A Favorite Pin Oak Tree: 19th Century Origins

The Pin Oak tree at the edge of the road in Eliza Howell Park is one of my favorite trees. It stands alone, with enough room for its branches to spread. 

At this time of the year, the leaves are fallen and the branches are bare.

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I first started paying close attention to this oak because the birds are attracted to it. Warbling Vireos have nested here twice in recent springs and both Red-bellied Woodpeckers and Blue Jays are all over it in late September and early October, collecting acorns.

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Photo by Margaret Weber

This is a quite large – and old – Pin Oak, a species that does not live as long as some other oaks. After having been asked several times how old it is, I decided to try to find the answer. There is no exact method of knowing the age of a living tree, but there is a widely used method of estimating the age.

The steps in estimating tree age are these:

  1. Measure the circumference of the tree at 4 ½ feet from the ground.
  2. Divide the circumference by pi (3.14) to get the diameter.
  3. Multiply the diameter (in inches) by the “growth factor” that has been identified for the specific species, based on how fast growing it is. (Different organizations have published the growth factors for different species.)
  4. The resulting number is the approximate age of the tree, in years.

Pin Oaks are moderately fast growing and have been given a growth factor of 3.0.

It is difficult to measure the circumference of a large tree by oneself so recently, when accompanied by Charon, another Eliza Howell enthusiast, we undertook the measurement.

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At 4 ½ feet high, the tree measured exactly 12 feet in diameter (144 inches).

144 divided by 3.14 = 45.86.

45.86 times 3.0 = 137.58

Using this method to estimate age, the tree is about 137 or 138 years old.

137 years ago was 1883. This is just an estimate, but it is probably safe to say that this tree began to grow before the twentieth century, long before this property was donated to Detroit for parkland.

It was already over 100 years old when I started enjoying it, appreciating it in all seasons. On hot summer days, when someone else has not claimed the spot, I park the car in its welcome shade as I take my walk.

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Across the road is the prairie flower field and the Pin Oak sometimes makes a lovely background for a flower picture — Joe Pye Weed in this case.

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Pin Oak leaves turn late in the Fall, in November in Eliza Howell. The bronze (?) shade is not as striking as the leaves on some other trees, but there is something very attractive about it.

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As oak trees go, Pin Oak trees do not have a long lifespan. This one is perhaps older than average. I hope it continues to provide beauty, food, shade, and nesting habitat long after my nature walk days are over.

Estimating the Age of Trees: November 11

Having learned recently about the effort to determine the approximate age of a large Bur Oak tree in the Rosedale neighborhood of Detroit, I decided to use the same method to arrive at an estimate of several large trees in Eliza Howell Park.

Anyone interested in assisting in this project is welcome: Sunday, November 11, at 1 p.m.

Please email if you are intending to come (so I can let you know if there is a late need to reschedule because of weather): leonard.weber9@gmail.com

This Pin Oak is one to be measured.

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The following steps are followed to get a non-invasive estimate of a living tree’s age:

  1. Measure the circumference at 4 and 1/2 feet from the ground (54 inches).
  2. Divide the circumference number by pi (3.14) to get the diameter.
  3. Multiple the diameter (in inches) by the growth factor which has been identified for the specific species. (Several organizations have estimated and published the growth factor for various species, based on how fast a species usually grows.)
  4. The resulting number is the approximate age of the tree, in years.

Another of the trees I plan to measure is this American Sycamore.

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I am hoping to measure about 8 large trees, different species, ones that are often noticed by park visitors and participants in nature walks. At present, when I am asked “How old do you think that tree is?” I can only give a general response.

This Eastern Cottonwood, the location of a Baltimore Oriole nest every year, is also on my list of trees to be measured.

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I have been asked specifically about the approximate age of the Bur Oak (next picture) at the edge of the path leading down to the floodplain.

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In my initial use of this formula for estimating tree age, I have found that not all online sites of growth factor information have the same number for a particular species. It will be necessary for me to do more research before November 11 in order to determine the most appropriate numbers to use.

As I noted in a February post (“Beech Trees and Beechnuts”), Passenger Pigeons used to eat many beechnuts. I am wondering whether this American Beech is old enough to have been visited by those legendary birds.

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As I get to know more about the flora and fauna of Eliza Howell Park, I realize how much more there is to know. And I look forward to this learning project.