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Comment by wxw | Hacker News Reader

I don't quite understand -- what is it about this technique that makes the trees grow perfectly straight and why is

> the lumber produced in this method is 140% as flexible as standard cedar and 200% as dense/strong,

This article is just a rehash or summary. Check out one of the sources it links to (since the other is broken) for details on the technique: https://mymodernmet.com/kitayama-cedar-daisugi/

The strength & flexibility I would guess are attributable to the lack of knots and the straightness of the grain.

One thing both writers keep doing that's annoying is calling it a cedar. The tree is cryptomeria japonica, known as sugi, which in English is sometimes known by various misnomers such as "Japanese cedar" and "Japanese redwood," both of which should be taken as more poetic than scientific.

Few trees called "cedar" are in the Cedrus genus. To be fair many of these were called a type of "cedar" before the Cedrus genus was even coined. Cedar really just means "a really good tree" (for woodworking)

TIL that PNW Western Red Cedars are not in fact, Cedar trees!

Again, what is and isn't a "true cedar" is a silly debate. Some of these trees were called cedars before Cedrus was even coined. Junipers and even citrus were called cedars long before Linnaeus came along. It really got applied to any tree that had scented, rot-resistant wood

In fact, most trees called cedars are NOT Cedrus.

I'm not caring so much about the Cedrus genus, as the dilution of the word through unimaginative overuse and over-application. But to the extent that it still means anything at all, I would say it means an aromatic evergreen, since those are the two traits that seem to unite all the various trees colloquially referred to as cedars.

They grow straight because they are shoots/suckers, and that's how tree biology works. And they are pruned every two years to prevent knots and side branches.

The lumber is dense/strong because the shoots have a robustness advantage due to being part of a mature tree with all its resources.

It’s exploiting the natural tendency of trees to create “waterspouts” through a technique called pollarding. When a tree suffers an injury it creates a bunch of new twigs that tend to grow straight upwards if the injury is on the upper branches. The waterspouts grow more slowly and so in this species of cedar they develop those desirable properties.

It is actually a type of cypress, not a cedar.

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