Assessing cumulative effects of anthropogenic and natural disturbances on forest carbon (C) stocks and fluxes, because of their relevance to climate change, is a requirement of environmental impact assessments (EIAs) in Canada. However, tools have not been developed specifically for these purposes, and in particular for the boreal forest of Canada, so current forest C assessments in EIAs take relatively simple approaches. Here, we demonstrate how an existing tool, the Generic Carbon Budget Model (GCBM), developed for national and international forest C reporting, was used for an assessment of the cumulative effects of anthropogenic and natural disturbances to support EIA requirements. We applied the GCBM to approximately 1.3 million ha of upland forest in a pilot study area of the oil sands region of Alberta that has experienced a large number of anthropogenic (forestry, energy sector) and natural (wildfire, insect) disturbances. Over the 28 years, 25% of the pilot study area was disturbed. Increasing disturbance emissions, combined with declining net primary productivity and reductions in forest area, changed the study area from a net C sink to a net C source. Forest C stocks changed from 332.2 Mt to 327.5 Mt, declining by 4.7 Mt at an average rate of 0.128 tC ha−1 yr−1. The largest cumulative areas of disturbance were caused by wildfire (139,000 ha), followed by the energy sector (110,000 ha), insects (33,000 ha) and harvesting (31,000 ha) but the largest cumulative disturbance emissions were caused by the energy sector (9.5 Mt C), followed by wildfire (5.5 Mt C), and then harvesting (1.3 Mt C). An existing forest C model was used successfully to provide a rigorous regional cumulative assessment of anthropogenic and natural disturbances on forest C, which meets requirements of EIAs in Canada. The assessment showed the relative importance of disturbances on C emissions in the pilot study area, but their relative importance is expected to change in other parts of the oil sands region because of its diversity in disturbance types, patterns and intensity. Future assessments should include peatland C stocks and fluxes, which could be addressed by using the Canadian Model for Peatlands.

中文翻译：

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自然和人为干扰对加拿大艾伯塔油砂地区森林碳平衡的累积影响；一项初步研究（1985-2012年）

评估人为干扰和自然干扰对森林碳（C）储量和通量的累积影响，因为它们与气候变化有关，这是加拿大环境影响评估（EIA）的要求。但是，还没有专门针对这些目的开发工具，特别是针对加拿大的北方森林，因此，EIA中当前的森林碳评估采用相对简单的方法。在这里，我们演示了如何使用为国家和国际森林碳报告开发的现有工具通用碳预算模型（GCBM），用于评估人为干扰和自然干扰的累积影响，以支持EIA要求。我们将GCBM应用于大约1。在艾伯塔省油砂地区的一个试验研究区中，有300万公顷的旱地森林，经历了许多人为（林业，能源部门）和自然（野火，昆虫）干扰。在过去的28年中，有25％的试验研究区域受到干扰。干扰排放的增加，加上净初级生产力的下降和森林面积的减少，使研究范围从净碳汇变成了净碳源。森林碳储量从332.2 Mt变为327.5 Mt，以0.128 tC ha-1 yr-1的平均速率下降4.7Mt。累积的最大骚扰面积是由野火引起的（139,000公顷），其次是能源部门（110,000公顷），昆虫（33,000公顷）和收割（31,000公顷），但是累积的骚扰排放量最大的是能源部门（9.5） C），然后是野火（5.5 M），然后收获（1.3 Mt C）。成功使用现有的森林碳模型对森林C的人为和自然干扰进行了严格的区域累积评估，符合加拿大EIA的要求。评估表明，在试验研究区中，碳排放扰动的相对重要性，但由于其扰动类型，类型和强度的多样性，预计它们的相对重要性在油砂地区的其他地区也会有所变化。未来的评估应包括泥炭地碳库和通量，这可以通过使用加拿大泥炭地模型来解决。符合加拿大环境影响评估的要求。评估显示，在试验研究区，碳排放扰动的相对重要性，但由于其扰动类型，类型和强度的多样性，预计它们的相对重要性在油砂地区的其他地区也会有所变化。未来的评估应包括泥炭地碳库和通量，这可以通过使用加拿大泥炭地模型来解决。符合加拿大环境影响评估的要求。评估表明，在试验研究区中，碳排放扰动的相对重要性，但由于其扰动类型，类型和强度的多样性，预计它们的相对重要性在油砂地区的其他地区也会有所变化。未来的评估应包括泥炭地碳库和通量，这可以通过使用加拿大泥炭地模型来解决。