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Author Topic: What are tree rings, and do all trees grow at the same rate?  (Read 11766 times)

Offline neilep

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I was just wondering...do all trees grow at the same rate ?..are the rings in trees equidistant ?

What causes the rings ?
« Last Edit: 30/12/2006 15:10:58 by chris »


 

Offline NewBill

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I was just wondering...do all trees grow at the same rate ?..are the rings in trees equidistant ?

What causes the rings ?
First an observation.  It's really more about the question than the answer.

Recently the big fir in my back yard scared all the neighbours by dropping boughs up to six inches in diameter under the weight of unusually wet sticky snow.  Cutting them into sections that I could carry back to my yard I examined their cores for rot to see if this very big tree, perhaps 60 - 70 feet may have to come down.  Believing rings are annular I also had a curiosity about how old the limbs themselves were.

Probably most of us, as kids, have looked at tree rings, especially in the forested temperate zones.  The assumption that there is one ring per year and that the width of that ring reflects an optimal year, that one can even distinguish grossly at least, some seasonality of a given year, is irresistible.

Getting away from rings all together  we can observe all manner of evidence that some trees grow very quickly and some others very slowly and that they seem superbly adapted to their environment.  On my lot there are Gary Oaks gnarled hard wood seeming unchanged year to year.  A great fir on the other hand seeded itself in a crack in the concrete cap around the periphery of the house about the time I moved in and it is now a couple of feet over the eves of the house.  Sadly I will have to remove it as it will undoubtedly do something nasty to my foundations one day.  I don't need to cut down this fir to know that it's rings are few, nor the oak to know that they are many over the same diameter.

Now that you pose the question I would be curious to see tree rings in equatorial zones where there may be a single season.  Also is it not the equatorial zones where the exotic hardwoods are harvested?  Do they have rings?
 

Offline Karen W.

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I have always been taught that the spaces between can be different and also tell the history of the tree and the changes in the weather during those times, a severe winter may be markd my a lets say perhaps a larger gap between the rings or slower growth something like that.. But I think that climate andt weather extremes dictate rings also for sure!.. perhaps rain and flooding also!
 

Offline eric l

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1 From what I remember, the rings in wood from equatorial forests are not as distinctly marked as in wood from the "temperate" zones.  In addition, wood from equatorial forests shows two sets of rings per year, because around the equator the year has two rainy seasons and two dry seasons !
2 There is not only a difference in colour, but also a difference in density.  There are instruments available that measure the variations in density over the thickness of plywood and/or particleboard, and they can also be used to measure the variations in density of "plain wood" (for lack of a better term). 
3 Microscopic evaluation shows that the clear parts of the rings have bigger cells than the dark parts.  The clear parts are "early" wood, the dark parts are summer wood (or late summer wood).
4 The width of the rings gives an indication as to whether a given season/year was more or less favorable for tree growth.  This succession gives a kind of bar-code that makes it possible to compare with wood that has been cut at a known date.  This is what is known as dendrochronology.
Once again, Wikipedia gives a good summary :
http://en.wikipedia.org/wiki/Dendrochronology
 

Offline Karen W.

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Thanks eric, nice to review old information and it is very interesting in all.. Thanks for the accurate info!
 

Offline neilep

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I was just wondering...do all trees grow at the same rate ?..are the rings in trees equidistant ?

What causes the rings ?
First an observation.  It's really more about the question than the answer.

Recently the big fir in my back yard scared all the neighbours by dropping boughs up to six inches in diameter under the weight of unusually wet sticky snow.  Cutting them into sections that I could carry back to my yard I examined their cores for rot to see if this very big tree, perhaps 60 - 70 feet may have to come down.  Believing rings are annular I also had a curiosity about how old the limbs themselves were.

Probably most of us, as kids, have looked at tree rings, especially in the forested temperate zones.  The assumption that there is one ring per year and that the width of that ring reflects an optimal year, that one can even distinguish grossly at least, some seasonality of a given year, is irresistible.

