New research suggests trees’ bark, along with their resident microbes, may play a significant role in reducing atmospheric methane, a potent greenhouse gas.
Trees have long been recognized for their ability to sequester carbon dioxide, but the study suggests that their capacity to absorb greenhouse gases more broadly could be roughly 10% higher than previous estimates.
Methane is the second-largest contributor to global warming after carbon dioxide, accounting for roughly 30% of the rise in temperatures since the industrial revolution. Though it is short-lived in the atmosphere, remaining for roughly a decade compared with centuries for carbon dioxide, methane is about 80% more potent as a greenhouse gas.
Swamps and wetlands are known methane emitters. Waterlogged trees can release methane from near the base of their trunks. However, little research has focused on methane and trees growing in well-drained soils — until now.
In the new study, researchers examined trees across the Brazilian Amazon and Panama in the tropics, temperate broadleaf trees in the U.K. and boreal forests in Sweden. They found the most methane absorption in tropical forests and the least in cooler temperate and boreal forests. Methane uptake in the trunks started about 2 meters (6.5 feet) above the forest floor and continued into the branches of some trees.
The researchers attribute the trees’ methane uptake ability to microbes living in their barks. Some microbes, such as bacteria and fungi, consume methane as part of their metabolic process. Before this study, soil microbes were thought to be the only terrestrial sink for methane, but this research suggests tree-dwelling microbes might absorb an amount equal to those in soil. That’s largely because of the sheer volume of trees on the planet. The researchers estimate that if the bark from all the world’s trees were laid flat it would cover the entire land surface of the Earth.
However, “unlike soil, which isn’t changing in area, forests are contracting and expanding through deforestation and reforestation – these changes can influence atmospheric methane,” Vincent Gauci, a professor at the University of Birmingham, U.K., and lead author of the study, wrote in The Conversation.
Gauci added that planting trees in optimal locations and selecting species particularly efficient at removing methane could enhance methane sequestration, a nature-based climate solution that has yet to be fully explored. It’s potentially a boon for the Global Methane Pledge in which countries pledge to reduce their methane emissions 30% by 2030.
This new information could potentially “ease the path to reforestation,” Gauci told Mongabay in a phone call. “This new evidence reinforces the importance of trees and forests for our climate system while demonstrating there is still much to learn about these valuable ecosystems,” Gauci said.
Banner image of researchers courtesy of Vincent Gauci.
Credits
