Part 1: Exploring the Humpty Dumpty Talus Slope

In Part 1, students go on a virtual expedition to study drought in the Hudson Valley using the same tools and analysis procedures as tree ring scientists. They explore the Humpty Dumpty talus slope site with Google Maps and learn about the importance of picking study sites where the ecology of the site shows that the trees will be sensitive to climate.

Part 2: Coring Trees and Observing Ring Patterns

In Part 2, students learn to evaluate patterns in tree-ring records by observing and comparing core samples. Then they re-evaluate their data to identify marker years and determine when periods of drought existed in the Hudson Valley region.

Part 3: Gathering Historic Drought Data

In Part 3, students use Climate Explorer, a powerful online tool, to map and evaluate recorded meteorological data. They then confirm that tree-rings are recording climate information by comparing their analysis of tree-ring data and observations of 'marker years' in Part 2 to the recorded data from Climate Explorer from the same year.

Part 4: Meet the Challenge

• Student Activity Sheet for Lab 2 - (PDF (Acrobat (PDF) 43kB Oct9 17))(Word (Microsoft Word 2007 (.docx) 78kB Oct9 17));
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• Excel spreadsheet for Part 2 (Excel 2007 (.xlsx) 34kB May19 17)
• Part 2 Tree Ring Analysis Answer Key -
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• Sample graphs and Teacher Notes for Part 3 - PDF (Acrobat (PDF) 501kB Jun2 16)

General Recommendations:


• To add a hands-on component, consider purchasing a core apparatus (about $240) Forestry Suppliers. Visit The Ultimate Tree-Ring Webpages for tips, advice on cleaning kits for your core apparatus, and more information. In part 2 of the lab, take students to a site with some trees and have them take a sample core from a set of trees.
• Explore the function of the Climate Explorer website. Generate time series and seasonal graph for your local region to use as examples when students attempt Part 3 of the lab.
• Review Google Maps and how to measure if you are unfamiliar with the program. If students are unfamiliar with using the program, go over the basic navigation techniques and do a sample measurement on the Humpty Dumpty talus slope image.
• Students need to access Excel or similar spreadsheet software in Part 2. Use the table given in Printable Materials to prepare one in a suitable medium for students to work with.
• Download and read the Sample Graphs and Notes for Part 3 pdf file before students begin this part of the lab.
Facilitation Tips:

Part 1 - Exploring the Humpty Dumpty Talus Slope


• In Part 1, after students watch the Dr. Ed Cook video, have a class discussion and ask for responses to the Stop and Think questions instead of having students record them individually.
• When students begin taking measurements of the talus slope site, ask for some students to compare answers to establish that they are using the correct unit (feet) and are getting approximately the same values.
Part 2 - Coring Trees and Observing Ring Patterns


• Go over the example shown in the directions in step 3. It is important for students to just look at intervals of 15 to 20 years at a time when determining the narrowest and widest rings in a sample. They will normally choose too many candidates. Stress to students that they are looking for only the very narrowest and widest rings in their 15 to 20 year sample. If two or three rings are equally narrow, or equally wide, they should all be marked on the spreadsheet. This doesn't happen very often though.
• Consider having a discussion to answer the final Stop and Think question: What are the "marker" years that you have found in the samples? In other words, which years consistently stand out for being very narrow or wide compared to their neighbor. Discuss reasons for variation in their results. As a group, select the four most commonly found candidates, preferably two dry and two wet marker years to study in Part 3 of the lab.
Part 3 - Gathering Historical Drought Data


• Lead a discussion at the end of Part 3 and have students discuss how well their results from Part 2 matched the data gleaned from Climate Explorer. Were students surprised by the results?

Assessment Options:


• Assess student understanding of topics addressed in this investigation by grading their responses to the Stop and Think questions and Activity Sheets for Parts 1 - 3.
• Use the Challenge project as the final exam for the Lab. Two challenges are presented. You may choose to have all of your students do option 1 and choose their own area of interest to investigate using Climate Explorer. More advanced students may prefer option 2, an exercise that uses actual tree ring data from a site in Mongolia. Option 2 is the more rigorous project since students use Climate Explorer and analyze tree ring data to derive their results concerning paleoclimate in Mongolia. Consider offering bonus points for students who select this option. These Challenges can be done in class as a more formal assessment of students' skills or be assigned as a take home project to give them more time to complete them.

• Cook, E. R., and G. C. Jacoby, Jr., 1977. Tree-ring-drought relationships in the Hudson Valley, New York. Science 198:399–401. CrossRef, PubMed
• Cook, E. R., and G. C. Jacoby, Jr, 1979. Evidence for quasi-periodic July drought in the Hudson Valley, New York. Nature 282:390–392. CrossRef
• Cook ER, Meko DM, Stahle DW, . (1999) Drought reconstructions for the continental United States. Journal of Climate 12: 1145–1162
• Cook ER, 2014. The Early Day of Dendrochronology in the Hudson Valley of New York": Some Reminiscences and Reflections. Tree-Ring Research Volume 70, Issue 2, pg(s) 113.118 doi: 10.3959/1536-1098-70.2.113. Abstract here http://www.bioone.org/doi/abs/10.3959/1536-1098-70.2.113
• Science Magazine 2012 podcast with Ed Cook about megadroughts in Central Asia: http://www.sciencemag.org/cgi/content/full/sci;328/5977/486/DC2
• Pederson N, Bell AR, Cook ER, Lall U, Devineni N, Seager R, Eggleston K, and Vranes KP, 2013: Is an Epic Pluvial Masking the Water Insecurity of the Greater New York City Region?*,+. J. Climate, 26, 1339–1354. doi: http://dx.doi.org/10.1175/JCLI-D-11-00723.1