Today was another of those too-rare days that I attack the worsening jumble of my desk in an effort to restore it to a more reasonable state of disorder. As usual while shuffling through the papers I saw two fire-engine-red, polka-dotted mushrooms looking up at me appealingly from a photograph in a magazine article. This time they stopped me. Tempted by that bright photo of fly agaric, Amanita muscaria, I took the pages to my desk and began what became a heady plunge into the inner story of mushrooms, forests, and even my own history.
The story centers on the intriguing fact that fungi and nearby plants, including trees, share in far-reaching underground trade and communications networks that cater to their special needs. My interest in the subject was reawakened by a 2016 Science magazine review article on “underground mycorrhizaldecades networking,” written by Marcel G. A. von der Heijden of the Swiss Institute for Sustainability Sciences and colleagues in Switzerland and the Netherlands.
The details of fungus-assisted networking emerged after a related biological mystery was unraveled in 1937 by an Austrian professor, Hans Molisch. Molisch updated and confirmed ancient theories that some plants produce “herbicide” chemicals that will target intruder plants and cause them to wither. The idea was shrugged off as an intriguing tall story for ages, but in more recent times scientists found evidence that a number of organisms, now including fungi, bacteria, algae and coral, will indeed cooperate with their neighbors.
I remember a childhood fantasy that trees could even think, only they had to do it much more slowly than humans. Imagine my delight, then, when an Internet search led me to an earlier article that, while it did not support my fantasy, it came close to it with a hard-to-resist title, “Plants talk to each other using an internet of fungus,” written in 2014 by the BBC’s Nic Fleming. “Hidden under your feet is an information superhighway that allows plants to communicate and help each other out,” read the subtitle. “It’s made of fungi.” Wow!
The fungus “superhighway” is like a vascular system, spreading out from the relatively tiny mushroom into a web of thin fungal threads (mycelia) that extend far beyond what’s visible above-ground, intertwining with the roots of neighbor plants that could be lettuces or oaks. The plants provide fungi with carbohydrate food and are rewarded with nutrients that include 80 percent of their phosphorus and nitrogen needs. The fungal network also apparently can also strengthen plants’ immune systems — Chinese researchers have reported that some mycelium networks can sense attacks by harmful fungi on “their” plants and transmit chemical warnings to other nearby plants.
Von der Heijden’s paper notes the extensiveness and subtlety that exist in what can be considered as below-ground ecosystems: they are complex and diverse and can move significant amounts of carbon from one tree root system to another. Nic Fleming reported that “the fungal internet exemplifies one of the great lessons of ecology: seemingly separate organisms are often connected, and may depend on each other. . . The wood wide web seems to be a crucial part of how these connections form.”
Cooperation of this complexity, in a plant world that most people consider only as a vast collection of mostly independent individuals, can only strengthen the human admiration of forests. “The true wood, the true place of any kind, is the sum of all its phenomena,” John Fowles wrote in The Tree. Though acknowledged as a brilliant writer he admitted that “What I gain most from nature is beyond words.” Nevertheless woodlands can be described as families so close that, as Priscilla Stuckey writes in her fine review of Fowles’s book, they can be considered “a togetherness of beings.” In the forest, she writes, “the very oldest tree, the Mother Tree, acts as the hub, connected to all, sharing with them what they need to survive. If a Mother Tree is cut down, the other trees fare less well.”
It is easy to accept the scientifically unproven idea that this amazing, quiet, invisible connectivity can be sensed by human beings. Yet forests and individual trees have been selected as sources of metaphysical importance literally for ages – mythology is rich with tree lore. The architecture of the great Gothic cathedrals of Europe have columns that could be imagined as tree-trunks, and fan vaulting reminiscent of treetop canopies. Maybe their architects intended this imitation of nature. Modern fiction borrows the idea of intelligent trees in, for example, the Lord of the Rings and the Avatar films.
In the magazine Nature Peter Fortey agrees that “The forest can behave as a single entity when it yields a great crop of acorns or beechnuts, or lies fallow for a year. Trees share a common response to weather and nourishment.” But, in this review of Peter Wohlleben’s The Hidden Life of Trees, he worries about the inclination to compare plants and woodlands to humans and human activity. While reading the Wohlleben book, Fortey found that, “After a while, the urge to attribute motivation to the behaviour of trees becomes irksome.” There’s a more enthusiastic review, with extracts, in Maria Popova’s excellent blog, Brainpickings.
Personally I like to read metaphysical musings on the plant kingdom. As I read Fowles on woodland connectivity in The Tree, my mind brought back a long-forgotten memory of a morning spent in an old forest near Haslemere, Surrey, on the edge of South Downs National Park. It was a mild late autumn day and after a short walk I sat at the foot of a great beech and felt something special. It was my first time at this particular wood, I was alone, and yet I felt inexplicably at home. Birds and squirrels had finished their morning activities, and now the only sounds came from the occasional skitterings of dislodged leaves and the only smell was the sweet scent of peat. Trees without number were anchored in a sea of russet and gold that continued on forever into the park. For a delectable few minutes I felt, and maybe for a flash I was, part of the forest’s remarkable unity.
So a midden of papers, books, and half-read magazines can be useful after all. Without mine I might never have returned to my thoughts about that other world that exists invisibly yet all around me, whether in English woods or my New Mexico backyard.