## / How Strong is a Tree?

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Some research via the American Alpine Institute.

http://blog.alpineinstitute.com/2017/09/tree-ratings-in-kn.html?m=1

TL;DR : Strong enough.

More relevant would be a similar study to figure the braking strain of grass, heather, that crap reedy stuff you get in wet N facing gullys and the ever popular brakens

The season play an important role
Post edited at 17:18

I can't resist linking to my photo of a "tree" I abbed off in Oman.... https://www.ukclimbing.com/images/dbpage.html?id=80871

Rick Weber has also done tree testing, probably in a more useful format than the one youÂ´ ve linked to. https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&ved=0ahUKEwjD...
and Graeber/Reynolds have also tested trees https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&ved=0ahUKEwj...

They may well be strong but they weigh far too much to carry on anything hard.

R

I'm not so sure, an acorn and a lot of patience...

Medium.

Did you send you mate down first?

As mentioned, it depends on many variables, including the roots. I was once gardening in a granite query in an attempt to create a couple of new routes. A small birch, 10 cm diameter, was growing on a 1 m wide and 10 m long grassy ledge. By pulling the tree with all my force, I was able to peel tree plus the entire turf off the ledge! I now think twice before slinging trees and bushes.

Interesting. Over here they often say the minimum for a tree is 'five [inches diameter] and alive'. That works out to pretty much the bottom of that list. It looks like then that this rule is not quite sufficient for a bomber anchor (at least according to this data - more data might provide higher ratings).

Full marks for joining in the thread before spamming. A true professional.

> As mentioned, it depends on many variables, including the roots.<

Quite. Including the state of the rock/cracks containing the roots.
While the research is not useless there must be so many variables that cynical judgement of anchor strength is obviously of major importance.
All trees must eventually die/fall....whatever their trunk size its probably a bad idea to belay on them shortly before they do so.
As an aside I've always assumed that once a rope or sling from the anchor runs over the ground and over an edge it can withstand greater loads. At least one of the quoted papers showed the test rig level with the tree and the strength could often be increased in real life.

I reckon heather is pretty strong, but grass is just so variable. That crap reedy stuff you get in wet n facing gullys (woodruff?) is crap and reedy, whereas bracken can be strong enough to pull up on, but I wouldn't want to ab off a clump, even in mid summer.
Islands Part One, Featuring Stuart Wood

https://www.ukclimbing.com/news/item/65359/islands_part_1

Watch the video at the bottom of the page

8.20mins

" Trees! Trees are f**king brilliant!"
Post edited at 18:03

> As mentioned, it depends on many variables, including the roots. I was once gardening in a granite query in an attempt to create a couple of new routes. A small birch, 10 cm diameter, was growing on a 1 m wide and 10 m long grassy ledge. By pulling the tree with all my force, I was able to peel tree plus the entire turf off the ledge! I now think twice before slinging trees and bushes.

The force you exert whilst standing next to a tree and pulling on it at shallow we say 4 foot high is totally different to the shear strength of it at ground level where your sling would be.
Not saying it wouldn't have failed because I have not seen the tree.

Yes - heather is totally bomber
Grass - very seasonal and difficult to get enough in your hand to give a reliable handheld, I generally 'dig' my fingers into the dirt if possible (thistles are pointless, bit like vegetable midges)
Woodruff (I'd forgotten the name) promises so much delivers so little.
Braken- hated on here, but it's reliable, pretty sure you could belay off it, a la snow bollard, must add never tried that, great for descending, much better than bare wet grass January through to March

I only skimmed the article. But they said they were looking for 20kN.

That seems alot if your are at the top of the route

> Not saying it wouldn't have failed because I have not seen the tree.

Let me put it this way: I wouldn't sleep comfortably in portaledge suspended from a tree of that sort...

20 kN for an anchor! That's one fat leader.

Most people wouldn't obtain that if they equalised two bolts with a sling, because the knot-weakened sling would be less than 20 kN.

> 20 kN for an anchor! That's one fat leader.

Well it was from the American Alpine Club.

As strong as a shiny star from the galaxy MACS0647-JD.

I relocated a few self seeders to useful positions above some of the crags in The County about 15 years ago. They have matured nicely.

> Yes - heather is totally bomber

Tell my missus that. 20 years or so on and she still witters on about me trying to kill us both.

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