Turns Out Fungi are Carbon Fiends

An overlooked network of fungi below our feet are quietly gobbling up tons of carbon, literally

Sep 08, 2023

Hiya!

I used to consider myself a grim reaper for plants, but that’s changed over the last couple of years. Now, I’d say I have a pretty decent green thumb and an impressive plant collection. I enjoy learning about the complexity and magic of plants almost as much as I love caring for them, so when I learned about today’s topic, I just had to share it with you. Granted, fungi aren’t technically plants, but they often have close relationships with them.

Anywho, fungi have been overlooked for centuries, but that’s changed over the last few years. These days, popular and scientific interest in fungi is growing — especially since Netflix released its award-winning documentary Fantastic Fungi in 2019. The more we learn about fungi, the more amazed and curious we become. In addition to all the potential uses fungi inspire, researchers discovered a previously unknown role fungi play in capturing carbon. Turns out, they capture far more than anyone ever dreamed.

Symbiotic Relationships

In a way, we’re only now beginning to truly comprehend just how intensely intricate and complex Nature’s webs are. The more we look, the more connections we find. I mean, we are only alive because plants turn carbon dioxide into oxygen. The same process simultaneously helps regulate the plant’s temperatures by reducing the amount of greenhouse gases in the atmosphere.

Many, if not most, of the connections we find in nature are symbiotic. Diversity, community, and mutually beneficial inter-species cooperation are not only found throughout Nature, but everything depends on it. One such relationship is between plants and fungi.

See, plants capture carbon from the air and use it to make fats and sugars, which they feed to teeny-tiny mycorrhizal fungi growing around their roots. In exchange, the fungi supply the plants with water, nitrogen, phosphorus, and other essential nutrients from the soil. Remarkably, a plant will match the fungi’s appetite. As in, the more carbon dioxide these fungi can gobble up, the more carbon the plant will capture.

This mutually beneficial relationship goes back several hundred million years and helped plants get established on land. Now, plants and mycorrhizal fungi are somewhat co-dependent and would struggle to survive without each other. Yet, we’re only recently discovering their connection.

Toby Kiers, executive director of the Society for the Protection of Underground Networks, a biologist at Vrije Universiteit in Amsterdam, and lead researcher in a study I’ll tell you about later, said,

“Mycorrhizal fungi have been largely overlooked. They represent an incredibly important part of the carbon cycle [and] we are only just beginning to understand how they work. The urgency to understand that and link it to biodiversity below ground is paramount.”

While plants get most of the credit and applause for their carbon-capturing abilities, it turns out that mycorrhizal fungi have a much bigger role and are responsible for capturing way more carbon than previously realized.

Mycorrhizal Fungi

Like photosynthesis aids us and all other oxygen lovers on the planet as a mere byproduct of the plant’s survival design, mycorrhizal fungi’s impact extends beyond providing nutrients to plants and feasting and storing carbon. For instance, a sticky compound created by the fungi helps hold the soil together, thus preventing erosion.

And their usefulness extends beyond their relatively short lifespan of just a few years. Kiers explains:

“This is my favorite part. After they die, they make ‘necromass,’ a dead underground network that acts as a scaffolding to hold the soil together.”

This “scaffolding” not only adds additional support preventing erosion but also locks the carbon safely underground. Incredible, right? As exciting as this news is — and there’s more good news I’ll tell you about soon — there’s one major threat to these awesome fungi and their relationship with plants.

Fertilizers.

Though perhaps not in the way you might first assume. If you’re like me, your first thought is that fertilizers kill off the fungi. But actually, in this case, fertilizers are a bit more like homewreckers breaking up a relationship than committing homicide.

Basically, if a plant can get all its nutrients from fertilizers, then it doesn’t need a relationship with the fungi. As the plants become less dependent on the mycorrhizal fungi, it stunts the growth of the underground fungal matrix — which in turn increases soil erosion and releases carbon once held in the soil back into the atmosphere.

Research shows that fertilized crops send only about a quarter as much carbon underground as native plants. And as we continue to rapidly convert wild lands into agricultural areas, the reduction will only continue.

According to Kiers, another pesky issue we need to watch out for is that fertilizer makes its way into our waterways and rain clouds. So when it rains, the fertilizer literally rains down on plants beyond croplands and hurts wild fungi in the process.

Still, now that mycorrhizal fungi are on our radar, experts are eager to learn more and see if there’s anything else about it that we’ve overlooked — and Kiers and her colleagues found a big one, which they published last June 2023, in the journal Current Biology.

The Study

The international team of researchers wanted a better estimate of how much carbon is pulled from the air and stored below ground due to the symbiotic relationship between plants and mycorrhizal fungi. So, they spent around two years gathering and examining information from 194 distinct data sets worldwide. The data came from massive forests, greenhouses, and handheld petri dishes.

They measured the amount of carbon dioxide each plant took in and the type of mycorrhizal fungi linked with it — then they added them all up and came up with a total of 13.2 gigatons of carbon dioxide. To put this in perspective, the International Energy Agency (IEA) reported a new record of 36.8 gigatons of carbon emissions in 2022.

In the end, the team of global researchers calculated that the long-overlooked underground network of mycorrhizal fungi absorbs about 36 percent of atmospheric carbon dioxide each year. The team also found that plants in a symbiotic relationship with mycorrhizal fungi can suck in eight times more carbon than plants without the fungi. That’s a pretty substantial increase.

Perspective Shift

Fungi are a new and exciting area to explore, and experts aren’t wasting any time. A different team of researchers discovered fungi could be used as eco-friendly fire-proofing materials for buildings and homes — and that’s just the beginning.

Isn’t Nature cool? I mean, it amazes us regardless of how much we know about it. Toddlers become excited by the magic of rain and snow without understanding the complex network of systems Nature created so that it does rain and snow. We can appreciate the beauty of a flower without understanding its medicinal properties or even photosynthesis. But when we do travel down the path of curiosity, seeking to learn more, we undoubtedly enter new levels of Nature’s wonder and end up with even more questions.

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