全球木质林产品碳科学研究动态及未来的重点问题

【目的】森林在全球碳循环中发挥着重要作用。作为森林资源利用的延伸,木质林产品是缓解气候变化的重要碳库。厘清木质林产品的主要生命周期阶段,归纳总结与之关联的木质林产品碳科学研究热点及未来可能的研究方向,以合理评价木质林产品的气候功能。【方法】以木质林产品的生命周期过程为基础,分“森林—在用—填埋”3个阶段归纳总结了木质林产品碳科学的研究动态及未来可能面临的科学难题。【结果】①森林阶段中,现有研究多采用以经验模型为主、过程模型为辅的方式核算和预测森林碳库碳储量,情景模拟和物质流分析可以利用运输和生产过程将森林阶段与在用阶段相结合,寻求最佳的森林管理策略。②在用阶段中,碳核算方法学的选择是国际争议的重点所在,木质林产品的替代效应也由于其可累积性和永久性成为碳核算过程中不可忽视的重要问题。③填埋阶段中,木质林产品分解缓慢或不分解,可以使碳储存的时间更久,一阶衰减法是估算固体废弃物填埋场中碳储量变化的常用模型,与甲烷排放相关联的可降解有机碳比例、甲烷产出比例等关键参数也是目前的研究重点。【结论】①对森林碳汇计量模型加以改进,解决其区域适应性问题能够降低森林阶段碳核算的不确定性;②合理估算木质林产品的替代因子及实现“碳中和”的时间有利于能源政策和森林管理政策的制定;③考虑固体废弃物填埋场中甲烷的回收再利用能够提高木质林产品全生命周期碳核算的准确性;④改进森林资源清查方法、完善林产品生命周期数据库能够更准确地评估木质林产品的温室气体减排潜力;⑤在全球尺度上统一碳核算方法学,同时公平地认定碳储量的归属、合理地在各贸易国间分配碳排放,将有助于加速木质林产品相关议题的国际谈判进程。

Research trends and future key issues of global harvested wood products carbon science

【Objective】Forests play an important role in the global carbon cycle. As an extension of forest resource utilization, harvested wood products are important carbon pools for climate change mitigation. By clarifying the main life cycle stages of harvested wood products, and summarizing the relevant research hotspots and possible future research directions of carbon in harvested wood products, it is of great scientific significance to rationally evaluate the climate function of harvested wood products. 【Method】Based on the life cycle process of harvested wood products, this paper summarizes the research trends and scientific challenges that may be faced in the future regarding the carbon science of harvested wood products in three stages: forest, in-use, and landfill. 【Result】 ① In the forest stage, existing studies mostly used the empirical model as a supplement to the process model to calculate and predict forest carbon stocks. The scenario simulation and material flow analysis can combine the forest stage with the in-use stage by using transport and production processes to seek the best forest management strategy. ② In the in-use stage, the choice of carbon accounting approaches is the focus of international controversy. The substitution effect of harvested wood products is also a major issue that cannot be ignored in the carbon accounting process because of its cumulative and permanent nature. ③ In the landfill stage, harvested wood products decompose slowly or do not decompose at all, consequently storing carbon for a longer time. The first-order decay method is a common model used for estimating the change in carbon storage in solid waste disposal sites. The key parameters associated with methane emission, such as the fraction of degradable organic carbon and the proportion of methane production, are the emphasis of the current study. 【Conclusion】① Improving the measurement model of forest carbon sinks can reduce the uncertainty of forest carbon accounting. ② Reasonable estimation of the displacement factors of harvested wood products and the time required to achieve “carbon neutrality” are conducive to the formulation of policies regarding the energy and forest management. ③ Considering the recovery and reuse of methane in solid waste disposal sites can improve the accuracy of carbon accounting in the entire life cycle of harvested wood products. ④ Improving forest inventory methods and perfecting the database of the forest product life cycle can facilitate a more accurate assessment of the mitigation potential of greenhouse gas emissions from harvested wood products. ⑤ Harmonizing carbon accounting methodologies on a global scale, equitably identifying the ownership of carbon stocks and as well as rationalizing the distribution of carbon emissions among trading countries, will help to accelerate international negotiations on issues related to harvested wood products.