Forest Wisdom, Mother Trees and the Science of Community

Forests have long occupied a fertile landscape in the human imagination. Places of mystery and magic – of wildness and wisdom – of vision and dreaming. Yet beyond mythic realms of imagination, we’ve largely treated forests as inert physical resources to satisfy human needs and desires. The main operative science behind this commodification has been market science – how to extract maximum resources and profits.

Suzanne Simard is a revolutionary researcher who is transforming the science of forest ecology and coming full circle to the wisdom held by First Peoples and traditional land-based cultures from time immemorial. The story Simard is uncovering can change our story for how we live on Earth and with each other – for the long haul.


Suzanne Simard, Professor of Forestry at the University of British Columbia, is an expert in the synergies and complexities of forests and the development of sustainable forest stewardship practices. Her groundbreaking research centers on the relationships between plants, microbes, soils, carbon, nutrients and water that underlie the adaptability of ecosystems, especially the below-ground fungal networks that connect trees and facilitate interplant communication.


  • Executive Producer: Kenny Ausubel
  • Written by: Kenny Ausubel
  • Senior Producer and Station Relations: Stephanie Welch
  • Co-Writer and Producer: Teo Grossman
  • Host and Consulting Producer: Neil Harvey
  • Program Engineer and Music Supervisor: Emily Harris

This is an episode of the Bioneers: Revolution from the Heart of Nature series. Visit the radio and podcast homepage to find out how to hear the program on your local station and how to subscribe to the podcast.

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NEIL HARVEY, HOST: One of the revolutionary researchers transforming the science of forest ecology is Suzanne Simard. She weaves a kind of ecological parable. It’s a story of community – of kinship – of diversity – of coevolution, cooperation and resilience. Call it the Tree of Life, as so many cultures have.

The story Suzanne Simard is uncovering can change our story for how we live on Earth and with each other – for the long haul.

This is “Forest Wisdom, Mother Trees and the Science of Community”. I’m Neil Harvey. I’ll be your host. Welcome to The Bioneers: Revolution from the Heart of Nature.

Forests have long occupied a fertile landscape in the human imagination. Places of mystery and magic – of wildness and wisdom – of vision and dreaming – sacred groves at the edge of civilization where enchanted beings dwell, where people become transformed in the ineffable face of danger, darkness and wonder.

Yet beyond these mythic realms of imagination, we’ve largely treated forests as inert physical resources to satisfy human needs and desires. Dating back to ancient Rome and Greece, this extractive mentality has toppled civilizations, turning forests into board feet, clearcutting what’s in truth a keystone in nature’s self-sustaining web of life.

The main operative science behind this commodification has been market science – how to extract maximum resources and profits.

Today the new emerging science of forest ecology is telling a very different story. It’s a story that’s both modern and ancient. Brilliant scientists are coming full circle to the wisdom held by First Peoples and traditional land-based cultures from time immemorial.

The daughter of a logging family who grew up in the towering forests of British Columbia, Suzanne Simard became a Professor of Forestry at the University of British Columbia where she studies forest science and the development of sustainable forest stewardship practices.

SUZANNE SIMARD: There are so many different kinds of forests in the world, so healthy is really place-dependent. The composition of forests it’s largely determined by climate. So a tropical forest looks way different than a temperate forest, which is in the middle latitudes, which looks way different than a boreal forest, which is in the high latitudes.

So diversity comes in many different ways, and really like this underlying principle that’s been proven in many studies, not just in forests, but in grasslands and in herbaceous communities in agriculture systems as well, that diversity increases productivity, it’s also related to health of the forest.

Suzanne Simard. Photo by Jdoswim.

HOST: Simard’s groundbreaking research centers on the complex interdependent relationships in forests among the trees, plants, fungi, microbes, soils, carbon, nutrients and water.

It’s hard to overstate the importance of forest ecosystems to the health of the web of life. Forests are rightly called the lungs of the planet, absorbing a third of global carbon dioxide emissions. Forested watersheds provide 75% of accessible global fresh water. And forests are home to nearly 80% of the world’s terrestrial biodiversity.

Although we know how profoundly forests matter, modern society knows surprisingly little about how they actually function as a system. What are we learning today?

We spoke with Suzanne Simard at a Bioneers Conference.

SS: So what is a diverse forest? In the boreal forests, which are the northern latitude forests, there’s not that many tree species. But if you look at vertical structure in this forest, those forests are extremely diverse. If you think of trees and how they vary in height, and their crowns are in different places, well then other animals and plants will live in those different niche spaces in that crown that’s very diverse.

