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This is the world's tallest tree--the coast redwood. It can grow as high up as 115.5 meters. Any taller, and the transportation of water in its vascular tissues would not climb all the way.

But in an alternate Earth, there are multiple species of angiosperm trees whose roots need to be completely submerged, therefore grow in seawater five to 25 meters beneath the surface. Such trees include a species averaging 150 meters tall and 12 wide, with crowns averaging 180 meters wide and branches 3.8 meters wide. Far smaller species grow in brackish and freshwater estuaries, riverbanks and lakeshores, the tallest standing 88.5 meters tall. Such trees with roots that need to be submerged 24/7 could have easier, more efficient water transportation, allowing them to grow taller even than the redwoods.

Wherever the water flows, these multiple species of mangroves and "megamangroves" form dense, near-impenetrable groves and forests. Each forest, in fact, has been described as "a Great Wall against storm surges". But can they be enough to deflect hurricanes and tornadoes?

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Water is about 1000 times denser than air, and in a hurricane the winds are about a factor 10 faster than the water flow during a storm surge (ballpark figures).

If we calculate the amount of energy contained in a unit of flowing volume, we see that

$E_{water}=1/2 \cdot m_{water} \cdot v_{water}^2 = 1/2 \cdot 1000 \cdot m_{air} \cdot (0.1 \cdot v_{air})^2 = 10 \cdot 1/2 \cdot m_{air} \cdot v_{air}^2 = 10 \cdot E_{air}$.

Based on the above, if the mangroves wall can withstand a water surge, it can also withstand an hurricane, since the energy delivered by the hurricane winds is about 10 times lower.

Consequently a solid and extended barrier will somehow deflect the winds.

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    $\begingroup$ It might deflect, or at least soften, the surface winds; but I don't think it can actually deflect a whole hurricane. The actual storm is as much as 10km up. It'll just glide right over the megamangrove. $\endgroup$ – elemtilas Apr 1 '20 at 4:06

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