Transcript

Latif:

Okay.

Opening:

You are listening to Radio Lab Radio Lab, from WNYC.

Jad A.:

I'm Jad Abumrad.

Robert Krulwich:

I'm Robert Krulwich.

Jad A.:

This is radio lab. Very good to actually be back here talking to you.

Robert Krulwich:

Yes.

Jad A.:

Yes, it's been a while.

Robert Krulwich:

Where have you told those people who might've missed what you been doing, what you've been doing, so they will not miss it.

Jad A.:

We just finished our first mini season of our first spinoff called More Perfect.

Robert Krulwich:

When are you going to have part two.

Jad A.:

Part two is a coming soon. I don't know. Not tomorrow.

Robert Krulwich:

Okay.

Jad A.:

But, but net but not long because we, yeah, there's there, there are definitely stories to tell for sure. And you know, and if you, if you haven't checked it out, check it out at radiolab.org/moreperfect. We're really proud of it.

Robert Krulwich:

Let me rescue you from this awkward situation by bring back into Radio Lab where I'd like to begin by building a tall, dark, dense green forest making towering trees to your left.

Robert Krulwich:

Okay. Right. And I, yeah, I need a bird. A lot of birds actually, and a little wind. So just give me some,

Jad A.:

Like, sound?

Robert Krulwich:

Yeah, birds please. Birds.

Jad A.:

Why did, like we haven't even started this,

Robert Krulwich:

Why? Isn't this what you do. You'd give me, like, I want wind, birds,

Jad A.:

I'm not like your sound puppet here.

Robert Krulwich:

But I can't, how do I, all right, nevermind. This story.

Jad A.:

You'll get your sound at some point.

Robert Krulwich:

Begins with a woman or, and at the time actually she was a very little girl who loved the outdoors and I mean really loved the outdoors.

Suzanne Simard:

When I was a little kid I would be in the forest and I just eat the forest floor. And I know lots of kids do that. But I was like,

Robert Krulwich:

You mean you got down on all fours and just,

Suzanne Simard:

I would just eat the dirt.

Robert Krulwich:

This is Suzanne Simard.

Suzanne Simard:

And so my mom always talks about how she had to constantly be giving me worm medicine because I was, I always had worms.

Robert Krulwich:

She's a forestry professor at the university of British Columbia and might as well start the story back when she was a little girl.

Suzanne Simard:

Well when I was a kid, I grew up in the rainforests of British Columbia, and my family spent every summer in the forest.

Robert Krulwich:

And her family included a dog named Jigs.

Suzanne Simard:

And so in this particular summer when the event with Jigs happened,

Robert Krulwich:

what kind of dog is Jigs, by the way?

Suzanne Simard:

He was not a Wiener dog. He was a, what was he?

Robert Krulwich:

You don't know what your dog,

Suzanne Simard:

Not a Basset hound, but he was a beagle.

Robert Krulwich:

Beagle.

Suzanne Simard:

He was a curious dog.

Robert Krulwich:

And on this particular day, she's with the whole family. They're all out in the forest. It was summertime and Jigs at some point just runs off into the woods, just maybe to chase a rabbit, whatever. Couple of minutes go by.

Suzanne Simard:

And all of a sudden we could hear this barking and yelping and we were all like, Oh my goodness, Jigs is in trouble. And so the whole family and uncles and aunts and cousins, we all rush up there.

Robert Krulwich:

But they followed the sound of the barking and it leads them to an outhouse.

Robert Krulwich:

And when they go in,

Suzanne Simard:

There is Jigs at the bottom of the outhouse. Probably six feet down at the bottom of the outhouse pit.

Robert Krulwich:

Oh dear.

Suzanne Simard:

You know, where we've all been, you know, doing our daily business. He'd fallen in, he's looking up at us, quite scared and very unhappy that he was covered and uhm, and toilet paper. And of course we had to get Jigs out. I mean, Jigs was part of the family and,

Robert Krulwich:

Since he was so deep down in there,

Suzanne Simard:

We had to dig from the sides.

Robert Krulwich:

To sort of like widen the hole.

Suzanne Simard:

Basically expanding it from a kind of a column of a pit to something that we could actually grab onto his front legs and pull them out. And so we were digging away and Jigs was, you know, looking up with his paws, you know, looking at us waiting.

