林业碳汇提升的主要原理和途径

降低大气CO₂含量、缓解气候变暖,已成为当今科学界和国际社会广泛关注的前沿热点问题。林业碳汇作为基于自然解决方案实现“碳达峰、碳中和”的一个重要途径,在应对全球气候变化方面发挥着基础性、战略性、独特的作用。林业碳汇不仅是森林碳汇,林产品碳汇也起着不可忽视的重要作用。林业碳汇潜力提升是一个森林生态系统净碳收支平衡和全产业链林产品碳汇的调控过程,主要包括无机碳的植物固定(光合过程、净生产力等)、土壤有机碳的周转与固定(动植物和微生物残体分解与黏土固定)、林产品碳的固持(林产品产量、木材转换效率、种类和使用寿命等)等3方面的调控原理。笔者从森林碳汇和林产品碳汇两个维度阐述了提升林业碳汇的主要原理、方法或途径。提升林业碳汇潜力的主要途径包括:①通过适地适树、适钙适树人工造林,以增加森林面积;②以完善森林经营措施来增加森林净生产力;③利用矿质黏土对有机碳的保护来增加森林土壤碳汇;④提升林产品产量和改进林产品用途以增加其寿命。在全球尺度上,增加森林面积或提高森林净生产力3.4%,或用可再生能源替换薪炭木材,再将薪炭木材用于制造锯材和人造板,都可以连续30 a每年增加1 Pg的碳汇量。减少全球森林火灾面积1/4或增加森林土壤有机碳含量0.23%,也可以增加碳汇1 Pg。此外,林业固碳还有巨大潜力可以挖掘。

Mechanisms and methods for augmenting carbon sink in forestry

Rising atmospheric CO₂ concentration is recognized as the major driver for global climate warming. Thus, reducing atmospheric CO₂ is also recognized as the main remediation method for climate change. Forestry practices play an essential role in atmospheric CO₂ sequestration and global environmental engineering. Forestry carbon sequestration includes forest carbon sequestration and forest product carbon sequestration. Carbon sequestration in forests relies mainly on processes of ecosystem carbon balancing and forest product production, including photosynthesis and ecosystem net primary productivity, stabilization of soil organic carbon, and wood use efficiency and product lifespan. Forestry carbon sequestration can be achieved through (1) expanding forest areas with afforestation practices guided by the “matching trees with site or calcium” principle; (2) increasing forest net productivity with integrated forest management of water, nutrients, and pest or fire control; (3) enhancing the stabilization of soil organic carbon content by clay minerals; (4) promoting the use and improving the lifespan of forest products. At the global scale, an additional 1 Pg (C) of carbon can be sequestrated each year for 30 years by increasing forest area or net productivity by 3.4%, or by converting fuel wood to sawn wood or wood-based panels. Furthermore, reducing carbon loss from forest fire by a quarter or elevating soil organic carbon by 0.23% can also decrease carbon emissions by 1 Pg (C) each year. Carbon sequestration in forestry has great potential for reducing atmospheric carbon dioxide and mediating global climate warming.