Methane emissions from tree stems a new frontier in the global carbon cycle

• Published in: The New phytologist Vol. 222; no. 1; pp. 18 - 28
• Main Authors: Barba, Josep, Bradford, Mark A., Brewer, Paul E., Bruhn, Dan, Covey, Kristofer, van Haren, Joost, Megonigal, J. Patrick, Mikkelsen, Teis Nørgaard, Pangala, Sunitha R., Pihlatie, Mari, Poulter, Ben, Rivas-Ubach, Albert, Schadt, Christopher W., Terazawa, Kazuhiko, Warner, Daniel L., Zhang, Zhen, Vargas, Rodrigo
• Format: Journal Article
• Language: English
• Published: England Wiley 01-04-2019; Wiley Subscription Services, Inc; Wiley-Blackwell
• Subjects: Active transport; Atmospheric models; Biogeochemistry; Carbon Cycle; CH4 transport; Ecosystems; Emission measurements; Emissions; Floodplains; Forests; Methane; Methane - metabolism; methane emissions; methanogenesis; Microorganisms; Models, Biological; Plant Stems - metabolism; Soil; Spatial distribution; spatial variability; Stems; temporal variability; Temporal variations; tree stems; Trees - metabolism; upland forests; Variability; Viewpoints; Water; wetland forests; temporal variability; methane emissions; wetland forests; spatial variability; upland forests; tree stems; methanogenesis; CH4 transport
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.15582

Tree stems from wetland, floodplain and upland forests can produce and emit methane (CH₄). Tree CH₄ stem emissions have high spatial and temporal variability, but there is no consensus on the biophysical mechanisms that drive stem CH₄ production and emissions. Here, we summarize up to 30 opportunities and challenges for stem CH₄ emissions research, which, when addressed, will improve estimates of the magnitudes, patterns and drivers of CH₄ emissions and trace their potential origin.We identified the need: (1) for both long-term, high-frequency measurements of stem CH₄ emissions to understand the fine-scale processes, alongside rapid large-scale measurements designed to understand the variability across individuals, species and ecosystems; (2) to identify microorganisms and biogeochemical pathways associated with CH₄ production; and (3) to develop a mechanistic model including passive and active transport of CH₄ from the soil–tree–atmosphere continuum. Addressing these challenges will help to constrain the magnitudes and patterns of CH₄ emissions, and allow for the integration of pathways and mechanisms of CH₄ production and emissions into process-based models. These advances will facilitate the upscaling of stem CH₄ emissions to the ecosystem level and quantify the role of stem CH₄ emissions for the local to global CH₄ budget.