Nature on our doorsteps: Trees recording time and weather

During a tree’s lifetime, it can experience many weather challenges including gusty storms, rain, frost and snow, drought conditions, and temperatures ranging from sub-zero to excessive heat.

All of these challenges affect the growth rate of a tree.

We can follow a tree’s annual growth rate by looking at the rings recorded in the wood in its trunk.

These rings are visible when a tree has been cut down and when the light and dark-coloured rings are exposed.  The area of wood between one dark ring and the next represents the growth of one year.

In springtime, the tissue just under the bark of a tree begins to grow rapidly.

This spring wood is comprised of many large, light-coloured plant cells which cause the tree to expand in width.

GROWING: Trees record time and the growing conditions during their lifetime

Later in summer, tree growth naturally slows down.

The cells formed at this time of the year are much smaller and are packed more closely together, forming the darker tree rings.

As each dark ring represents the end of one year’s growth, we can tell the age of a tree by counting these rings.

Bad weather can slow down the formation of the light-coloured spring wood, resulting in narrow annual growth rings.

Tree rings therefore record not just the age of a tree, but they also record previous weather patterns.

By Rosaleen Dwyer.