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Crown shyness

en.wikipedia.org

332 pointsedward48 comments

The question is far from resolved (especially since it’s likely a case of convergent evolution across many species) but there have been a couple developments that haven’t made it into the wikipedia article. The most interesting ones are that there is a positive correlation between crown shyness and tree slenderness [1] and between crown shyness and leaf shape [2].

The former is especially interesting because it implies that crown shyness is an explicit strategy for resource management beyond just responding to the availability of light, since it presumably also improves the survivability of the species. The latter is interesting because it might be an adaptation to other environmental stresses like wind damage.

As always, more questions than answers :-)

[1] https://pubmed.ncbi.nlm.nih.gov/33713413/

[2] https://esj-journals.onlinelibrary.wiley.com/doi/10.1111/144...

Just wondering...what percentage of trees display this behavior? I have never seen this in my neck of the woods.

The best estimate I can give you is "not many" but it hasn't been exhaustively studied, especially with tens of thousands of tree species. I would like to point out though that crown shyness is a lot easier to observe in monoculture forests that were replanted after logging. A diverse forest with lots of trees is really hard to observe tree shyness in because it's a specific adaptation between members of one or a few species. If they're standing next to another species that doesn't cooperate, the shyness might not be readily visible.

It's also not universal, which is why it's increasingly believed to be some sort of stress response. One patch of trees in a forest may exhibit it while another patch of the exact same species a few hundred feet away might not. It might even be the case that this is an old adaptation that most trees are capable of but no longer need.

My experience with winter forests is that almost all trees display shyness when without leaves.

Makes sense. Thanks!

Trees that display crown shyness patterns include:

  * Species of Dryobalanops, including Dryobalanops lanceolata and Dryobalanops aromatica (kapur)
  * Some species of eucalypt
  * Pinus contorta or lodgepole pine
  * Avicennia germinans or black mangrove
  * Schefflera pittieri
  * Clusia alata
  * K. Paijmans observed crown shyness in a multi-species group of trees, comprising Celtis spinosa and Pterocymbium beccarii

The way I’ve always imagined crown shyness (from a total less-than-layman perspective where I’ve only casually read about the topic) is from a game theory/selfish gene perspective. Trees of the same species will share a lot of the same genes, and genes that code for non-shyness will grow to the detriment of the trees around them. Trees which critically are very likely to share a lot of the same genes. So that non-shyness gene will lose out in the long run against genes that code for shyness.

It’s similar to the prisoner’s dilemma, with shyness being “cooperate” and non-shyness being “defect”. Groups of trees with cooperative strategies would do better collectively (and win out), even if a non-cooperative individual can beat a cooperative individual every time.

Veritasium had a great video on this very topic today, in fact: https://youtu.be/mScpHTIi-kM

In “the hidden life of trees” the author talks about forests being stronger than individual trees. Which I believe agrees with your conclusion.

As a tree you don’t want to get dwarfed, starved and die. But you also don’t want to kill your neighbors either since they could be providing a wind break and helping you survive. Essentially their evolution has taught them that sharing, within reason, is an optimal strategy than pure greed.

The book goes into much more detail. I’m paraphrasing.

https://ncase.me/trust/ If people want to derp around with an iterated prisoner's dilemma sim, try this, it's fun!

Related. Others?

Crown Shyness - https://news.ycombinator.com/item?id=33217484 - Oct 2022 (1 comment)

The mystery of tree 'crown shyness' - https://news.ycombinator.com/item?id=24431062 - Sept 2020 (1 comment)

Crown shyness - https://news.ycombinator.com/item?id=14998591 - Aug 2017 (36 comments)

I learned about this from “A Prayer for the Crown Shy”. Great book.

Becky Chambers' other series, The Wayfarers, has a similar relaxed vibe and a very deep world to spend time in. If you're looking for action, it won't satisfy, but if you just want to be somewhere else for a while, it's great. I particularly enjoyed "Record of a Spaceborn Few," the third in the series.

The first and fourth were my favorites in that series.

I like robot and monk too. Her short “To teach, if fortunate” is also good. So much talent.

I think it's "To be taught, if fortunate".

Now I feel fortunate

The first two had a bit of action. I was intrigued to realize that every book in the Wayfarers series had smaller scales and lower stakes than the one before. They're all excellent.

Thank you! I’m looking for a new book to read.

Agreed. A very chill, relaxed book.

It’s in a similar box to Mushishi, which is a really laid back anime without any real antagonists. I’d recommend it to anyone who liked the Monk and Robot series.

Those two books came to me at a time when I was very receptive to and in need of their messages, and I'm still digesting them a year later. Very short, highly recommended to anyone who cares about: emotion, our place in the world, or cool futuristic societal and technology ideas. My favourite sci fi.

My favorite restaurant is called [Crown Shy](https://www.crownshy.nyc/) after this very thing. Enjoy but please try to keep what little secret is left by not spreading the good word too widely.