Robert Krulwich:

And they're digging and digging and digging and all of a sudden she says she looks down into the ground and she notices all around them where the soil has been cleared away. There are roots upon roots upon roots in this thick, crazy tangle.

Suzanne Simard:

We're sitting on the exposed root system, which has like, it is like a mat. It's, it's like, it's just a massive mat of intertwining, exposed roots that you could walk across to never fall through.

Robert Krulwich:

She says, it was like this moment where she realizes, Oh my God, there's this whole other world right beneath my feet.

Suzanne Simard:

Jigs had provided this incredible window for me, you know, in this digging escapade to see how many different colors they were, how many different shapes there were, that they were so intertwined. As abundant, as what was going on above ground. It was magic for me.

Jad A.:

Well, what, so what's the end of the story? Did Jigs, did Jigs emerge?

Suzanne Simard:

Jigs emerged. We pulled Jigs out and we threw him in the lake with a great deal of yelping and cursing and swearing, and Jigs was cleaned off.

Robert Krulwich:

But that day with the roots is the day that she began thinking about the forest that exists underneath the forest. And now if you fast forward roughly 30 years, she then makes a discovery that I find kind of amazing. She's working in the timber industry at the time. This is by the way, what her entire family had done, her dad and her grandparents.

Suzanne Simard:

And when I came on the scene in the 1980s as a Forester, we were into industrial, large scale, clear cutting in Western Canada, huge machines, loaders and cats.

Robert Krulwich:

She says a timber company would move in and clear cut an entire patch of forest and then plant some new trees.

Suzanne Simard:

And you know, my job was to track how these new plantations would grow.

Robert Krulwich:

And she says she began to notice things that, you know, one wouldn't really expect, like trees of different species are supposed to fight each other for sunshine. Right? You've heard that.

Jad A.:

Yeah, absolutely. They shade each other out.

Robert Krulwich:

They shade each other out. And they fiercely, you know, they, they push each other away so they can get to the sky. But she was noticing that in a little patch of forest that she was studying, if she had, say, a birch tree next to a Fir tree. And as she took out the birch,

Suzanne Simard:

The Douglas fir became diseased and, and died. There was some kind of benefit from the birch to the Fir. There was a healthier community when they were mixed, and I wanted to figure out why.

Robert Krulwich:

Well of course there could be a home, any number of reasons why, you know, one tree is affected by another, but she had a kind of maybe call it a Jigs-ian recollection.

Jad A.:

Flashback.

Robert Krulwich:

Yes. Because she knew that scientists had proposed years before that maybe there's an underground economy that exists among trees that we can't see. And she wondered whether that was true.

Suzanne Simard:

And so I designed this experiment to figure that out. It was a simple little experiment.

Robert Krulwich:

Here's what she did. She went into the forest, got some trees,.

Suzanne Simard:

Douglas fir, birch and cedar. And then I would cover them in plastic bags. So I'd seal the plant the tree in a plastic bag. And then I would inject gas. So tagged with a, with an isotope, which is radioactive.

Robert Krulwich:

So these trees were basically covered with bags that were then filled with radioactive gas.

Suzanne Simard:

Yeah.

Robert Krulwich:

Which the trees,

Suzanne Simard:

Would just suck up through photosynthesis.

Robert Krulwich:

So now they have the radioactive particles inside their trunks in their branches.

Suzanne Simard:

We had a Geiger counter out there. As soon as we labeled them, we used the Geiger counter to -- and ran it up and down the trees, and we could tell that they were hot, they were boo boo boo boo boo, right?

Robert Krulwich:

And the idea was she wanted to know like once the radioactive particles were in the tree, what happens next? Would they stay in the tree or would they go down to the roots? And then what happens? And what she discovered is

Robert Krulwich:

that all these trees, all these trees that were of totally different species, were sharing their food underground. Like if you put a food into one tree over here, it would end up in another tree, maybe 30 feet away over there. And then a third tree over here. And then a fourth tree over there. And a fifth tree over there. Sixth, seventh, eighth, ninth, 10th, 11th, all in all turns out one tree was connected to 47 other trees all around it. It was like, it was like a huge network.

Suzanne Simard:

And we were able to map the network. And what we found was that the trees were the biggest and the oldest were the most highly connected. And so we, you know, we identified these as kind of like hubs in the network.

