Scientists are uncovering a hidden ally in the fight against climate change and air pollution: the microscopic communities living on tree bark. Far from being an inert shield, bark turns out to be a bustling habitat where microbes feed on greenhouse and toxic gases, quietly scrubbing the air around us.
By revealing how these organisms consume methane, carbon monoxide and even hydrogen, recent research suggests that forests are doing more atmospheric cleanup than their leaves and trunks alone can explain. I see this work as a fundamental shift in how we think about trees, from passive carbon stores to complex, living systems whose bark microbiomes are active players in the climate system.
The hidden ecosystem living on bark
For decades, climate models have treated tree bark as a surface, not an ecosystem. That view is now being overturned by evidence that bark hosts trillions of specialized microbes that form dense, structured communities. These microbes occupy tiny crevices and films of moisture on the bark, where they encounter a steady flow of trace gases diffusing out of the atmosphere and from inside the tree itself, creating a kind of microscopic marketplace of energy sources.
Researchers working with Jan have shown that these bark-dwelling organisms are not just present, they are metabolically active and diverse, including bacteria that can use methane, carbon monoxide and hydrogen as fuel. One team described how tree bark hosts trillions of such microbes that actively remove greenhouse and toxic gases, indicating that the outer skin of trees is a far more dynamic interface with the atmosphere than previously assumed.
Microbes that eat methane, carbon monoxide and hydrogen
The most striking discovery is that many of these bark microbes are methane eaters. Methane is a potent greenhouse gas, and I find it significant that microbial communities on trunks can oxidize it before it escapes into the wider atmosphere. Studies linked to Jul have shown that upland tree woody surfaces act as a sink for atmospheric methane, with microbes in the bark using specialized enzymes to convert methane into carbon dioxide and biomass, effectively shaving off part of the gas’s warming potential.
Detailed analyses of bark samples reveal that these methane oxidizers sit alongside microbes that consume other trace gases. In particular, scientists have identified bacteria that oxidize carbon monoxide and hydrogen, expanding the range of pollutants that bark can help remove. One investigation reported that microbes that oxidize carbon monoxide were abundant in bark, while another line of work described how bark microbes eat gases such as methane and hydrogen out of the atmosphere, as highlighted in coverage of bark microbes that eat gases.
From lab experiments to real trees in the field
To move beyond petri dishes, scientists have turned to live trees, measuring how gases move in and out of bark in real time. I see this as a crucial step, because it tests whether the microbes are actually influencing the atmosphere rather than just showing potential in controlled conditions. Using chambers strapped to trunks, teams working with Jan have tracked fluxes of methane, carbon monoxide and hydrogen, comparing bark sections with different microbial communities and environmental conditions.
The results indicate that bark microbes do not simply sit idle on the surface, they actively pull gases out of the air. One set of experiments in live trees measured the movement of gases through bark and showed that specific microbial “jobs” were happening in real time, while another report on hidden tree bark microbes described how different trees and sites showed different amounts of trace gas uptake, reinforcing the idea that this is a widespread but variable process.
How much methane can bark really remove?
The natural question is scale: are these microbial clean-up crews a curiosity, or do they matter for the global methane budget? Early estimates suggest the impact is far from trivial. Work summarized under Jul indicates that upland tree woody surfaces, including bark, contribute a measurable share of global atmospheric methane uptake, challenging older models that focused mainly on soils. In parallel, researchers have argued that trees and their microbes absorb millions of tons of methane each year, implying that forests are more deeply woven into the methane cycle than previously recognized.
One analysis of microbes in tree bark concluded that trees and their microbes absorb millions of tons of methane each year, while a separate line of research on trees that reveal a climate surprise reported that microbes living in tree bark are significant consumers of atmospheric methane. I find it telling that these independent efforts converge on the same message: bark microbiomes are not a rounding error, they are a meaningful sink that climate models will need to incorporate.
Rethinking forests, reforestation and climate policy
These discoveries force a rethink of how I, and many policymakers, have viewed forests in climate strategies. Until now, trees have been valued mainly for the carbon they store in wood and soils, and for the shade and moisture they provide. The new work suggests that the microbial layer on bark adds a separate service, continuous removal of methane, carbon monoxide and hydrogen from the air, which could change how we prioritize species, forest structure and even urban planting schemes.
Scientists working with Jan and DOI have argued that this will change the way we think about trees, because it reveals a second, microbial pathway by which forests shape the atmosphere. One detailed explanation of global possibilities notes that bark microbes could be harnessed in reforestation efforts, while a related report from Jan on microbes in tree bark emphasizes that there are trillions of these organisms and that resident microbes shape the atmosphere. As researchers share these findings in venues such as the Jul presentation on global atmospheric methane uptake, I expect forest policy to gradually shift, treating bark microbiomes as a strategic asset in both climate mitigation and air quality management.
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