Understanding forks a bit more

[jomoco]

The opinion of an elderly tree mortician, in awe of his subject, indeed humbled by them.

 

Most noble forms of life on this planet IMHO!

 

Jomoco

[scotspine1]

It was proven that there is no compressive force pushing forks with included bark apart.

 

there's compression in a compression fork pushing the two stems towards each other, who ever said there was a compressive force pushing them apart?

 

 

 

.

[Kveldssanger]

there's compression in a compression fork pushing the two stems towards each other, who ever said there was a compressive force pushing them apart?

 

 

 

.

 

Wouldn't the compressive forces actually push the two stems away from one another, though? The force comes from the centre of the union, not the periphery, and the tensile forces on the outside of either stem at the confluence would imply that it's an outward-acting force. Yes, the compression emanates at the centre, but the compressive force itself forces the stems apart, I would think.

[Paul Barton]

So you're essentially saying artificial support does not weaken a branch over time?

 

Not sure if that question is to me, but nope, that's not what I'm saying.

[jomoco]

Are you saying that some people advocate installing a dynamic brace in trees with no visible faults? I've not come across that.

 

I recommend dynamic braces in trees that exhibit weak unions - the intention being that the brace would prevent damage or injury by arresting a major failure but otherwise allowing the fork some natural flexure which may promote reaction wood enough to strengthen the weak area.

 

 

Sent from my iPhone using Arbtalk

 

Certainly reads as if you are bracing/supporting a perceived weak union at a maximum flexing point, and claiming it promotes reaction wood and strengthens that union.

 

The question to ask yourself here is whether that branch's identical twin left alone and unaided in nature, flexed further, stressing a greater area of phloem and cambial tissue, and therefor reacted more vigorously piling on more compression/tension wood growth, than it's twin wearing a brace?

 

Jomoco

[Island Lescure]

there's compression in a compression fork pushing the two stems towards each other, who ever said there was a compressive force pushing them apart?

.

 

I was always under the impression that the growth of increments within forks was slowly adding more compressive force in the fork, in effect with a chance of pushing the fork apart.

[jomoco]

David Humphries was kind enough to provide this link to a study of how some tree species graft together naturally to encapsulate tight compressive V crotches, and form nice broad U crotches above them!

 

http://naturaculture.sites.go1.com.au/sites/naturaculture.sites.go1.com.au/files/Tree-Welding-and-Natural-Grafts-the-Magic-of-Myrtaceae.pdf

 

Amazing awe inspiring stuff, eh?

 

Jomoco

[silky fox]

"Reactive Generating Organisms"...very inspiring.

[scotspine1]

Wouldn't the compressive forces actually push the two stems away from one another, though? The force comes from the centre of the union, not the periphery, and the tensile forces on the outside of either stem at the confluence would imply that it's an outward-acting force. Yes, the compression emanates at the centre, but the compressive force itself forces the stems apart, I would think.

 

 

I was always under the impression that the growth of increments within forks was slowly adding more compressive force in the fork, in effect with a chance of pushing the fork apart.

 

my experience of working in trees with co dom included bark unions tells me that once the weight is removed above the union you can often see the two stems sitting closer together, in fact I've seen a climber get his foot jammed as the space between the stems closed after he removed a head above the union.

 

Often see the saw jamming in the cut if it's started from the outside of the union as the compression from the other side forces the other stem down on the bar of the saw.

 

The way round that is to bore into the centre of the union and cut outwards.

[treeseer]

Great observations by Cassian, who is now back in jolly Old!

 

That grafting and occlusion can be trained by scraping the included bark out of forks.

Occlusion and fork strength auf slater.pdf

Slater - The Failure of Forks.pdf