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

Area of Science:

• Environmental Science
• Forest Ecology
• Biogeochemistry

Background:

• Tree stems in various forest types (wetland, floodplain, upland) are sources of methane (CH4) production and emission.
• Significant spatial and temporal variability exists in tree stem CH4 emissions, with ongoing debate regarding the underlying biophysical mechanisms.

Purpose of the Study:

• To identify key research opportunities and challenges in understanding tree stem CH4 emissions.
• To improve estimates of CH4 emission magnitudes, patterns, and drivers.
• To trace the origins of CH4 produced and emitted by tree stems.

Main Methods:

• Review and synthesis of existing research on tree stem CH4 emissions.
• Identification of critical knowledge gaps and future research directions.
• Proposal for integrated measurement strategies (long-term, high-frequency, large-scale) and mechanistic modeling.

Main Results:

• Highlighted the need for high-frequency, long-term, and large-scale measurements to capture fine-scale processes and ecosystem variability.
• Emphasized the importance of identifying specific microorganisms and biogeochemical pathways involved in CH4 production.
• Stressed the necessity of developing mechanistic models that incorporate CH4 transport within the soil-tree-atmosphere continuum.

Conclusions:

• Addressing research challenges will refine CH4 emission estimates and elucidate drivers.
• Integrating CH4 production pathways and transport mechanisms into models is crucial.
• Advances will enable accurate upscaling of stem CH4 emissions and their contribution to global CH4 budgets.