Australian researchers have uncovered a vast, invisible ecosystem living in tree bark that helps clean the air of climate-warming and toxic gases. The discovery could reshape how cities and countries plan tree planting for both climate and health.
Australian scientists have uncovered a hidden climate ally living just beneath the surface of the world’s forests: trillions of microbes packed into the bark of every tree, quietly scrubbing the air of harmful gases.
The discovery, published in the journal Science, suggests that trees do far more for the planet than simply absorb carbon dioxide through photosynthesis. Their bark-dwelling microbes also remove other powerful climate-warming and toxic gases from the atmosphere, potentially boosting the climate benefits of forests and urban trees.
Researchers led by Monash University’s Biomedicine Discovery Institute and Southern Cross University spent five years sampling trees across eastern Australia, from freshwater wetlands and coastal heath to mangroves and upland forests. They then used advanced genomic and biogeochemical tools to identify the microbes living in bark and measure what they are doing.
They found that the bark of every tree is teeming with microscopic life.
“Each tree hosts trillions of microbial cells on its bark,” co-first author Bob Leung, a research fellow in the Monash Biomedicine Discovery Institute, said in a news release. “Yet their existence and roles have been overlooked for many decades until now.”
These microbes are not just passive passengers. The team showed that many of them are highly specialized for life on trees and are actively feeding on gases that affect Earth’s climate.
“Remarkably, most of these microbes are tree-adapted specialists that feed on climate-active gases,” Leung added. “They consume methane, hydrogen, carbon monoxide, and even volatile compounds released by the trees themselves.”
Methane and hydrogen are important climate-active gases, while carbon monoxide is both climate-active and a toxic air pollutant. By using these gases as food, bark microbes effectively turn tree trunks and branches into living filters that clean the surrounding air.
The scale of this hidden process is enormous. Co-first author Luke Jeffrey, a research fellow at Southern Cross University, noted that when you add up all the bark on all the trees on Earth, the surface area is staggering.
“Counting all trees on Earth, the total global surface area of bark covers an area roughly the same as all seven continents combined,” he said in the news release. “This microbial activity across this massive ‘bark continent’ is potentially removing millions of tonnes of climate-active gases every year.”
Those gases can come from the atmosphere or from inside the tree itself. As they are consumed by microbes in the bark, the air around forests is effectively being cleansed, adding a new layer to the climate and health benefits of trees.
The team studied a range of Australian species, including paperbark, swamp box, swamp oak, banksia, golden wattle, mangrove, grey ironbark and grey gum. Across these diverse forests, the researchers found rich and varied microbial communities, suggesting that different tree species host different microbial partners with different abilities.
That variation could become a powerful tool for climate planning.
Chris Greening, a professor in the Monash Biomedicine Discovery Institute who co-led the study with Damien Maher, a professor at Southern Cross University, sees major potential in using this new knowledge for climate action.
“We now know different trees host different microbes,” Greening added. “If we can identify the trees with the most active gas-consuming microbes, they could become priority targets for reforestation and urban greening projects.”
That would allow planners to design forests and green spaces not only for shade, biodiversity and carbon storage, but also for their ability to clean the air of multiple pollutants.
Greening added that the discovery could benefit both climate and human health. Carbon monoxide, for example, is a dangerous pollutant produced by vehicles, fires and some industrial processes. Microbes that remove it from the air could help reduce exposure in and around forested and urban green areas.
For public health and environmental policy, the findings open up a new dimension. Trees have long been promoted as a natural solution to climate change because they lock away carbon dioxide in their wood and leaves. This research suggests that their bark microbiomes add another, previously uncounted service: removing other gases that warm the planet or harm human lungs.
The work also highlights how much remains unknown about the living networks that support Earth’s climate.
“This research is really the tip of the iceberg in terms of expanding our understanding of how trees and microbes interact,” added Maher. “The diversity of microbes that we found living in the bark of these trees suggests that we may need to rethink how trees and forests control Earth’s climate now and into the future”.
Future studies will likely explore which tree–microbe partnerships are most effective, how these communities respond to pollution and climate stress, and how land managers might protect or enhance them. For students and young scientists, the findings underscore that even familiar landscapes still hold big surprises.
From a distance, a forest may look like a collection of trunks, branches and leaves. Up close, this research shows that every tree is also a skyscraper for microscopic life, with bark surfaces stretching across a “bark continent” that rivals all seven continents combined. As the world searches for scalable, nature-based climate solutions, those tiny residents of tree bark may prove to be some of the planet’s most important, and previously invisible, helpers.
Source: Monash University