在全球变暖背景下,甲烷 (CH₄) 作为陆地生态系统中仅次于CO₂的重要温室气体受到了广泛关注,其在百年时间尺度上的温室效应潜力是CO₂的28~34倍,对全球变暖的贡献占20%~30%。现有对森林生态系统CH₄的研究主要集中在土壤,但基于热带森林地表排放估算和卫星CH₄通量之间的差异报告,以及近年的研究证明了树木是森林CH₄预算的重要来源和汇。笔者综合分析了树干CH₄的来源、通量大小、影响因素及其对陆地碳预算的影响,结果发现:①树干释放出的CH₄是来自土壤或者树木心材,然后主要通过树干扩散释放到空气中;②树干CH₄的通量范围为(-37.5±18.75)~(16 937.50±6 812.50) μmol/(m²·h);③树干表面CH₄通量具有较大的时空差异性,这些差异主要来自树种、年龄、组织类型、立地特征和环境条件等;④在不考虑树干CH₄通量的前提下,森林湿地 (或木本沼泽) 生态系统的CH₄释放量部分可能被低估,而旱地或者高山森林中CH₄的吸收量部分可能被高估。树干甲烷作为陆地碳循环的“新成员”,应该被充分重视,这对于预测未来全球气候变化具有重要意义。

Methane (CH₄) as the second most important greenhouse gas in terrestrial ecosystems after carbon dioxide (CO₂) has received extensive attention in the context of global warming. With the same quantity (number of moles) of greenhouse gas, the greenhouse effect of CH₄ in 100 years is 28 to 34 times that of CO₂, and atmospheric CH₄ is responsible for approximately 20% to 30% of global warming. Reports of a discrepancy between emissions-based estimates and satellite-based estimates of CH₄ sources in tropical forests have generated interest in tree surfaces as a neglected source. Numerous studies in recent years have also proved that trees are an important source and sink of forest CH₄ budget. By review in published literatures, this paper comprehensively analyzed the source, flux size, influencing factors of CH₄ in tree stems and its impact on terrestrial carbon budget. We found that: ① CH₄ released by the stems was produced in the soil or in the heartwood of the tree, and then diffused through the stems into the air.② The flux range of stems CH₄ was from(-37.5±18.75) to (16 937.50±6 812.50) μmol/(m²·h).③ The CH₄ flux on the surface of the stems had a large spatiotemporal difference, which mainly comes from the species, age, tissue type, site characteristics and environmental conditions. ④ The CH₄ released from forest wetland (or woody swamp) might be underestimated, while the CH₄ absorption from dryland or alpine forests might be overestimated, without considering the CH₄ flux from the stems. As a new member of the terrestrial carbon cycle, tree-stems methane should be given sufficient attention, which was of great significance for predicting future global climate change.