UA Tree Ring Lab Tour
Dendrochronology Lab Tour November 2018
Cameron Becker, Cohort 2
On Saturday November 17, seven Arizona Master Naturalists took a tour of the University of Arizona Bannister Tree Ring Laboratory organized by the Advanced Training Committee. The Naturalists gathered in front of the (relatively) new building at 10am and were met there by the Laboratories Lead Docent, Randall Smith. Before even entering the Lab Mr. Smith proved to be a wealth of knowledge on a wide variety of topics. For example he informed us that the Lab actually consists of two entities, the Laboratory itself and the Archive, which have both been in the new facility for five years now. Named after the former Director, Bryant Bannister, the exterior of the building is surrounded by steel tubes which are meant to move slightly and resemble quaking Aspen leaves. The tubes originally moved more than they do now but were restricted after finding out that the noise they created was so loud it caused people in the building to be sick. Mr. Smith also informed us that he is a bit of a naturalist himself as he makes observations for Natures Notebook of two plants in the Krutch Garden on campus (a Jojoba and Wolfberry if you were curious!)
As we entered the front room of the building we were greeted by a massive ‘tree cookie’ cut from a giant sequoia tree from Sequoia National Park in 1931. Dr. A. E. Douglass, who founded the Tree Ring Lab and the science of dendrochronology, was originally looking for a connection between solar activity, specifically sunspots, which have a 22-year cycle pattern to another natural cycle measurement on earth. Ponderosa Pine rings are the easiest tree rings to read and within 15 years of work Douglass had used 7,500 samples to create a master chronology. Many other fields of have made connections with the use of dendrochronology such as research in archaeology, fire ecology, as well as in the study of climate and precipitation trends. Geologists and physicist on the Universities campus use dendrochronology to calibrate their carbon 14 dating machines. Dendrochronology has also been used for less obvious fields including to help solve murder cases and determine the providence of musical instruments.
Mr. Smith gave us a presentation in their conference room passing around samples of tree rings ‘cookies’ and explaining some of the work that is done in the building. The last part of the tour was a visit to the labs on the third floor which smelled amazing from all the different sections of wood stored there. We were able to see the workspace of scientists actively working on a historic harbor site found in Istanbul called ‘Yenikapi harbor’ as well as samples from the site. Some of the wood piers found at the archaeological site were sent across the world to this lab for analysis. They have determined that some of the wood is from oaks outside of Turkey and the scientists are using the data collected to piece together ancient trade routes with connections to Northern Africa, Morocco and the Balkans.
The Bannister Tree Ring Laboratory is a truly unique gem that we have here in Tucson. It has widespread connections throughout our community and provides a wealth of knowledge about our world and a connection to our local history and sense of place. A big thank you to Randall Smith for the tour and the huge amount of knowledge he conveyed to our group. Looking forward to visiting again soon!
Pima Master Naturalists 
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