Tree methane: Getting to the root of it.

Trees are understood to emit large quantities of methane, particularly in tropical wetland environments; however, little is known about the source of tree methane emissions. We aim to understand the form of methanogenesis behind tree methane in the Brazilian Amazon and the source of this methane. In order to compare methanogenesis between different systems, isotope samples were taken from trees, soil and flood water at two sites. Initial isotopic analysis shows that there is no significant difference between soil and tree methane samples, whereas water-sampled methane was significantly different from both soil and tree samples. Hydrogen isotope analysis will further our understanding of the specific methanogenesis process in the soil-tree-atmosphere continuum. These preliminary results suggest tree methane is soil derived, which is critical in enhancing our understanding of both the global methane budget and the role trees play in methane emissions.