Robert Krulwich:

And when you look at the map that you see your circles sprouting lines and then connecting to other circles also sprouting lines and it begins to look a lot like an airline flight map, but even more dense.

Suzanne Simard:

It's just this incredible communications network that, you know, people had no idea about in the past, because we couldn't, didn't know how to look.

Jennifer:

It's definitely crazy. I mean, you're out there in the forest and you see all these trees, and you think they're individuals just like animals, right?

Robert Krulwich:

Mhm.

Jennifer:

But no, they're all linked to each other.

Robert Krulwich:

This is Jennifer Frazier. She's a science writer.

Jennifer:

And I write a blog called the Artful Amoeba at Scientific American.

Jad A.:

I like your title.

Jennifer:

Thank you.

Robert Krulwich:

I spoke to her with our producer Ledif Nasser and she told us that this, this network has developed a kind of a nice punny sort of name.

Jennifer:

The Wood Wide Web.

Robert Krulwich:

The what?

Jennifer:

The Wood Wide Web.

Robert Krulwich:

You mean, like the World Wide Web? It's now the Wood Wide Web? It sounds a little like Elmer Fudd. The Wood Wide Web.

Jennifer:

Yeah.

Jad A.:

So this Wood Wide Web, is this just like the roots, like what she saw in the outhouse?

Robert Krulwich:

No, no, no, no, no, no. It's far more exciting than that and sophisticated and interesting and astonishing. It is. It involves a completely separate organism. I haven't mentioned yet. I mean this is going places.

Jad A.:

What creature? Where are we going?

Robert Krulwich:

I'm not going to tell you. I'm going to just go there. I mean we went and looked for ourselves. I don't know where you were that day. Annie McEwen, Stephanie Tam, our intern, and he's our producer. We decided all to go to to check it out for ourselves, this thing I'm not telling you about, we went to the Bronx to the Botanical Gardens, because,

Jad A.:

That's far you have to travel here in New York to get to actual greenery.

Robert Krulwich:

Actually, there's beautiful green sward New York has and when we went up there there was this tall man waiting for us. An expert.

Annie:

Is that Roy?

Roy Halling:

That is.

Robert Krulwich:

His name is Roy Halling. And Roy, by the way, comes out with the strange, it's like a rake.

Annie:

He's got a trowel.

Robert Krulwich:

But it has like an expandable,

Roy Halling:

It's a truffle rake.

Robert Krulwich:

Oh, it's an extend,

Robert Krulwich:

Oh listen to that.

Jad A.:

Oh, that sounds dangerous.

Robert Krulwich:

So we're up there in this, in this old forest with this guy.

Roy Halling:

So there's an Oak tree right there. It should have some.

Robert Krulwich:

And he starts digging with his rake at the base of this tree. He shoves away the leaves, he shoves away the top soil.

Stephanie:

Can the tree feel you ripping the roots out like that?

Roy Halling:

I hope not.

Robert Krulwich:

And so now we're down here. Pulled out a sapling root, of some sort?

Roy Halling:

It's just getting started, they're called feeder roots.

Robert Krulwich:

We're carefully examining the roots of this Oak tree on our knees with our noses in the ground. And we can't see anything. I mean I see the dirt.

Robert Krulwich:

You see anything white yet? You see anything,

Roy Halling:

It's like I said, it's early in the season, so.

Robert Krulwich:

He said something about that's the wrong season. I thought, okay, so this is just stupid. But then,

Roy Halling:

Finally. Do you have the lens?

Robert Krulwich:

He gives us a magnifying glass, you know one of those little jeweler's glasses? Handheld?

Roy Halling:

Have a look there.

Robert Krulwich:

And he hands it to Annie.

Annie:

Wow.

Roy Halling:

You see it there?

Annie:

Oh yeah!

Roy Halling:

The white,

Robert Krulwich:

Let me, can I see it?

Annie:

Yeah, go for it.

Robert Krulwich:

Oh my gosh, I do see them.

Jad A.:

What do you see?

Robert Krulwich:

Little white threads attached to the roots.

Robert Krulwich:

Smaller than an eyelash. Maybe just a 10th the width of your eyelash, but white translucent and hairy sort of.

