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Hi, I'm Lindsay.
And I'm Marshall.
Welcome to Tumble, the show where we explore stories of science discovery.
Today we're asking, do trees think?
You mean, are trees like to tree or not to tree?
That is the question.
Let's dig into it and find out if trees are having deep thoughts in the forest.
We'll discover that there's a lot more happening in the soil than you might think.
Today's question comes from tumble listener Alden.
Hi, my name is Alden and I am nine years old.
And my question is, do trees think?
I think they do.
Well, Alden's pretty confident that trees are thinkers.
Yeah, and he already seems to know a bit about the science.
I think scientists could figure it out by looking at trees' roots and seeing if they can actually send messages through mushroom roots.
Wait, trees can send messages through mushroom roots?
Like, are these text messages or do they use WhatsApp?
Like, is he right?
That's what we'll try to find out.
But first, let's ask our listeners.
Do you think trees think?
Why or why not?
And how would scientists find out?
Think about it, because we'll be back with a scientist who will help us root out the answer.
So to answer Alden's questions about whether trees think.
I knew we had to answer two big questions.
What two questions?
Well, first, what would it mean for a tree to think like they don't have brains like us?
But do trees have some other kind of way to think?
Yeah.
Like, can you think without having a brain?
Yeah.
And the other question is, do trees communicate through mushroom roots like Alden suggested?
Yeah.
I'd never heard of that before.
I don't know what you're talking about.
Well, I found a young scientist named Natalia Mondi who can help us tackle all of these questions.
I love investigating and exploring and trying to understand the whys and the hows of the world working.
You know, I love investigating and exploring and trying to understand the whys and the hows, too.
So maybe we'd be friends.
I think so.
Well, the part of the world that Natalia's most interested in exploring is forest ecosystems, which is why I called her to answer Alden's question.
Because Natalia actually studies forests from the place where trees and mushroom roots meet.
In the soil.
She's been doing that since she was little.
I was always into digging in the dirt.
Yeah, who doesn't love digging in the dirt when they're kids?
Yeah, but Natalia really took it to another level.
When I was really little.
Actually, I was always eating so much soil that my mom took me to the doctor when I was two.
Natalia grew up in Hawaii and when she was a toddler, the beach was like an all-you-can-eat buffet.
I was eating sand on the beach and soil from the backyard and she took me to the doctor because I wouldn't stop and she was like what is wrong with my child?
It turns out I just had a sodium deficiency.
So I thought that was really cool that my body was seeking out sodium from sand and soil.
Somehow, Natalia's body knew that she wasn't getting enough sodium.
Sodium is a nutrient that we usually get through eating things with salt, but it's also a mineral found in sand and dirt.
Well, that's incredible.
So I guess that's why she wanted to be a soil scientist.
Just, Natalia's dirt cravings went away, but her curiosity about soil stayed on.
When I was applying to university, I was like I want to study soil science.
Okay, so I guess we're getting closer to forests because trees grow in soil.
Right, and so do mushroom roots.
And Natalia had realized that everything in the forest is connected.
That's a realization she'd gotten from a TED Talk called How Trees Talk to Each Other.
I just remembered the concept really resonating with me, that trees have intelligence and that trees talk to each other below this underground network.
Ooh, an underground network like that group of crime-fighting moles.
Well, that sounds really cool, but you might want to explain to everyone what a TED Talk is.
TED Talks are a very popular series of talks given by scientists and other experts on all kinds of subjects, and you can watch them on YouTube too.
Natalia came across this one by a forestry scientist named Dr Suzanne Simard, and it struck a chord with Natalia.
I felt like it was the perfect connection of my love of the ground and my love of the forests.
In the video, Dr Simard told the story of how her research in the Canadian province of British Columbia led to the finding that trees were talking to each other through the soil.
Whoa, I want to go to this place and look at these trees.
So did she?
She did.
She went to the University of British Columbia, which happens to be where Dr. Simard teaches.
