A process-based model for assessing the impacts of reservoirs and forest harvesting on the carbon budget of aquatic ecosystems

森林采伐和水库蓄水等人类活动对全球碳循环，特别是陆地生态系统的大气二氧化碳排放产生了深远的影响。水库蓄水导致水体和沉积物中发生的生物地球化学过程发生短暂和永久性的变化，而森林采伐强烈地改变了陆地有机质(TOM)向水生生态系统的通量。作为与政府合作伙伴(加拿大环境部、可持续发展组织、L的环境和魁北克公园)合作努力的一部分，我们提议利用分析有机生物地球化学的最新进展，对(I)导致TOM在水生系统中退化或固存的因素，以及(Ii)森林采伐和水库蓄水对这些因素的影响，从分水岭尺度温室气体排放预算的变化方面，建立精细的分子理解。为了推广我们的方法，并在全国范围内验证我们的结论，我们将开发一个新的基于过程的模型(集成碳循环模型-ICC模型)，将陆地生态系统和水生态系统联系起来。该模型将使用一小部分水生生物地球化学示踪剂来整合(I)湖泊或水库中的碳动态，以及(Ii)森林采伐对TOM出口的修正，以最终提供这些不同环境下温室气体排放预算的估计。最终目标是产生生物地球化学和模型知识，并将其转让给我们的政府合作伙伴，以协助他们确定这种干扰对人为温室气体排放或水生生态系统清除量的长期影响和意义。

Human activities such as forest harvesting and reservoir impoundment have profoundly impacted the global carbon cycle and, in particular, the atmospheric carbon dioxide (CO2) emissions of land ecosystems. Reservoir impoundment leads to transient and permanent changes in the biogeochemical processes taking place in the water column and the sediments, while forest harvesting strongly modifies the fluxes of terrestrial organic matter (TOM) to aquatic ecosystems. As part of a collaborative effort with governmental partners (Environment Canada, Ministère du Développement Durable, de l'Environnement et des Parcs du Québec), we propose to exploit the latest advances in analytical organic biogeochemistry to develop a fine molecular understanding of (i) the factors responsible for the degradation or sequestration of TOM in aquatic systems, and (ii) the impact of forest harvesting and reservoir impoundment on these factors in terms of changes in the greenhouse gas (GHG) emissions budget at the watershed scale. To generalize our approach and verify our conclusions in aquatic ecosystems across the country, we will develop a new process-based model (Integrated Carbon Cycle Model - ICC model) linking the terrestrial and aquatic ecosystems. This model will use a short list of aquatic biogeochemical tracers to integrate (i) carbon dynamics in lakes or reservoirs, and (ii) modifications in TOM exports due to forest harvesting, to ultimately provide estimates of GHG emission budgets in these contrasting environments. The ultimate goal is to generate and transfer biogeochemical and modeling knowledge to our governmental partners to assist them in determining the long-term effects and significance of such disturbances in relation to anthropogenic GHG emissions or removals from aquatic ecosystems.