Bark-dwelling methanotrophic bacteria decrease methane emissions from trees

Emissions of the powerful greenhouse gas methane from both lowland and upland forest trees can be highly significant, yet tree stem emissions are largely overlooked in global methane budgets. A unifying feature of tree stem methane emission is gas transport through the bark medium. However, it remains uncertain whether methanotrophy occurs within the bark, process that may attenuate methane emission. Using multiple lines of evidence, we show that unique microbial communities are dominated by methanotrophs of the genus Methylomonas, mitigating tree stem emission of methane into the atmosphere.