Within the natural environment, the aboveground world tends to draw the most attention. But threading through the ground in forests and habitats alike are complex, interconnected networks of fungi. A largely unknown function of fungi is its intimate relationship with forests, a system which allows trees to share resources, water and even communicate with each other. This system is known as the Mycorrhizal network, made from threads of fungal mycelium that connect tree to tree. 

Let’s give a quick rundown of what fungi actually are. While mushrooms are typically the first thing people think of when fungi are mentioned, they are actually only a small part of the fungal organism. They function similarly to fruit in trees. The mushrooms sprout up aboveground, eventually opening and spreading spores throughout the ecosystem. These spores can take root and create new fungi. The part of the fungus that is hidden underground is known as mycelium. It is composed of small branching threads that can bore into tree roots, connecting trees to one another. 

These Mycorrhizal networks are key parts of the forest ecosystem. They are especially helpful for the establishment of young saplings, which do not have as much access to the sun. Surrounding trees can give them the nutrients they need to survive. More established trees, known as “hub trees,” can help less established trees. Trees are more likely to share resources with members of their same species and there is evidence that trees can even recognize and help out their offspring. The networks also allow trees to send and receive distress signals, alerting other plants of potential threats. Imagine you’re a tree being attacked by an insect herbivore. What do you do? You warn your fellow trees of the threat through the Mycorrhizal network to alert them to begin producing chemicals that deter these insects.

So what do the fungi get in return? Trees supply the organisms with carbon-rich sugars that are derived from photosynthesis. In return, the fungi act as a network and provides trees with scavenged nutrients. 

Beyond being important for the health of forest ecosystems, the Mycorrhizal network is also a large carbon sink. It processes and uses carbons produced by trees, keeping this carbon out of the atmosphere. Currently, the Mycorrhizal network’s biggest challenges are deforestation and pesticide use. 

Much is still unknown about these underground communication systems. They are incredibly complex and widespread, and so much more is yet to be discovered. The Radiolab podcast “From Tree to Shining Tree” introduced me to the topic of fungi. I would highly recommend this episode to anyone who wants to learn more about this fascinating subject.