And then also belowground in those boreal forests, that are not very species rich in trees, are immensely species rich in fungi. And I think that one of the reasons that they’re very diverse there is because those fungi and the bacteria are acting on a very difficult environment to extract or to get resources like nitrogen and phosphorus that they can deliver to the plants. So they all have their own special little niche space that they occupy there.

In a tropical forest, it’s a totally different thing, where you could have hundreds of species in a hectare, of trees, whereas belowground there’s only a couple hundred of mycorrhizal fungal species it depends on where you’re looking, or which forest you’re in.

Even so, there’s the basic principle that a fully accessed community with lots of niche space is a productive community. That’s how the biodiversity works.

HOST: A community anchored in diversity is among the first principles in this ecological parable. But because industrial capitalism has treated forests first and foremost as profit centers, it has led to so-called “managing” them more like a factory than an ecosystem, exactly contrary to the very underpinnings of healthy forests.

Suzanne Simard experienced this lethal disconnect first hand while herself working as a forester. Along the way, she fell through the rabbit hole into the below-ground world of forests. She found, as the Hermetic Axiom suggests, “As above, so below.”

SS: I became interested in the below-ground world when I was actually practicing forestry, and the things that we were doing and people were doing in the industry — which was clear cutting, planting trees, weeding out things – plants – that they didn’t want, trees they didn’t want, trees like birch and aspen and cedar, making way for just one or two species — I thought it was wrong because it wasn’t the way I had observed how forests function and are patterned in nature, and I thought we should be emulating nature more closely.

And when I was studying these forest practices, I was observing that there’s a lot of disease in those forests. They’re really stressed out. The trees growing by themselves in these rows are not happy. They die. There’s a lot of death. So I wanted to understand why that was and how we could change that.

And of course I was always interested in how the forest works, but I knew that a lot of this disease came in through the soil, and so I thought, well, that’s the first place to look. And I was interested in how fungi interact with trees.

And so I started looking at these forests where they had cut out the unwanted species and cleaned them, kind of like biodiversity cleansing in forests, and to see what happened to the mycorrhizas. And the diversity of the mycorrhizal fungi went way down, just like it went way down with the trees. And that’s because different plants host different species of fungi, and so there’s a lot of co-evolution that goes on between these creatures, these symbionts. And so when you get rid of one of the symbionts, the other one goes too.

So that meant, too, that the potential for these trees to be connected by these fungi below ground also went down. So I figured out through many studies – that trees of different species were connected, and when the connections were severed or they were not nurtured – so not nurturing them means growing single species and weeding out all the other native plants – when they’re not nurtured, those symbionts die or they’re very low diversity.

And then I realized through many more experiments that when you sever those links that the communication between the trees actually is severed as well. I was able to show that when trees can’t interact like that, can’t have relationships through their connections, that they’re more at risk of disease. And so when that microbiome was not there, then the pathogens could really act or really take over these other trees when they were by themselves.

HOST: Just as nature banks on diversity and builds from the bottom up, it rewards cooperation. As microbiologist Lynn Margulis put it, Earth is a “symbiotic planet”– revealing another piece of the ecological parable puzzle.

Simard’s research has further found that – although the forest is a raucous symphony of life – it also has amazing soloists. Among these soloists are “Mother Trees.” It turns out they’re crucial to the vast below-ground cooperative networks that connect, protect and nourish all trees – connections well known to ancient aboriginal cultures. There’s good reason to call them “Mother Trees.”

SS: Most people don’t know this, but when you’re walking in the forest, you see these big, tall trees, and you think, Oh, that’s the tree. But actually there’s as much going on below ground as above ground.

A tree grows tall, but it’s got a root system but they also grow outwards. And a mature tree in our temperate forest will have root systems that go out like 30 meters. That’s like 100 feet. The root systems are as wide as the tree is tall. So that means that in trees, in a fully occupied forest, are only like a few meters apart, so that means that their root systems are completely overlapping.

On top of that, every root tip on those trees, those massive overlapping root systems, every root tip has got a mycorrhizal fungus that’s linked to all the other trees.

A big old tree will produce cones and set seed. The seed falls at whatever time of the year. It disperses its seed often in the spring. Those seeds fall to the forest floor, and there’s immediately, as soon as they fall to the forest floor, there’s a lot of communication going on between the seed and the bacteria and the fungi in the soil.

So then the seed germinates, and within a month or two, the root, the hypocotyl of that seed, becomes colonized by a mycorrhizal fungus. That fungus is actually part of the big old tree that produced the seed, so that big old tree has already got a network of fungi, and the seedling, with its little root system, hooks into the network of the old tree

The old tree immediately starts communicating with the seedlings through the network. And the way that the old tree does that is it sends carbon down its phloem, into its root system, into the mycorrhizal network, and then the little seedling takes it up, and when a seedling is really young, just like in our own kids, they can’t look after themselves completely. It takes a little while. They’ve got to build leaves and they’ve got to grow a little taller, and they’ve got to photosynthesize enough that it’s more than respiration so that they can produce their own food. But at first they can’t do that, especially if it’s shady.

