Tree Rings Tell About the Past

Tree rings are studied by scientists because of the information that scientists can learn from them.  But, do you know what exactly they are and how they can help scientists study the past?

tree rings

How many rings can you count?

What are tree rings?

As hard as it may be to believe, tree rings are not shiny pieces of metal that trees keep on their branches or twigs.  Instead they are layers of growth around the trunk of a tree that look like rings when the tree is cut down.

Every year a tree adds new growth to its trunk.  Each ring of new growth is made up of some light and  some dark sections of wood.  The light sections are the new growth that is added in the spring when the tree is growing the fastest.  The dark sections are made in the summer when the rate of growth has slowed down.  These rings are known as growth rings.  It is possible to tell how old a tree is/was by counting the number of rings.

Unfortunately, you can not see the tree rings until the tree is cut down.  But, if you happen to see a tree stump look closely to see what you can observe.   Try to count the number of rings to see how old that tree was.  Are some of the rings close together or farther apart?  What do you think that means?

tree rings

Notice the alternating light and dark colors in the rings.

Why do scientists study tree rings?

Scientists study tree rings because they give a window into what an area was like in the past.  They are able to do this because trees do not grow the same amount every year.  Some years, such as years when there is a good amount of rain, trees grow much more than in other years and the tree rings would show this by being larger or farther apart from each other.  In other years, such as years of drought, the tree may not grow much at all and the rings would be very close together.

Since trees live for such a long time they are good ways of storing knowledge of the way the world was in the past in certain areas.  Trees can live hundreds or even thousands of years.  During that time the world can change a lot and by studying those tree rings scientists are able to see what life was like and if there have been changes in the climate (climate is the general weather patterns of an area over a long period of time) of an area.

What can scientists learn from tree rings?

As I explained above scientists are able to learn about times of drought or times when there was a lot of rain.

Some of the other things that scientists can learn about are: fires, insect plagues or damages, diseases, injuries, and air pollution.