The Wood Wide Web

The Wood Wide Web

Posted: February 2, 2017

Imagine you're walking through a forest. Everything might seem quiet...but beneath your feet is a flurry of conversation. All the plants around you are actually talking to each other. The trees and the shrubs and the flowers are passing information back and forth, with serious life and death consequences. So, how are they communicating? They’re using a giant network of fungi—one so pervasive and powerful that some scientists have started comparing it to the Internet. They’re calling it the “Wood Wide Web.”

I’m Anna, and this is Gross Science.

The so-called Wood Wide Web is made up of what are called “mycorrhizal fungi.” There are many different types of mycorrhizal fungi, but generally these little guys will grow on the roots of plants and provide them with water and nutrients—like nitrogen and phosphorus—in exchange for sugars. While they’re incredibly thin, the threads of the fungi can be up to 1000 times the length of a tree root. This allows the fungi to connect together many different plants. Once connections are made, the fungi can act almost like the neurons in our brain, transporting signals from plant to plant. And these networks are everywhere. It’s estimated that around 90% of land plants are connected to some kind of mycorrhizal network.

So, how can plants use these networks? Well, to begin with, they can help each other out in times of stress. For example, during the fall months, when paper birch trees lose their leaves and can’t produce sugar, Douglas-fir trees may shuttle them nutrients through the fungal network. And in the summer, when paper birch trees have lots of leaves, they send sugars to young Douglas-fir saplings growing in their shadows.

Plants can also warn each other of danger. Douglas-fir trees connected by a fungal network can alert their ponderosa pine neighbors if they’re attacked by budworms. In response, the neighboring ponderosa pine trees will produce insect-repelling chemicals—even though they haven’t been directly exposed to the insects themselves.

Mycorrhizal fungi can also enable parental care of among plants. Some adult trees will help out their younger relatives by sending those seedlings more nutrients through the fungal network than they send to strangers. The adults may even make more room for them in the soil by reducing the number of their own roots.

But not everyone is so generous. Much like our internet, things can sometimes get a little nasty on the Wood Wide Web.

Take Black Walnut trees, for example. They can spread poison through the network, hindering the growth of their neighbors. And the fungi making up the network can be just as tricky. Mycorrhizal fungi tend to pick favorites. They may share resources with one species of tree, but bleed another species dry without giving anything back in return. The fungi may also judge a plant's health. If they think it’s too weak or sick, they may not allow it to receive nutrients or danger signals from the network.

Now, we’re only beginning to understand how complex these relationships get. But imagine the possibilities for agriculture and forestry. If we find out certain species share well across the network, maybe we can plant them near each other to yield better harvests, or grow healthier forests.

So next time you’re walking through the woods or the park don’t forget to thank the fungal web beneath your feet.

Ew.

PRODUCTION CREDITS

Host, Producer, Editor, Animator

Anna Rothschild

Writer, Researcher

Eliza Lehner

Camera, Sound

Rachel Aviles

Special thanks to Dr. Suzanne Simard.

FOOTAGE AND STILLS

Original Footage

©WGBH Educational Foundation 2017

Forest waterfall

Pond5/ownway

POV Looking up through the trees

Pond5/Beachfrontprod

In forest

Pond5/Rozum

Blueberry Bush

Pond5/capecodvideos

fern, forest flower

Pond5/leont

Time-lapse of growing fly agaric mushroom, RGB + ALPHA matte (720p)

Pond5/zygistudio

SFX

Jelly Mangling On Plate

Freesound/lolamadeus

Jelly Wobbling On Plate 1

Freesound/lolamadeus

Leaves

Freesound/dsoadigital

Ice Styrofoam Crackling Foley

Freesound/td6d

Machine Sucking and Expelling Air

Freesound/rob3rt

Basket Creak

Freesound/sheepfilms

SFX Gross Guts Slime Goo

Freesound/perel

Leather2

Freesound/everheat

Tape Pulling Off Surface

Freesound/baryy

Poof of Smoke

Freesound/planman

Produced by WGBH for PBS Digital Studios

POSTER IMAGE

Time-lapse of growing fly agaric mushroom, RGB + ALPHA matte (720p)

Pond5/zygistudio

Want more info?

Pathways for below-ground carbon transfer between paper birch and Douglas-fir seedlings:
http://bit.ly/2kocFzg

Defoliation of interior Douglas-fir elicits carbon transfer and stress signalling to ponderosa pine neighbors through ectomycorrhizal networks:
http://go.nature.com/2ko1iaS

Suzanne Simard’s TED Talk:
http://bit.ly/2kodnMW