Robert Krulwich:

And while it took us a while to see it, apparently these little threads in the soil,

Jennifer:

They're everywhere.

Robert Krulwich:

And when you measure them, like one study we saw, found up to seven miles of this little threading

Suzanne Simard:

In a pinch of dirt.

Robert Krulwich:

What?

Latif:

A pinch?

Jennifer:

Mhm.

Jad A.:

What is thing? Is it like, is it a plant? What is it?

Robert Krulwich:

What kind of creature is this thing?

Jad A.:

Yes. What is it?

Robert Krulwich:

This is the fungus. Which by the way is definitely not a plant.

Jennifer:

They're are some other kind of category, and for a long time they were thought of as plants, but now we know after having looked at their DNA of fungi are actually very closely related to animals. They're one of our closest relatives, actually.

Robert Krulwich:

Now back in the day,

Jennifer:

This all has a history, of course.

Robert Krulwich:

When people first began thinking about these things, we're talking in the 1600s, they had no idea what they were or what they did, but ultimately they figured out that these things were very ancient because if you look at 400 million year old fossils of some of the very first plants,

Jennifer:

You can see even in the roots of these earliest land plants,

Robert Krulwich:

You can see those threads.

Jennifer:

This is a really ancient association.

Robert Krulwich:

And then later scientists finally looked at these things under much more powerful microscopes and realized the threads weren't threads really, they were actually,

Jennifer:

Tubes.

Robert Krulwich:

Hollow.

Jennifer:

These little tubes.

Latif:

Tubes?

Jennifer:

Tubes. And the tubes branch, and sometimes they reconnect.

Robert Krulwich:

So there seem to be under the ground, this fungal freeway system connecting one tree to the next, to the next to the next. People speculated about this, but no one had actually proved it in nature in the woods until Suzanne shows up.

Suzanne Simard:

And there was a lot of skepticism at the time. But over the next two decades, we did experiment after experiment after experiment that verified that story. And,

Jad A.:

Wait a second, wait a second, what is this? Why is this network even? They're like, why would the trees need a freeway system underneath the ground to connect and why would the, why would the fungi want to make this network?

Suzanne Simard:

Why are they going to this trouble of creating this big network?

Jad A.:

Yeah.

Suzanne Simard:

Well they do it because the tree has something, the fungus needs and the fungus has something that tree needs.

Robert Krulwich:

Let me just back up for a second so that you could, you can, to set the scene for me.

Jad A.:

Yeah.

Robert Krulwich:

When you go into a forest, you see a tree, a tall tree. So what is the tree do?

Jad A.:

What's its job?

Robert Krulwich:

What's its job? It's soaks in sunshine takes the CO2 out of the air, carbon dioxide, which has of course carbon, C, in it.

Jad A.:

The oxygen.

Robert Krulwich:

Yeah. And it keeps the C.

Suzanne Simard:

Carbon, which is science speak for food,

Robert Krulwich:

It turns that carbon into sugar, which it uses to make its trunk and its branches. Anything thick you see on a tree is just basically air made stuff.

Jad A.:

Carbon and sugar are the same thing?

Robert Krulwich:

Yeah. You can think of the carbon is basically the sugar that builds the tree. However, if that's all they had was carbon.

Roy Halling:

It'd only be this tall.

Robert Krulwich:

Oh, that's Roy, again, he's holding his hand maybe a foot off the ground.

Robert Krulwich:

It would be a teeny tree?

Roy Halling:

It would be smaller.

Robert Krulwich:

So if all a tree could do is get carbon from the air, you'd have a tree the size of a tulip. A floppy tulip. Huh. A tree needs something else. And what a tree needs are minerals.

Jennifer:

Minerals from the soil. Very similar to the sorts of vitamins and minerals that humans need.

Robert Krulwich:

What kind of minerals does a tree need?

Suzanne Simard:

Like nitrogen and phosphorous.

Jennifer:

Magnesium.

Suzanne Simard:

Potassium and calcium and,

Jennifer:

Copper.

Jad A.:

Why? What do these do for the tree?

Robert Krulwich:

Like can a tree stand up straight without minerals or can,

Suzanne Simard:

It can't. No.

Robert Krulwich:

It can't?

