Methane is one of the most important greenhouse gases released into the atmosphere by human activity. Trees also emit some of it, and several studies which have analysed these flows in generally cold or humid forest ecosystems have shown a positive balance, i.e. a net emission of methane into the atmosphere.
We already knew that bacteria present on tree bark are capable of intercepting this gas as a source of energy (methanotrophy). New results from a study conducted in different types of forest (tropical, temperate and boreal) have just been published, showing that trees absorb methane on a large scale.
Here are a few key points from the study:
- Some non-submerged forest ecosystems have negative methane flux balances, i.e. a net capture of the gas (methane sink).
- Spreading the bark surface of all the trees on Earth on the ground would cover the equivalent of the Earth’s surface, making it a major methane sink.
- The capacity to absorb methane increases with the surface area of the trunks, and therefore the age of the trees.
- Tropical and subtropical biomes make the greatest contribution to methane capture because the heat favours the activity of methanotrophic bacteria.