How Trees Talk to Each Other

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Why you should care

Because there are hidden worlds beneath your feet. 

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The world as we know it would go kaput without underground networks. They allow individuals to trade valuable goods, mothers to give advice to their children and different species to find a common language. You may never have seen these networks, but rest assured — they’re just below your feet.

It’s fungus.

You’ve probably never seen fungus as forest researcher Suzanne Simard presents it in her TED Talk, co-premiering today on OZY. In the forest, a web of mycelium — the rootlike stuff under mushrooms — connects trees to one another, like an information superhighway. As Simard discovered in her native Alberta, mycelia allow trees to exchange valuable nutrients like carbon, phosphorus and nitrogen. Fungus connects trees “in a lively two-way conversation,” Simard says, and the conversation can take place between different species, like birch and fir. “Trees talk,” she says.

And it’s not small talk either. These networks are crucial to the health of forests. In an April study in Science, researchers estimated that some 40 percent of the carbon in a tree’s fine roots comes from the underground trade. And a few months ago, NASA scientists devised a way to assess the health of forests from space — by detecting the strength of the fungal associations around trees.

These webs of mycelia are white and gauzy, deep enough to make contact with trees’ roots, and “so dense that there can be hundreds of kilometers of mycelia under a single footstep,” Simard says. Mycelium’s propensity to grow, and fast, gives forests a measure of resilience. But in an age of clear-cutting and climate change, we can’t take forests for granted. In the end, there’s little doubt: It takes a forest to raise a tree.




Numbers and factoids — fodder for your next cocktail party.