Can trees talk to each other?

Sure! Here’s a sanitized version of the transcript:

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(Phone beeping) – Hi, it’s Doug. What’s the oldest tree in the world? Some scientists think it’s the bristlecone pine trees, which are found in a few mountain ranges in the western United States. Some of them can live to be nearly 5,000 years old. Someone named Ava has a question about trees like these. Let’s give Ava a call now. (Phone beeping) – Hi, Doug. – Hi, Ava. – I have a question for you. Can trees talk to each other? – Ooh, that’s a great question. If trees could talk to each other, certainly trees like these bristlecone pines would have a lot of interesting stories to tell. But trees can’t talk to each other in the same way that we do. They don’t have mouths or hands or any of the body parts humans use to communicate. Still, what if we broaden the word “talk” to mean just communicate or send any kind of message to each other? Can trees do that? Well, if you’d asked me before, I would have said, “I really don’t think so.” But recently, I noticed a group of trees. As I stared at them, I noticed something interesting. I’m curious what you notice. Before I say anything more, now would be a good time to pause the video and discuss. Okay, you ready? What I notice is that there’s a little bit of space between each treetop, almost as if these trees can send messages or communicate to keep from getting in each other’s way. Now, maybe that’s just the way they grew, because that’s how they got the most sunlight for each tree. But it makes me wonder, could trees actually work together like this? And if they did work together, wouldn’t they have to share information to do that? Like maybe send messages to each other? A scientist named Suzanne Simard has thought a lot about these questions. Suzanne studies trees, but not just any part of the tree. You see, when she was younger, Suzanne played a lot in a forest near her home. She used to love to lie on her back and watch the tops of the trees waving around in the wind high above her. Then one day, she saw something in the forest that changed how she saw it forever. She saw a hole in the ground. That’s it, just an ordinary hole, nothing special about it. But when young Suzanne looked down into the hole, what she saw amazed her. It wasn’t just dirt down there. There was so much life poking through the soil, from wiggling worms to crawling bugs to tangling roots. That was the moment Suzanne realized there’s a whole world under the trees as well, every bit as detailed and interesting as the world above. As an adult now, her research focuses on understanding everything that’s going on below the soil at the roots of the trees in the forest. As she explored the underground forest world, Suzanne started paying attention to tiny living things in the soil called fungi. You might have seen some parts of fungi called mushrooms above the ground before, but there’s a whole other world of fungi below the surface. These fungi form chains underground that look like long strings. Suzanne noticed that these fungi strings don’t just grow in random spots. They grow between the roots of trees, connecting the forest in a huge underground fungi web. Suzanne wondered, “What can trees do with all these underground connections? Can they use them to share things or even communicate?” She set up an experiment to answer her question. She gave one tree in a forest a very specific nutrient. She waited an hour, then checked to see if that nutrient showed up in any other trees in the forest, and it did. The special nutrients Suzanne gave the tree traveled down the tree’s roots through the fungi web into the roots of another tree. These two trees weren’t touching at all, but they could still share nutrients because their roots were connected by strings of fungi. Now, this isn’t exactly trees talking, but you might think of it as a kind of communication. Trees linked by underground fungi can share what they have the same way you might swap a snack with a friend. And Suzanne thinks trees might share more than just nutrients through the fungi web. She thinks trees might actually use these connections to send messages to each other. Suzanne and another scientist named Yuan Yuan Song did an experiment on injured trees. When they studied a tree injured by bugs, they noticed the tree was producing an unusual chemical. That chemical traveled from the roots of the sick tree through the fungi web to a nearby healthy tree. Then the healthy tree started doing something amazing. It made a sticky substance to defend against bugs. It’s a daring idea, but Suzanne argues that we might think of the chemical the sick tree sent as a message, a warning signal to other trees saying, “Hey! Watch out! There are dangerous bugs around here.” The nearby tree got the message and started protecting itself. So can trees talk to each other? Well, they don’t communicate in words, but some scientists think forests can share nutrients and warnings with the help of a huge web of underground fungi. Still, not everyone is convinced yet. Some scientists think we don’t know enough to say that trees can even communicate at all. We have lots to discover about what’s really going on in forests, but one thing is clear. There’s so much more going on in a forest than what we see above ground. Maybe you’ll be the next scientist to add to what we know about the complicated lives trees live right under our feet. That’s all for this week’s question. Thanks, Ava, for asking it. Now, we’ll be back with a new episode in a couple of weeks, but in the meantime, here are some older questions from the question jar. You can vote on which one you think we should send out next week. You can choose from, “Why do leaves change color in the fall?” “Why do people eat turkey on Thanksgiving?” or “Why are pumpkins orange?” So submit your vote when the video’s over. We want to hear from all of you watching. There are mysteries all around us. Stay curious and see you next week.

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