In 1854, Henry David Thoreau published Walden, an extensive rumination on his two years, two months and two days spent in a cabin in the woodlands near Walden Pond. It was situated on a plot of land owned by his friend, mentor and noted transcendentalist Ralph Waldo Emerson.
Thoreau’s escape from the city was a self-imposed experiment – one which sought to find peace and harmony through a minimalistic, simple way of living amongst nature. Voicing his reasons for embarking on the rural getaway, Thoreau said, “I went to the woods because I wished to live deliberately, to front only the essential facts of life.”
Walden cemented Thoreau’s reputation as a key figure in naturalism; his reflections have since been studied, his practices meticulously replicated. But in the knowledge that Thoreau’s excursion into the woods was a means to better understand how to integrate into society, curious minds are left to wonder what essays and aphorisms Thoreau would have produced had he known what the botanists of today know of nature’s very own societal networks.
As scientists have now discovered, what lies beneath the ground Thoreau walked upon, and indeed beneath the ground anyone walks upon when near trees, is perhaps the most storied history and study of collaborative society in something which is now known as the mycorrhizal network or the “Wood Wide Web”.
Coined by the journal Nature, the term Wood Wide Web has come to describe the complex mass of interactions between trees and their microbial counterparts underneath the soil. Spend enough time among trees and you may get a sense that they have been around for centuries, standing tall and sturdy, self-sufficient and independent. But anchoring trees and forestry everywhere, and therefore enjoining them into an almost singular superoganism, is a very intimate relationship between their roots and microbes called mycorrhizal fungi.
Understanding the relationship between the roots of trees and mycorrhizal fungi has completely shifted the way we think about the world underneath them. Once thought to be harmful, mycorrhizal fungi are now known to have a bond of mutualism with the roots – a symbiotic connection from which both parties benefit.
Despite the discovery being a recent one, the link between the two goes as far back as 450 million years. A pinch of soil can hold up to seven miles worth of coiled, tubular, thread-like fungi. The fungi release tubes called hyphae which infiltrate the soil and roots in a non-invasive way, creating a tie between tree and fungus at a cellular level. It is this bond which is called mycorrhiza. As a result, plants 20m away from each other can be connected in the same way as plants connected 200 metres away; a hyphal network forms which brings the organisms into connection.
At the heart of the mutualistic relationship is an exchange; the fungi have minerals which the tree needs, and the trees have carbon (which is essentially food) which the fungi need. The trees receive nitrogen for things such as lignin – a component which keep the trees upright, and various other minerals such as phosphorus, magnesium, calcium, copper and more. In return, fungi get the sugars they need from the trees’ ongoing photosynthesis to energise their activities and build their bodies. The connection runs so deep that 20-80% of a tree’s sugar can be transferred to the fungi, while the transfer of nitrogen to trees is such that without the swap, trees would be toy-sized.
It’s a bond that has resulted in some remarkable phenomena. Suzanne Simard, an ecologist at the University of British Columbia, has researched into these back and forth exchanges and has found that rather than competing against one another as often assumed, there is a sort of teamwork between the trees facilitated by the mycorrhizal fungi.
In one particular example, Simard looked at a Douglas fir tree planted next to a birch tree. Upon taking the birch tree out, there was a completely unexpected result: the fir tree – instead of prospering from the reduced competition for sunlight – began to decay and die. The trees were connected underground via the mycorrhizal system, transferring carbon, nitrogen and water to one another, communicating underground, talking to each other. As Simard says in her TED talk, “it might remind you of a sort of intelligence.”
It has been documented that trees share food not just with trees of the same species, but with trees of all kinds of species, forming a social network which some have come to describe as a socialist system. Growth rates are positively affected while seedlings face greater chances of survival. There is in fact a group of plants – the mycoheterotrophic plants of which there are around 400 species – which wouldn’t survive without the mycorrhizal network. These plants are unable to photosynthesise and are therefore heavily dependent on other plants for carbon and minerals.
Over the years, Thoreau has had his fair share of critics who deemed his trip to the woods nothing more than an exercise in self-indulgence and narcissism. Perhaps if Thoreau had the chance to head back to Walden Pond with the knowledge of the Wood Wide Web at hand, he would fully understand that no one man is an island, as no one tree is a forest.