Getting away from rings all together  we can observe all manner of evidence that some trees grow very quickly and some others very slowly and that they seem superbly adapted to their environment.  On my lot there are Gary Oaks gnarled hard wood seeming unchanged year to year.  A great fir on the other hand seeded itself in a crack in the concrete cap around the periphery of the house about the time I moved in and it is now a couple of feet over the eves of the house.  Sadly I will have to remove it as it will undoubtedly do something nasty to my foundations one day.  I don't need to cut down this fir to know that it's rings are few, nor the oak to know that they are many over the same diameter.

Now that you pose the question I would be curious to see tree rings in equatorial zones where there may be a single season.  Also is it not the equatorial zones where the exotic hardwoods are harvested?  Do they have rings?

THANK YOU for this wonderful observation....it sounds you live in a rural location.

I really appreciate your post with great interest.
 

Offline neilep

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I have always been taught that the spaces between can be different and also tell the history of the tree and the changes in the weather during those times, a severe winter may be markd my a lets say perhaps a larger gap between the rings or slower growth something like that.. But I think that climate andt weather extremes dictate rings also for sure!.. perhaps rain and flooding also!

THANK YOU KAREN MAM...yes I too have heard about the information that can be gathered from analyzing tree rings...they are like living record keepers of climatic changes.....it's a shame that (I suppose )one has to kill the tree to get at the data !!
 

Offline neilep

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1 From what I remember, the rings in wood from equatorial forests are not as distinctly marked as in wood from the "temperate" zones.  In addition, wood from equatorial forests shows two sets of rings per year, because around the equator the year has two rainy seasons and two dry seasons !
2 There is not only a difference in colour, but also a difference in density.  There are instruments available that measure the variations in density over the thickness of plywood and/or particleboard, and they can also be used to measure the variations in density of "plain wood" (for lack of a better term). 
3 Microscopic evaluation shows that the clear parts of the rings have bigger cells than the dark parts.  The clear parts are "early" wood, the dark parts are summer wood (or late summer wood).
4 The width of the rings gives an indication as to whether a given season/year was more or less favorable for tree growth.  This succession gives a kind of bar-code that makes it possible to compare with wood that has been cut at a known date.  This is what is known as dendrochronology.
Once again, Wikipedia gives a good summary :
http://en.wikipedia.org/wiki/Dendrochronology

THANK YOU VERY MUCH ERIC !!...as always...such a wonderful wealth of information you give.
Fascinating stuff

THANK YOU...hugs the ERIC !!
 

Offline Karen W.

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Yes I imagine they do! I donknow if they could bore a hole all the way through removing a large plug without hurting the tree or something. Do you think that is possible?
 

Offline eric l

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Boring all the way through a tree is not more damaging than bore one inch deep on both sides.  All activity (growth, transport of water and nutrients...) takes place in the layer just below the bark. 
In some cases, the dendrologists seal the hole with wax to prevent the tree from "bleeding".  Some species heal better than others, in which an open wound may be liable to all kinds of infection. 
 

Offline chris

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As Eric has so eloquently explained, all the metabolic activity of a tree occurs in the leaves, the roots, and in a thin layer beneath the bark. The core of the trunk, where the "wood" is, is metabolically inert; it's dead tissue. The cells that produced this have undergone a process called lignification (from the latin words lignum, for wood, and facere, to make). Their cell walls have been packed with a large water-repelling polymer called lignin, which makes up about 30% of the weight of a tree, and the end-walls between individual cells have been broken down, producing long tubes of linked cells that stretch from the roots to the leaves. This allows the tree to move water and dissolved salts up these drinking straws. They are referred to as xylem.

Every year a fresh cluster of xylem-producing (and other) cells are born from a population of stem cells (no pun intended) beneath the bark. The rate at which the cells grow and develop into woody xylem is proportional to the amount of energy that the plant has available to it. Because growth occurs seasonally, surging in the summer and arresting in winter, it produces a series of concentric rings. One ring maps onto one growing season.

Plants make energy in their leaves by using the green pigment chlorophyll to convert light into chemical energy in the form of sugar. These sugars are then re-deployed around the plant where they are used to drive the chemical reactions that lead to growth. The more energy a plant makes, the more energy it has to spend on growth.

Therefore, the better the growing conditions in a given year (optimal water, light, temperature, trace elements), the more energy the plant can harness, the more xylem (and other tissues) it can lay down, and hence and the more it will grow - and the fatter that years growth ring will be.