Suzanne Simard:

No, so for example, lignin is important for making a tree stand up straight. And lignin is full of nitrogen, but also compounds like nitrogen is important in DNA, right? It's an integral part of DNA.

Robert Krulwich:

Oh, so this is, like, crucial. If I want to be a healthy tree and reach for the sky, then I need, I need rocks in me somehow. Liquid rocks.

Suzanne Simard:

You do. You need the nutrients that are in the soil.

Robert Krulwich:

And that's where the fungus comes in.

Suzanne Simard:

The fungus has this incredible network of tubes that it's able to send out through the soil, and draw up water and mineral nutrients that the tree needs.

Latif:

Wait. I thought, I thought tree roots just sort of did, like, I thought, I always imagined tree roots were kind of like straws. Like, the tree was, like, already doing that stuff by itself, but it's the fungus that's doing that stuff?

Jennifer:

Yes, in a lot of cases it is the fungus. Because tree roots and a lot of plant roots are not actually very good at doing what you think they're doing.

Robert Krulwich:

She says the tree can only suck up what it needs through these -- mostly through the teeny tips of its roots, and that's not enough bandwidth.

Jad A.:

Wait. So, okay. So the fungus is giving the tree the minerals.

Robert Krulwich:

Yeah.

Jad A.:

What is the tree given back to the fungus?

Robert Krulwich:

Remember I told you how trees makes sugar?

Jad A.:

Yeah.

Robert Krulwich:

So that's what the tree gives the fungus. Sugar.

Jennifer:

The fungi needs sugar to build their bodies, the same way that we use our food to build our bodies.

Suzanne Simard:

They can't photosynthesize. They can't take up CO2. And so they have this trading system with trees.

Robert Krulwich:

She says what will happen under the ground is that the fungal tubes will stretch up toward the tree roots, and then they'll tell the tree,

Suzanne Simard:

With their chemical language, I'm in the neighborhood. Can you, will you soften your roots so that I can invade your root system? And the tree gets the message, and it sends a message back and says, Yeah, I can do that.

Robert Krulwich:

And then those little tubes will wrap themselves into place.

Roy Halling:

Well, you can see the white stuff is the fungus.

Robert Krulwich:

And we saw this in the Bronx. The little threads just wrapping themselves around the tree roots.

Roy Halling:

The last kind of part of the root gets tangled just around the edge.

Robert Krulwich:

And it's in that little space between them that they make the exchange.

Jad A.:

What exchange would that be, Robert?

Robert Krulwich:

That would be sugar, minerals, sugar, sugar, minerals, sugar, sugar, minerals, mineral sugar, minerals, sugar, minerals, and so on.

Jad A.:

What? I forgot to ask you something important.

Robert Krulwich:

Yes.

Jad A.:

If the, if the tube system is giving the trees, the minerals, how is it getting it? The minerals?

Robert Krulwich:

How's it getting the minerals?

Jad A.:

Is it just pulling it from the soil?

Robert Krulwich:

Well, that's a miracle. That's like that is I got to say doing this story. This is the part that knocked me silly.

Jad A.:

We'll be right back.







Jad A.:

I'm Jad Abumrad.

Robert Krulwich:

I'm Robert Krulwich.

Jad A.:

This is radio lab and uh, so wait, what was the, what was the answer to my question about how, how does a fungus get the minerals?

Robert Krulwich:

Oh, it's, it's a three pronged answer. What a fungus does is it, it hunts it mines, it fishes, and it strangles.

Jad A.:

What, how the hell,

Robert Krulwich:

I'm not making this up. In 1997 a couple of scientists wrote a paper which describes how fungi.

Jennifer:

Have developed a system for mining.

Robert Krulwich:

Jennifer says that what the tubes do is they worm their way back and forth through the soil until they bump into some pebbles.

Jennifer:

These little soil particles,

Robert Krulwich:

Packets of minerals, and then

Jennifer:

They secrete acid and these acids come out and they start to dissolve the rock.

Robert Krulwich:

It's like they're drilling.

Jennifer:

And the fungus actually builds a tunnel inside the rock and it can reach these little packets of minerals and mine them.

Latif:

What?

Jennifer:

If you look at these particles under the microscope, you can see the little tunnels they curve. Sometimes they branch, they look just like mining tunnels.

Robert Krulwich:

This is very like if you had a little helmet with a light on it, like a human would.

