Dr. Nicole Davi
Originally presented 13 Dec 2003
(revised 2017)
Introductory Presentation by Dr. Michael J. Passow
View the introductory slideshow for this workshop
Today’s program marks the first time Earth2Class has presented the work of the Tree Ring Laboratory, one of the world’s premiere groups of dendrochronologists (which is one of the finest sesquipedalian terms ever coined!) Trees provide excellent records of changes in climate and other environmental variable, and we hope that the introductory PowerPoint and Nicole Davi’s talk will stimulate your understanding of this interesting and useful branch of science.
Also be sure to check out some of the educational activities suggested in the web sites linked through the “Resources” section.
Science Content
View Nicole Davi’s Presentation
Year to year changes in environmental conditions cause characteristics of the annual growth rings to also vary from year to year. So, a stand of trees growing in desert conditions (xeric) produce a narrower ring during dryer years. Similarly, these same trees will produce wider rings during wet years. Trees growing near upper timberline (or the latitudinal treeline), where there is generally ample moisture for tree growth but where conditions tend to be colder, are subject to temperature stresses. So, during warm years the trees will produce wide rings and during cold years will produce narrower. Scientists at the Tree-Ring Lab study annual growth rings of old trees to learn about past environmental changes. By combining living and dead wood scientists can extend tree-ring paleoclimate records back hundreds to thousands of years.
This talk will focus on a network of tree-ring sites developed to extend and better evaluate regional-scale climate variability in the Wrangell Mountain region of Alaska. Development of a network of well-replicated long-term paleoclimatic records will help define regional climate and put recent regional environmental change into long-term context.
Our tree-ring records show that the twentieth century is the warmest of the past four centuries and that several of the coldest years reconstructed coincide with major volcanic eruptions. The network is also correlated positively with both reconstructed and recorded Northern Hemisphere temperatures and is consistent with well-dated glacier fluctuations in the Wrangell Mountains.
Resources
Here are selected web sites about tree ring studies suggested by Nicole Davi:
http://web.utk.edu/~grissino/resources.htm#Educ
http://www.pbs.org/wgbh/nova/vikings/treering.html
http://ny.usgs.gov/pubs/fs/fs05797/html2/FS057-97.html
http://www.ltrr.arizona.edu/lorim/lori.html
http://www.ngdc.noaa.gov/paleo/education.html
http://www.pbs.org/wgbh/nova/teachers/activities/2817_methusel_01.html
http://dendrochronology.net/introduction.asp#
http://www.lessonplanspage.com/ScienceSSMyLifeAsATree-RingsBarkCambiumHeartwoodK4.htm
A related interesting story involving dendrochronology, Lamont research, and famous violins can be found at
http://www.earth.columbia.edu/news/2003/story12-03-03.html
Climatic conditions in the late 17th-early 18th century revealed through the study of tree rings may have be critical to the tonal qualities of instruments created by Stradivarius and Amati in Cremona.