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Steve Nix

Estimating a Standing Tree's Age Without Boring or Cutting

By January 16, 2013

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A Tree's Rings

Foresters determine tree ages by counting the growth rings of a severed tree stump or by taking a core sample using an increment borer. Still, it is not always appropriate to use these invasive methods to age a tree. There are noninvasive ways to estimate tree age in common trees where they are grown in a forest environment. There is also a way to roughly age a tree by using a "rule of thumb" for street and landscape trees.

A Tree's Growth Rings - Photo by Steve Nix


March 20, 2013 at 1:20 pm
(1) Eileen McGlynn says:

That formula for determining the age of the tree can’t be right for my tree. It is 120 inches around the circumference and it is a Norway Maple. I had to measure it a little under the 4.5 foot level because it branches off into 2 trunks. At a little under 4 feet it is 120 inches exactly. But using the above formula makes it over 1,000 years old. Are my math skills that off even with a calculator? Can a Norway Maple grow that old?

March 20, 2013 at 2:21 pm
(2) forestry says:

All beginning calculations are to determine the diameter of a tree using a measure of tree circumference in inches and converted to DIAMETER in inches – nothing more. You then choose a listed tree species growth factor and multiply it by the DIAMETER in inches (NOT circumference).

120 in. circumference divided by 3.14 (pi) = 38 in. diameter

I did not include a Norway maple species growth factor. A red maple with a diameter of 38 inches is 4.5 which when multiplied equates very roughly to 171 years of age (38 X 4.5 = 171).

April 28, 2013 at 2:42 pm
(3) kevin m snodgrass says:

I have a silver maple in our back yard, I know it is exactly 37 years old. I did the computation, 54 inches divided by 3.14 equals 17.20 multiplied by 3 growth rate, would make it 51 years old. I know, it was pampered a bit and taken care of, would you suggest I reduce the growth rate to 2, which would make it about 35 years old. Also, why do we significantly increase the growth rate in very old or ancient trees that are in a landscape? Is this because, orginally, they were not pampered. Thank you for your assistance.

April 28, 2013 at 2:50 pm
(4) Kevin M. Snodgrass says:

I also have a very large oak, I think red oak or black oak in my yard in Pekin, Il. I have not measured the circumference yet, but plan on it this week. I believe it will measure anywhere between 15 to 18 feet, 180 to 216 inches or so. Since this is in my front yard, and a very, very old tree, do I increase the growth rate from 4 to 5 or something like that. I believe it will be well over 200 years old. Thank you.

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