Jennifer:

Yeah, maybe not with a helmet, but yeah,

Latif:

It's like Snow White and the Seven Tubes or something.

Jad A.:

Wow.

Robert Krulwich:

And that's just the beginning. Jennifer told Letif and I about another role that these fungi play,

Jennifer:

And that's hunter.

Jad A.:

Hunter.

Robert Krulwich:

What do you mean? Like the plant is hunting?

Jennifer:

No.

Robert Krulwich:

Oh, hunting for water. I mean the fungus fungus is,

Jennifer:

No, no, no. The fungus is hunting.

Latif:

The fungus hunter!

Robert Krulwich:

How do you meet? How do you mean?

Jennifer:

So there's these little insects that lives in the soil, these just adorable little creatures called springtails.

Robert Krulwich:

They're sort of flea-sized and they spend lots of time munching leaves on the forest floor.

Suzanne Simard:

They're called springtails, because a lot of them have a little organ on the back that they actually can kind of like deploy and suddenly, boing!, they spring way up high in the air.

Robert Krulwich:

In the David Attenborough version. And if you want to look on YouTube, he actually takes a nail,

David Attenboro:

This pin will give you an idea.

Robert Krulwich:

And he pokes it at this little springtail, and the springtail goes boing! And you don't see it anywhere. It's gone.

David Attenboro:

Into the air.

Robert Krulwich:

Then of course because it's the BBC, they take a picture of it. It's doing like a triple double axle back flip or something into the sky.

David Attenboro:

It's the equivalent of a human being jumping over the Eiffel Tower.

Robert Krulwich:

Anyhow.

Jennifer:

One of the things they eat is fungus.

Robert Krulwich:

But then scientists did an experiment where they gave some springtails some fungus to eat. They sort of put them all together in a dish and then they walked away and then they came back,

Jennifer:

And they found that most of the springtails were dead.

Robert Krulwich:

Instead of eating the fungus, it turns out the fungus ate them.

Suzanne Simard:

In the little springtail bodies that were a little tubes growing inside them.

Latif:

What?

Suzanne Simard:

And this is what makes it even more gruesome. They somehow have a dye, and don't ask me how they know this or how they figured it out, but they have a little stain that they can put on the springtails to tell if they're alive or dead. When they did this, they saw that a lot of the springtails that had the tubes inside them were still alive.

Latif:

Oh, that's cruel.

Suzanne Simard:

Yes.

Robert Krulwich:

The fungus were literally sucking the nitrogen out of the springtails, and it was too late to get away. No boink anymore.

Suzanne Simard:

And then they did experiments with the same fungus that I'm telling you about that was capturing the springtails and they hooked it up to a tree.

Robert Krulwich:

And then they did experiments with the same fungus that I'm telling you about that was capturing the springtails, and they hooked it up to a tree.

Suzanne Simard:

Well, 25% of it ended up in the trees.

Robert Krulwich:

So they figured out who paid for the murder.

Latif:

Right.

Robert Krulwich:

The trees did.

Latif:

Is there anyone whose job it is to draw little chalk outlines around the springtail?

Robert Krulwich:

Inspector Tail is his name. He's the only springtail with a trench coat and a fedora.

Robert Krulwich:

I have even, I can go better than even that. There's, they have found salmon in tree rings, like as in the fish.

Jad A.:

In the tree?

Robert Krulwich:

In the tree. Well, in a way.

Jad A.:

How in the hell?

Robert Krulwich:

Apparently, bears park themselves in places and grab fish out of the water, and then, you know, take a bite and then throw the carcass down on the ground. The fungi, you know, after it's rained and snowed and the carcass has seeped down into the soil a bit, the fungi then go and they drink the salmon carcass down and then send it off to the tree.

Jad A.:

Oh fuck off.

Robert Krulwich:

And the tree has,

Jad A.:

That's fucking bananas.

Robert Krulwich:

Evidence of salmon consumption. I was like, floored.

Jad A.:

Wow, that's insane.

Robert Krulwich:

Salmon rings in trees.

Jad A.:

That's insane.

Robert Krulwich:

And look, and beyond that there are forests, there are trees that the scientists have found where up to 75 percent of the nitrogen in the tree turns out to be fish food.