And Natalia found herself taking one of her classes.
But it took her a while to make a connection back to the TED Talk.
Two months in, I realized I was like, wow, this is the lady.
I was like, this is that woman who gave that amazing TED talk.
Wait, she didn't recognize her?
No, she didn't recognize her.
But just like the video, the class inspired her.
And now Natalia could actually talk with Dr. Samard about her research and ideas.
And we just had amazing chats.
And then by the end of the course, she was like, do you want to work with me?
And I was like, yeah.
Well, that's amazing.
It was meant to be.
Natalia now works with her scientific hero, studying how healthy forests work and how to use that knowledge to help forests that might be unhealthy.
So what is it that makes a forest unhealthy?
That is a really great question.
To understand that, we have to know what makes a forest healthy to begin with.
And Alden's question is actually a big part of what makes a healthy forest.
Natalia says that when a forest is healthy, trees can easily think or communicate.
Trees can send communications all the way from the tips of their leaves down into their roots and then between the fungus and the adjacent trees.
That can kind of be like neurons firing in your brain, but it's all held together by the different organisms that are growing and crawling around within the soil.
So to me that's kind of like thinking Well, that's kind of an incredible way of thinking about thinking.
Yeah, it's not how we think, about thinking as humans, where we have a conscious thought, like what we want to have for breakfast, for example.
It's more like our bellies send a signal to our brain that it's time to eat.
Right.
So but trees don't really like have breakfast, I guess.
Maybe they do.
I don't know.
But what kind of thoughts would they have?
Well, Natalia gave me an example of how trees communicate when it's time to grow.
And so if a tree were thinking I need to grow and they start growing from the top, they can send a chemical signal down from cell to cell to cell all the way, from the very top, traveling all the way down to their roots.
And they can send out a signal to the mycorrhizae that are growing with the roots.
Maiko Raizei.
Band name.
Called it.
Right.
Natalia broke down the roots of the word.
Maiko is the root for mushroom and Raizei is the root for root.
So Maiko Raizei is like mushroom roots, essentially.
Okay, so she's talking about the root of the word for mushroom roots.
So the word root, mushroom roots.
Yeah, it's very meta.
Yeah.
So the mushrooms you actually see in the forest are just a very small part of the fungus.
In a forest body is composed of that part that's growing above ground, but most of it is actually these little tubes that are stretching and growing throughout the soil.
You can have kilometers and kilometers of this mycorrhizae under just your footprint on the ground.
Wow.
The mycorrhizae enter the tree roots and connect to each other, making it possible for the tree to send and receive signals through the entire forest.
It can be like a telephone line.
Like one tree calls up and he's like back in the day you had to dial up and then get connected through and that mycorrhizae can be like a connector.
And the mycorrhizae will say, okay, hey tree, I'm connecting you to your neighbor.
Wow, so like the mushrooms are like old-fashioned switchboard operators.
Yes.
So, through these chemical signals, the tree sends this message to the mycorrhizae hey, I really need some carbon or I really need some phosphorus, because those are nutrients that trees need to grow.
The mycorrhizae send the message far and wide through the forest, and once they find the nutrients, they send it back to the tree.
And then it goes back all the way up to the very top.
And then the tree can grow.
And so in order to think, it's really the tree and the mushroom together.
It's the tree and the mycorrhizae collectively saying, hey, bud, I need this.
And then the mycorrhizae is like, yeah, I got you, bud.
So they're forest buds.
So Alden was like completely right.
Scientists do study mushroom roots to find out how trees think.
But you mentioned that is just how things work in healthy forests.
Do trees still think in unhealthy forests or do they just think unhealthy thoughts?
And what is it that makes a forest unhealthy anyway?
And can they get healthy again so they can think better?
Well, those are all great questions and we'll answer them when we dig deeper into Natalia's research into a forest that's been through some really tough times and how she's helping it recover its thoughts.
Oh, how?
That's what we'll find out right after this quick break.
We're back.
