Abstract：
Trees can play different roles in the regulation of fluxes of methane (CH4), a greenhouse gas with a warming potential 83 times greater than that of carbon dioxide. Forest soils have the greatest potential for methane uptake compared to other land uses. In addition to their influence on soil CH4 fluxes, trees can act directly as a source or sink of CH4, by transporting CH4 produced in the soil and harbouring the key microorganisms involved in CH4 production and consumption (methanogens and methanotrophs). Tree CH4 fluxes can vary between species characterized by different traits that influence transport and modify the availability of CH4 reaction substrates as well as the habitat for methanogens and methanotrophs. Despite their important role in modulating CH4 fluxes from forest ecosystems, the identity and role of tree traits influencing these fluxes are poorly consolidated in the literature. The objectives of this paper are to 1) Review the functional traits of trees associated with their role in the regulation of CH4 emissions; 2) Assess the importance of inter-specific variability in CH4 fluxes via a global analysis of tree methane fluxes in the literature. Our review highlights that differences in CH4 fluxes between tree species and individuals can be explained by a diversity of traits influencing CH4 transport and microbial production of CH4 such as wood density and secondary metabolites. We propose a functional classification for trees based on the key traits associated with a function in CH4 emissions. We identified the fast-growing species with low wood density, species adapted to flood and species vulnerable to rot as functional groups which can be net sources of CH4 in conditions favorable to CH4 production. The global analysis further demonstrated the importance of taxonomy, with other factors such as land type and season in explaining variability in tree CH4 fluxes.
摘要：
树木在甲烷(CH4)通量的调节中可以发挥不同的作用，一种温室气体，其变暖潜力是二氧化碳的83倍。与其他土地利用相比，森林土壤吸收甲烷的潜力最大。除了它们对土壤CH4通量的影响外，通过运输土壤中产生的CH4并包含参与CH4生产和消费的关键微生物（产甲烷菌和甲烷营养菌），树木可以直接充当CH4的来源或汇。树CH4通量可以在以不同性状为特征的物种之间变化，这些性状会影响运输并改变CH4反应底物的可用性以及产甲烷菌和甲烷营养菌的生境。尽管它们在调节森林生态系统的CH4通量中发挥了重要作用，影响这些通量的树木性状的身份和作用在文献中没有得到很好的巩固。本文的目的是1）回顾与它们在CH4排放调节中的作用相关的树木的功能特征；2）通过文献中对树木甲烷通量的全球分析，评估CH4通量的种间变异性的重要性。我们的评论强调，树种和个体之间CH4通量的差异可以通过影响CH4运输和CH4微生物产生的性状的多样性来解释，例如木材密度和次生代谢产物。我们根据与CH4排放中的功能相关的关键特征，提出了对树木的功能分类。我们确定了木材密度低的快速生长物种，适应洪水的物种和易腐烂的物种作为官能团，在有利于CH4生产的条件下可以成为CH4的净来源。全球分析进一步证明了分类学的重要性，与其他因素如土地类型和季节来解释树木CH4通量的变化。
