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  • The internet connects more than half of the world's population

  • through an invisible web of servers, computers, and devices.

  • It has changed our lives in countless ways

  • by allowing otherwise separated people to interact

  • and by providing access to vast amounts of information.

  • But humans aren't the only organisms on the planet

  • with an invisible interconnected network.

  • While plants might seem like isolated, solitary individuals,

  • they're capable of communicating with each other,

  • sometimes over considerable distances,

  • all thanks to their special relationship with fungi.

  • Nearly all plant species we know of have a mutually beneficial relationship

  • with soil fungi called mycorrhizae.

  • Mycorrhizae grow a network of small, branching tubes, called a mycelium,

  • that extends throughout the soil, including inside of or around plant roots.

  • And these allow the fungi to absorb nutrients from the soil,

  • like nitrogen and phosphorus, which plants struggle to extract.

  • So they basically barter: in exchange for those hard-to-get nutrients,

  • the plants trade the fungi carbon in the form of sugars.

  • And ultimately, together, both can thrive when they otherwise wouldn't.

  • This symbiotic relationship between plants and fungi

  • was discovered in the early 1900s, but it wasn't until 1997

  • that we understood just how deep this underground network goes.

  • Ecologist Suzanne Simard had a hunch

  • that plants weren't just sharing nutrients with fungi, but also with each other.

  • To test her hypothesis,

  • she and her colleagues infused trees in a forest

  • with a traceable, radioactive form of carbon,

  • and later took samples from neighboring trees.

  • And it turned out many nearby trees had the radioactive carbon, too,

  • proving that plants could send nutrients back and forth to one another.

  • Not only that,

  • they seemingly distributed the nutrients where they were needed most.

  • Plants need light energy to turn carbon dioxide and water

  • into sugar and oxygen

  • thanks to that magical process called photosynthesis.

  • So those in shade have less sugar to go around.

  • Simard found that these shaded, energy-deficient trees

  • ended up with more of the radioactive carbon

  • than their sunbathing counterparts.

  • So it's basically the plant-fungi equivalent of feeding the hungry.

  • Continued research into these underground networks,

  • called Common Mycelium Networks,

  • has revealed that plants are not only able to gain access to more nutrients,

  • they can also engage in sophisticated communication

  • bytalkingchemically through mycelia.

  • And, it turns out, they're saying quite a bit!

  • Generally, any seedling that's plugged into the Common Mycelium Network,

  • or CMN, has a higher likelihood of surviving.

  • And plants that areonlineare generally healthier, too.

  • Researchers think this has to do with having access

  • to an early warning system.

  • When a plant is attacked, it releases chemicals

  • that tell nearby plants something bad is coming their way.

  • This communication happens with airborne compounds,

  • but also through a CMN.

  • And other plants heed this warning.

  • For example, when tomato plants are connected by a CMN,

  • and one plant is attacked by a pest,

  • nearby plants will activate their defenses before the pest reaches them.

  • Scientists are only just starting to understand

  • how important these plant networks are.

  • They've discovered that entire forests can be interconnected,

  • but like with our internet,

  • connectivity throughout an ecosystem isn't evenly distributed.

  • Older, larger trees are more connected,

  • kind of like some servers in the human internet.

  • These highly connected trees are called hub or mother trees.

  • They have big root networks that host a greater diversity of mycorrhizal fungi,

  • and that allows them to interact with a lot of other plants.

  • They do play favorites, though

  • Scientists have shown they can send 'care packages' of extra nutrients

  • to their kin to help them survive, which is how they got the mommy moniker.

  • And they also can help forests transition during times of change.

  • When they're injured or dying, they release a surge of carbon

  • into the network which nurtures the next generation of trees,

  • even if they're a different species.

  • Of course, no internet is complete without hackers.

  • Some plants can claim territory and influence community dynamics

  • by sending toxins into the CMN.

  • Black Walnuts will use these networks

  • to release toxins into the soil, for example.

  • Those that are immune to the toxins thrive, while others struggle or die off.

  • And harmful worms, parasitic plants, and fungi

  • can find their way to the plants they target by following chemical trails

  • emitted by the mycorrhizae underground.

  • It's amazing to think that this chemical information superhighway

  • was right below our noses for eons and yet we had no clue.

  • But now that we can finally plug in, it might just help us connect

  • with the planet's flora in much more constructive ways.

  • Knowledge of this interconnectivity is helping improve our relationship to plants,

  • including things like forest conservation and agriculture.

  • For example, preserving the highly connected mother trees from deforestation

  • ensures mycorrhizal fungal diversity,

  • and helps forest regrowth happen more quickly.

  • And farming in soil with a CMN means plants can warn each other

  • of invading pests, which may reduce the need for pesticides.

  • Like with the human internet, the internet of the earth increases security,

  • awareness, and knowledge for those connected to itincluding us.

  • Thanks for watching this episode of SciShow!

  • If you liked learning about plant symbiotic relationships,

  • you might like our episode on how plants recruit bodyguards.

The internet connects more than half of the world's population

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B1 中級 美國腔

地球的互聯網。真菌如何幫助植物交流 (The Earth's Internet: How Fungi Help Plants Communicate)

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    robert 發佈於 2021 年 01 月 14 日
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