When we left off, we discovered how trees think, by sending messages through mushroom roots or mycorrhizae.
That's how trees participate in the forest food web without having to move an inch.
Oh man.
So I just sit on the couch and I like think hey, I need some snacks and then a bunch of mushroom roots.
Just go get the snacks and bring them back to me.
I'm just rooted there on the couch covered with mushroom roots.
That sounds fun.
That sounds disgusting.
Well, for trees, it works.
And it's not gross.
It's just how they do it.
And it's very cool.
But anyhow, back to Natalia.
She's using that knowledge of how trees think in a healthy forest to figure out how to help a forest that's unhealthy.
A forest on the Pacific coast in Canada.
We are looking at a forest that has been affected by mining and logging and it's currently sick.
All the trees were cut down at the same time, a thing called clearcutting and then people mined the land for gold using a powerful chemical.
And then they let the trees grow again, and then they clear-cut it again, and then the trees grew up one more time.
Wow, okay, so it's been a forest, and then not a forest, and then a mine in the middle.
So it's trying to be a forest again.
Right.
This forest is on the land of the Quaker Nation, a small indigenous nation in Canada.
Natalia is part of the scientific team guided by the Quaker people to restore the forest.
Now you go into the forest and it's really dark and it's not very diverse.
There's only a few types of trees and they're crowded together.
There's not enough light getting through the branches for plants to grow beneath them.
This is what happens to a lot of the forests that are clear-cut.
The trees are very skinny and they're all growing really close together, and a lot of them have diseases.
Okay, I mean, I guess that really does sound like a sick forest.
It must be hard for the trees to think, with the forest being so weak and being so packed in together.
Yeah, it's kind of like when you're sick, all you want to do is sleep and you have to give your body and brain a rest because they're not strong enough to do your normal things.
And when a forest is sick, it's harder for trees to do their normal things too.
So what can you do to make a forest healthy again?
Natalia told me, the biggest thing that you can do is actually cut down more trees, especially the diseased or dead ones.
That gives the healthiest trees a better chance to survive and brings light into the forest for other plants.
Because once light can touch the ground then these understory berry plants and herbs can start growing back and it can start promoting a different kind of diversity in the forest.
So, before Natalia and her team got started, they took what's called a survey of the forest, getting information about what trees are there, what plants are there.
And importantly for Natalia, what's in the soil?
What I'm doing particularly is sampling little tubes of soil.
Natalia digs up samples or examples of what soil is like in a particular place.
We put them into these boxes that are negative 80 degrees Celsius.
And then we take that out and we do a bunch of chemistry with them.
And then we're able to extract the DNA.
Sounds like a fancy thing to do with dirt.
So what does soil DNA tell you?
And so we're able to tell who is there in the soil and who is doing what.
How are they able to tell who is in the soil and what they're doing?
Is anyone just like mopping up in there?
Well, the DNA comes from all the different microbes or tiny organisms like bacteria that live in the soil.
Because a lot of the time they're kind of slimy, like they're making slime in the soil.
See, that tells me that they don't have parents who are concerned about how their kitchen might look.
Right.
We're not talking about slime that kids can make and leaves a sticky mess.
Right.
I'm not sure that this is better, but it's the waste that microbes leave behind.
Oh, way better.
Well, Natalia extracts or pulls out the DNA from that waste to find out what kind of microbes are making it and what they're doing in the forest.
Like, who is sending carbon around?
Who is storing it deep into the soil?
In the forest, carbon is always being traded around.
And so, by identifying the microbes that are moving carbon around the forest, Natalia and her colleagues can draw a better picture of how the forest works, or how it doesn't work.
So if we go back to the thinking and the wisdom idea, the soil is the memory of the forest.
Well, what does it mean that the soil is the memory of the forest?
It's the idea that the soil is the base of everything in the forest.
And even though a lot of bad things have happened in the forest that Natalia is studying, the soil still holds information and knowledge of what the forest used to be.