Using very ancient trees (some of which are over 5000 years old) and wood samples, which can be accurately carbon-dated, together with other other measures such as oxygen isotope fractionation, scientists are now beginning to reconstruct historical weather patterns for certain geographical areas.

Chris
 

Offline Karen W.

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Boring all the way through a tree is not more damaging than bore one inch deep on both sides.  All activity (growth, transport of water and nutrients...) takes place in the layer just below the bark. 
In some cases, the dendrologists seal the hole with wax to prevent the tree from "bleeding".  Some species heal better than others, in which an open wound may be liable to all kinds of infection. 

OH< so they really do bore holes in them!! I did not know that.. It just seemed a good idea to learn more about certain things.. Thats interesting!!
 

Offline NewBill

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THANK YOU for this wonderful observation....it sounds you live in a rural location.

I really appreciate your post with great interest.

Within city limits.  There is some effort to preserve the remaining trees.



http://web.uvic.ca/~bgorman/Nov27/Nov27.html [nofollow]

« Last Edit: 06/01/2007 07:11:54 by NewBill »
 

Offline BillJx

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What are tree rings, and do all trees grow at the same rate?
« Reply #13 on: 16/02/2007 19:03:16 »
OH< so they really do bore holes in them!! I did not know that.. It just seemed a good idea to learn more about certain things.. Thats interesting!!
[/quote]

Yes, it's simple to do.  I'm not a forester but used to use a boring tool routinely in forestry surveying, measuring regrowth of second growth forest, undergrowth, soil conditions etc. It's a hollow drill that's turned by hand and extracts a narrow core of wood so that you can examine the rings.  You can see evidence of fire, years of poor and good growth as well as age.
Off topic, if you're interested. . .  you can get an idea of an evergreen tree's health, particularly of the root system, by looking at the top.  If it's getting healthy new growth at the top, the roots are healthy.  If the top growth is yellowish, watch out for your house in a windstorm.
 

Offline neilep

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What are tree rings, and do all trees grow at the same rate?
« Reply #14 on: 17/02/2007 15:07:44 »
OH< so they really do bore holes in them!! I did not know that.. It just seemed a good idea to learn more about certain things.. Thats interesting!!

Quote
Yes, it's simple to do.  I'm not a forester but used to use a boring tool routinely in forestry surveying, measuring regrowth of second growth forest, undergrowth, soil conditions etc. It's a hollow drill that's turned by hand and extracts a narrow core of wood so that you can examine the rings.  You can see evidence of fire, years of poor and good growth as well as age.
Off topic, if you're interested. . .  you can get an idea of an evergreen tree's health, particularly of the root system, by looking at the top.  If it's getting healthy new growth at the top, the roots are healthy.  If the top growth is yellowish, watch out for your house in a windstorm.

THANK YOU for this Billjx,

........and for your wonderful post.

So as Eric mentioned above.......it is obviously OK to bore holes into a tree without causing it harm.  Did you used to seal the hole up with something !?...if you did..did you cover the hole or completely fill it ?

just curious......THANKS...and WELCOME to the site. :)

« Last Edit: 17/02/2007 15:09:15 by neilep »
 

Offline Karen W.

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What are tree rings, and do all trees grow at the same rate?
« Reply #15 on: 17/02/2007 16:44:06 »
ME TOO! I was curious about how they covered up the hole, or filled it in too? Now I woned if they used Like a dormant paint or spray for sealing the wound, or simply plug it back up?
 

Offline BillJx

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What are tree rings, and do all trees grow at the same rate?
« Reply #16 on: 18/02/2007 13:46:23 »
ME TOO! I was curious about how they covered up the hole, or filled it in too? Now I woned if they used Like a dormant paint or spray for sealing the wound, or simply plug it back up?
We didn't treat them at all.   As someone else pointed out, the living part of the tree trunk is only the thin layer between the bark and the wood.  It's frequently exposed by birds, insects, broken branches etc etc and the borer only makes a small hole.
 

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What are tree rings, and do all trees grow at the same rate?
« Reply #16 on: 18/02/2007 13:46:23 »

 

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