What causes this?

[Gary_C]

I just finished a large job in the St. Croix State Forest in northern Minnesota. Just before I started cutting this job a spring windstorm went thru the area and blew down some of the marked trees along with some that were intended to be saved. All the down trees were uprooted and laid down in one direction and I did not hear of any reports of a tornado in the area, although one did go thru an area about 30 miles southeast of the site. As a result, I had to deal with a large amount of low quality logs and to save time, I left many as full length stems with the tops removed to be bucked later.

I set up a log cutting deck at the end of the pile logs and salvaged all the logs I could. Here is a picture I took in August in the dust of an ongoing drought.


There were many logs of both Red Oak and Sugar Maple that had what I called "twist" in them and this is an extreme example.


This one was obviously fractured in the storm and originally I thought perhaps there was some circular winds that caused the damage. However, there were also many logs that were still intact and yet had that same spiral grain. I did ask the DNR Forester about one Sugar maple and his only explanation was that many years ago the area had apparently been "high graded" and what was left was junk. Some places were so bad that it was better to cut all and start over.

But I still wonder what causes this type of spiral grain in both red oak and sugar maple?

[SwampDonkey]

Were there bad leans in the trees that show the spiral checking/splitting? Occurs in tracheids of compression wood and fibres of tension wood of hardwoods which develop in the living tree and not related to drying.

[source: Textbook of Wood Technology]

Looks like there was quite bow to that tree, as if leaning when it grew.

[Don P]

I don't know Gary. That is a lefty, if you would keep an eye out for if there is a pattern of left or right twist  ???

[thecfarm]

I have a FEW trees like that and I own about 120 acres of woods.I see it more in my cedar than the hard wood.I have cut trees like that,but have never had them come apart like that.I don't think I have ever seen in in my Red Oak.I have seen it in White Maple,but only a couple times.

[Norm]

We have some woods on a back 40 where a tornado went through many years ago. While I was clearing it out I found trees down that looked just like the one you showed. If yours all twist the same direction I would think it's weather related.

[Ron Wenrich]

It looks like spiral grain to me.  If I recall correctly, spiral grain is a hereditary thing.  High graders probably would have left that behind, so it could reseed the area.  The one that looks like it exploded is probably due to so much tension inside the wood.  They're a real joy to saw in the mill.

[SwampDonkey]

I agree. Mechanical damage from wind or otherwise wouldn't cause that. Try and twist a 1 inch diameter stick in your hand, and imagine a wind or tornado against a 14 inch diameter tree. ;)

Now in hind site, a leaning tree will not necessarily develop twist. I've seen some huge Sitka spruce as straight as n arrow that had bad spiral grain. We used codes for defect during cruising. For spiral grain we divided the trunk in 10ths between the 5 m and 6 m mark (ocular estimate) and if the grain wrapped across 5/10ths of the tree trunk it was code 5 under the spiral grain column. The compass man would call, '^spiral grain _five' as he was responsible for quality and pathology calls in the bottom 3rd of the tree. ;D

[Tom]

We get a lot of tornados in Florida that tear/twist the tops from trees.  They make it seem as easy as twisting a celery stalk.  Patches of trees, where the wind set down, will have the tops removed and 3 to 10 feet of trunk  splintered where it was twisted to failure.  Still, the splinters are straight and the trunk isn't permanently twisted the same as your log, which acually has grown in a twist.   While a circular wind may have caused the damage, it certainly didn't cause the twist. I agree.

[PawNature]

Yep, Ron is right he got it from his mother or father.

[Tom]

Are you saying that Ron twists to the left? :D

[SwampDonkey]

Oh, but I think he's right handed isn't he?  ;D

[Tom]

Salvaging tornado wood is a real chore.  Even straight line winds don't leave much.

I've seen both and sometimes it is confusing to identify and agree with the media/insurance people.  I think there must be a big difference lin damage done by circular as opposed to straight line winds when it comes to insurance coverage.  For some reason there is always an effort to blame damage on straight line wind first.

[Ron Wenrich]

I always thought you had to be a little twisted just to get into this business.   :D

[Tom]

I agree.  And it helps to have a volume of wind to survive on the forum too. :D

[SwampDonkey]

I seen both to, although not real common here. The only difference I could see was a tornado makes a narrow path through the woods, while a big hurricane force wind pushes everything over in a big wide swath. Last year we had a big tornado take out several 100 acres of mixed hardwood/softwood forest and in the fall of 1995 we had thousands of acres of softwood blow over in a hurricane force winds. They both were a real treat to salvage.  : In that hurricane hit area the fir regen was so thick after the salvage that it was like trying to climb in the pickup without an open door.  :D :D

[Tom]

We have hurricanes and tornadoes, but we also have a straight line wind called a shear.   It manifests itself in downbursts and straight winds too.  You probably hear about them in association to airports the most.   The storm that crossed Florida a year ago around Deland and orlando was one of thes storms.   The tops were torn from pines as if a great hand had just snapped them off.  The bulk of the trunk remained.   It reminded me of a chef snapping the tender tops from stalks of asparagus.  Storms will contain both tornadoes and these straight winds.  The insurance companies seem to draw a distinction for some reason.

[Phorester]

Most researchers feel that this is hereditary. 

Now for the big question; do such trees twist in one direction north of the equator, and the oppositite direction south of the equator?   ;D

[Gary_C]

I just returned from the final walk through of this job. Here is a picture I took 3-08-06 after the cleanup in the small area in the southwest corner where the blowdown was the worst. Note the rootballs in the distance and they are all tipped from the southwest to the north east.

However here is a picture I just took of one stump that was obviously twisted in the blowdown.


Also, during my brief walk through, I found some recent additional blowdown trees. Most of the trees in this area are 60-70 feet tall and you can see how shallow the soil and roots are on these trees.


This is a picture of some of the area after thinning.


There was a lot of low quality maple on this job and I did take over 500 cords of maple pulp to the mill as well as 30-40,000 bd ft of hard maple logs. Plus I have about 200 cords of red oak firewood to cut and split along with the 50-60,000 ft of red oak sawlogs.

I have not yet sawed any of the maple but I have seen a number of logs from trees that were not down that had this spiral twist. It also appears that many have signs of birdseye and quilted figure so hopefully there will some good from cutting these low quality trees.

[Sprucegum]

That picture with the snow scared the heck out of me before I read the date 

Interesting thread, I haven't seen anything like it in this country - yet.

[SwampDonkey]

I dug up some more info on spiral grain.

• It is present is most all conifers and is either left or right spiral.


• It has been found that the grain of wood in a young conifer usually has a left spiral. As the tree ages the left spiral gradually diminished until the grain is straight then keeps twisting to the right spiral, which increases with age.


• A tree going through this twisting cycle may be anywhere from 70 to 130 years old before it develops right spiral grain.


• Heavy right spiral grain twist is one of the indicators of old growth.

[Source: Silvics of Common Maritime Softwoods and Hardwoods, 4th ed.]