Have you ever wondered how old a tree is? There are many trees in a forest that are hundreds of years older than you. Some can even live for thousands of years! But how can you tell how old a tree is exactly? One of the most common and accurate ways people figure this out is by counting the darker rings inside of the tree’s trunk. But there’s one major downside to this way of doing it: you have to cut it down.
Though experts and other professionals have valid reasons for this type of research, it’s harder to justify cutting down a tree for just the average curious person. But we get it. There’s something about trees that some people can’t just stop thinking about. At Mr. Tree, we still find ourselves wanting to learn more. We’ve been in the residential and commercial tree servicing business for over 30 years, and we want to help you figure out mysteries like how old your tree is. If you’re looking at a completely healthy tree and wondering how you can tell how old it is, know that you don’t necessarily have to cut into it.
You can tell how old a tree is without damaging it at all. Though not as accurate as counting the internal rings of a tree, this method will give you a pretty close estimate and isn’t too hard to figure out. With just a soft measuring tape and some knowledge about the species, you’ll be able to estimate the age of any tree you come across. Here’s a method for finding out how old a tree is without cutting it down.
Learn the species
Just because one tree is larger than another doesn’t necessarily mean that it’s older. Some trees just grow at different rates. Knowing what kind of tree you’re examining will be a big help when trying to estimate its age. For example, a redwood tree can grow incredibly high, but a large majority of that veritable growth is done within its first 100 years. And remember, trees can live for over a thousand years. Even if two trees are in close proximity to each other, slight differences in their appearance and species could mean that they aren’t capable of reaching the same size.
If you can’t identify a tree on your own, the Arbor Day Foundation provides a free, step-by-step tree identifying process. It will ask you questions about the location and appearance of the tree, providing you with the correct identification once all the questions are answered. Once you know a tree’s species, you can get started on estimating the tree’s age, so do as much research as you can so that you can identify the definitive species for your tree.
Measure the circumference
Once you know your tree’s species, the next step you’ll take in estimating its age is measuring its circumference. If you’re unfamiliar, the circumference is the distance around the tree trunk. Use your soft measuring tape and wrap it around the tree completely, almost like giving it a hug, to get its complete measurement. Experts recommend doing this at breast height, or DBH (approximately 4.5 feet above the ground). Measuring at this height will allow you to get the most accurate circumference reading.
If the tree is on flat ground, taking the measurement is simple. But if the tree is sitting on a slope or angle, you’ll need to know where exactly to stand to take the measurement. The City of Portland Oregon suggests measuring it at right angles to the trunk, 4.5 feet along the trunk’s axis. This will give you an average height to measure that’s between the shortest and longest sides of the trunk. Be sure to take this measurement in inches and write it down because you’ll need it later on.
Calculate the Diameter
Once you’ve taken the circumference measurement of the tree, you’ll then want to figure out the tree’s diameter. The circumference of the tree is the measurement of the circle of the trunk, and the diameter is the distance between the middle of that circle. It’s not possible to actually measure a tree down the center without cutting it, but it is possible to get the measurement. To find the diameter, you’ll have to divide the circumference of the tree by 3.14 (pi). Take note of this measurement and you’re one step closer to finding out the estimated age of your tree.
Learn the Tree’s Growth Factor
The last step in this process is to multiply the diameter of the tree by its growth factor. Different species of trees have different growth factors, which is why it’s so important to know what kind of tree you’re looking at. The Minnesota Department of Learning provides this list of tree species and their growth factors.
Know that these numbers are considered more accurate for trees that are growing healthily in a forest environment. Though they can still be used for trees in your neighborhood, those trees are exposed to tougher conditions than trees in a forest. Restricted environments for growth, exposure to fumes and chemicals, or bad soil are all possibilities of things that can change a tree’s normal growth factor. Still, this method can be used to get a rough estimate for those trees as well. After you multiply the diameter of the tree by the growth rate for its species, the resulting number is the estimated age of the tree! You’ll be surprised and impressed by the age of the trees you measured.
This way of achieving an estimate for how old a tree is, is a great alternative to damaging a tree by cutting it down. Still, the only way to know exactly how old a tree is without cutting it is by growing the tree yourself. And growing that tree on your property can create a thriving asset to your home when maintained correctly. Mr. Tree in Portland, Oregon, provides residential tree trimming and pruning services that will make sure your tree stays as healthy as possible.