Methane emission from feather moss stands.

Area of Science:

• Microbial Ecology
• Forest Biogeochemistry
• Methane Cycling

Background:

• Forests are not always net sinks for atmospheric methane (CH₄).
• Specific methane sources and microbial functions within forests are understudied.
• Feather moss stands, known carbon dioxide sinks, lack investigation regarding their role in methane cycling.

Purpose of the Study:

• To investigate methanogenic rates and pathways in feather moss stands.
• To analyze the methanogenic microbial community composition in temperate and boreal forest feather moss.

Main Methods:

• Quantified potential methane emission rates from intact moss stands under aerobic conditions.
• Determined methanogenic potentials under anaerobic conditions, assessing microbial origin and pathways (hydrogenotrophic vs. aceticlastic).
• Analyzed microbial community composition using archaeal 16S rRNA and mcrA gene sequencing.

Main Results:

• Feather moss stands exhibited low-rate methane emission under aerobic conditions (19-133 pmol CH₄ h^-1 gdw^-1), influenced by temperature and water content.
• Active methanogenic archaea (Methanobacteriaceae, Methanosarcinaceae) were identified, producing methane via the hydrogenotrophic pathway.
• Accumulation of ¹³C-depleted acetate indicated fermentation as the source of precursors for methanogenesis.

Conclusions:

• Feather moss stands harbor active methanogenic microbial communities.
• These communities contribute to net methane emission from forests, primarily through hydrogenotrophic methanogenesis.
• This research highlights a previously overlooked source of methane within forest ecosystems.