So that mother tree sends carbon, and later we also found that the mother tree sends nitrogen, and it sends water, and it sends signals, and can recognize whether they’re kin or not kin. And so this communication goes on between the parent tree, the mother tree, and the offspring.

Teenagers will talk to each other as well. They can be linked together and communicate. It doesn’t have to be mother and kin.

We know that they recognize which seedlings are related to them and which ones are strangers. And we think that there’s certain kinds of kin recognition signaling molecules involved in this, but we don’t know what they are. We know that carbon is part of the story because we know that mother trees will send more carbon to kin than strangers. So it could be that carbon is part of this signaling molecule, but we don’t really know for sure. So there’s some work to be done there.

HOST: Science is just beginning to scratch the surface when it comes to learning about how plants communicate. What else are trees up to?

One finding was a vast public health hotline coursing through the forest.

SS: The other communication language that we’ve been looking at is stress signaling. So if one tree is stressed, it can send signals to neighbors that say, Hey, I’m stressed out and you need to watch out, and you need to increase your own defense.

The big old trees are the ones that have the biggest crowns and they photosynthesize the most, and so they’ve got the most surplus carbon, and so they send the carbon into the network. And usually they—the other trees that are smaller and have less carbon through photosynthesis are the sinks. So it’s like this source-sink thing going on between big old trees and the younger, smaller trees. And that’s, we think, is how the carbon is moving through the network is it’s following a source-sink gradient from really replete areas to depleted areas.

So it’s redistributing the resources so that the community as a whole is vibrant and healthy, even the ones that are maybe struggling in the shade, they’re getting help from the neighbors through the network.

And there’s studies that also show not just below ground but above ground that this kind of communication is going on between trees about stress and injury, and that they change the community health based on that signaling. It’s like a public immunization program.

HOST: As we begin to look, listen and learn, what science is unearthing about the depth and complexity of forest ecosystems is astonishing. For instance, how is it that rivers and oceans reach deep into the life cycles of the forest?

One of the primary elements necessary for plant health is nitrogen. In some regions near rivers up to 75% of the nitrogen in trees can be traced to fish.

SS: Through lots of studies in Washington and British Columbia, they’ve been able to determine that this nitrogen is transported into the forest by different animals – bears and wolves and eagles – and that this nitrogen ends up not just in the trees but in other plants and even in the insects that are associated with those plants. But nobody knows how it gets from the salmon that’s been eaten by the bear and maybe pooped out or just left to decay, how it gets from that point into the tree.

And so what we’re trying to do is figure out how the mycorrhizal network picks up the nitrogen.

And then most interesting how that mother tree then moves that nitrogen through the network into the forest and how deep into the forest does it go? And what is the ocean influence? How far does it go into the forest?

And we think that it goes a longways, and without the salmon, the forest suffers, without the forest, the salmon suffers because the forest provides cover for the streams, which makes it habitable for the salmon. It’s a really great example of how animals and salmon and trees, and even people because they harvest the fish, are all linked together.

And it’s not just in those forests, but even in the Douglas fir forests where I live and do my research, the animals are all part of dispersing the spores, and eating the spores, and the spores of the mycorrhizal fungi which colonize the seeds in those animals, also the squirrels will harvest the cones and eat the seeds in the same place that they defecate out the spores, and then the colonization of the seed happens right there. So the squirrel or the animal is an integral and critical part of the loop between the fungus and the tree.

I think the more we look, the more we’re going to see that these links are strong, and they’re there, and there are multiple pathways.

HOST: When Charles Darwin published On the Origin of Species in 1859, it revolutionized our understanding of evolution. His theory of natural selection became popularized as “survival of the fittest.” 

But he did NOT mean an amoral struggle for existence where might makes right — where the ruthless pursuit of self-interest automatically cleaves to the greatest good. 

What Darwin was actually saying was that the “fittest” were the best fitted to existing conditions at a given historical moment in a specific environmental context. 

In other words, evolution is coevolution, navigating by the North Star of symbiosis. That’s exactly what Suzanne Simard’s ecological parable is showing.

SS: We’ve had this misconception that healthy forests are made of all fast-growing trees, and that the biggest and fastest-growing is the best thing, but no, it’s not true at all.

If everybody’s a strong competitor– if everyone’s an alpha tree, then they’re going to fight each other to death, through shading and so on. If you have a structured forest where you’ve got small ones, and big ones helping out the small ones, and mid-canopy trees, and different species, they’re occupying all the niches in that forest, that diverse forest, and so that’s actually a much healthier forest, is to have that kind of diversity.

