A recent scientific study has focused on a virtually invisible aspect of forests: the microorganisms that live in the bark of treesFar from being mere passengers, these microbes act as an additional cleaning layer that helps remove greenhouse gases and toxic compounds from the air.
Beyond the well-known ability of trees to capture carbon dioxide (CO₂) through photosynthesisThis finding reveals that the bark functions as a true biological filter. Trillions of microbial cells participate in the elimination of gases such as methane and carbon monoxide. reinforcing the role of forests in the fight against global warming and at the same time improving air quality.
A climate "superpower" hidden in the bark of trees
The research, led by experts from Monash University and Southern Cross University, both in Australia, describes how the cortex houses highly specialized microbial communitiesFor decades, little attention had been paid to its function, even though each tree contains an enormous number of microbial cells on its surface.
The scientific team spent five years taking bark samples in different ecosystems of eastern Australia, from wetlands and high mountain areas to mangrove forestsThey then applied advanced genomic and biogeochemical techniques to identify what these microorganisms are, how they are organized, and what they feed on exactly.
The results show that most of these microbes are specifically adapted to living in treesand that their main source of energy is gases that influence the climate. They not only utilize compounds emitted by the trees themselves, but also gases present in the atmosphere that penetrate the bark.
Among the substrates they consume, the following stand out: methane, hydrogen, and carbon monoxideas well as other volatile compounds. By metabolizing these gases, microorganisms convert potentially harmful molecules into less problematic forms, thus reducing their environmental impact.
This biological process does not replace photosynthesis, but it does complement it. While the leaves capture CO₂, The crust and its microbes take care of other greenhouse gases and pollutants, expanding the range of substances that trees are able to remove from the air.
The planet's "crustal surface": a new climate actor
One of the most striking conclusions of the study is the enormous global dimension of the tree barkIf the surface area of bark from all the trees on the planet were added together, the resulting area would be comparable to the combined area of the seven continents. In other words, there is a kind of "eighth continent" made up entirely of bark.
That gigantic surface functions as a biological reactor distributed worldwidewhere millions of tons of greenhouse gases can be consumed each year. Some of these gases come from within the trunk itself and some from the atmosphere, but in both cases the microbes act as an additional carbon sink.
For researchers, this mechanism implies to rethink the real weight of forests in the global climate balanceUntil now, the emphasis has been almost exclusively on biomass and CO₂ retained in trunks and leaves, but the bark and its microbial communities add another layer of complexity and efficiency to the system.
The exact magnitude of the contribution is still being quantified, but estimates suggest that this microbial activity could be removing pollutants from the air. significant quantities of methane and other gases with high warming powerIn the context of the fight against climate change, any natural process that contributes in this direction takes on special relevance.
This approach also requires a review of certain climate and gas cycle models, which could be underestimating the role of tree-associated microorganismsIntegrating this information would improve the accuracy of projections and allow for the design of more refined mitigation strategies.
Impact on air quality and health
In addition to climate change, the microbes in the crust help address a problem very close to the daily lives of citizens: air pollution in urban and peri-urban environmentsOne of the gases that these organisms are able to use as a resource is carbon monoxide, well known for its toxicity to humans.
Carbon monoxide is a colorless and odorless gas that, in high concentrations, can be dangerous to your healthThe ability of certain bark microbes to consume and transform it reduces its presence in the air, and adds extra health value to the presence of trees in cities and industrial areas.
In Europe, where numerous cities are grappling with recurring episodes of poor air qualityThe protection and expansion of green spaces could benefit from these kinds of findings. It's not just about absorbing CO₂, but also about fostering microbial ecosystems capable of reducing certain local pollutants.
The research suggests that, when planning parks, street tree rows, or reforestation areas near urban centers, it is advisable to take into account Which tree species harbor more efficient microbial communities? when processing harmful gases.
Although the exact relationship between species, bark type, and microbial composition is still being unraveled, experts point out that Not all trees offer the same potential for gas removalThis opens up an interesting line of work for adapting the green design of European cities to both climate and public health objectives.
Microbes, trees and reforestation policies in Europe
One of the ideas that emerges from the study is that, if it were possible to identify precisely which trees concentrate microbes with the greatest capacity to consume greenhouse gasesThey could be prioritized in reforestation and environmental restoration projects.
The European Union is currently promoting programs of mass tree planting and forest restoration as part of their climate strategies. Incorporating the microbial component into these plans would allow for a more precise selection of species and improve the effectiveness of long-term investments.
In countries like Spain, where coexist very diverse ecosystems, from wetlands to Mediterranean forests and mountain areasThe potential to leverage this knowledge is particularly broad. Different types of bark and environmental conditions could favor the presence of microbial communities with complementary functions.
The authors of the paper suggest that the next step will be to catalog the microbial communities of the bark more systematically in different regions of the world, to relate forest types, climate, and gas absorption capacity. This information would be useful for both forest managers and administrations responsible for designing environmental policies.
As more detailed data becomes available, further developments could be made Technical criteria for integrating the microbial factor into tenders, regulations and land-use plansIn this way, the choice of species would not only respond to landscape criteria or drought resistance, but also to their "microbial efficiency".
From basic science to land management
The discovery of this climatic "superpower" of trees is the result of years of basic research in microbiology and biogeochemistrywithout an immediate application in mind. However, the results are beginning to align with current discussions about how to strengthen carbon sinks naturally.
Scientists emphasize that it is not a matter of viewing the crust's microbes as a miracle solution to global warmingbut rather as one more element to add to a broad set of measures. Even so, understanding these processes helps us make better use of the resources that nature already provides.
At the same time, the work highlights the need to preserve mature forests and entire ecosystemsbecause the associated microbial communities take years to form and reach their full potential. The degradation or fragmentation of forests not only affects trees and wildlife, but also disrupts these delicate, invisible balances.
In practice, this type of finding can inspire new ways to integrate science and environmental planningFrom the local scale (design of parks and green corridors) to large-scale forest restoration programs, what was once seen as mere bark is now interpreted as a living tissue with a relevant chemical and ecological role.
Taking into account the combined action of leaves, wood, roots, and associated microbes, forests emerge even more clearly as key natural infrastructures to mitigate climate change, reduce certain air pollutants and strengthen the resilience of European territories to extreme events.
Everything suggests that, from now on, our approach to trees will need to be more detailed: it's not enough to count how many are planted or how much biomass they accumulate, but we should also look at... what happens in that thin layer of crust teeming with microscopic life, which silently acts as an unexpected ally against greenhouse gases.
