A vignette of history
By Robert A. Hedeen
By Robert A. Hedeen
While hiking through a forested area north of Rockford the other day I came upon the stump of a white oak tree that had recently been felled. It had been a magnificent tree as the bole was about 30 inches in diameter. I counted approximately 99 growth rings, so the seedling from which the tree originated must have laid down its first ring of wood around 1902 or 1903.
In reconstructing the past, archaeologists consult the artifacts of earlier civilizations, historians read the archives of another era, paleontologists examine the fossils of long dead animals and plants, and dendrochronologists study the growth rings in trees and aged wood. Having nothing better to do at the time, I decided to play amateur dendrochronologist and attempt to reconstruct the events that occurred during the life of the tree.
As it is estimated that one acorn in 10,000 produced by an oak will avoid the squirrels, other nut gatherers, and boring insects and will find a favorable spot for germination and growth, I regarded the stump with some respect. I realized that when the primary stem of the seedling first broke through the soil, Theodore Roosevelt was in the White House, and my ancestors were farming the prairies of northern Illinois and the hills of eastern Tennessee and Kentucky.
You begin examining the oldest growth rings that are the innermost. I readily observed the first eight from the center were broad and evenly spaced, indicating abundant light and moisture had been available, and the young oak had grown rapidly. By about 1910, however, the rings became asymmetrical, with one side of the circle being drawn out to one side. Tree ring experts call this phenomenon reaction wood as it clearly shows something pushed against the sapling causing it to lean to one side.
By the end of World War I in 1918, the small tree was growing straight again, but restrictions of the spaces between the rings indicated other trees or woody shrubs were crowding it. The roots and crowns of the competitors were taking the necessities for plant growth, water and sunlight, from my oak and stunting its growth. By 1925 the rings indicated the surrounding trees had been eliminated or thinned out in some way, and an ample supply of sunlight and water had become available again.
For the next ten years the tree experienced vigorous growth, but about 1935 a forest fire or bolt of lightning scarred it and disrupted the ring pattern. In successive years it was evident that eventually new wood built up and covered the wound made by the fire or the bolt of lightning.
In 1941, when the United States entered World War II, narrow rings appear, suggesting there was a dry spell of one or two years duration. As the white oak was a strong mature tree, it survived the drought and grew normally for about the next 10 to 15 years. Around 1955, however, another series of narrow rings was evident. Perhaps this period of restricted growth was due to an attack of some type of boring or defoliating insect, or some sort of blight.
From 1955 to the year it was cut down, the white oak grew more or less normally. The wood in the spaces between some of the rings was less than that between other rings, indicating that some years during this period were better than others for maximum growth.
As I contemplated the piles of decayed sawdust lying next to the stump, I sensed that they were more than mere fragments of wood; in fact, the sawdust represented an integrated record of 100 years of natural history. My respect for the tree, with its life spanning the 20th century, was deepened.
When the 19th century author, naturalist, and transcendentalist Henry David Thoreau witnessed the felling of a large tree near Walden Pond, he wondered if he would meet that tree again in heaven. However, my admiration and respect for the tree that had once stood tall in northern Illinois did not match that of Thoreau.
During the 100 odd years the white oak lived it stored the energy of the sun in the wood it manufactured. I hope that when the wood is burned in some stove or fireplace, and the latent energy is released in the form of heat, the homeowner will appreciate the trees contribution to his comfort. If he does, the sun did not shine and the tree did not live in vain.
Dr. Robert Hedeen is a former resident of eastern Maryland, with degrees in zoology and botany. He is a former professor of biological science. He has had 30 scientific papers published, has written numerous magazine articles, and is the author of two books on marine biology of Maryland.