Older member here, have lurked for a while, but new to posting.
here goes ...

We have on our property line, (an old property line that's traceable back to the 1700's) a majestic white oak in great shape.
About a foot above ground level it measures a little over 21 feet in circumference, hence about 6 1/2' in diameter.
The property line has a handful of additional oaks half the diameter (still pretty large), but this one clearly stands out as the biggest by far.
Probably the only way to truly know the age is to ring count, but short of doing that, how old could this tree be ?
Any wood cutters, lumber folks woodcrafters care to venture a guess.
The tree is located in the upper Hudson Valley of New York if that could have a bearing on it's age.

Thanks in advance, great topics on this forum, really enjoy it.

Great question, can't wait to hear a great answer.

No way of knowing without a ring count but white oaks can live five to six hundred years.

what warrior said.

open grown trees put on diameter a lot quicker than those growing in over stocked or fully stocked conditions.

Yep, the differences between field grown and forest grown would almost have you thinking two different species.

Does is still produce?

Kbayduck seems I have had the same experience with a Burr oak here on the prairies, Historically it was written they put drop traps around it to catch Passenger pigeons from 1820 onward. The tree was cut down in 1990 and had a 5 foot diameter. The local expert that was aging oak trees thought he found the "mother load" since he had local data back to 1400 Ad.
Unfortunately that was not the case. Aerial photo graphs from WW1, cause they did trench training in that area and trained the air-boats and bi-planes to read ground troops etc. Then someone looked at those photos and there was a little house with a cresent moon on the door with this tree fully positioned. Every night from the 1860 to 1960 someone watered that tree sorta speak. The city then put in sewer and water. Old habits die hard till the old man moved out in 1970.
Did I mention it was on Sharpe right next to Winchester

Get with a forestry professional or college that has forestry curriculum and have someone come out a take a core sample with a core sampling tool. That would likely yield a suitable ring count for accurate aging.

generally a good idea, but you'd need a hellish increment borer to reach the center of that tree!

Can't help you with the age, but that's a monster for NYS. Check out the NY Big Tree Register. The biggest white oak (Dutchess) in their book is almost 21 feet circumference. You should remeasure your tree at breast height (4.5 feet), not near the base. There are a couple other measurements that go into calculating the total score, but yours sounds like it could be right up there....
Big Tree Register - NYS Dept. of Environmental Conservation
https://www.dec.ny.gov/animals/5248.html

There is an ancient oak near me, the Sacred Oak of the Oley Valley. It is a Chinkapin Oak (white oak family).

It has a girth of 21' 2", a 118' spread and is 73 feet tall.

No core sample have been taken that I am aware of. It is estimated to be more than five hundred years old.

Elders of the Lenni Lenape tribe have certified the tree has been venerated for 480+ years. The current owner, a horticulturist, places the tree's age at approximately 700 years.

White oaks in our area (Q. garryana) tend to be slow growers. I've seen some stumps down in the brush lands from a cutting that took place 100 years ago (stumps still solid one inch down into the wood) and 20-30 " diameter stumps had around 200-250 years of age.

Doing some checking it states unmolested the average age is about 300 years with some living to be as old as 600 years old. As to how old your tree is? It may not be much or any older than those much smaller if it is growing in an area where the roots can expand way out and in good loam type soil. Those relating to forest stands are correct as to growth rates. Also some trees can be growing in poor soil or over a rock etc. etc. so size is only a modest method to stating age.

Bryce

Wow. Neat thread. Hurricanes have got several old growth trees at home over the years, not much left with any size other than a few oaks, some old longleaf pines, and a sycamore so big it gave indians shade for sure.

Core sample do have a few problems because some years the rings do not grow on some sides, as well insect defoliation sets up to have sometimes 2 rings.

Just think about what some of those trees have seen!

Moosetrot

Without a super long increment borer you can't do anything but guess the tree's age. I have some oak on my place that are a foot across but less than 30 years old.....I know because I had the spot clear-cut in 1994. I was once cutting pulp and hired to take out every other row in an extensive Red Pine plantation. As I worked my way up a row I came to a sand blow area (where the topsoil had all blown away years before). There were Red Pine growing in that near-sterile sand that were the exact same age as the 10-12+ inch Red Pine I was harvesting, because they were still in rows and spaced the same as the ones I was cutting. This plantation was just over 30 years old, and some of those little Reds were bonsai sized....less than 1 1/2 or 2 inches across, and 2 1/2 feet tall. Another tree growth example is a couple Red Pine in the north part of our county that were used as "witness trees" during the original U.S. government survey in 1852. These trees are maybe 22"-24" in diameter today. They had to have been large enough to use as witness trees in 1852, so it doesn't appear they have grown much at all in the 169 years since they were first used. I have no clue how to post a link, but if you Google "WITNESS TREE WORK/Houghton Lake Resorter" you can see a 12 year old photo of the two trees.
My mother planted a Weeping Willow near the lakeshore of the little lake I grew up on, 38 years later, the guy I sold the house to had the willow removed. It was over 4 foot in diameter at breast height. When it comes to size, where a tree grows is just as important as how long it grows.

We cut one down that was 5-1/2 ft across. Or, I should say, we hired someone to cut it down.

Counted the rings a few times and everybody came up with slightly different answers but all were close to 260 yrs old.

Would love to see a picture of your tree with a person standing by it for reference

337 years 6 months and 5 days. That’s my best guess. Welcome