How much might a tree that was already old change in 70 years?

There is an article somewhere about trees in central park that were torn down by a thunderstorm not long ago. The woman who wrote the article knew particular trees, and they meant something to her if I remember correctly. Each tree is carefully watched. I’ll find the link if I can.

Cute. But of course you can’t see the rings until you cut it down. What I’d like to know is if a person trying to find the right spot by looking for the landmark tree is going to be able to recognize it 70 years later. Will 70 years’ growth change it much besides making it thicker? Will it gain a lot of height? Will its basic configuration be the same?

I would expect someone with a knowledge of tree growth to be able to answer this—for example, a tree can change a lot in more than half a century; or, a distinctive feature would still be distinctive; or, a feature such as X would look the same, but a feature such as Y would be grown over by bark.

@Jeruba, I am not 70 plus years old yet, but I have seen pictures of the same tree taken over time. If you are trying to help someone find said tree, other landmarks might help more, but it would still be possible to recognize it (if you were a tree person and really paid attention to it). I find most folks don’t pay close enough attention. There is a particular sycamore tree that I have been painting pictures of and sketching for years—I know this one tree extremely well and have no doubt that I would be able to recognize it. Not sure I could say the same for other trees.

If this is for a story or something, a piece of metal (that itself could survive the years) might become part of the bark of the tree over time (the bark would grow over it to some extent), but it would help with recognition. I am thinking long enough pieces of metal fencing or a metal rod that was impaled in the tree. Not sure initials carved into an oak would make it (wrong kind of bark for carving anyway) and a rope from a swing likely wouldn’t either (a chain might though). If your character has any artistic talent and could have committed the image to memory, it would certainly help.

@Jeruba I think it would depend on how old the tree was when you last saw it. If it was still in the first 20 years or so of growing, I think there would be major changes to it’s size and shape. But, if it was already 50 years old, I think it’s general shape would appear the same, it would just be wider and possibly taller. I’m just guessing though from what I’ve seen in my 28 years a life so far.

If the tree was already well established before the 70 year absence, then you will most likely see the greatest change in thickness (weight) instead of height. As the tree gets older, the tree needs to add more biomass in trunk thickness to support the greater height. Something along the lines of a 2:1 – 4:1 ratio of biomass gained in trunk thickness vs. biomass gained in height. Obviously this will vary based on the particular tree species in question, and its growing habits, but it is a general way to view the expected growth.

If you had a general idea of the age of the tree, there is a way to count the number of rings (to get a more exact age estimate) without harming the tree. You could use an increment borer to drill a small hole into the pith of the tree, and extract a small sample of the core (the extracted sample is smaller than a pencil in diameter, and would not harm the tree, provided you don’t take numerous samples). Additionally, if you knew some of the history of the area in question (drought years, fire occurrences, etc.), you could correlate that data with the ring sample, to get an even clearer picture of the tree’s age. Hopefully this would be able to help you find out if it is in fact the tree you were looking for.

Increment borers are available at any forestry supply store, or you could contact the local US Forest Service office for more information about where to find them.

The pioneers used to cut a blaze in trees to mark their trails. If the tree was slow enough growing, and the blaze was large enough, someone with intimate knowledge of the trees and blaze patterns would be able to identify at least the marker trees. If they are still there and otherwise undamaged.

I have carved my initials into a tree when I was 10. When I last went back for a visit at 40, my initials were still there.

I didn’t want to say this was for fiction because I wanted real answers. Thanks for both the scientific and the artistic—they are both relevant.

Nonetheless, @Kayak8, your guess is correct: it’s for a story. The character last saw the tree when it stood near her family’s farmhouse. She was ten. Now she’s 81, and the farmhouse is gone, the farm is gone, the village has become a town, and nothing looks as she remembered it except this tree. I want her to know the tree without having carved anything in it or planted a piece of metal. I just want to know that she could really find the same tree and be able to explain why.

@Ltryptophan, my response to your remark no longer makes sense since you changed it. I thought your comment about a tree and a woman adding rings with age was cute.

@Jeruba, I think you still make sense!

In Hong Kong some trees grow funny because of some weird obstruction (e.g., fence) while they are small, and when they grow big the fence might be gone but there’s still some weird contortion in their trunk. I wish I had some pictures… some of them are amazing, you look at them and think: how did they get like that?

In N Wis the natives used to bend saplings over or twine the branches of to nearby saplings together to mark a trail. Many of these trees grew with bends in their trunks or the branches fused together.