The Secret Language of Trees

What Is The Secret Language of Trees? How Do They Communicate With One Another and Why?

Table of Contents

The following YouTube video explains the secret language of trees far better than I ever could and I recommend watching it if you want to understand trees and other plants.

For ease and educational reasons I have added the typescript, which I’ve transcribed as faithfully as I can, to help explain the concept and the work of people such as Suzanne Simard and Albert Frank, both pioneers in their time. But to really understand the topic I suggest you watch this 15 minute video from start to finish. It is really worth it .. and I’ve now seen it several times.

Tree roots, the secret language of trees — Trees grow large roots. It’s in their nature! They don’t care about the shape of planting holes

This video is of particular interest to me as it links closely with the work we are doing in our community food forest.

Earth is home to around 1 billion trees that belong to over 60 thousand species and they live on every continent but Antarctica. And while they may seem extremely vulnerable to environmental changes seeing as they can’t get up and leave when the climate no longer suits them, trees have actually been around for close to 400 million years. They’ve survived all four extinction events that they’ve been around for and their ability to break down rocks, create soil, and siphon carbon dioxide from the air and replace it with oxygen is what made our planet habitable for humans.
But however grateful foresters, poets, and lumberjacks might be for their presence, trees have always been a bit difficult to understand. When it comes to finding similarities between trees and animals, there’s not a lot to work with. Trees are immobile, don’t have blood or lymph or nervous systems, and only need sunlight and water to produce their own supply of food. They can live for thousands of years, growing slowly, taller, and wider. One great basin bristlecone pine is over 5,000 years old, and even in a forest, they seem like solitary individuals competing for access to sunlight but otherwise having no interactions with their neighbors.
But as it turns out, there’s more to trees than meets the eye. It was only a matter of looking deeper down to the roots instead of up to the canopy. While we might only see and hear the birds and squirrels filling forests with noise, there’s a vast network of communication happening right under our feet. Trees share resources, pass on warnings, and relay information over the generations, a network of trees talking. It allows the forest to behave as if it’s a single organism and makes scientists rethink the evolution of tree life. Is it based on competition or cooperation, and by understanding this network, we might be able to unlock secrets that will help in our fight against deforestation and climate change as a whole.
On our planet, mutualism is a fundamental part of many organisms’ biology. The clownfish that gets protection from an anemone, the anemone that gets nutrients from the fish, the cleaner wrasse who eats parasites from reef fish, the reef fish staying healthy, the bees that gather nectar from flowers while the pollen stuck to their bodies pollinates it. But perhaps the most widespread and ecologically significant symbiosis is one we can’t see, a partnership between soil fungi and land plants.
In 1885, German botanist Albert Bernard Frank first proposed the idea that plant roots and the fungi around them were working together. In the last century, nearly all of Frank’s major hypotheses have been unequivocally demonstrated. We now know that plant and fungal associations, known as mycorrhizal associations, are present in almost all ecosystems, from deserts to tropical forests, and that about 90 percent of terrestrial plants are connected to some form of mycorrhizal fungi network.
Mycorrhizae are a fungus that grows in association with the roots of a plant in a symbiotic relationship. The most common fungal networks are made of arbuscular mycorrhiza, named for the Latin “arbiscule,” meaning little tree. The threads of this fungi penetrate the root cells of their host and form tiny structures inside them. This is how they interact with the trees and share resources with them. The other major class of fungi are ectomycorrhizal fungi. These fungi form a sheath around the roots of their hosts and grow between the plant cells to exchange nutrients. They have a symbiotic relationship with fewer plants than the arbuscular mycorrhizae, but their hosts tend to be the most economically important trees, as they are often the most widespread trees that we use for timber.
While the two classes of fungal networks belong to very different species, their relationship with the host plants is quite similar. The fungi pick up water and nutrients from the soil, including phosphorus and nitrogen, which are both important for plant growth, and transfer them to their plant hosts. In return, the plants transfer their fungal friends between four and twenty percent of their photosynthate, the sugars they produce by photosynthesizing. This relationship is the backbone of all our forests on Earth, and without it, life on land as we know it may have never emerged.
