Mycorrhizal fungi help a third of all fossil fuel emissions get absorbed into soil

Why it matters: The mycelial underground network of mycorrhizal fungi helps store a huge amount of carbon dioxide in the soil. So much, in fact, that scientists are studying a way to exploit the fungi’s capabilities to mitigate environmental issues brought by greenhouse gases in the atmosphere.

The secret to stop global warming from becoming even more of a disaster than it is today could lie within the symbiotic relationship between mycorrhizal fungi and plants, scientists say. It’s a “living” partnership born 400 million years ago and still thriving to this day, which provides plants with nutrients through the subterranean network of fungal threads known as mycelium.

In exchange for nutrients that are essential to plant growth, fungi take some of the sugars produced through photosynthesis and carbon dioxide for themselves. This plant-fungus relationship has been known for a while, but new research published in Current Biology is providing hard numbers for the potential role of mycorrhizal fungi in removing a significant amount of CO2 from the atmosphere.

Led by Dr. Heidi Hawkins, research associate on plant-soil-microbe interactions at the University of Cape Town, South Africa, the study estimates that each year plants take 13.12 gigatons of carbon dioxide equivalents (CO2e) from the atmosphere and put them into mycorrhizal fungi in the soil. This type of symbiotic fungus is helping store an incredible 36 percent of yearly fossil fuel emissions safely in the ground.

The research is providing a new “awareness” of the potential role that these fungi play in controlling rising CO2 levels, Hawkins said. Much of the focus on global warming has been placed on protecting and restoring forests as a “natural way to mitigate climate change,” Hawkins explained, while little attention has been paid to the fate of the “vast amounts of carbon dioxide” moved from the atmosphere during photosynthesis and into the ground to mycorrhizal fungi.

Mycorrhizal fungi use the carbon compound they get from plants to expand and strengthen their underground mycelial network. Yet, the researchers still have to understand how long the fungi can retain carbon. “While mycorrhizal fungi certainly contain and release carbon into the soil,” Hawkins said, right now we don’t know whether the fungi act as a “carbon store” (keeping the carbon in their body) or a carbon sink (increasing carbon over time).

While more research is needed to study the role of mycorrhizal fungi in the CO2 cycle, the scientists are already suggesting some practical actions like conserving areas known for a high allocation of carbon in the soil thanks to those “specific mycorrhizal associations.” This means that we need to preserve forests and heathlands, just like we have been doing for a while in the most climate-aware parts of the world.