WTF, I just finished watching this YouTube video and came to hn out of muscle memory and see the same exact restaurant

https://youtu.be/pkQ50oXPQ4A?si=w8fXbrY4w5b3lddM

It has a Michelin star, pretty sure there ain’t no secrets involved in this story.

FWIW I found it much easier to get a reservation at Crown Shy last minute compared to most nice restaurants in NYC, starred or not. Didn't even realize it was starred until after (probably a good thing so I don't set expectations too high).

A restaurant with a Michelin star is a fairly common experience in NYC.

There are 70 of them. Out of 23,650 restaurants in total.

Yes. There are 23+k restaurants, how many of those are "fine-dining"? Put another way, you could go to a different Michelin starred restaurant every week in NYC and still not go through the list...

Also, not all Michelin restaurants are that good... (In NYC, I think they are because it is so competitive but I've been disappointed in SF and Hong Kong for instance).

So FYI - just because a restaurant has a Michelin star, it doesn't mean it is always packed nor good.

I hope their food taste is better than their website taste cos that site is an abomination.

Up to a certain price point, restaurant websites are inversely correlated with food quality. Presumably, once they get successful enough to charge for fine dining, they can also afford to pay for a decent website.

You must have seen some truly _horrible_ websites, then, because that is...well, not _good_, but perfectly fine.

The math tells me that all forest canopies should be Voronoi tesselations. And apparently, in some not-too-dense monoculture forests of similarly-aged trees, they observably are.

Where I live, in the moderately dense mixed second-growth forests of the North American northeast, I have to trust the mathematics since neither the sugar maples, elms (RIP), ash (RIP) and red oaks nor any of the abundant coniferous species that grow here demonstrate any kind of crown shyness. Maybe the aspens or birches do, I'll have to remember to check them after the leaves are out next June.

Social distancing, tree edition.

Air gapping for network security, tree edition.

They need the sunlight to prevent organic matter on the ground to dry and not decay in a way that could cause rot.

Trees also need to prevent infection from other trees, need to prevent damage from colliding from other trees, and mass damping doesn't work if trees are touching.

But they also want to be close in order to share nutrients through their roots.

There are many reasons why trees would want to do this, from an evolutionary standpoint.

Looks like an environmental puzzle from witness.

I have never heard of this before. Quite an amazing phenomenon. And it's pretty amazing how these type of structures, referring to the nerve like channels, reappear in different contexts.

Looks like it's a case of "leaves have evolved to not mess with each other intra-tree" and the environmental data used for it is broad enough that it also works inter-tree.

It seems like a very sensible and polite resolution.

In an alternate universe we might see crown hyperaggression where trees are constantly fighting it out along their crown lines...

The strangler fig would like a word (https://en.wikipedia.org/wiki/Strangler_fig)

in some forests, some trees have been seen to grow long upward branches into their neighbours, the article i read suggested that this was in an attempt to cause fire by friction and burn out the top of the tree, so the attacker could take the space in the canopy

After trying to start a fire using a stick and bow, it's hard for me to imagine the wind generating enough energy to make a live tree catch fire.

Your arms may tire, but the wind does not. It may take luck, but only needs to work once per tree.

Even with limitless energy, I think that wood that is dry enough to ignite is too brittle to sustain the force necessary.

Limbs sliding back and forth would strip the tinder and create long smooth patches which would cool between cycles in the high winds. You might end up with a charred coating on the limbs and sawdust all over the ground, but I don't think you'd get flame.

You really need the spin of a bow drill to concentrate the kinetic energy in a small enough patch, and you need tinder nearby.

You make some good points. How about improving the conditions for fire? The friction may not be enough to ignite, but it could be enough to increase the dryness both through friction and mechanically brushing away water. By stripping small bits of bark surrounding the area around the contact point it could create an area that would be more predisposed. Although upon reflection I think the fire hypothesis is remote. Although, I could see it causing enough damage over time to restrict the victim tree's growth on that branch, or even killing the branch outright due to damage or disease caused by the injury. If the aggressive tree had adaptations that reduced its susceptibility to disease it could be a net win.

Source? I'd really like to see that article, because quite frankly, it sounds like utter bs to me

It was a print article in a science magazine from maybe 20 years back. I doubt there’s much chance of finding it now. You may be correct though, I guess it could as easily be an attempt at inosculation?

One of my all-time favorite records is entitled Crown Shyness. The eponymous track [1] uses this phenomenon as a metaphor for feeling alone while depressed. The branches are so close, but just out of reach. I always thought it was a beautiful analogy.

[1] https://www.youtube.com/watch?v=rHkdU105HNA

The article only lists a few species however I seem to see this feature all the time among trees not listed on the article's list.

I wonder if this helps reduce the transmission of infectious disease from one tree to another.

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