Australian researchers co-led by Southern Cross University have discovered a hidden climate superpower of trees. The trees' bark harbours trillions of microbes that help scrub the air of greenhouse and toxic gases.
It's long been known that trees fight global warming by consuming carbon dioxide (CO2) through photosynthesis. But a new study published in Science shows their microbial partners take up vast amounts of other climate-active gases too.
MAIN PHOTO: Johannes Dittmann, a PhD candidate at Southern Cross University, measures methane fluxes in a tropical wetland by using equipment attached to the tree trunk he's standing next to (credit Luke Jeffrey Southern Cross University).
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DR LUKE JEFFREY (VOICEOVER): Trees are among our planet's greatest allies. In drawing down carbon dioxide from the air, they release the oxygen we breathe. They also provide food and habitat for life on Earth. But trees can actually do something far more remarkable than we've previously realised. We often think of bark as just a tree's outer layer, a kind of natural protective armour. But we've discovered that hidden within the bark is an unseen world of microscopic life.
Over five years, collaborative research between Southern Cross University and Monash University has revealed that tree bark hosts abundant and busy microbial communities. Using advanced metagenomic sequencing, we've explored the bark microbial diversity and to see what kind of metabolic tools they possess. We've studied trees in various ecosystems spanning from freshwater wetlands to upland forests, taking flux measurements under different conditions. We discovered that these microorganisms are secretly feeding on important climate active gases. These include methane, a potent greenhouse gas, hydrogen, an indirect greenhouse gas, carbon monoxide, a toxic gas, and a range of other volatile compounds too. Turns out there are trillions of microbes within just a square metre of bark acting like hungry biofilters of the atmosphere around us. This is significant because the global surface area tree bark is similar to the entire terrestrial land surface area of Earth. This suggests trees offer a hidden climate benefit. Beyond capturing carbon, their bark microbiome also helps clean the air of toxic gases whilst reducing greenhouse gases, too.
Our ongoing and exciting research is now exploring which tree species, which conditions, and what ecosystems are most effective at doing this. This knowledge may eventually guide forest management, conservation, and climate change mitigation strategies. Thanks to our ongoing research collaboration between Southern Cross and Monash University, we're only just beginning to understand how deeply trees and their bark microbial communities within help support life on Earth.
The study, conducted primarily by Dr Luke Jeffrey at Southern Cross University's Faculty of Science and Engineering and Dr Bob Leung at Monash University's Biomedicine Discovery Institute (BDI), rewrites our understanding of how trees and their resident microbes shape the atmosphere.
"Each tree hosts trillions of microbial cells in its bark," said Dr Leung, a co-first author. "Yet their existence and roles have been overlooked for many decades until now."
The researchers spent five years sampling trees across eastern Australia, including wetland, upland, and mangrove forests*. The sites were located just south of the Gold Coast within the Tweed Shire, particularly the wetland and upland forests between Cabarita and Pottsville.
The team then used advanced genomic and biogeochemical techniques to determine, for the first time, the identities, capabilities and activities of the microbes living in their bark.
"Remarkably, most of these microbes are tree-adapted specialists that feed on climate-active gases," Dr Leung said. "They consume methane, hydrogen, carbon monoxide, and even volatile compounds released by the trees themselves."
Dr Jeffrey, also a co-first author, said the scale of this hidden process was 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. "This microbial activity across this massive 'bark continent' is potentially removing millions of tonnes of climate-active gases every year.
"These gases can come from the atmosphere or from within tree stems. By consuming these unwanted gases, microbes in bark are essentially cleansing our air and enhancing the benefits of trees in multiple ways."
Professor Chris Greening from Monash's Biomedicine Discovery Institute, who co-led the study with Southern Cross University's Professor Damien Maher, said there was much long-term potential to use these findings for climate action.
"We now know different trees host different microbes," Professor Greening said.
"If we can identify the trees with the most active gas-consuming microbes, they could become priority targets for reforestation and urban greening projects."
Professor Greening added that the discovery could benefit both climate and human health.
"In addition to being a climate-active gas, carbon monoxide is also a toxic air pollutant. Tree microbes are helping scrub it from the air and so improve air quality," he said.
Equipment attached to the trunk of a Melaleuca tree stem, located along the Tweed Coast, to measure gases (credit Luke Jeffrey Southern Cross University).
Professor Damien Maher of Southern Cross University said there were many more discoveries to be made in this research area.
"This research is really the tip of the iceberg in terms of expanding our understanding of how trees and microbes interact," he said.
"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."
*The tree species included paperbark (Melaleuca quinquenervia), Swamp box (Lophostemon suaveolens) and Swamp oak (Casuarina glauca) from freshwater wetland forest; Banksia (Banksia integrifolia) and Golden wattle (Acacia longifolia) from coastal heath forest; Mangrove (Avicennia marina) from mangrove forest; Grey ironbark (Eucalyptus siderophloia) and Grey Gum (Eucalyptus propinqua) from upland forest.
Study details
'Bark microbiota modulate climate-active gas fluxes in Australian forests' by P. M. Leung and L. C. Jeffrey et al, Science 391, eadu2182 (2026)
Published in Science