Jad A.:

From just bears throwing fish on the ground?

Robert Krulwich:

Yeah. So you, if you would take away the fish, the, the trees would be like blitzed, hobbled really.

Jad A.:

And is it as dramatic in the opposite direction? Like the fungus seem to be giving the trees a lot of minerals. At, like, from the trees perspective, how much of their sugar are they giving to the fungus?

Robert Krulwich:

Oh. Well, I asked Suzanne about that. Like, two percent or 0.00000001 percent? Or,

Suzanne Simard:

No. Well, people have been measuring this in different forests and ecosystems around the world, and the estimate is anywhere from 20 to 80 percent will go into the ground.

Robert Krulwich:

Wait, wait, wait, what?

Suzanne Simard:

Yeah. 20 to 80%.

Robert Krulwich:

Of the tree's sugar goes down to the mushroom team?

Suzanne Simard:

Into the roots, and then into the microbial community, which includes the mushroom team, yeah.

Robert Krulwich:

The point here is that the scale of this is so vast, and we didn't know this until very, very recently. You have a forest, you have mushrooms. Now, it turns out that they're networked, and together they're capable of doing things, of behaviors, forestrial behaviors, that are deeply new. We're just learning about them now, and they're so interesting.

Robert Krulwich:

Just for example,

Suzanne Simard:

Let's say it's -- times are good. The tree has a lot of sugar. I don't really need it all right now. I'll put it down in my fungi. And then when times are hard, that fungi will give me my sugar back and I can start growing again.

Robert Krulwich:

What do mean, the fungi will give me my sugar back?

Latif:

It's like a bank? It's like a savings account?

Suzanne Simard:

It is! It is like a bank!

Robert Krulwich:

She says, we now know the trees give each other loans.

Jennifer:

Oh yeah. Back and forth. Seasonally. They can also send warning signals through the fungus.

Suzanne Simard:

Yeah. So we've done experiments, and other people in different labs around the world, they've been able to figure out that if a tree's injured,

Robert Krulwich:

It'll cry out in a kind of chemical way.

Suzanne Simard:

And those chemicals will then move through the network and warn neighboring trees or seedlings.

Jennifer:

That's something bad is happening. I'm under attack.

Suzanne Simard:

There's an enemy in the midst.

Robert Krulwich:

So if a beetle were to invade the forest, the trees tell the next tree over, Here come the, like Paul Revere, sort of?

Suzanne Simard:

Yes. That seems to be what's what happens.

Robert Krulwich:

So you can -- you can see this is like a game of telephone. One tree goes Uh-oh. The next one goes, Uh-oh. And then they do stuff.

Suzanne Simard:

They start producing chemicals that taste really bad.

Robert Krulwich:

So the beetles don't want to eat them.

Suzanne Simard:

It'll go ick, I don't want that.

Robert Krulwich:

One of the spookiest examples of this Suzanne mentioned, is an experiment that she and her team did where they discovered that if a forest is warming up, which is happening all over the world, temperatures are rising, you have trees in this forest that are hurting. They don't do well in warm temperatures and their needles turn all sickly yellow. They will send out a Oh, no! This is not so good signal through the network. But also,

Suzanne Simard:

The other important thing we figured out is that, as those trees are injured and dying, they'll dump their carbon into their neighbors. So -- so carbon will move from that dying tree. So its resources, its legacy will move into the mycorrhizal network into neighboring trees.

Robert Krulwich:

Oh, so it says to the newer, the healthier trees, here's my food, take it, it's yours.

Suzanne Simard:

Or it could be like, okay, I'm not doing so well, so I'm going to hide this down here and my, mycelium.

Robert Krulwich:

Okay. I don't know if you're a bank or if you're an, so it's not necessarily saying give it to the new guy.

Suzanne Simard:

Well we don't know. I mean again, it's a tree. It doesn't think, but,

Robert Krulwich:

I know, I'm just trying to make sure I understand this. I realize that none of these conversations are actually spoken.

Latif:

Give it to the new guy?

Robert Krulwich:

Give it to the new, but that's what she's saying.

Suzanne Simard:

Yes, yes.

Robert Krulwich:

Suzanne says she's not sure if the tree is running the show and saying like, you know, give it to the new guy or maybe it's the fungus under the ground is kind of like a broker and decides who gets what.

