[RADIOLAB INTRO]

JAD ABUMRAD: Hey, I'm Jad Abumrad.

ROBERT KRULWICH: I'm Robert Krulwich.

JAD: This is Radiolab. Very good to actually be back here talking to you.

ROBERT: Yes.

JAD: Yes, it's been a while.

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

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

ROBERT: When are you gonna have part two?

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

ROBERT: [laughs] Okay.

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

ROBERT: Let me rescue you from this awkward situation by bringing you back into Radiolab, where I'd like to begin by building a tall, dark, dense green forest. Towering trees to your left and to your right.

JAD: Okay.

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

JAD: You mean, like, sound?

ROBERT: Sound, yeah. Birds, please. Birds.

JAD: Why? We haven't even started this?

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

JAD: I'm not like your sound puppet here.

ROBERT: [laughs] But I can't—how do I—all right, never mind. This story ...

JAD: You'll get your sound at some point. [laughs]

ROBERT: ... begins with a woman, or at the time actually she was a very little girl who loved the outdoors. And I mean, really loved the outdoors.

SUZANNE SIMARD: [laughs] When I was a little kid, I would be in the forest and I'd just eat the forest floor. And I know lots of kids do that. But I was like ...

ROBERT: You mean, you got down on all fours and just ...

SUZANNE SIMARD: Yeah, I would just eat the dirt.

ROBERT: 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. [laughs]

ROBERT: 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: And her family included a dog named Jigs.

SUZANNE SIMARD: And so in this particular summer when the event with Jigs happened ...

ROBERT: What kind of dog is Jigs, by the way?

SUZANNE SIMARD: He was not a wiener dog. He was a—what was he?

ROBERT: You don't know what your dog was?

SUZANNE SIMARD: [laughs] Not a basset hound, but he was a beagle.

ROBERT: Beagle.

SUZANNE SIMARD: Yeah. He was a curious dog.

ROBERT: 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 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 out there.

ROBERT: So they followed the sound of the barking and it leads them to an outhouse. And when they go in ...

SUZANNE SIMARD: There's Jigs at the bottom of the outhouse. Probably six feet down at the bottom of the outhouse pit.

ROBERT: Oh dear!

SUZANNE SIMARD: 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 in um ...

ROBERT: Oh.

SUZANNE SIMARD: And toilet paper. And of course we had to get Jigs out. I mean, Jigs was part of the family and ...

ROBERT: Since he was so deep down in there ...

SUZANNE SIMARD: We had to dig from the sides.

ROBERT: 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 him out. And so we're digging away and Jigs was, you know, looking up with his paws, you know, looking at us waiting.

ROBERT: 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 is like—it is like a mat. It's like it's just a massive mat of intertwining, exposed roots that you could walk across to never fall through.

ROBERT: 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.

ROBERT: 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: 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 late 1980s as a forester, we were into industrial, large scale, clear cutting in Western Canada. Huge machines, loaders and Cats

ROBERT: 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: 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: Yeah, absolutely. They shade each other out.

ROBERT: They shade each other out. And they fiercely—you know, 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 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: Well of course there could be a whole—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: 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: So 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: So these trees were basically covered with bags that were then filled with radioactive gas.

SUZANNE SIMARD: Yeah.

ROBERT: Which the trees ...

SUZANNE SIMARD: Would just suck up through photosynthesis.

ROBERT: So now they have the radioactive particles inside their trunks and their branches.

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

ROBERT: 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 that all these trees, all these trees that were of totally different species, were sharing their food underground. Like, if you put 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, tenth, eleventh. 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: And when you look at the map, what 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 FRAZIER: 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: Mm-hmm.

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

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

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

LATIF NASSER: I like your title.

JENNIFER FRAZIER: Thank you.

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

JENNIFER FRAZIER: The Wood Wide Web.

ROBERT: The what?

JENNIFER FRAZIER: The Wood Wide Web.

LATIF: [laughs]

ROBERT: 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 FRAZIER: Yeah.

