Growth Rings

[Gary_C]

On the last pine thinning I cut, the forester was looking at the growth rings on some thin slices of Norway Pine in this case. We counted about 40 rings in about a 15 inch diameter butt and you could see the wide rings up to about 20 years and then they got narrower till you could barely see between the rings as they were so close together. These were planted in 6 ft rows but had been previously thinned by a storm in some places, but not everywhere.

Obviously the reason for a thinning is to get more growth and after a thinning you should see wider spacing on the rings. But my question is should there be a natural narrowing of the rings as it grows because of the volume of growth material required at larger diameters? Or put another way, will that tree after a thinning go back to the wide spacing of growth rings that occured in the early years?

[SwampDonkey]

In any tree species there is a maximum annual increment attainable on a site in that climate, genes also play a role. But as to opening the stand more with a second thinning, if your increasing crown volume your going to increase increment. Increased diameter obviously increases annual volume, but ring width will not diminish with increased girth unless it has reached a point in it's life it is declining in health. In your case it seems you have seen what happens when the tree canopy closes back in after a few years from the thinning. The base of the crown lifts faster than the new crown being produced at the top of the canopy. One other note is that red pine does not have a lot of genetic variability. If you see crooked ones it's most likely damage and not genes.

[Ron Wenrich]

I think tree age has something to do with it.  I've always found that its hard to release an older tree, especially if its been suppressed.  Some foresters and timber markers will tell landowners that those trees will grow.

A younger tree will have better vigor and respond quicker to a release cutting.  I've noted on some oak butts that you can tell the various stages by looking at the growth rings.  I have seen growth rates come back after a tree has been thinned and left.   I can often spot them at several intervals, meaning a few thinnings.  Oak wasn't a very valuable species until the late '70s.  So, they were often left behind.

You can also see when there were years of drought and when there were defoliations from the gypsy moth.  Those rings won't be as wide.

But, the only way you increase tree growth is to allow for crown expansion.  When expansion stops, so does the growth.

[Mooseherder]

I noticed the same thing on the Spruce that was used for the Hightop table project.
The last 7-8 years growth didn't keep pace with the previous 25.
May have something to do with crowding although the area wasn't all that thick.
Maybe soil conditions changed or the tree was weakened by wind years ago.
The reason I mention that is because this tree was a blow down.
Heck maybe the site conditions are fine and the growth cycle of this tree had run it's course.

[SwampDonkey]

40 or 50 years in the case of the red pine and spruce isn't even old.  If it were balsam fir then it would have reached about it's maximum potential in the southern portion of NB, but up this way and north it probably has close to 20 more years before it goes down hill to it's demise by 80-90 years.

There is also a difference if you try to release an overtopped suppressed tree versus crowded trees. One exception is red spruce, which will respond when released from long suppression periods. Try that with balsam fir and you might as well grind it up for mulch. There is now some evidence that fungus causing but rot actually inoculates trees like fir or spruce at a very young age and it's not so much due to suppression, low vigour or aging when it attacks. However, probably can't dispute the assumption that poor health amplifies it.  Up here we do a pre-commercial thinning (PCT) in softwoods and later by another 25 years a commercial thinning is done. They tried it at 10-12 years to thin post PCT, but the economics isn't there. I've seen the stands they tried it in and the trees were not far along enough and barely allowed to have crown lift. I marked trails on one site that the trees were barely 5 inches, the guy doing the work about went broke. Same problem I heard from others as well. From studies on densities thinned I've found 25 years post PCT is the optimal point for a commercial thinning in spruce-fir here in the NE. There is lots of tree ring growth data.

[Jeff]

This is a fun thread.

[SwampDonkey]

Hey Jeff, did you count the rings on Moose's cookie from initial release toward the centre to the outer rings that start crowding again? I just noticed myself, around 25 years.

[Mooseherder]

The outer rings that are surpressed looks like the last 12 rings, with each one getting more narrow than the next.
Here is another angle of the same log.

[SwampDonkey]

You'd like to thin that again before it goes back into slower growth for long to keep the increment up, but not only that the volume grows like a bell curve not a constant slope.

[Mooseherder]

You may be able to see the outer rings better on this photo.

[Tom]

You need to see the whole end of the log to tell, but it looks like that direction to the right of the second picture (about 2:00) and the bottom of the first picture (about 5:00) are the same, and were on the bottom of a leaning tree or the tree was on the outside of the plantation where that side got all of the sun.  It's rings are larger and the orange color indicates reaction/compression wood.  Differences in the type of wood found there, on the sides of the tree and the tight grain of reaction wood that might exist on the other side of the tree will make boards do strange things on a sawmill, as the tension is released.

I suspect that the tightening of the rings on the outside of the tree was due to another canopy closing, or possibly the result of the drought we have suffered in the last few years.

