Fungi are one of the most steadfast forms of life on earth. They are biologically distinct from both animals and plants, containing features of both. Fungi can only move by growing larger, but can’t convert sunlight into food, so aren’t plants. They consume carbon-based foods, but can’t move independently, so aren’t animals.
They’re a truly fascinating life form with many incredible properties, and they may also be key to protecting our planet.
Many know mushrooms as a food source that can be both found in shops and easily foraged. They’re known as sustainable crops because growers convert byproducts and waste from other agricultural sectors into the compost or medium used to grow mushrooms. Mushroom farms, therefore, usually have a smaller environmental footprint than almost any other farm.
Beyond this, mushrooms also require minimal energy or water inputs. Growing one pound of mushrooms only generates 0.7 pounds of CO2 equivalents (in comparison, using one gallon of fuel in the US emits nearly 20 pounds). They also don’t require much land, with one acre able to produce 1 million pounds of mushrooms, and they can be grown year-round.
But this isn’t the only benefit of fungi. In fact, they can help us in many ways.
Keeping plants alive
In particular, a type of fungi called mycorrhizal fungi is critical to ecosystems. A mycorrhiza is a mutually beneficial relationship between a fungus and a plant, and it refers to the role the fungus plays in the plant’s root system (also known as its rhizosphere).
The word mycelium also refers to the fine, fibrous roots you may have seen from mushrooms. These intricate root systems form the mycorrhizal networks, stretching between plant roots and into the soil. There are two main types of mycorrhiza: ectomycorrhizae and endomycorrhizae. Ectomycorrhizae are fungi that don’t penetrate their host’s cell walls, instead their mycelium (roots) form a crisscrossed pattern-like structure around the plant’s roots. As the plants gather energy from the sun through photosynthesis, carbohydrates and nutrients are passed to the fungus. In return, the fungus gives the plant water and minerals from the soil.
Mycelium feeds the fungi growing from them and supplies fresh nutrients to surrounding plant life, while also cleansing the soil of toxins. During the winter, when daylight is reduced, some plants depend on fungi for sugars, nitrogenous compounds, and other nutrients that the fungi can absorb from waste materials in the soil. Fungi essentially keep these plants alive and, in places like lowland forests where mycorrhizal fungi are abundant, create sprawling mycelial networks that connect trees so they can exchange nutrients and chemical messages.
Beyond keeping plants healthy, the presence of these fungi has a large impact on carbon sequestration. Recent research found that, while any forest can absorb CO2, some forests are much better at it than others due to which mycorrhizal fungi are present in that forest’s microbiome. Trees form partnerships with many different root fungi, but ectomycorrhizal fungi, in particular, help trees absorb CO2 even faster.
It was previously thought that carbon was stored in forest floor waste such as dead leaves, but this research found that large amounts of carbon are stored within soil thanks to these complex root networks.
Plants sequester carbon from the air for photosynthesis, sharing some of that carbon with fungi, while fungi break down minerals in the soil that would otherwise be inaccessible to plants, providing essential nutrients such as nitrogen, phosphorous, and potassium.
The incredible thing is that ectomycorrhizal fungi behave in strategic ways, offering more minerals to plants that offer them more carbon. In return, plants will offer more carbon to fungal species that offer them more necessary minerals. This essentially means that the more ectomycorrhizal fungi in soil, the more carbon sequestered.
Thanks to fungi there’s twice as much carbon locked in the ground as in the atmosphere. One square meter of healthy soil can contain 12,000 miles of tangled fungi filament.
“So essentially the more fungi grow in soil, the more carbon dioxide [that] can be drawn out of the atmosphere”
Ectomycorrhizal fungi can also slow decomposition, keeping carbon locked in the ground for longer (this is similar to blue carbon systems, which store larger amounts of carbon as material decays more slowly), and helping soil retain moisture.
Some scientists have stated that fungal mycelium is the largest repository of biological carbon in healthy soils.
When plants pull in CO2, this carbon becomes part of the soil when the plants die and decompose. The rate at which CO2 leaves the soil can have a huge impact on emissions.
Researchers from the University of Texas, Boston University and the Smithsonian Tropical Research Institute profiled more than 200 soil composites from around the world, finding that soils dominated by ectomycorrhizal fungi (which don’t penetrate their host’s cell walls) contained up to 70% more carbon than soils dominated by endomycorrhizal fungi (which do penetrate their host’s cell walls). This is because the ectomycorrhizal fungi extract nitrogen much more efficiently and quickly. They essentially outcompete the microbes living in the soil, slowing their ability to decompose dead plant matter and keeping carbon in the ground.
Unfortunately, ectomycorrhizal fungi aren’t the most common fungi, only forming in the roots of around 2% of plant species (compared to 85% of plant families for endomycorrhizal fungi). Ectomycorrhizas can usually be found in the roots of woody plants like birch, beech, willow, pine and rose.
This means that, beyond focusing on reforestation, conservation efforts must also focus on cultivating fungi and healthy soil to increase carbon sequestration.
