Oldest Trees, Tree Rings, Past Climate, Oak Trees, Dendrochronology
Tree-ring analysis revealed 33 living white oaks (Quercus alba) in Iowa that began growing before 1700. We analyzed cores of wood 4 mm in diameter, each extracted from a radius of a tree trunk. The oldest white oak, found in northeastern Warren County, began growing about 1570 and is thus over 410 years old. We also found a chinkapin oak (Quercus muehlenbergii) over 300 years old. Ring widths from the white oaks are well correlated with total precipitation for the twelve months preceding completion of ring formation in July. Reconstructions of annual (August-July) precipitation for 1680-1979, based on the tree rings, indicate that the driest annual period in Iowa was August 1799-July 1800, and that the driest decade began about 1816. Climatic information of this kind, pre-dating written weather records, can be used to augment those records and provide a longer baseline of information for use by climatologists and hydrologic planners.
Proceedings of the Iowa Academy of Science
© Copyright 1983 by the Iowa Academy of Science, Inc.
Duvick, Daniel N. and Blasing, T. J.
"Iowa's Oldest Oaks,"
Proceedings of the Iowa Academy of Science: Vol. 90:
, Article 9.
Available at: http://scholarworks.uni.edu/pias/vol90/iss1/9