[SwampDonkey]

Tom, dark or reddish brown late-wood is typical of eastern spruce. From the way the camera view point was I think has a lot to do with how out of round the tree was. There was some type of injury (or the cut was just near a branch) when it was younger, see the rings take a dimple around that dark radial line? A little wider late-wood in this case is probably better growing conditions. Drought isn't much of a problem most years in this region.

[Gary_C]

Here is a picture of one of the slices we looked at.

 



It's kind of hard to see as this piece was picked up in the woods and was a trim piece from the end of a tree. I counted about 40 rings total and it was around twenty years that growth started to diminish. From what you have said, I would guess that that would not have resumed those wide early growth rings just because it had been surpressed so long.

[SwampDonkey]

Gary, you may get a boost again, I'm actually quite sure you will to be quite honest, but it will take probably 5 years to see it at the least. Your trees are not all that old. My point is you want to keep that increment up, you've only gotten 3% interest for 20 years compared to 12% from the previous 20 years if someone had been on the ball. So many folks just stick trees in the ground and don't want to do the next steps.

[Clark]

Very interesting topic.

I'd agree with Donk, there is a maximum growth that can be obtained.  I would add that if the thinnings have been properly timed then you shouldn't see much of an increase in growth but rather a continuation of previous fast growth. 

I would also say that trees will eventually reach an age where there is very little response in diameter growth.  This is a grey area that is highly variable.  Senescence in trees can take decades and trying to define when a tree is in senescence or has began to senesce can be very difficult. 

Gary, that red pine you're thinning will definitely take off.  As Ron said, as long as it wasn't severely suppressed they'll start gaining again.  Last spring I cored a red pine that had been part of a seed tree cut.  When I was there the tree was 16" dbh and 113 years old, ten years earlier it had been 13.5" dbh!  They can grow really well even when they are older, something most people and textbooks don't believe.

Clark

[Gary_C]

Gary, you may get a boost again, I'm actually quite sure you will to be quite honest, but it will take probably 5 years to see it at the least.

Well, it's not my stand, it belongs to the state and it actually quite a mess. The buckthorn and prickly ash were taking over and as far as I could find out, it had not been thinned previously but a bad storm had gone thru and thinned some of the weakest trees but in scattered places. That had allowed the underbrush to grow to at least 15 feet high. I guessed part of the reason for me thinning the stand was so I could drive down the buckthorn. 

Here is a before and after.

 



 




Then in another part of the stand, there was white and red pine along with a central patch of walnut and the walnut was being antagonistic to both the red and white, plus the blister rust was killing a lot of the white pine. And in a third stand, the white pine was younger and was under heavy attack by blister rust and probably was either too rich of soil or not planted close enough so it was limby and poor form. It wasn't a very nice job all the way around.

Actually the main reason for the original question was because I have been working on a lady that is presently living in her home place, her parents are both gone, and she is sitting on a nice 40 acre and 30 year old stand of red pine that is in need of a first thinning. The trees are as thick as dog hairs in there and it is very clear underneath. I have been telling her that she will get a big growth spurt if it is thinned but she professes to be a "tree hugger" and even though she agrees it needs thinning, she has a lot of reasons for not doing it. But I have stopped in three times and we have a very nice back and forth and though she says I'm persistant and hasn't thrown me out yet, she probably will not ever allow anything to be cut.

So I just asked this to verify what I have been telling her, but it probably will not do any good. But there's still some hope as she said she enjoys talking about it, though she says she would have to be carried out of there before any trees were to be cut. 

Probably wasting my time and yours, though I've learned something here. 

[jim king]

I have yet to get an answer as to why the rings on woods here turn out like this.  Any ideas ?¿

 

[SwampDonkey]

Gary, your cookie unlike Moose's doesn't indicate to me any kind of disturbance at all. It tells me that the crowns began to close in at about 18 years after it was planted. We would have thinned it before then with brush saws, probably by year 10 because they get big buts quick. I think we might be planting red pine a little tight unless we wish to loose some growth until a commercial thinning is viable. That seems to case here. You would go broke at year 18 with big machinery in there unless your chipping the whole plantation like some are around here.

[SwampDonkey]

Jim, I would say a lot of that is stain streaks caused by bacteria or fungus and nothing to do with growth rings. The tropical trees don't have as well defined rings because there is no abrupt change in ring growth due to early and late-wood growth.

[Ron Wenrich]

Jim

Are the growth rings always the same in each species, or are they something that you occasionally find?  If its the same all the time, then its a characteristic of the wood.  Something like walnut turning brown in the heartwood.

If its something you find on occasion, then its probably bacterial.  We get "mineral" in red oak.  Its black steaks, and is quite often associated with the growth rings, but not as pronounced as you have.  Its bacterial and only occurs in certain areas.