Tree-Rings and the Aging of Trees: A Controversy in 19th Century America

Abstract

During the late 19th Century there was considerable debate in the United States among members of the legal profession, the general public and even some scientists about the validity of using tree rings to determine tree age. In an earlier boundary dispute case in Maryland (1830) the Honorable Theodorick Bland rejected the use of tree rings to establish the date when a purported witness tree was marked with an identifying blaze. Bland did not believe that there was enough scientific evidence or legal precedent to support this idea. A review of the current scientific literature of the time, however, indicates that most scientists, especially in Europe, accepted that tree rings could be used to determine age. In the United States, however, this idea was debated, particularly in the late 19th Century, in both the popular press and scientific publications. The main argument of opponents such as A. L. Child was that the number of tree rings was often wildly in excess of the known age of the tree. These inconsistencies were likely because of the inexperience of the observer, mistaking earlywood and latewood for separate rings, and the presence of a small number of false rings, sometimes called secondary rings. The great ages reported for the giant sequoias may have also raised doubts among the public. Among scientists, however, the relationship between ring number and tree age and between ring width and climate became widely accepted. Several cases heard in both Federal and State Courts as well as Bernhard E. Fernow’s Age of Trees and Time of Blazing Determined by Annual Rings laid to rest any doubt of the relationship between tree rings and age in temperate forests, i.e. one ring equals one year’s growth, and showed that the date when a witness tree was blazed could be easily determined from a cross-section of the trunk.