It seems mushrooms may be more magical than we thought. Long associated with fairytales and other realms of consciousness, mushrooms are now giving researchers a whole new dimension to explore — under the forest floor. It turns out that what we regarded as mushrooms before are only the pop-up fruits of an extensive underground network – a living system that connects not only fungi across the forest, but trees as well. These connections in turn allow trees to “talk” to each other, constantly exchanging information and even nutrients over this network. How?
Termed “mycorrhizal network”, from the Greek words mykós (fungus) and riza (root), long thin filaments of fungus, termed “hyphae”, intertwine with and penetrate tree roots, creating a functional, extended root system that connects tree to tree and plant to plant. In modern terms, it’s been coined the “Wood Wide Web”, and it’s lit up with nutrients and information being passed between trees and plants. In return, the mycorrhizal network feeds off the tree’s sugars, which allow the hyphae to grow even further. It is estimated that 90% of land plants are connected to a mycorrhizal network, a symbiotic relationship between trees and fungus estimated to be 450 million years old.
This system explains how parent trees can provide nutrients to their saplings to make them stronger, how certain species can poison surrounding trees in order to achieve dominance, and how dying trees can reallocate their resources to healthier trees instead. If a tree is under attack by insects, it can send chemical signals to other trees in warning. The network also passes nutrients from the soil to trees that trees, lacking the necessary enzymes, would not be able to get on their own. In addition, the network can support non-photosynthesizing plants called mycoheterotrophs, which can tap into the network and extract nutrients for their own survival and growth.
With this fascinating new perspective, no longer is the forest just a quiet, restful place. There is a constant buzz of activity hidden beneath our feet, and in some cases, over vast swaths of land.
The largest known mycorrhizal network in the world has been found in the Blue Mountains in Oregon, covering three square miles. And because this network is just a single organism, it’s now considered the largest living organism on Earth – displacing the blue whale, which previously held that position. Taken altogether (if it were possible to dig it all up), the fungus is estimated to weigh between 7,500 and 35,000 tons. That’s a lot of whales – one blue whale on average weighs only 150 tons.
This particular species, the Armillaria, commonly known as the honey mushroom or shoestring mushroom, seems to have a negative relationship with the forest – over time, it slowly kills the pine trees it’s connected to. Baffled DNR scientists and timber harvesters have tried experimenting with other species in hopes of finding one that is impervious to its attack. Of all they have tried, they have found possibly one.
Other researchers have simply accepted this scenario as a natural process that they aren’t going to have much impact on. Nature is doing what nature does – breaking down trees and returning them to the soil. Perhaps there’s a greater intelligence at work here than what scientists can understand or try to change. At the very least, the mycorrhizal network simply has to be regarded as one with the forest.
A plant scientist in England, Merlin Sheldrake, son of renowned scientist Rupert Sheldrake, agrees. Rather than viewing trees as single, independent life forms, the forest can actually be considered a superorganism of trees and the mycorrhizal networks that connect them. He has devoted his work to studying mycorrhizal networks – what he calls social networks – between trees. He was inspired by another plant scientist, E. I. Newman, whose 1988 paper titled “Mycorrhizal Links Between Plants: Their Functioning and Ecological Significance” first gave argument for the existence of mycorrhizal networks.
In other words, it’s only within the past 30 or so years that the existence of mycorrhizal networks has dawned on the consciousness of scientists – so there is still a lot to learn. In fact, understanding these biological social networks may completely change the way we understand forest ecosystems. Already they have changed the way we see them, or rather, picture them in our mind’s eye.
On a trek out to the Epping Forest near London, Sheldrake digs his hand into the soil. He explains that hyphae are almost invisible, the filaments are so fine and thin. Laser technology to scan underground is too crude to pick up on the network too. So in most places, the realm of the mycelial underground largely has to be imagined, and has become another place where science meets art: writer and illustrators alike have done their part to describe and visualize “the kingdom of the gray,” as Sheldrake quotes the writer China Miéville.
Sheldrake is an artist himself, and uses his art to connect to the fungi kingdom in yet another way: by playing accordion in a band, the Gentle Mystics. Reverence of fungi is infused into their musical style, and serves as another way to show his audience a holistic view of the forest.
For Sheldrake, mycorrhizal networks represent mystery and magic. He has specialized in studying mycoheterotrophs, the previously-mentioned non-photosynthesizing plants that plug in to the network without appearing to give anything back to it. One genus he studied in particular, Voyria, is a gentian family member with purple, star-shaped flowers, and may have paid it forward instead – root samples taken from it, along with several others, gave Sheldrake the data he needed to create a stunningly detailed, visual map of the underground network of the Panama island jungle he was studying. Perhaps unsurprisingly, it’s described as “a firework display of meshing lines and colors”.
That’s why, for every clear-cut scientific paper Sheldrake publishes on the Wood Wide Web, he’s also publishing a corresponding paper describing behind-the-scenes work— the Aha moments, happy accidents, and unexpected connections. Science is, after all, about asking questions and being open to the answers, and it may be that studying mycorrhizal networks sheds new light on human networks too.