October 2012 Archives
In today's class, we'll start out final exercise, which will introduce you to an industry-standard software tool used to extract environmental signals from tree-ring data.
To get ready for our exercise, first download a copy of the program 'ARTSTAN' from the software page at the Lamont-Doherty Tree-Ring Program.
Second, you should also download a copy of the Dendrochronological Program Library (DPL), which we may need for our work on Thursday.
For Mac users running OX X Lion or later, download the most recent version of ARSTAN and the DPL from the Lamont Lab's FTP site:
Third, download a copy of the ARSTAN manual (arstan_description.pdf).
Overview In this exercise, you'll use Google Earth to examine the global network of tree-ring data. We'll review the geographic distribution of tree-ring records and discuss why tree-ring data are common in some regions and rare in others (or completely absent). This assignment will help you understand why there are geographic biases in the application of tree-ring research and identify frontier regions for future research.
Useful resources Google Earth is available as a free download at http://www.google.com/earth/ index.html. The International Tree-Ring Data Bank is maintained by the NOAA Paleoclimatology Program and the World Data Center for Paleoclimatology at http://www.ncdc.noaa.gov/paleo/ treering.html.
Instructions for exercise: PDF
I need to tweak the schedule for lectures a little bit to make up for the time we lost 2 weeks ago. On Tuesday (October 23), we'll discuss the history of dendrochronology, so in preparation, I'd like you to review two papers from our reading list:
Shulman (1954), Longevity under adversity in conifers. Science 119, 396-399.
Pederson (2010), External characteristics of old trees in the Eastern Deciduous Forest. Natural Areas Journal 30, 396-407.
As luck would have it, Aeon Magazine just published a great story about the ancient bristlecone pines and their role in the development of dendrchronology. It's a really interesting read, so you should check that out too.
I won't forget the first time I saw one of these erect tree-corpses, leering at me like a scarecrow beside the snow-covered road. The tree's exposed wood had aged into rich tones of gold and copper, and it seemed to leap out of the rock like a petrified flame.
Overview In this exercise, you learn how to use an industry-standard software application to confirm visual cross-dating through statistical measures of similarity or dissimilarity. We'll use the program COFECHA to assess the quality of cross-dating in one set of tree-ring width measurements and to identify potential dating errors in another set.
Instructions for exercise [PDF]
Ring-width measurements for Cat Mesa, New Mexico: [RWL]
Ring-width measurements for another ring-width record from NM: [RWL]
The set of 'problematic' ring-width measurements: [RWL]
Due Please submit a written (typed) response to both sets of questions from Part One and Part 2 at the beginning of class on Thursday, October 11. We'll discuss your findings in class on October 18 ('Sampling strategies').