WEBVTT - How Big Can a Tree Grow?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff

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<v Speaker 1>Lorn Vogel bomb here. Back in two thousand and eight,

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<v Speaker 1>a study proposed that the maximum height for a Douglas Fir,

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<v Speaker 1>one of the world's tallest types of trees, is right

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<v Speaker 1>about at four hundred and fifty three feet. That's one

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<v Speaker 1>hundred and thirty eight meters. But why is there a

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<v Speaker 1>specific limit. Trees are nature's skyscrapers, but as it turns out,

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<v Speaker 1>nature has hemmed them in. That's because trees can only

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<v Speaker 1>physically pull water so far up their trunks. The transporters

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<v Speaker 1>in question are a type of dead cells called tray kids,

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<v Speaker 1>with deep pits that help move water from one long,

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<v Speaker 1>skinny cell to the next. The diameter of these all

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<v Speaker 1>important pits shrinks as you ascend into a tree's upper reaches,

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<v Speaker 1>complicating water transport. Eventually, the flow of water reaching the

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<v Speaker 1>leaves and branches near the top dwindles or stops entirely,

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<v Speaker 1>and the struggling sections experience drought stress and they become

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<v Speaker 1>dehydrated and die, establishing a de facto maximum height for

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<v Speaker 1>that tree. Researchers think these progressively narrowing pits actually help

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<v Speaker 1>trees survive. A height poses the problem of air bubbles.

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<v Speaker 1>The taller the tree, the more likely it will develop

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<v Speaker 1>a xylum embolism, which is when air bubbles get in

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<v Speaker 1>and block the passage of water through the xylum, which

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<v Speaker 1>is the tissue that makes up a tree's vascular system

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<v Speaker 1>and allows it to transport water and minerals from the

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<v Speaker 1>roots to the rest of the plant. A xylum embolism

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<v Speaker 1>is similar to a human air embolism, in which air

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<v Speaker 1>enters the bloodstream and causes potentially severe complications. The trachid's

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<v Speaker 1>chain shape near the top of the tree to try

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<v Speaker 1>to prevent such air bubbles and withstand the increased pressure

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<v Speaker 1>of water being pulled three hundred feet up in the air,

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<v Speaker 1>but that protection comes at a price less water and

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<v Speaker 1>as the ree searchers suggest, a cap on how tall

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<v Speaker 1>trees can grow. Another tree height study positive the maximum

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<v Speaker 1>height of all trees at four hundred and twenty six

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<v Speaker 1>and a half feet or one hundred and thirty meters.

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<v Speaker 1>The study examined coast redwoods, currently the world's tallest trees,

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<v Speaker 1>and based projection on factors like existing weather conditions, photosynthesis levels,

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<v Speaker 1>water flow, and carbon dioxide levels. And not surprising. Health

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<v Speaker 1>factors like water flow and photosynthesis decreased in the higher

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<v Speaker 1>portions of the massive trees, while unhealthy factors like carbon

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<v Speaker 1>dioxide increased, But ultimately, as with the furs, it all

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<v Speaker 1>comes down to xylum. These redwoods pull water up through

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<v Speaker 1>their trunks as other trees do, although they can absorb

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<v Speaker 1>some water from the fog that often surrounds them in

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<v Speaker 1>their native California and Oregon environments. Before attaining their maximum height,

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<v Speaker 1>they shoot up about ten inches that's twenty five centimeters

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<v Speaker 1>every year. But of course, tree size is more than

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<v Speaker 1>just height. The world's heaviest and most voluminous tree is

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<v Speaker 1>General Sherman, a giant sequoia, one of two types of

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<v Speaker 1>redwood found in California, the other being the taller, skinnier

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<v Speaker 1>Coast redwood that we just mentioned. General Sherman is estimated

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<v Speaker 1>to weigh over six thousand tons and encompass fifty two

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<v Speaker 1>thousand cubic feet that's about one thousand, five hundred cubic meters.

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<v Speaker 1>Located in California's Sequoia National Park, General Sherman is two

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<v Speaker 1>hundred and seventy five feet tall that's eighty four meters

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<v Speaker 1>but it's not the world's tallest tree. That honor belongs

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<v Speaker 1>to a coast redwood named Hyperion, which clocks in at

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<v Speaker 1>three hundred and seventy nine feet tall that's one hundred

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<v Speaker 1>and fifteen meters. A general Sherman also isn't the world's

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<v Speaker 1>widest tree. It has a trunk circumference of one hundred

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<v Speaker 1>and two feet or thirty one meters, but it's beat

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<v Speaker 1>out by l Arbol de Tule in Wajaca, Mexico, which

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<v Speaker 1>has a maximum circumference of one hundred and seventy eight

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<v Speaker 1>feet or fifty four meters. So there are different ways

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<v Speaker 1>of considering tree size, just as there are various ways

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<v Speaker 1>of considering what might be the world's largest living organism.

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<v Speaker 1>Some scientists consider massive reefs like Australia's Great Barrier reef,

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<v Speaker 1>to be giant singular organisms. There are also huge fungi

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<v Speaker 1>out there, such as a fungus discovered in Washington State

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<v Speaker 1>that spans one five hundred acres that's six hundred hectares.

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<v Speaker 1>But we are talking about trees here, and the world's

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<v Speaker 1>most massive living organism may be one group of quaking

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<v Speaker 1>aspen trees located in the mountains of Utah and nicknamed

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<v Speaker 1>Pando Latin for I spread. A Pando is considered one

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<v Speaker 1>organism because the trees in the group share an identical

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<v Speaker 1>genetic code and a common interconnected root system. The Pando

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<v Speaker 1>trees are basically clones of one another, and new trees

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<v Speaker 1>are made as stems spread out as far as one

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<v Speaker 1>hundred feet or thirty meters from the base of the

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<v Speaker 1>original tree and then periodically take root, creating new genetically identical,

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<v Speaker 1>interconnected trees. The process, known as vegetative reproduction, is also

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<v Speaker 1>how strawberries and many other plants reproduce. Pando is made

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<v Speaker 1>up of some forty seven thousand trees spread across one

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<v Speaker 1>hundred acres or forty hectors, and maybe up to eighty

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<v Speaker 1>thousand years old, but in testament to the massive size

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<v Speaker 1>of California's redwoods, this batch of forty seven thousand trees

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<v Speaker 1>weighs only about six thousand, six hundred tons, only a

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<v Speaker 1>little bit more in total than General Sherman. Today's episode

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<v Speaker 1>is based on the article how Tall can a Tree Grow?

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<v Speaker 1>On HowStuffWorks dot com, written by Jacob Silverman. Brainstuff is

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<v Speaker 1>production by Heart Radio in partnership with Hostiff Works dot

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<v Speaker 1>com and is produced by Tyler Klang. Four more podcasts

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<v Speaker 1>from my Heart Radio. Visit the iHeartRadio app, Apple Podcasts,

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<v Speaker 1>or wherever you listen to your favorite shows.