THE NATURAL LORDS OF TIME STAMPS – TREE RINGS
If you want to have an example of how a time stamp or mark is essential to record events, you need look no further than your nearest tree. When you see the rings on a cross section of a tree’s trunk you are getting more than just the age of the tree. You are also getting an accurate record of what happened around that tree each year of its life.
You might think that this is an ancient form of gathering historical data. In reality observing tree-ring patterns to reconstruct the history of life around that tree only came into being in 1894 when a gentleman by the name of A.E. Douglas started dating wood by looking at the growth ring patterns of trees. Working in Arizona, Douglas started noticing that wide rings of certain species of trees were produced during wet years and that rings narrowed during dry years. And so was born the new science named dendrochronology.
How the “time stamping” actually works in a tree to create the ring starts with the fact that a layer of wood is added each year to a tree’s trunk. This establishes the ring. In the spring the tree focuses its energy on producing new growth cells. These cells are initially large, but they progressively decrease through the summer and into fall when the cells die. The contrast between these smaller old cells and the next year's larger new cells is enough to establish a ring. Adequate moisture and a long growing season result in a wide ring. A drought year may result in a very narrow one.
Dendrochronology has advanced to a point where we can determine more than rainfall of a certain year. Many other environmental factors can be evaluated such as climate change, pollution and wind. In fact, during this time of concern about global warming, dendrochonology is helping scientists to see if we are experiencing normal climate patterns. With the help of computers, scientists are comparing the ring records of many trees to construct maps of former regional climates.
With dendrochronology scientists can also see how climate affects human behavior. As reported in an article by Thomas Maugh in the June, 1981 issue of Science, Samuel K. Eddy of Syracuse University found that the size of tax payments (a measure of agricultural production) in the ancient Greek town of Byzantium was proportional to the thickness of tree rings. Eddy found that the smaller the ring the smaller the tax payments and the larger the ring the more money that was collected. He also found that the years of constitutional crisis in Athens were usually preceded by one or two dry years.
It is truly amazing what one can find when an accurate time stamp is recorded and attached to a document, object or living organism.