Termite mounds mitigate half of termite methane emissions.

Area of Science:

• Environmental Science
• Microbiology
• Ecology

Background:

• Termites contribute significantly to global methane (CH4) emissions, yet estimates vary widely due to missing knowledge of CH4 turnover in colonies.
• Microbial methane oxidation within termite mounds is poorly understood, impacting accurate global emission calculations.

Purpose of the Study:

• To quantify methane (CH4) production, oxidation, and transport in North Australian termite mounds.
• To investigate the location and extent of microbial CH4 oxidation within different termite species' mounds.
• To estimate termite biomass using CH4 turnover and establish a reliable oxidation factor for global CH4 emission estimates.

Main Methods:

• Utilized a one-box model integrating gas-tracer tests, inhibitor approaches, and stable-isotope techniques.
• Conducted in situ measurements and field tests on excavated mounds of three North Australian termite species.
• Quantified CH4 production, oxidation, and transport dynamics within the mound environment.

Main Results:

• Demonstrated widespread in situ CH4 oxidation in termite mounds, mitigating 20-80% of produced CH4.
• Identified mound material or underlying soil as primary locations for CH4 oxidation, influenced by mound porosity.
• Estimated mean termite biomass ranging from 22 to 86 g/kg of mound material across species.
• Calculated a mean CH4 oxidation fraction (f_ox) of 0.50 ± 0.11, suggesting a buffered process.

Conclusions:

• Termite mounds significantly mitigate methane emissions through microbial oxidation.
• The study provides a robust method for estimating termite biomass and a reliable oxidation factor for global CH4 budgets.
• Understanding CH4 turnover in termite mounds is crucial for accurate climate change modeling.