Boreal forests are often managed to maximize wood production, but other goals, among which climate change mitigation, are increasingly important. Hence, it is necessary to examine synergies and trade-offs between forest production and its potential for carbon sequestration and climate change mitigation in forest stands. To this aim, we develop a novel mass-balanced process-based compartmental model that allows following the carbon path from its photosynthetic fixation until its return to the atmosphere by autotrophic or heterotrophic respiration, or by being burnt as wood product. Following carbon in the system allows to account for how long forest ecosystems and wood products retain carbon away from the atmosphere (i.e., the carbon transit time). As example, we apply the model to four management scenarios, i.e., mixed-aged pine, even-aged pine, even-aged spruce, and even-aged mixed forest, and contrast metrics of performance relative to wood production, carbon sequestration, and climate change mitigation potential. While at the end of an 80 yr rotation the even-aged forests held up to 31% more carbon than the mixed-aged forest, the mixed-aged forest was superior during almost the entire rotation when factoring in the carbon retention time away from the atmosphere, i.e., in terms of climate change mitigation potential. Importantly, scenarios that maximize production or amount of carbon stored in the ecosystems are not necessarily the most beneficial for carbon retention away from the atmosphere. These results underline the importance of considering carbon transit time when evaluating forest management options for potential climate change mitigation.

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碳固定量、运输时间和采伐木材产品的命运决定了北方森林管理的气候变化减缓潜力——模型分析

北方森林的管理通常是为了最大限度地提高木材产量，但其他目标，其中包括减缓气候变化，也变得越来越重要。因此，有必要研究森林生产及其在林分中固碳和减缓气候变化的潜力之间的协同作用和权衡。为此，我们开发了一种新颖的基于质量平衡过程的隔室模型，该模型允许跟踪碳从光合作用固定到其通过自养或异养呼吸或作为木制品燃烧返回大气的路径。跟踪系统中的碳可以计算森林生态系统和木制品将碳保留在大气中的时间（即碳传输时间）。例如，我们将该模型应用于四种管理场景，即混合龄松、同龄松、同龄云杉和同龄混交林，以及与木材产量、碳固存和碳排放相关的绩效对比指标。减缓气候变化的潜力。虽然在 80 年轮伐期结束时，同龄森林比混合龄森林多持有 31% 的碳，但当考虑到远离森林的碳保留时间时，混合龄林在几乎整个轮伐期中均表现更佳。大气，即气候变化减缓潜力。重要的是，最大化生态系统中碳的生产或储存量的情景并不一定最有利于碳保留远离大气。这些结果强调了在评估潜在减缓气候变化的森林管理方案时考虑碳传输时间的重要性。