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

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

JAD: What creature? Where are we going?

ROBERT: I'm not gonna tell you. I'm gonna just go there.

JAD: Come on!

ROBERT: We went and looked for ourselves. I don't know where you were that day. Annie McEwen, Stephanie Tam, our intern—Annie'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: That's far you have to travel here in New York to get to actual greenery.

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

ANNIE MCEWEN: Is that Roy?

ROY HALLING: That is.

ANNIE: Roy!

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

ANNIE: He's got a trowel.

ROBERT: But it has like an expandable ...

ROY HALLING: It's a truffle rake.

ROBERT: Oh, it's an extend—oh listen to that!

JAD: Oh, that sounds dangerous.

ROBERT: And 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: And he starts digging with his rake at the base of this tree. He shoves away the leaves, he shoves away the topsoil.

STEPHANIE TAM: Can the tree feel you ripping the roots out like that?

ROY HALLING: I hope not.

ROBERT: And so now we're down there.

ROBERT: Pulled out a sapling root of some sort?

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

ROBERT: 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: Do you see anything white yet? You see anything?

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

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

ROY HALLING: Finally. Do you have the lens?

ROBERT: ... he gives us a magnifying glass, you know one of those little jeweler's glasses? Handheld?

ROY HALLING: Have a look there.

ROBERT: And he hands it to Annie.

ANNIE: Wow!

ROY HALLING: You see it there?

ANNIE: Oh yeah!

ROY HALLING: The white ...

ROBERT: Let me—can I see it?

ANNIE: Yeah, go for it.

ROBERT: Oh my gosh, I do see them.

JAD: What do you see?

ROBERT: Little white threads attached to the roots.

ROBERT: Smaller than an eyelash. Maybe just a tenth the width of your eyelash, but white, translucent and hairy sort of.

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

JENNIFER FRAZIER: They're everywhere.

ROBERT: 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.

JAD: What?

LATIF: A pinch?

JENNIFER FRAZIER: Mm-hmm.

JAD: What is this thing? Is it like—is it a plant? What is it?

ROBERT: What kind of creature is this thing?

JAD: Yes. What is it?

ROBERT: This is the fungus, which by the way, is definitely not a plant.

JENNIFER FRAZIER: They 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, that fungi are actually very closely related to animals. They're one of our closest relatives, actually.

ROBERT: Now back in the day ...

JENNIFER FRAZIER: This all has a history, of course.

ROBERT: ... 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 FRAZIER: You can see even in the roots of these earliest land plants ...

ROBERT: ... you can see those threads.

JENNIFER FRAZIER: This is a really ancient association.

ROBERT: 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 FRAZIER: Tubes.

ROBERT: ... hollow.

JENNIFER FRAZIER: These little tubes.

LATIF: Tubes?

JENNIFER FRAZIER: Tubes. And the tubes branch, and sometimes they reconnect.

ROBERT: So there seemed 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.

JAD: Wait a second, wait a second, what is this—why is this network even there? 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: Yeah.

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

ROBERT: Let me just back up for a second so that you could—to set the scene for you.

JAD: Yeah.

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

JAD: What's its job?

ROBERT: 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: The oxygen.

ROBERT: Yeah. And it keeps the C.

SUZANNE SIMARD: Carbon, which is science speak for food.

ROBERT: 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 into stuff.

JAD: Carbon and sugar are the same thing?

ROBERT: Yeah. You can think of the carbon as 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: Oh!

ROBERT: That's Roy again. He's holding his hand maybe a foot off the ground.

ROBERT: It would be a teeny tree?

ROY HALLING: It would be smaller.

ROBERT: 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.

JAD: Huh!

ROBERT: A tree needs something else. And what a tree needs are minerals.

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

ROBERT: What kind of minerals does a tree need?

SUZANNE SIMARD: Like nitrogen and phosphorous.

JENNIFER FRAZIER: Magnesium.

SUZANNE SIMARD: Potassium and calcium and ...

JENNIFER FRAZIER: Copper.