HOST: Simard says that symphony of diversity is exactly why it’s so important to conserve these mother trees. 

There’s a parallel in marine ecology and fisheries management, where it’s increasingly common for regulators to protect what they call BOFFFs – Big, Old, Fat, Fecund, Females. Pound-for-pound, in some species BOFFFs can produce vastly more life than any other fish in the population. Protect Big Old Fat Fecund Females, and the population will thrive. 

Simard’s work has shown that the same holds true for trees. As forests are jamming into fast forward to try to adapt to radically accelerating climate change, protecting mother trees will be an essential practice for supporting climate-resilient forests.

The implications of Suzanne Simard’s research extend beyond large-scale forests. She says our expanding understanding of plant communication can also offer promising practical applications, especially in this time of severe climate stress. One example is in agriculture, helping plants share much needed water in times of drought.

SS: So like a winery, for example, the roots will be accessing a very narrow niche space in the soil, and that makes it very vulnerable so that when there’s a drought, they can’t access water that might be in different places in the soil profile.

So what can you do? You can actually start mixing plants, and if you know about the species of the plants and how they communicate with each other and how they interact with each other, you can actually start creating polycultures of plants so that you have some that are deep-rooted ones, you have some that are sort of middle-rooted ones, some that are—maybe the vineyards are shallow rooted. And what happens under a drought situation is that those plants, the deep-rooted ones, like the trees, will access water in the deep aquifers, bring it up, and share it with the vineyards, for example, through mycorrhizal networks. And then you keep the whole system watered. The water cycles through the system and it keeps it living, and a living canopy will trap more water, there’s more transpiration going on, there’s–you know, they’re accessing other parts of the soil profile that are bringing up nutrients as well, and then if you do that, you have a resilient system. But that’s all based on our understanding of how these plants are able to communicate with each other and access different pools of resources in soils that results in a really healthy and resilient plant community.

HOST: If there’s one fundamental systems error in the modern mind, it’s the delusion that as human beings, we’re apart from nature. In truth, we’re a part of nature. We are one small late-blooming branch on the 3.8 billion-year-old Tree of Life.

As a forest ecologist, Suzanne Simard says the ecological parable of forests has direct and timely relevance to how we can organize our human societies.

SS: It’s a very potent mix of looking at these patterns and processes in nature, and how can we use that to help us understand these other systems, because these systems, basically from what we’ve discovered, is that they’re patterned very similarly. So we can learn a lot from that, like just say, in society about cooperation. Well you know, cooperative societies where specialists in different areas, even though they’re diverse and have different roles, if they can cooperate on different levels, then you have a more robust community that’s more productive and healthy, and the people within it are healthier.

And then of course combining society with a good functioning healthy ecology also is of course a potent mixture for happiness and health.

HOST: Suzanne Simard believes that the story of interdependence and mutual aid emerging from the science of forest ecology is already deeply wired in our collective psyche. It’s embedded in spiritual and religious traditions, and in family and social codes.

The leap today is to expand those ethics of right relationship to the natural world.

Although scientists scrupulously avoid ascribing human qualities to the natural world, Suzanne Simard uses the term “forest wisdom.” For a scientist who rigorously documents the astonishing sophistication and complexity of this forest symphony, is it in fact valid to apply words such as “intelligence” and, yes, “wisdom?”

SS: I started using that word when I realized that—or my science was showing me that we can deconstruct a forest and look at the mechanisms, like of  communication and networks, but there’s so much of it that is beyond explanation. We’re not ever going to fully know, because there’s a lot of emergent things that come out of that that you just can’t trace.

And to me that’s intelligence, and wisdom – that it’s more than just a bunch of parts that are working together. It’s more than just a bunch of networks. It’s more than just a bunch of leaves. It’s that they’re all working together to create something that’s much, much more than that.

But there’s also that mother trees can recognize her kin and intentionally transfer carbon to her kin seedlings to favor them. That’s a behavior that has got intention and consequences, and there’s decision-making going on there. Right? There’s a choice. And we could deconstruct that to physics or something like that, but when we were starting to discover that she recognized her kin and could send more resources, I thought that’s wisdom, because there’s intention there. There’s a sentience.

There’s a lot of resistance among, you know, more traditional scientists of using those kinds of words to describe plant behavior and how they perform and function, but that’s just because we’ve invented those words for ourselves and now we’re applying them. But they’re apt descriptions when you look it up in the Oxford Dictionary. It is intelligence. It is wisdom.

HOST: Call it the Tree of Life. Call it Forest Wisdom…

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