Ah, the forest. Rich, verdant and vast. Great columns of sentry-like conifers tower over a diverse floor of understory, shrubs, vegetation—all interwoven into the loamy earth by a symbiotic act of trust. Our nation’s southern pine forest stretches from the southeastern coastline to somewhere just west of Bastrop, Texas. From the air, it sprawls hard and inanimate. But once on the ground, from the inside, it’s very much alive and sensitive. When your foot first touches the duff, they know you’re here. A huge network of plants is abuzz, whispering to one another with voices you never hear. While we search for intelligent life throughout our solar system an elaborate society already exists under our feet, a realm known as the rhizosphere. And it’s been here all along, some 458 million years before Homo erectus ever took his first step! As societies go, it’s far more organized and stable than our own.
It’s not that we’ve been clueless all this time; like climate change, scientists have been informing a world that, until recently, refused to take it seriously. Plants communicating with one another? How could that be? They’re just mere plants—without sensation. But it’s true—and it starts with mushrooms!
The history goes all the way back to the 19th century when a German biologist named Albert Frank first discovered a symbiotic relationship between fungal colonies and the roots of other plants. More to the point, it’s the tiny below-ground threads of mushrooms—their root system, if you will—that interconnect with the roots of different plants, even different species. The degree of interconnectedness is such that some researchers say it’s now hard for them to see trees as individual entities anymore!
Fungi have existed on earth almost twice as long as land plants. We have evidence that in past extinction events, fungi not only survived but led the way for new returning life. 250 million years ago an extinction known as the PT Boundary killed more than 90% of life on the planet. Directly after, the fungus Reduviasporonites dominated for hundreds of years without any trees, and in the aftermath, soils were renewed. 65 million years ago, an asteroid impact caused another massive extinction, jettisoning enormous debris into the atmosphere, choking off sunlight. Since fungi do not require light, another fungal explosion occurred. After the 2011 Bastrop County Complex wildfires, what was the first sign of life to appear? It was a bright orange fungus, brilliantly contrasted against charred tree trunks and the ashen forest floor.
So, let’s get familiar with some terminology. Forest mushrooms, which commonly pop up through the leaf litter, are a form of fungi. The above ground portion of the mushroom is the “fruit” of the plant while the mass of thin threads, known as mycelium, is the vegetative part. The word mycelium literally means “more than one,” a plural form of the word mycelia. A mass of mycelium is given the name mycorrhiza, or, for its vast interconnectedness, a mycorrhizal network.
Fungi are the source of most all decomposition that happens on our planet. The filamentous weaving of the mycelial network grows through cell walls of plants and secretes acids and enzymes that break down debris on the forest floor—something akin to an externalized stomach. They digest the material and return carbon, nitrogen, hydrogen, and minerals back into the ecosystem in forms that insects, plants, mammals and many other organisms can use and benefit from. In so doing, the network joins together the four pillars of life on our planet: fungi, bacteria, plants and animals.
Since the 1960’s scientists have learned that fungi help plants locate water and provide certain nutrients through mycelium entangled in their root systems. Like the NYPD, this interlaced system looks out for the welfare of its community by providing protection for the individual trees and plants which make it up. One of the ways it does this is by providing antibiotics (bacteria) which help fight disease. Through a process called “priming,” these antibiotics (and other protective compounds) are stored in the roots and triggered when a plant comes under attack.
Just plugging into the mycorrhizal network makes plants and insects more resistant to disease. Research from Washington State University found that honeybees that consumed mycelium extract had lower levels of harmful virus. Ants figured this out long ago. By farming fungal mycelium in their nests, ants have been using antibiotics to prevent diseases from destroying their homes for some 50 million years. Man has known about antibiotics for less than a century! You can read more about antibiotics and ants in our August 2014 newsletter article, Ancient Farmers (https://txmn.org/lostpines/files/2014/07/LPMN-July-August-2014-newsletter.pdf ).
This protective covenant works in other ways too. In 1983 two studies proved that poplars and sugar maple trees warn each other about worrisome insects. When one tree becomes infested, it warns others which begin to produce a type of chemical insecticide in defense. Not all fungi are helpful. In 2010, Ren Sen Zeng of South China Agricultural University in Guangzhou demonstrated that when plants are attacked by harmful fungi, they release chemical signals into the mycelia that warn their neighbors.
There’s also a maternal component. Older more seasoned trees (“mother” trees) have the most fungal connections. They have deeper root systems and draw water from deeper sources, which is passed on to younger saplings. These village elders detect distress signals from struggling trees and send them needed nutrients—all via mycelium. As a sort of payment for its services, the mycorrhizal network retains about 30% of the sugar that the connected trees generate through photosynthesis. The sugar fuels the fungi, which in turn collects phosphorus and other mineral nutrients into its mycelium, which are then transferred to and used by the trees.
Ecologist Suzanne Simard of the University of British Columbia discovered exchanges of nutrients between Douglas fir trees and paper birches. Without this “help,” she says some seedlings wouldn’t stand a chance. Simard verified in one study that food-strapped seedlings stuck in the shade received carbon from nearby trees to help them along.
Fungus expert Paul Stamets has been studying this system under an electron microscope since the 1970’s, yet it has taken decades of research by him and others to uncover the sheer breadth of the phenomenon. Many of the early scientists were waved off as “wingnuts.” By the late 90’s however, they had proven that trees transfer carbon, nitrogen, phosphorus and other nutrients through this mycorrhizal network. Today, the phenomenon of plant communication is no longer in doubt. In fact, it’s routinely referred to as “earth’s natural Internet” or the “woodwide web.”
But just like the human internet, the fungal internet has a dark side. Plants’ fungal connections mean they are never truly alone, and that malevolent neighbors can harm them. In the search for light and water, for example, some trees (American sycamores, black walnut, sugarberries and others) release toxins to slow the competition in a process known as “allelopathy.” They do this through the network. One plant (phantom orchid) cannot produce its own energy through photosynthesis, so it steals carbon from nearby trees to survive, accessing nutrients through mycelia threads connecting them. Other orchids, known as “mixotrophs,” can photosynthesize but steal from others anyway—when it suits them.
In 2011, chemical ecologist Kathryn Morris grew golden marigolds in containers with mycorrhizal fungi. Half of these containers were designed to stop fungal networks from growing in them. In the containers where the fungi could grow, levels of two introduced harmful compounds were 179% and 278% higher than in cylinders without fungi. It has been theorized that mycelium can also attract bad actors from the animal world. The same chemicals that bring helpful fungi and bacteria to a plant’s roots are thought to also signal worms and other harmful organisms looking for a snack. This theory, however, has not yet been proven.
Today we know that approximately 90% of all land-based plants are connected through the mycorrhizal network. What irony! Do you remember the blockbuster movie Avatar, and its mystical world where all organisms were connected together? Wouldn’t it be magical if, in our own forests, we could see the mycorrhizal network, in its luminosity, all around us, lighting up the pulsing outlines of all forest plants? How much does it understand? Does it, for example, know when the darkness settles in and fireflies spark the summer nights? Does it know when fall is on the horizon and geese are in flight or when the winter dawn is breaking pale?
It all leaves me with more questions. Are plants intelligent? Whatever drove plants to link up in the first place? Do plants have instincts? Do their coordinated actions constitute behavior? Is it possible that fungal networks make up the infrastructure of our ecosystem, the foundational food web, the cellular fabric in which all land-based organisms are nurtured? Bottom line: plants share the essential vibrancy energizing all things in the universe. All life is related.
By Larry Gfeller