Rapid bark-mediated tree stem methane transport occurs independently of the transpiration stream in Melaleuca quinquenervia

Published: 31 October 2023| Version 1 | DOI: 10.17632/kgw463f844.1
Luke Jeffrey


This electronic data available here was used to write the manuscript titled: Rapid bark-mediated tree stem methane transport occurs independently of the transpiration stream in Melaleuca quinquenervia, which was accepted in New Phytologist (27/10/2023). A summary of the research findings in this publication are: • Tree stem methane emissions are important components of lowland forest methane budgets. The potential for species-specific behaviour among co-occurring lowland trees with contrasting bark characteristics has not been investigated. • We compare bark-mediated methane transport in two common lowland species of contrasting bark characteristics (Melaleuca quinquenervia featuring spongy/layered bark with longitudinally-continuous airspaces and Casuarina glauca featuring hard/dense common bark) through several manipulative experiments. • Firstly, the progressive cutting through M. quinquenervia bark layers caused exponential increases in methane fluxes (~3 orders of magnitude), however sapwood-only fluxes were lower, suggesting that upward/axial methane transport occurs between bark layers. Secondly, concentrated methane pulse injections into exposed M. quinquenervia bark, revealed rapid axial methane transport rates (1.42 mm/s), which were further supported through lab-simulated experiments (1.41 mm/s). Lab-simulated radial CH4 diffusion rates (through bark) were ~20-times slower. Finally, girdling M. quinquenervia stems caused a near-instantaneous decrease in methane flux immediately above the cut. In contrast, girdling C. glauca displayed persistent, though diminished, methane fluxes. • Overall, the experiments revealed evidence for rapid ‘between-bark’ methane transport independent from the transpiration stream in M. quinquenervia, which facilitates diffusive axial transport from the rhizosphere and/or sapwood sources. This contrasts with the slower, radial ‘through-bark’ diffusive-dominated gas transportation in C. glauca.



Southern Cross University


Evolutionary Biology, Wetland Ecosystem, Plant Biogeochemistry, Methane Cycling, Forest Ecosystem, Carbon Dioxide Flux, Greenhouse Gas


Australian Research Council


Australian Research Council


Australian Research Council