tree coring

The quest for the oldest trees at Kendal at Oberlin.

On March 1, 2023, Roger Laushman, Professor of Biology at Oberlin College and Conservatory, led a group of Kendal residents and staff at a tree coring workshop. An increment borer was used to remove a sample from three trees, a black walnut (Juglans nigra, Bartram Arboretum ID = 899, near the old construction entrance), a shagbark hickory (Carya ovata, shown in video, shown in video) and a burr oak (Quercus macrocarpa). The core from the hickory is shown in the inset. The oak and the hickory are in the forested area in the southeast corner of the Kendal campus and not included in the tree inventory (approximate location in image).

A specialized tool, called an increment borer, is required. After removal of some bark, the beeswax-lubricated auger is aimed at the center or pith of the tree. Clockwise turning of the borer advances the tool to the desired depth. The extractor tray removes the sample that is placed in a straw for safety and transportation. The freshly extracted hickory core is shown. After the core is dried and sanded, tree rings can be counted to determine the age of the tree. A variety of other examinations can be performed to further characterize the sample as discussed in Valerie Trouet’s book,Tree Story The process does not damage the tree and has been used safely on many of the world’s oldest and most important trees. The clicking sound comes from the tree itself. Spectral characteristics of the sound differ among species.

increment borer