Hello, I was hoping someone might be able to help me list potential causes for twisted limb breaks. I am thinking pathology possibly weakening the limb allowing for the type of break seen in the photo by wind damage, snow load, human agent. Are there any causes that I am over looking or perhaps a list of plant diseases that might contribute to a break like the one in the photo? Thank-you!
Is the brown object in the middle of the break a pupa of a wood-boring insect? If so, that is an obvious agent of limb weakening.
That is an excellent question, thank-you vitog. Sadly, I do not have an answer. I have not seen this actual break in person. This picture is being offered on a different message board with the claim that it could only be done by something with hands gripping it and twisting it, therefore (believe it or not) Bigfoot. I am arguing that there any number of natural causes for a break like this that must be top of the list before one introduces imaginary creatures to the mix. Sasquatch enthusiasts like to find twisted breaks like this and assert it could only be the result of something with massive strength gripping the limb and twisting it to the breaking point. I am arguing otherwise, but thought it would be helpful to seek some experienced opinions on what types of things (other than non-existent ape men) could cause breaks like this in the forest. Thanks!
I hadn't realized this was a thing. Well, there are plenty of trees that twist due to a number of reasons, and the twist isn't revealed until the bark is removed (or the branch broken). An example of these that are readily spotted in British Columbia's interior are ponderosa pine trees. Here's a study on the biomechanics of grain spiral in ponderosa pines: http://www.math.utah.edu/~cherk/publ/spiralf.pdf (Why grain in tree trunk's spiral: a mechanical perspective). From that study, they found that if the grain angle was greater than 37°, the failure prediction (of breaking) increases dramatically for that species. That angle could be higher or lower for other species. It just seems like there are easier explanations to me for the phenomenon.
Thank-you for the response and the linked study. I completely agree, re: easier explanations. Common explanations and bigfoot do not go hand in hand.
I have a tree/shrub that was twisted and broken about 7 feet from ground. It’s close to house in a corner. No other trees have damage. Looking for a cause…
I observed this type of break a few months ago when the top of a large arbutus twisted and fell over. It had been growing almost parallel to the ground and, when it became weighted down with heavy snow, I think that that snow load was heavier on one side of the canopy. As a result, I think it began to break first on that side rotating the trunk as it fell.
When I studied forestry at the Estonian Agricultural University, I learned, that timber has different strength in different directions and against different kind of forces. The easiest way to break a timber is the way how wood is chopped, through the center, separating wood fibers from each other longitudinally. That's the case also on the photo above. It seems, that there was a bend at the breaking point, so wind pushing the branch side-wise actually separated wood fibres longitudinally like an ax, when wind force was untwisting existing twist. I have crushed numerous wooden test samples under hydraulic press for measuring the difference in strength, and can confirm, that timber really is weakest against cracking along the wood fibers.
