The natural world is full of wonders. Walking around the forest, many of these wonders are in plain sight, but one of the most fascinating secrets of the forest is out of sight, beneath our feet. Below ground, extensive and intricate networks of fungal organisms connect the forest. The mycelium and mycorrhizal networks transfer water, nutrients, and information between trees. These networks are a key part of the forest ecosystem and help our forests thrive.
What are mycelium and mycorrhizal networks?
The part of a fungus we’re familiar with — the mushroom — only makes up a small part of the organism. The majority exists below ground in the form of mycelium. The mycelium is made up of tiny threads that bore into tree roots and grow into large networks. These networks are called mycorrhizal networks, from the Greek words for fungi (myco) and root (rhiza).
Through these networks, trees in the forest exchange water and valuable nutrients with one another. They have a symbiotic relationship with the fungi, which retain some carbon and sugars for their own growth. There’s even research to suggest that trees are able to communicate with each other through these mycorrhizal networks.
How do mycorrhizal networks function?
Studies have shown that trees living near one another transfer water and nutrients to one another through mycorrhizal networks. The older, more established trees in the network are called “hub trees” or “mother trees.” Their roots go deeper into the soil, which means they have access to even more resources to pass to other trees. Research also shows that trees “talk" to each other by sending chemical signals through mycorrhizal networks. They can send and detect distress signals, and send resources to trees in need.
There’s still much that we don’t know about the mechanisms of mycorrhizal networks. Many have characterized the way that trees communicate and share through the networks as kind and charitable, but some researchers have pointed out that there could be more of a competition element. For example, trees are more likely to share resources with other trees of the same type. This suggests that one reason trees use the network is to promote the survival of their own species. There are trees that share resources with other species, but only if they are part of the same mycorrhizal network.
How do these mycelium and mycorrhizal networks benefit the forest?
Mycelium and the mycorrhizal networks that they create are integral to a healthy forest. Learn more about their benefits
They’re good for tree health
It was previously believed that trees created all of their food through photosynthesis. However, research on the mycorrhizal networks revealed a woodwide web through which trees pass and receive water, carbon, sugar, and other valuable nutrients. If a tree has additional resources that it doesn’t need, they are absorbed by the mycelium at its roots. A tree in poor health can then access those excess nutrients through the mycelium network.
They promote the growth of new trees
The sharing of resources can be particularly beneficial for young trees. Saplings in the understory have limited access to sunlight, an essential part of photosynthesis. In the absence of enough light, mycorrhizal networks allow saplings to receive food from established trees with plenty of access to sunlight.
They help protect trees from threats
Chemical signals that trees send through the mycelia help protect against threats. If a tree is being attacked by an invasive species, pest or disease it may send out distress signals and information. For example, in the case of insect herbivores, trees can produce chemicals that are harmful to the pests, or compounds that will attract their natural predators.
They play an important role in processing carbon
Soil is a natural carbon sink, similar to plants and oceans. Mycorrhizal networks process carbon that is brought in by trees. They capture large amounts of carbon and retain it in the soil. Keeping more carbon out of our atmosphere.
Why do mycorrhizal networks need to be protected?
It’s clear how fundamental mycorrhizal networks are to forest health. Sadly, changes to environments largely driven by humans pose a threat to their existence. Deforestation and chemical pesticides can all severely damage and disrupt mycorrhizal networks. This has a knock-on effect on all the trees and wildlife in the surrounding area. And of course, it hampers the networks’ abilities to absorb carbon. This is just another reason why it’s so important to nurture and protect our forests.
Next time you’re in the forest, take a moment to think about the amazing mycelium network beneath your feet. Amidst the peace and quiet, the forest floor is a hive of activity, working hard to make the forest the beautiful place it is. Take a breath and appreciate this natural wonder that’s sustained our forests for thousands of years and will continue helping them thrive in years to come.