Age of a tree

atula

Now I know that we can find out the age of a tree by counting the rings of the main trunk of the tree. But then for this method we will have to cut the tree down..
Isnt there any other way of finding out the approximate age of a tree just by looking at it or something????

mdvaden

Increment borers...

Increment Borers

If you go to REPLY #17 in this Treeworld thread, I posted a LINK to a page with video (video link) of me using one...

Historic Artifact: Catalpa in Jacksonville, Oregon

On the linked page, I estimated the tree's age based on the core extracted and a few other observations.

Again, that's Reply #17 where the link is.

Eric Frei

Tree rings can be unreliable in tropical/semi tropical areas like where I live as there's more than one growing season and you can have many rings for 1 year.

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Sean Freeman

Erics correct tree rings are pretty useless to us in calculating the age of tropical trees, we have to base estimations on our knowledge of the growth rates of particular species in our area compared to specimens that the planting date is known and verified..certainly not a perfect method by any means.

Even in the temporate regions of the world tree rings become meaningless when it comes to many aging veteran trees that loose their heart wood to decay...then all you can count are the rings in the outer shell or the branches.

mdvaden

Do they keep a record of cut trees for which ages are clearly known, as a gauge to compare with?

I was thinking about how how core samples have been taken out of very old European buildings for which the dates are known (the timbers), and how those can be used to verify the age of of antique musical instruments supposedly from the same era. I think Dr. Shigo mentioned it in his tree biology book, too.

atula

I remember reading somewhere that the age of a tree can also be found out by measuring the girth. For a tree that is growing with other trees every 12 mm of growth is equal to one year and a tree that is growing all alone the ration is 25 mm to one year.

Eric Frei

Interesting concept but I wouldn't trust that too much as each location has variables and so do species.

It's tough but around here I'm pretty darn close at guessing tree ages ... but this is a new country as such and most vegetation is planted within last 200 years.

Old bush trees are harder to tell but you get bit of an idea.

Try to find the source of that info ... I always like to check the facts.

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TrevMcRev

A lot of the times in suburbia they're as old as the house.

Sean Freeman

Lets face it even a poor declining tree is likely to outlast the newer houses being thrown up these days

Tree Machine

I'm wondering how old this one is. The non-traditional stump cut doesn't allow a good counting of the rings,
but the stump grinder guy sure loves it.

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atula

Here Eric, I performed a google search and found this pretty interesting way to find the age of a tree,

Do tell me if this is a good way....

The link is
http://www.athensclarkecounty.com/do...nt/tcn_age.pdf

mdvaden

That's more of what we would call a "guess", but it can be far from correct with some trees.

What you read there, is similar to what I did for the Catalpa? Did you read the page in the link I posted?

But I had an advantage - I did a core sample as well, and most of the growth rings were approximately the same size from year to year. Also, I was able to take a core 14" deep, and only need to estimate for the remaining 3".

In Oregon, I volunteered at a demonstration forest Magnus Tree Farm for the World Forestry Center - my friend was the curator. He showed me a cross-cut piece of a Douglas fir tree. It would have been about 20" diameter while standing.

The inner (and older) 10" or so of diameter, had about 80 growth rings. And the rest, or younger 10" of diameter (outer) showed about 30 growth rings.

Why, is unknown. It could have been shaded for nearly a century, then surrounding trees were removed. The point is, without a core sample from a tree like that, measuring diameter is totally unreliable.

It can be more reliable for trees that have been growing alone out in the open, but if the trees are quite old, we may or may not know whether they were within dense forests centuries ago, etc..

Eric Frei

Atula, what I thought, simply a mathematical calculation based on ave annual ring growth for species divided into trees radius.

Things change, often on cut trees you'll notice that the inner rings are wider than the outer, that's opposite to Mario's post (but Mario is corrrect too). The reason is if all things never change (environmentally/water/soil etc) as the tree gets older it has a larger surface area (mass) to grow another shell over. Also as the tree gets mature and consumes more of the resources around it ... it grows slower.

It's a theoretical method, an educated guess.

Recently at a job there was a HUGE FICUS tree, massive. The owner planted it and knew exactly how old it was. It was only 18 years old! I guessed 30 to 50 but what happened is he lives near the beach on sand and there's underground water only 8' down. This monster has tapped that and gone nuts. When you cut it latex runs out of it like a tap.

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ninikins

So the rings in a tree trunk thing is actually correct? I mean, you can averagely guess the age like that. I always thought it was false.

Eric Frei

The rings are created by a cycle of dormancy and growth ... thereby saying a ring is 1 year.

But in reality some places (semi tropical) dont have a genuine dormancy period and can experience more than one growing period a year resulting in multiple rings for a years growth.

It has been found by both anecdotal and scientific methods that some trees in tropical type regions grow according to available water resources.

Where I live in winter it is common to have 24C days. However winter traditionally is our dry season and summer our wet. Now if it does rain a lot in winter (unusual but can happen) the trees grow, sometimes a darn lot! So what happens through a calendar year is trees might have 3 or 4 rings for various growing conditions pertaining to rain.

Many times I can tell when cutting trees or even palms for that matter how wet years were in the past ... currently we are experiencing drought conditions and palms have small heads and tapers and in real wet years the head region will fatten up ... trees similar but with growth rings.

But lets say down is some place where it's cold in winter, deciduous trees that lose their foliage and sit there dead looking for months there will be definate rings that YOU CAN COUNT ON. In those rings you'll also see bad years and good years by the width of the ring.

Hope that helps.

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mdvaden

Some areas like where I live - basically - yes.


Try this article here, and the external links on it too...

Dendrochronology - Wikipedia, the free encyclopedia

ninikins

Thanks, mdvaden! I guess I should've googled myself, hehe.

SageMother

Along the same lines,

I have heard that you can get information about dramatic atmospheric changes and catastrophes by looking at the number of rings, their width, and their color.

Is this true or just wishful thinking enmasse?

Sean Freeman

Hardly wishful thinking this little tree resulted in the entire science community having to recalibrate their concepts of dating ancient sites.....
Dendrochronology
little tree massive impact

Eric Frei

That darned stump again! Man scientists just cant leave that thing alone.

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atula

From all these discussions above, what I can understand is first I need a borer to extract the core of the tree and second, I need to pratice a lot and study a lot n lot of trees to estimate the age of a tree....

Eric Frei

Yes's all round however there's one more thing you can do that will increase your accuracy as I think where you live may be a little tropical.

You can also extract a core from a tree of same species with DEFINATE KNOWN AGE (call this the "control" tree). Then count the rings and you'll know on average how many rings per year. Of course it's best if this control tree is older too as you'll get a better average.

For example, core from 15 year old Black Bean Tree has 24 rings.

Core from your tree has 287 rings.

Maths says average 1.6 rings per year so your tree is 179 years old.

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pomme

there was a program on years ago where they pulled an Oak out of an Irish peat bog using the growth ring patterns they overlayed known weather patterns and tied together the growth rings with a volcanic eruption in iceland. typing this reminded me the program was about why a Scotish tribe moved south over 1 generation leaving lands they had used for centuries. the tree rings showed that there was extensive pollution to the sky and the weather was unseasonally cold for a number of years

Eric Frei

Ahhh, the volcanic cloud perhaps.

That's the theory of why dinosaurs became extinct, a comet hit the earth and send a cloud of dust so thick that the planet was dark and cold ... dinosaurs etc couldn't adapt and went extinct.

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pomme

it was facinating how the dendrochronlogy backed up the theories of the scientists and tied the whole thing together

mdvaden

You can order those. Maybe the tool is sold in your area as well.