Methane emissions from terrestrial plants under aerobic conditions

Area of Science:

• Environmental Science
• Biogeochemistry
• Plant Physiology

Background:

• Atmospheric methane concentration has nearly tripled since pre-industrial times, significantly impacting climate.
• Methane is a key greenhouse gas influencing atmospheric chemistry, stratospheric ozone, and water vapor.
• Natural methane sources were predominantly attributed to biological processes in anoxic environments.

Purpose of the Study:

• To investigate a novel, unrecognized process of methane formation within terrestrial plants.
• To quantify methane emissions from living plants and plant litter under oxic conditions.
• To assess the implications of this new methane source on the global methane budget.

Main Methods:

• Utilized stable carbon isotope analysis to identify methane formation pathways.
• Conducted laboratory and field incubation experiments with intact plants and detached leaves.
• Scaled observed methane emissions to estimate global source strength.

Main Results:

• Demonstrated that terrestrial plants readily form methane in situ under oxic conditions.
• Observed significant methane emissions from both intact plants and detached leaves.
• Estimated a global methane source strength of 62-236 Tg yr(-1) from living plants and 1-7 Tg yr(-1) from plant litter.

Conclusions:

• Identified a previously unrecognized biological methane source originating from living plants.
• This plant-based methane production has significant implications for the global methane budget.
• The findings necessitate a reconsideration of natural methane sources and their role in past climate change.