I think that it's really amazing, because you can tell what the forest wants to be like and how the forest used to be versus how it is now.
Natalia told me that those signals start to reveal themselves when the ecosystem begins to heal, when more diverse plants start to grow and when the mycorrhizal network is reconnected and then trying to shape it into a future version of a balanced ecosystem where it can experience some fire and it can experience some wind and it can experience disturbances, but it won't rock the boat so hard that the tipping point will be reached.
So it becomes a healthy, thinking forest again that can respond and recover from damage.
That's the idea.
I asked Natalia what she hoped the trees would be thinking or saying after the forest is recovered.
Maybe the trees will be saying thank you, but they'll also be telling us about how the land likes to be cared for.
I like to imagine a tree saying thank you and also bring me more snacks.
I'll just lie here and say bring me more snacks.
So let's find out what Alden learned from this episode.
I learned that it's possible to talk while you're unconscious if you're a tree.
And mushroom roots are called mycorrhizae.
And people might eat dirt if they have a sodium deficiency.
And there are scientists who study dirt.
Wow, it really sounds like Alden learned a lot here.
And I do think we answered his question that trees do think or talk or communicate or whatever you want to call that thing where they send messages through mushroom roots.
Yeah, so Alden was right.
And learning more about it made him even more curious.
Another question i have is do trees talk to other kinds of trees, or just the same type of tree that they are?
That's a great question.
It makes me wonder if trees have different languages like, is their tree german?
Or if a tree falls in the forest, can other trees hear it?
They're like ah, what happened to fred?
I guess there's always more to think about with trees.
Indeed.
Now that you've learned how Natalia studies forests through their soil, think about what you might be able to learn from soil.
If you've dug in the dirt before, and who hasn't, think about what that dirt looked like.
What are the differences between soil that you've dug up in a forest, dirt in the backyard or in a park, and sand that you get to shovel on the beach?
When you have the chance, collect samples or little piles of dirt from all those different locations.
Label them in cups and jars, then compare them.
Are they different colors?
Do they have different sized grains?
Use a magnifying glass to get a closer look of what they might be made from and write down what you observe.
Then show us your soil collections.
Send us a picture and your observations to tumbledpodcast at gmail.com.
We'd love to see them.
Thanks to Natalia Mondi, Master's student in Forest and Conservation Sciences at the University of British Columbia.
Natalia works with the Mother Tree Project with Dr. Suzanne Simard.
And special thanks to Alden and his mom for sending in his great questions and recordings.
You can send us your questions for future episodes at tumblepodcast at gmailcom or through our website sciencepodcastforkidscom.
Thanks as well to our Patreon members.
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When you join at the $5 level or higher, you'll get ad-free episodes, special chances to be on the show, and of course, birthday shoutouts, which are coming right up when you sign up at the $5 level or higher at patreon.com slash tumblepodcasts.
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Did you know that we make Tumble in Spanish?
It's called Tumble en Español and it's adapted and hosted by native Spanish speakers Nuria and Alvaro.
Find it at tumbleenespañol.com or search for Tumble en Español wherever you get your podcasts.
Elliot Hajaj is our assistant producer.
Sarah Robertson-Lentz is our managing editor and created the episode art.
Mixing and mastering is by Gary Calhoun James, and I'm Lindsay Patterson.
I'm the executive producer of Tumble, and I wrote this episode.
And I'm Marshall Escamilla, and I make all of the music for Tumble.
Tumble Science is a production of Tumble Media.
Thanks for listening, and stay tuned for more stories of science discovery.
All right, everybody, here we are at the end of the episode.
And listen, by now, you know what's going on.
We got the birthday shout outs.
That's what it's time for.
I said that earlier and now we're doing it anyway.
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Thanks so much, you guys, for signing up for our Patreon.
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Okay, and now on to the birthdays.
So first of all, a happy belated birthday to Mateo on March 28th.
Happy 10 orbits around the sun with love from mommy and papa.
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May your love of science and animals always bring you joy and discovery.
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