But in recent decades, scientists have realized it’s not just the individual tree and the fungi that have a relationship. Trees themselves are connected by this intricate, vast network.
The first inkling that trees might actually work together came in a study in the early 1980s. Scientists planted pines side by side in a box in the lab, then inoculated their roots with the mycorrhizal fungi to establish an underground fungal network. Then they tagged the photosynthetic sugars produced by the donor pine with radioactive carbon. They placed photographic film over the side of the root box, hoping to see where the radioactive particles traveled from one plant to the other. When they developed the film, they saw the path that the charged particles had taken, and the path was through the mycorrhizal fungal network, traveling from one tree to the other.
The idea that trees may share resources presented scientists with an evolutionary paradox. Trees have always been known to evolve by competing, not cooperating. Trees grow tall to reach the most sunlight, and their roots branch far and wide to suck up the most water. Those that get shaded or reach less water often don’t survive. If trees of the same species or even of different species shared resources, scientists would need to reconsider their understanding of how trees have evolved. This idea is what got researcher Suzanne Simard excited.
In one of her early experiments, she looked at nutrient exchange between Douglas fir trees and paper birch trees, two different species that grow together in forests and sometimes compete for space and light. She planted fir, birch, and cedar seedlings in a trio, labeled the paper birch with the radioactive isotope carbon-14, and the Douglas fir with a stable isotope, carbon-13. She then covered the fir with a shade tent, reducing the amount they were able to photosynthesize. If the two trees were linked in a mycorrhizal network, cooperating with one another, then the surplus of photosynthetic sugars from the birch should flow into the roots of the fir.
Suzanne Simard found that the birch and fir trees indeed shared resources. In fact, the more shade the fir was covered by, the more carbon-14 it received from the birch, and the cedar did not receive either of the isotopes. Further experiments showed that these two species could share nitrogen and resources in both directions, depending on the season and conditions. These species exist in an alternate feedback system, helping each other when the other needs it, allowing them both to remain healthy.
It’s not just a matter of sharing resources. Other experiments have looked at the chemicals trees produce to signal that they’re being damaged by voracious insects, pathogens, or human activity. One experiment looked at tomato plants connected through an arbuscular mycorrhizal network. When some of the plants were infested with leaf-chewing caterpillars, healthy neighbours activated four defence-related genes within six hours, preparing for the incoming threat. In other words, they knew trouble was coming and were getting ready. These plants fared better, and the caterpillars munching on the second set of plants didn’t grow as large.
There’s also evidence that trees of the same species have some form of kin recognition through their fungal networks. They can identify which trees are most closely related to them and direct more resources toward those trees. These experiments show us that trees aren’t solitary individuals but live in a cooperative harmony with one another. If neighbouring trees die, gaps open up in the protective forest canopy. While more sunlight can boost the remaining trees’ photosynthesis, it also makes them more vulnerable to extreme conditions. If trees of the same species share resources, it allows them to live longer and reproduce more frequently in a stable, healthy forest.
When mother trees, the largest and oldest in the forest, are logged, the forest’s communication network is disrupted. Disease and insect infestations can spread more easily, threatening the entire ecosystem. To maintain a resilient forest, it’s crucial to retain mother trees. This not only nurtures the next generation of trees but also helps in preventing the loss of carbon from the ecosystem. Trees that are part of this network can mitigate the impact of climate change and be more productive, healthy, and diverse.
This knowledge of interconnected trees and their symbiotic relationships opens doors to sustainable forest management and agricultural practices. It’s not only about preserving our forests but also finding ways to apply these principles to other areas, like agriculture. Preserving mother trees and maintaining the connections between trees can help us confront climate change, minimize deforestation, and foster a more eco-friendly future.
Typescript of the Real Language of Trees .. for education purposes.