Why trees can't grow taller than around 100 metres | Hacker News Reader

Why trees can't grow taller than around 100 metres

newscientist.com

137 pointsdrucken18 comments

In contrast, http://news.ycombinator.com/item?id=5083564 describes a 2004 study that gives 130m as the limit, and claims a world record of 125m. Also, http://en.wikipedia.org/wiki/Hyperion_(tree) is 115m.

However, this theory is less observational; that, IMO, makes it a better one, even if the maximum height it predicts is of by 10% or so.

In fact, that is fairly typical for scaling laws. For example, bumblebees and swans are outliers in the field of flying insects, respectively flying birds. That is why, in those circles, a standard joke is that bumblebees cannot fly, and swans can fly, but cannot take off from the ground.

> Also, http://en.wikipedia.org/wiki/Hyperion_(tree) is 115m.

And the tallest reliably measured australian mountain ash (Eucalyptus regnans) was 112m, with disputed claims of individuals in the 130m range.

Iirc albatrosses actually can't take off from the ground. They need to jump off a cliff with an updraft. So they're very careful about where they land.

> Iirc albatrosses actually can't take off from the ground

Of course they can.

https://www.youtube.com/watch?v=gKTfcs6LL6A

Hmm...

Having now gone back and researched that a little better, it's only Waved Albatrosses I was thinking of and sources seem to disagree on whether they can take off from flat ground or not. They certainly prefer a cliff, and will make a long walk to get to one if necessary.

Oops, apparently, one can get upvotes for giving a reference to the thread one is posting in. That first link should have been http://news.bbc.co.uk/2/hi/science/nature/3643899.stm

This is an interesting video with an alternate explanation - the pressure required to get water to the top of the tree. Normally you can only suck a water column up 10 meters, and that's using a perfect vacuum - but trees can grow higher than that. The secret sauce is that in a liquid rather than a gas, you can have a negative pressure.

http://www.youtube.com/watch?v=BickMFHAZR0

So, how long until someone engineers some 'helper pumps' to assist trees in pumping nutrients around. Be nice to see some 1000-foot trees in manhattan to crowd out some skyscrapers.

>>Sugars accelerate as they move

That's no way to describe the diffusion gradient.

Also, this paper does not cover all of Plantae, so for all we know, other Embryophytes may be limited in height by an entirely different factor.

The creatures that we call trees, and the Earth had experimented with a lot of different types of trees, are in fact much higher if we count the roots.

Yes, but the tallest trees (California redwood) have shallow root systems (a couple meters). Are there trees commonly over 100 meters counting the roots?

I remember learning this in my high school biology class a few years ago. I recall the limit as being 120 meters because of the force of gravity.

Xylum and phloem... memories.

"Xylum up, phloem down"

Gravity and cohesion-tension theory.

This doesn't seem to preclude a tree that's taller than that, but simply an outlier in its leaf size. Unless I'm misunderstanding something...

The New Scientist article isn't very clear. The paper proposes that tall trees are unable to gain energy from leaves above a certain length (my not great understanding is that a larger leaf can generally move more energy than a shorter leaf, but a longer stem can only move so much, limiting the useful leaf size).

This is why I love HN - the fact that this kind of post can make it to the front page.

It's pretty rare..

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