JAD: Why? What do these do for the tree?

ROBERT: Like, can a tree stand up straight without minerals or can ...

SUZANNE SIMARD: It can't. No. [laughs]

ROBERT: 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: 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: 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 FRAZIER: 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: 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: Wait. So, okay, so the fungus is giving the tree the minerals.

ROBERT: Yeah.

JAD: What is the tree given back to the fungus?

ROBERT: Remember I told you how trees makes sugar?

JAD: Yeah.

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

JENNIFER FRAZIER: 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: 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. Like, I can start softening up my cell walls and make room for you."

ROBERT: And then those little tubes will wrap themselves into place.

ROBERT: It's a little white thread.

ROY HALLING: Well, you can see the white stuff is the fungus.

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

JAD: What exchange would that be, Robert?

ROBERT: That would be sugar, minerals, sugar, minerals sugar, minerals, sugar, minerals sugar, minerals, sugar, minerals, sugar, minerals, sugar, minerals, and so on.

JAD: [laughs] What? I forgot to ask you something important.

ROBERT: Yes?

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

ROBERT: How's it getting the minerals?

JAD: Is it just pulling it from the soil?

ROBERT: Well, that's a miracle. That's like—that is—I gotta say doing this story, this is the part that knocked me silly.

JAD: We'll be right back.

[LISTENER: Hello, this is Ricardo from beautiful Monroe, New York. Radiolab is supported in part by the Alfred P. Sloan Foundation, enhancing public understanding of science and technology in the modern world. More information about Sloan at www.sloan.org.]

JAD: I'm Jad Abumrad.

ROBERT: I'm Robert Krulwich.

JAD: This is Radiolab. And so wait, what was the—what was the answer to my question about how does a fungus get the minerals?

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

JAD: What, how the hell?

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

JENNIFER FRAZIER: Have developed a system for mining.

ROBERT: 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 FRAZIER: These little soil particles.

ROBERT: Packets of minerals, and then ...

JENNIFER FRAZIER: They secrete acid, and these acids come out and they start to dissolve the rocks.

ROBERT: It's like they're drilling.

JENNIFER FRAZIER: 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 FRAZIER: 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: This is very like if you had a little helmet with a light on it, like a human would. [laughs]

JENNIFER FRAZIER: Yeah, maybe not with a helmet, but yeah,

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

JAD: Wow.

ROBERT: And that's just the beginning. Jennifer told Latif and I about another role that these fungi play.

JENNIFER FRAZIER: And that's hunter.

LATIF: Hunter.

JENNIFER FRAZIER: Mm-hmm.

ROBERT: What do you mean? Like the plant is hunting?

JENNIFER FRAZIER: No.

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

JENNIFER FRAZIER: No, no, no. The fungus is hunting.

LATIF: The fungus hunter!

ROBERT: How do you mean? How do you mean?

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

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

[ARCHIVE CLIP, David Attenborough: This pin will give you an idea.]

ROBERT: And he pokes it at this little springtail, and the springtail goes boing!

JAD: [laughs]

ROBERT: And you don't see it anywhere. It's gone.

[ARCHIVE CLIP, David Attenborough: Into the air.]

ROBERT: 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.

[ARCHIVE CLIP, David Attenborough: It's the equivalent of a human being jumping over the Eiffel Tower.]

ROBERT: Anyhow ...

JENNIFER FRAZIER: One of the things they eat is fungus.

ROBERT: 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 FRAZIER: And they found that most of the springtails were dead.

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

SUZANNE SIMARD: In the little springtail bodies there were a little tubes growing inside them.

LATIF: What?

ROBERT: Ooh!

SUZANNE SIMARD: And this is what makes it even more gruesome. They somehow have a dye, 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: 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: To try to calculate how much springtail nitrogen is traveling back to the tree.

SUZANNE SIMARD: Well, 25 percent of it ended up in the trees.

ROBERT: Oh! So they figured out who paid for the murder.

LATIF: Right!

ROBERT: The trees did.

