In some trees (coincidentally, thin-barked ones), the growth is so rapid that the wire cuts in within a month or three. In others, such as pines and other conifers, the wire can stay on for a year or more without cutting. I have a ponderosa pine that can go 3 years before the wire needs to be removed (it's also about 200 years old).
Anyway, the point is that it is at times very easy to go longer than you should, and after the wire starts to "cut in," removal will leave a scar. Some trees rebound quickly and after some time you can't see that anymore. Others will show those scars for life. So, there is a concern for constriction damaging a tree, but I think in the vast majority of cases we have broken camp and moved on long before this could cause a problem. Tincture of time is a treatment modality used by many medical people and I think it applies to this as well. We just aren't applying a sufficient force for long enough.
Bringing up the air layering technique I mentioned previously: In some cases, it takes a tree so long to form roots with stripping the bark that some use a wire constrictor which is wrapped circumferentially around the trunk and tightened down until it is cutting severely into the bark. This may need to be left on for 2 years or more, and more wires may need to be added to prevent the cambium from growing over the wire, which essentially means that the tree "swallows" the wire.
I'm not saying that you cannot damage a tree by girdling. I've seen it many times when rabbits gnaw at bark on young trees. If you damage the vascular layer underneath the cambium (called the xylem), it will inhibit the ability of the tree to transport sap up to the canopy. That's one reason air layering can be so tricky--you have to remove the cambium without damaging the xylem. However, in full-size trees with a xylem layer an inch or several thick, I can't imagine tree straps constricting enough to damage this.
So, again, I just can't imagine the method you use to apply tree straps is going to be the determining factor of whether the tree is damaged or not. What we need, to be entirely sure, is at least an informal study where someone hangs regularly from specific trees, with regular documentation of the local and general effects. I'm not volunteering for this, BTW, I'll just keep happily hanging with my tree straps and not worrying about it.
"I fish because I love to; because I love the environs where trout are found, which are invariably beautiful... because, in a world where most men seem to spend their lives doing things they hate, my fishing is at once an endless source of delight and an act of small rebellion; because trout do not lie or cheat and cannot be bought or bribed or impressed by power, but respond only to quietude and humility and endless patience...." --Robert Traver
Wow, what a complete and useful answer bonsaihiker! You increase my knowledge of trees many fold in just that short write-up.
That definitely answers any concern I had on the topic. Thanks.
We must, indeed, all hang together, or assuredly we shall all hang separately. - Ben Franklin
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