。与不可再生资源发电相比，这些排放量较低，但必须将其置于气候变化导致的快速变化的环境中。事实上，水库淹没了以前主要是森林的地区，以及水生和湿地生态系统。人们通常认为这些是净碳汇，但在气候变暖时，这可能会发生变化，干旱、火灾和虫害可能会变得更加频繁。因此，为了能够预测水电站对气候的净影响，我们需要了解完整的周围景观对气候的影响，以及这种影响如何演变。我们建议对位于魁北克省诺德地区的La Romaine流域采取这种做法。La Romaine综合体项目于2009年启动。在2021年完工时，该综合体将包括四个水力发电厂，每年产生8.5 TWh的能源和四个水库，总面积为280平方公里。我们将监测La Romaine河的一个子流域的碳通量，确定子流域内的碳储存热点，并确定从子流域的水输出的碳的命运。我们将利用这一详尽的实地研究结果来模拟拉罗曼河下游流域的碳功能，最终能够预测这种森林景观在碳循环中的作用。我们的项目不仅有助于魁北克省负责发电、输电和配电的公用事业公司评估水电生产的真实环境成本，而且还有助于更好地为加拿大的战略提供信息，即部分依赖其森林的碳汇功能来缓解未来的气候变化。

Hydropower is the main source of electricity to Quebecers and to Canadians, and is an increasingly important export product to the US. Reservoir flooding for hydropower production emits carbon dioxide and methane, two important greenhouse gases. These emissions are low compared to electricity production from non-renewable resources, but they have to be put in the context of a rapidly changing environment due to climate change. Indeed, reservoirs flood areas that were previously largely forests, in addition to aquatic and wetland ecosystems. It is generally assumed that these are net carbon sinks, but this may change in a warmer climate, where droughts, fire and insect epidemics may become more frequent. Hence, to be able to project the net impact of hydropower reservoirs on the climate, we need to understand the impact of intact, surrounding landscapes on the climate, and how this impact evolves. We propose to do this for the La Romaine watershed located on the Côte Nord region of the province of Quebec. The La Romaine complex project was initiated in 2009. At completion in 2021, the complex will comprise four hydroelectric power plants yielding 8.5 TWh of energy per year and four reservoirs covering a total area of 280 km2. We will monitor the carbon fluxes of a subwatershed of La Romaine river, determine the carbon storage hotspots within the subwatershed, and determine the fate of carbon exported in the water from the subwatershed. We will use the results from this exhaustive field study to model the carbon functions of the lower La Romaine watershed, to eventually be able to project the role of this forested landscape in the carbon cycle. Our project will not only be useful to the utility responsible for generation, transmission, and distribution of electricity in the province of Quebec (Hydro-Québec) to assess the true environmental cost of hydropower production, but also to better inform Canada's strategy to partly rely on the carbon sink function of its forests to mitigate future climate change.