Suzanne Simard:

You know, I don't completely understand.

Robert Krulwich:

She says, one of the weirdest parts of this though is when sick trees give up their food, the food doesn't usually go to their kids or even to trees of the same species. What the team found is the food ends up very often with trees that are new in the forest and better at surviving global warming. It's as if the individual trees were somehow thinking ahead to the needs of the whole forest.

Suzanne Simard:

So we know that Douglas fir will take, a dying Douglas fir, will send carbon to neighboring Ponderosa pine. And so why is that? Like so, and I think that, you know, the whole forest, then, there's an intelligence there that's beyond just the species.

Robert Krulwich:

Wait a second. Wait a second. You just used a very interesting word.

Suzanne Simard:

I know Robert. I have, you know what? It's 10 o'clock out to go.

Robert Krulwich:

Oh, all right.

Suzanne Simard:

This is getting so interesting.

Robert Krulwich:

Unfortunately, right at that point, Suzanne basically ran off to another meeting, but,

Suzanne Simard:

Hello, Suzanne speaking.

Robert Krulwich:

Oh there you are, hi.

Suzanne Simard:

Hi Robert.

Robert Krulwich:

Hi.

Robert Krulwich:

We did catch up with her a few weeks later.

Robert Krulwich:

When we last left off, I'm just saying, you just said intelligence. Now, isn't, doesn't, don't professors begin to start falling out of chairs when that word gets used regarding plants?

Suzanne Simard:

Yes. We don't normally ascribe intelligence to plants, and plants are not thought to have brains, but when we look at the below ground structure, it looks so much like a brain, physically, and then now that we're starting to understand how it works, we are going well. There's so many parallels.

Jennifer:

I do find it magical. I think there is something like a nervous system in the forest, because it's the same sort of large network of nodes sending signals to one another. It's almost as if the forest is acting as an organism itself. You know, they talk about how honeybee colonies are sort of super organisms, because each individual bee is sort of acting like it's a cell in a larger body. Once you understand that the trees are all connected to each other, they're all signaling each other, sending food and resources to each other, it has the feel, the flavor, of something very similar.

Robert Krulwich:

Special thanks to Dr. Teresa Ryan of the University of British Columbia, Faculty of Forestry, to our intern Stephanie Tam, to Roy Halling and the Bronx Botanical Garden, and to Stephenson Swanson there.

Jad A.:

And to Annie McEwen and Brenna Farrow who both produced this piece.

Robert Krulwich:

Thank you.

Jad A.:

All right, Krulwich.

Robert Krulwich:

Okay. It's time, time for us to go and lie down on the soft forest floor.

Jad A.:

Yeah, and hopefully not be liquefied by the fungus beneath us.

Robert Krulwich:

Nice final thought. Bye everybody. Bye. I'm Robert Krulwich.

Jad A.:

I'm Jad Abumrad.

Robert Krulwich:

For Radio Lab.

Jad A.:

Thanks for listening.

Voicemail:

Start of message.

Roy Halling:

This is Roy Halling, researcher specializing in fungi at the New York Botanical Garden.

Jennifer:

This is Jennifer Frazer, and I'm a freelance science writer and blogger of The Artful Amoeba at Scientific American.

Roy Halling:

Radio Lab is produced by Jad Abumrad.

Jennifer:

By Jad Abumrad.

Roy Halling:

Dylan Keefe is our Director of Sound Design.

Jennifer:

Soren Wheeler is Senior Editor.

Roy Halling:

Jamie York is our Senior Producer.

Jennifer:

Our staff includes Simon Adler, Brenna Farrow, David Gebel.

Roy Halling:

Matt Kielty, Robert Krulwich, Annie McEwen, Andy Mills, Latif Nasser, Malissa O'Donnell.

Jennifer:

Kelsey Pagett.

Roy Halling:

Arianne Wack.

Jennifer:

And Molly Webster.

Roy Halling:

With help from Alexandra Leigh Young, Jackson Roach, and Charu Sinha.

Jennifer:

Our fact-checkers are Eva Dasher and Michelle Harris. And remember, if you're a springtail, don't talk to strange mushrooms. Actually that's good advice for anyone.

Roy Halling:

Thank you. Bye.

Voicemail:

End of message.

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