LATIF: Yeah. Is there anyone whose job it is to draw little chalk outlines around the springtails?

ROBERT: [laughs]

SUZANNE SIMARD: [laughs]

ROBERT: Inspector Tail is his name. He's the only springtail with a trenchcoat and a fedora.

ROBERT: I have even—I can go better than even that.

JAD: Huh.

ROBERT: There's—they have found salmon in tree rings, like as in the fish.

JAD: In the tree?

ROBERT: In the tree. Well, in a way.

JAD: How in the hell?

ROBERT: 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: Oh fuck off.

ROBERT: And the tree has ...

JAD: That's fucking bananas!

ROBERT: Evidence of salmon consumption. I was like, floored.

JAD: Wow, that's insane!

ROBERT: Salmon rings in trees.

JAD: That's insane!

ROBERT: 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: From just bears throwing fish on the ground?

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

JAD: [laughs] 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: Ah. Well, I asked Suzanne about that.

ROBERT: 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: Wait, wait, wait, what?

SUZANNE SIMARD: Yeah. 20 to 80 percent.

ROBERT: Of the tree's sugars goes down to the mushroom team?

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

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

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

SUZANNE SIMARD: There's an enemy in the midst.

ROBERT: 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: 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: So the beetles don't want to eat them.

SUZANNE SIMARD: It'll go "Ick, I don't want that."

ROBERT: 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: Oh, so it says to the newer, the healthier trees, "Here's my food, take it, it's yours."

SUZANNE SIMARD: [laughs] Or it could be like, okay, "I'm not doing so well, so I'm gonna hide this down here in my mycelium.

ROBERT: 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." Boom.

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

ROBERT: 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: Give it to the new—but that's what she's saying.

SUZANNE SIMARD: Yes, yes.

ROBERT: 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: 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: 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, and I have to go!

ROBERT: Oh, all right.

SUZANNE SIMARD: This is getting so interesting.

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

[phone ringing]

SUZANNE SIMARD: Hello, Suzanne speaking.

ROBERT: Oh there you are, hi.

SUZANNE SIMARD: Hi Robert.

ROBERT: Hi.

ROBERT: ... we did catch up with her a few weeks later.

ROBERT: 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 ow, there's so many parallels.

JENNIFER FRAZIER: 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: Huh.

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

JAD: And to Annie McEwen and Brenna Farrell who both produced this piece.

ROBERT: Thank you.

JAD: All right, Krulwich.

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

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

ROBERT: [laughs] Nice final thought. Bye everybody.

JAD: Bye.

ROBERT: I'm Robert Krulwich.

JAD: I'm Jad Abumrad.

ROBERT: For Radiolab.

JAD: Thanks for listening.

[ANSWERING MACHINE: Start of message.]

[ROY HALLING: This is Roy Halling, researcher specializing in fungi at the New York Botanical Garden.]

[JENNIFER FRAZIER: This is Jennifer Frazier, and I'm a freelance science writer and blogger of The Artful Amoeba at Scientific American.]

[ROY HALLING: Radiolab is produced by Jad Abumrad.]

[JENNIFER FRAZIER: By Jad Abumrad.]

[ROY HALLING: Dylan Keefe is our director of sound design.]

[JENNIFER FRAZIER: Soren Wheeler is senior editor.]

[ROY HALLING: Jamie York is our senior producer.]

[JENNIFER FRAZIER: Our staff includes Simon Adler, Brenna Farrell, David Gebel ...]

[ROY HALLING: Matt Kielty, Robert Krulwich, Annie McEwen, Andy Mills, Latif Nasser, Malissa O'Donnell ...]

[JENNIFER FRAZIER: Kelsey Pagett ...]

[ROY HALLING: Arianne Wack ...]

[JENNIFER FRAZIER: And Molly Webster.]

[ROY HALLING: With help from Alexandra Leigh Young, Jackson Roach, and Charu Sinha.]

[JENNIFER FRAZIER: 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.]

[ANSWERING MACHINE: End of message.]

 

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