Tree Rings

TIMBER

Ontario Department of Lands and Forests

Geraldton District Weekly Report

April 20^th, 1971

The Oldest Living Things on Earth and Their Message by G. T. Marek

Some time ago scientists found that certain species of trees showed marked variations in the width of their annual growth rings.  Investigating this matter further they found that these variations were related to variations in precipitation.  In a dry year a narrow annual ring of growth was formed;  in an average year a ring of average width resulted;  and in a wet year the rings were abnormally wide.  By examining the wood of representative sample trees, the year to year climate of the region could be established as far back as the age of the oldest tree.   This precipitated a great interest in very old trees and a search began for them.  As a result the oldest living things on earth were discovered at an elevation of 11,300 feet, namely the bristle cone pine trees (Pinus aristata) in Inyo National Forest, California.

The age of any tree can be established without the need for cutting it down by taking a core sample with an increment borer.  This is a drill equipped with a hollow, tube like bit that extracts a rod like core of wood extending from the bark to the pith.  This core contains a sample of every growth ring of the tree.  After extraction the core, which is thinner than a pencil, is examined.  This can be done by naked eye or by examination under a microscope.  Working with cores extracted from the bristle cone pines the ages of trees 4,600 years old were discovered and a complete climatological record that extended back more than 4,000 years was established.

In the course of this work it was found that the same easily recognizable combinations of wider and narrower rings occurred in many trees indicating specific climatic cycles that took place over certain periods of time.  This led to significant ring patterns and by matching these patterns in timbers found in prehistoric Indian ruins it was possible to extend the calendar more than 6,000 years into the past.

In this way by decoding the information contained in wood we are able to read the message of the trees, some of which are living and others that are dead.  No one can predict what interesting facts may be revealed through further studies of trees.

D.E. Gage, District Forester