Last Updated on July 28, 2021 by Neil Mackengie
If you were to cut down any tree more than one year old and look at the cross-section, you would see alternating bands of light and dark wood. The two bands together are called “the annual ring”, and they make up the amount of wood formed by the tree during a single growing season or year.
Why are the bands lighter and darker?
This is because the wood grows in a different way during the different seasons. In spring and early summer, the cells of the wood are bigger and have thinner walls. This makes them look lighter.
In late summer, the cells are smaller, have thick walls, and are closely packed together. This makes a darker band.
So What Are The Usages of Those Rings?
The age of a tree can be told by counting the annual rings. When you look at the rings of a tree, you will notice that they vary in width and in many other details. These variations are caused by the weather conditions that prevailed during the given season. A difference in the light, the amount of rain, and the minerals in the soil will produce a difference in the rings of a tree (and outside of the tree and that is bark).
That is why scientists often use the rings to obtain a clue to the weather conditions that prevailed years ago in certain parts of the world.
Who a tree grows, the wood of the tree is not the only thing that increases in size from year to year. Additions are also made to the bark of the tree. This is done by means of a thin band of living, dividing cells be- tween the wood and the bark.
This layer is called “the cambium”.
The new cells which are formed on the wood side of the cambium become wood. The cells formed towards the outside become bark.
Why do some trees have rings and others don t?
Most trees grow in groups, known as stands, and each tree in the stand has a similar life cycle. The trees in the same stand all have roughly the same age and appear to have the same growth rate, with each tree roughly the same size and structure. This is known as co-variability. However, a group of trees can be divided into trees that have rings and trees that do not have rings; this is known as variability.
How Do Tree Rings Indicate Age?
In the past, we’ve seen how ancient tree rings can give an idea of how old a tree is, but new research indicates that tree rings may also be able to tell us about how old a particular tree is, and how it changed over time. Tree rings are formed by the formation of new cells on the bark of the tree. Each time a new cell is added, it pushes the bark up a centimeter, which creates a new ring. While a tree can have as many as 100 rings, some trees have only one or two rings, while others have many.