You may have heard you can tell how old a tree is by counting the rings. While on the surface this may appear like nothing more than a nifty little tree gimmick, it’s actually a mechanism that goes much deeper than that.
The study of tree rings is called dendrochronology—“dendro” which means “tree,” “chron” which means “time,” and “ology” which means “the study of.” Therefore, dendrochronology is the study of trees over time. People have been observing the rings of trees and hypothesizing their value as far back as about 300 BC (!), but it was Leonardo da Vinci who correctly hypothesized what tree rings meant. In a collection of his writings entitled A Treatise on Painting, he observed: “The rings around the branches of trees that have been sawed show the number of its years and which [years] were the wetter or drier [according to] the more or less their thickness.” Please keep in mind that da Vinci made this (correct) observation sometime in the last two decades of the 1400s (!). While I can’t speak for you, had I been alive in the 1400s, I highly doubt I would have been hypothesizing about tree rings.
This makes trees what you might call “long term bioindicators.” In other words, trees and their forest communities are essentially libraries that document, chronicle, and archive the natural world. This is important for two reasons: 1) Trees can provide environmental records dating back hundreds and possibly thousands of years. Human records of the environment (if there are any at all) are likely no more than a couple hundred years old, and even then, there’s no telling what condition they’re in. Trees are our window to the past. 2) Dendrochronology can help inform us about specific cyclical weather and climate patterns that could repeat themselves in the future, like droughts.
Curious to give dendrochronology a try yourself? Follow these steps!
- Find a tree stump or a tree that has been cut down.
- You’ll likely notice light and dark rings on the stump. These correspond to the same year. Light rings form in spring and summer, dark rings form in early fall.
- Count the dark rings in order to get the age of the tree.
- If the spaces of the tree are very wide, this means that conditions were good and rain was plentiful. Very thin width between rings indicates the opposite.
Now, you may not be predicting future droughts with the above information, but who knows—it wouldn’t be the first time I inspired someone to become a dendrochronologist off a blogpost! (Just kidding, it would be.)