For example, Chile became the first country in the world to include the Fungi Kingdom in its environmental legislation. This allows Chilean fungi to be included in the study and evaluation of environmental impacts throughout the country as well as the country’s environmental protection laws. This is something we need to see replicated across the world.
Nature-Based Solutions (NBS) to climate restoration should, therefore, not only focus on what we humans can see above the ground, but also make sure that the fungi-infused sub-surface ecosystem is healthy as well. Doing so will allow forests and grasslands to be restored more quickly and sequester more carbon dioxide in the process.
“Wherever it says ‘flora and fauna’, we need it to say ‘flora, fauna and funga’ – it’s the third F,” she said. “And wherever it says ‘plants and animals’ in any regulation it should say ‘plants, animals and fungi’.
Cleaning up waste
Fungi are also nature’s recyclers, with different species able to eat a variety of things. They can clean up contamination in the environment through a process called mycoremediation, where they absorb radioactive contaminants and heavy metals, while studies show that mycelium can degrade plastic (thanks to a fungus found in the Amazon). According to 2018’s State of the World’s Fungi report, this mushroom can grow directly on the surface of plastic and can break down the material.
Plus, fungi can even take on crude oil.
In a 2008 TED talk, Paul Stamets discussed an experiment where mycelium spores were put on diesel and petroleum waste spill. The spores absorbed the pollution and sprouted oyster mushrooms, which attracted insects, which brought birds that dropped seeds, and “our pile became an oasis of life,” Stamets said. “These are gateway species, vanguard species that open the door for other biological communities.”
A researcher at the Netherlands Institute of Ecology also found that inoculating unproductive land with fungi-rich soil from an established ecosystem will help land becomes productive, as it starts imitating the ecosystem from which the soil was transplanted. Zurich’s Crowther Lab confirmed these findings, learning that certain species of fungi were associated with a three-fold increase in tree growth in the wild. This research could be vital to ensuring reforestation and rewilding is successful in future.
Finally, scientists have discovered a mushroom extract that could provide immunity to bees threatened by infectious viruses.
“Our work showed that feeding bees mycelium-extracts of some polypore mushrooms reduced pathogenic viruses hundreds to thousands of times in less than two weeks,” he says. “These viruses threaten worldwide food biosecurity. And the extracts from polypore mushrooms have also been shown in the laboratory to reduce viruses pathogenic to other animals, including humans.”
But that’s not all. Fungi also hold a lot of potential when it comes to materials.
Recently student Katy Ayers in Nebraska built a fully functional canoe from mycelium. Emissions from the construction industry and built environment are significant (cement alone accounts for 8% of global CO2 emissions) but mycelium offers an alternative. Their web-like filaments act as a natural binder, growing to form huge networks by digesting nutrients from agricultural waste while bonding to the surface of the waste material. They act as a natural self-assembling glue, with the entire process using biological growth rather than expensive, energy-intensive processes. This also makes it possible to upcycle agricultural waste into alternative materials that are more sustainable, biodegradable and cheaper while also having good thermal and fire-resistant properties.
The US-based company Ecovative Design has also made a packaging material from mycelium, while research suggests they could be used for everything from building insulation to furniture to a replacement for plastics, styrofoam and even concrete blocks. All of these developments are still in very early stages but hold major potential.
But, of course, fungi need protection, particularly from nitrogen pollution. Burning fossil fuels doesn’t just emit CO2, but also nitrous oxide gas, which eventually rains down as nitrogen pollution. Plus, nitrogen fertilisers used in industrial agriculture also blow into neighbouring ecosystems or run off into water systems.
Trees partnered with ectomycorrhizal fungi are extremely sensitive to nitrogen. Research found that forests exposed to high levels of nitrogen pollution have far fewer trees that harbour ectomycorrhizal fungi, which directly results in a loss of carbon from these carbon soils and accelerates climate breakdown.
We were truly surprised that small changes in microscopic soil fungal communities (the forest microbiome) can lead to landscape-level changes in where different forests are, detectable at the scale of an entire continent. While our study only considered forests in the United States (because this is where scientists have the most forest data), these findings have implications for forests all over the world.
As countries transition away from fossil fuels nitrogen pollution will decrease, creating a double win from a just transition as it will also restore ectomycorrhizal forests and help them store more carbon. However, nitrogen pollution is on the rise in parts of the world burning more fossil fuels. A global effort towards a swift, just transition to renewable energy, alongside technology that removes nitrous oxide from current fossil fuel emissions and a shift towards regenerative agricultural practice and away from artificial nitrogen application, will all help. In turn, more carbon is stored, biodiversity flourishes, and the power of fungi can continue to be explored.
How to learn more
If you want to learn more, here are a few places to start.
- Watch the film Fantastic Fungi
- Read Mycelium Running: How Mushrooms Can Help Save the World
- Follow The Fungi Foundation, the world’s first NGO dedicated to fungi who are also committed to learning more about how Indigenous people have used fungi for generations. Their Fungi Foundation Elders programme is mapping every known ancestral and traditional use of fungi in the world.