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Hey smart people, Joe here.
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Beneath your feet there is a secret network.
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This network trades resources, transmits information, and can even go to war.
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I know what you're thinking, and no, this isn't the world wide web.
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It's something much older.
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450 million years older.
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And it makes life on Earth as we know it possible.
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This is the wood wide web.
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The most important social network on Earth.
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[MUSIC]
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Walk into a forest and just listen.
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(forest noises)
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You can't hear it, but the forest is communicating.
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If you've never noticed this before it's because all of this is happening below your
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feet.
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The wood wide web is a network created by fungi.
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They're called mycorrhizal fungi and these fungi live in and around the roots of trees
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and other plants.
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Fungi are a huge domain on the tree of life, and as you've probably noticed by now, nobody
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knows how you're supposed to actually say it.
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I'm going with “fun guy” because that's what I am.
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Fungi include molds, mushrooms and yeasts, and as a whole they are essential to making
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all of Earth's organic garbage and dead stuff decompose and disappear.
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While some fungi do resemble plants, they are definitely not plants.
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They're technically more closely related to animals… but really fungi are a form
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of life like no other.
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Fungi don't fossilize well so it's hard to know exactly when they first appeared in
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the evolutionary scene, but some fossil records show mycorrhizal fungi have been living in
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this partnership since the first land plants appeared in the Paleozoic, around 400 million
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years ago.
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These underground fungi are essential to plant survival.
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They also extend hair-like filaments called hyphae into the soil which pump water even
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more efficiently than the tree's own roots.
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Just like we need our vitamins and minerals to grow, so do trees.
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Plants from rose bushes to towering redwoods need these micronutrients to survive!
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And mycorrhizal fungi are efficient little miners.
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They use acid to bore holes into rocks and fish out nitrogen and phosphorous.
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In exchange for all this subterranean service, a tree provides the mycorrhizal fungi with
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sugar, created through photosynthesis.
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Trees release between 20-80% of the glucose they create to their fungal partners.
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And older trees, the grandpop-lars and grandma-ples, have more complex fungal interconnections
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than younger trees.
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But these mycorrhizal fungi do more than trade minerals, water and sugar with their host
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tree.
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They also form massive branching networks of the fungal threads, called mycelium, that
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can extend thousands of acres, connecting entire forests.
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If you dig into the forest dirt, you may see these thousands of tiny white tubes if you
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look closely.
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In a single pinch of dirt these hyphae, when lined up, can extend 11 km!
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And these networks act as fungal freeways for shipping chemical currencies.
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The fungi can act like a seasonal bank account for trees, giving loans of sugar if the trees
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need an extra boost.
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Scientists have found that if a tree is dying, it will release its extra glucose into the
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wood wide web where it can delivered to younger nearby trees, even trees of a different species.
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Trees can also use the network to send out warning signals.
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If insects bite into one tree, it can send a chemical signal through the wood wide web,
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and when trees deeper in the forest receive this insect alert message, they produce bitter
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compounds that make their leaves less tasty to those same insects.
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"The Ents are going to war!"
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Some trees, like black walnuts, even use the network to spread chemical attacks, sabotaging
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other trees that try to grow too close.
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Across the globe, there are two main types of these mycorrhizal fungi that make up the
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wood wide web.
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Trees in cooler climates tend to host one type, which create huge interconnected networks
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that cover massive areas.
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But warmer, tropical forests tend to be dominated by a different type, which create smaller,
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more localized networks.
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It's like the difference between big, national chain stores and your local farmers' market.
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The balance between these two types of wood wide webs is important to Earth's climate.
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In general, the massive interconnected forest fungal webs tend to lock up carbon in the
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soil as they decompose stuff.
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And the more local network fungi tend to release more carbon dioxide into the atmosphere.
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As global temperatures warm up, forests are changing, and the balance of these two types
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of fungal networks is changing too.
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More of the planet covered with tropical forests means those large, carbon-storing fungal networks
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will be replaced by the more localized fungal networks which release carbon into the air,
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which will just accelerate climate change, which, even though plants eat CO2, is still
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not good.
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So next time you're walking through a forest, take a moment to think about the very small
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but also very large network that exists under your feet.
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Just because you can't log on to the wood wide web, doesn't mean you aren't connected.
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It's time we think of forests as more than trees.
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Stay curious.
