pine truck twist

[JNB]

I was at Devils Tower and noticed a number of large
pines (lodgepole I think) that were dead and the trucks spiraled
WHY the spiral???

 

[BonsaiJedi]

I've been following an online thread discussing just this question. Although it won't necessarily answer your questions it will shed some light:

http://www.nativetreesociety.org/threads/spiraling_grain.htm

 

[Dixie1]

doesn't wind do this? i have noticed this in colorado when going up a ski lift and you see dead trees where the bark is completely gone and the tree is spiraled. i just assumed wind.

 

[BonsaiJedi]

"Spiral grain is very common and occurs in most of the tree species in the
eastern U.S. About 95% of trees have counterclockwise spiral, and 5%
clockwise (this is data from a survey I did myself of about 20 tree species
in MN). What varies a lot among species and among individuals within
species, is how pronounced the spiral is. It varies from almost straight to
some trees that look like a spring. In some species the bark follows the
spiral and in others the bark can be straight but have spiral wood
underneath. I have never been able to find out why wood has spiral grain,
and I have asked some of the best scientists in the world."

The quote above is from Dr. Lee Frelich, one of the better known forest ecologists in the country. I've seen the hypothesis about spiraling and wind before but I've also seen enough spiraled trees in the forest (away from prevailing winds) to think it may not be entirely wind related.

but it is certainly an interesting topic. Just to add to the confusion...I know of a stand of Greenspire Lindens outside of an art museum where several of the trees have an obvious twist to them but not all of them, and they certainly appear to have come from the same stock. Why do some spiral and the other do not? The world may never know....

 

[PB]

Recent studies have indicated that the amount of spiral and direction of spiral is inherited from the parents. Here is a link to a study.

http://www.afs-journal.org/index.ph...d=129&url=/articles/forest/pdf/2002/05/13.pdf