girdling pines

[Burnham]

Murph, did you worry at all about weakening the tree that you were getting ready to climb? I'm not saying that what you did WOULD weaken it enough to cause concern, just that it might feel that way to me, and wondered if you gave it any thought. Size at girdling point would be everything here, along with general condition.

 

[MasterBlaster]

I wouldn't think that would weaken the tree.

 

[ROLLACOSTA]

i guess this would work on all conifers??

 

[Burnham]

Master B--You are probably right, but here's what I was thinking...if you take a 1 inch girdling cut on a 12 inch cylinder, you have reduced the area of that cylinder by a bit over 30 percent. That will be weaker just because it's smaller, but we all have climbed 10 inch trees without concern. Where I felt a little tickle at the back of my mind was thinking about how such a cut to a cylinder would reduce the resistance to a lean (caused by the climbers weight, wind, natural lean, or a combination of these). By removing the outermost edge of the cylinder, you would reduce the resistance that the outermost edge of that cylinder offers to compression as lean occurs. Then, might tension forces exerted on the side opposite the lean that usually could not begin to act start to do so? Might shearing of holding fibers occur at much lower levels of force than we'd normally expect? I don't feel like I'm expressing myself very well. Does anyone see what I'm getting at?

As I stated in my earlier post, I don't know the size of the trees that Daniel treated this way. But my gut tells me that at some point a tree would be large enough for this to be of absolutely no concern, just as at some point a tree would be small enough that it would be obvious that a 1 inch girdling cut would surely compromise its' strength.

I just don't know where that line might be .

 

[MasterBlaster]

I suppose it all has to do with what kind of rigging you're going to do in the smaller trees.

 

[John Paul Sanborn]

And the laoding you'll be doing with jist working in it.

What force will the top put on it as it comes out?

 

[John Paul Sanborn]

How about someone plotting a graph on the % loss of cross section with a 1 inch cut as the d increases

 

[Burnham]

John Paul--While I was thinking about it I just worked up numbers for a 12 inch stem and a 20 inch stem.

12 inch reduced to 10 inch is a loss of area from 113.1 sq. in. to 78.5 sq. in., or a reduction of 30.5%.

20 inch reduced to 18 inch is a loss of area from 314.1 sq. in. to 254.7 sq. in., or a reduction 18.9 %.

 

[murphy4trees]

Good points about the loss of area/strength... Something to consider... an inch doesn't seem so small when it's a third of the fibers...

So here are the pics... somebody else try this and tell me I'm not haulucinating..

These trees stood for three days after being limbed..

 

[murphy4trees]

Here's another shot

 

[murphy4trees]

and another

 

[murphy4trees]

Seen enough ???
Last one..
I'll have to go back and souble check just how deep those kerfs are...

 

[John Paul Sanborn]

Originally posted by murphy4trees
Seen enough ???
Last one..
I'll have to go back and souble check just how deep those kerfs are...

It's still imperical, we need you to do 365 more of them with carefull documentation on depth of cut date/time duration between girdling and limbing.....

 

[MasterBlaster]

I would LOVE to try that! My only problem is I don't usually meet the tree until I'm fixing to gear up. I'll definitely try it the first chance I get.

 

[Tree Trimmer]

Originally posted by John Paul Sanborn
How about someone plotting a graph on the % loss of cross section with a 1 inch cut as the d increases

Here you go: x-axis is diameter in inches, y-axis is percent of cross-sectional area decrease (Old Area - New Area)/Old Area

This is assuming a 1 inch cut was made all the way around (i.e. 2" decrease in diameter)

It looks like 15" and up won't make a big difference so maybe that's a safe lower limit for a non-leaning single stem...???

 

[murphy4trees]

MB,
You can girdle the tree just prior to climbing...

 

[John Paul Sanborn]

Originally posted by Tree Trimmer
Here you go: x-axis is diameter in inches, y-axis is percent of cross-sectional area decrease (Old Area - New Area)/Old Area

This is assuming a 1 inch cut was made all the way around (i.e. 2" decrease in diameter)

It looks like 15" and up won't make a big difference so maybe that's a safe lower limit for a non-leaning single stem...???

over 30% loss of cylinder strength is concidered to be critical in a hollow tree, maybe 20 inches and over would be better.

Another thought would be to take some stems and to comparative pulls to show if there is any differance in needed force, then see if you can break the stem.

I would be comfortable with larger ones, but we are working on assumptions and SWAG.

 

[rumination]

whats SWAG?

 

[John Paul Sanborn]

Originally posted by rumination
whats SWAG?

Scientific
Wild
Assed
Guess

 

[MasterBlaster]

Or bunk reefer