Before you start, there are a couple of things that you should understand. Every year, trees grow a new layer that forms under its bark. Each one of these layers forms around the previous layers. The bark is the hard outer part of the tree that you can see. It both covers and protects the inside of the tree from harm. When a tree has been cut down, its stump will tell you a lot. A tree stump is the part of the tree that's been left in the ground after the rest of the tree has been cut down. If you look at the stump, you'll see a lot of rings. These tree rings aren't just on the stump either. If you look at the bottom of the cut tree, you'll see them there too. Each of these rings is one of the layers of yearly growth. That means every ring is a year in the life of the tree! To get an idea of what the age of the tree is, count each of the tree rings.
Guessing a tree's birthday by counting its rings is more than just fun, it can also teach you a lot. Every ring also tells a story about the tree, like how easy or hard its life was. Some of these rings will be dark and others will be light. You'll also see that some of them are fat and some are very thin. The way that they look can tell you things about the tree like whether it was injured by a fire, what years were wet and rainy, and when there were dry years with very little rainfall.
You can also learn the age of a living tree, but don't worry! You don't have to cut it down or hurt it in any way. All you need is a measuring tape and the help of an adult. To start, you'll need to measure the circumference of the tree. This means measuring the distance around the tree. Use your measuring tape to measure up the tree four and a half feet from the ground. Mark the spot with tape or chalk. This should be the widest part of the tree. If you're not tall enough to reach that's okay, just ask your parent or teacher to help or stand on a step stool. Next, wrap the measuring tape around the tree at the spot that you've marked. Measure the tree and write it down in inches. Every inch is about one year of the tree's life. If you're having trouble turning feet into inches, an adult can help with the math.
Some types of trees have different growth rates. This means some trees grow really fast and other trees may grow slower. Because of that, some trees could be older than what you've measured and some could be younger. Measuring the circumference of a tree is the easiest way for kids your age to guess, or estimate, the age of most living trees and is a good place to start.
Finding a Tree's Birthday