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Geography 423/523: Advanced Biogeography
Dendrochronology (tree-ring analysis) is the study of
historical patterns of tree growth for the purposes of dating events,
reconstructing past climate, and various other objectives. |
Required
Texts:
Speer, J.H. 2010. Fundamentals of
Tree-Ring Research. The University of Arizona Press.
Mainly for Geog 523: Dendroclimatology. Edited by Malcolm Hughes, Thomas Swetnam, and Henry Diaz. Available freely at: http://www.springerlink.com/content/ 978-1-4020-4010-8/contents/ |
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Trees occurring in seasonal climates are one of the few groups of organisms that preserve an annual growth record within their tissues. The records contained in tree rings are an invaluable source of information of past events: climatic events (including patterns in rainfall, temperature, glacier movement, and river discharge), disturbances to forests, and ages of buildings, archeological sites, and furniture. Acquiring and using tree-ring data requires special knowledge and tools. Topics covered will include the basics of wood anatomy and the structure of trees, methods (field, laboratory, and statistical), and overview of some of the most interesting findings of tree-ring research. A major portion of the course will be an individual research project, requiring significant out-of-class time. You will gain experience with tree-ring analysis, but more importantly, you will design and execute all parts of a research project. See below for details. Prerequisites: Geog 323, or permission of the instructor. For permission, contact me by email and list relevant course experience including courses in geography, math and biological sciences. Previous experience summarizing data and preparing data graphics will be an asset. Further information on the field of dendrochronology is available on the Ultimate Tree-Ring Web Pages. Grading will be based on:
Standard stuff here: During lecture please be respectful of everyone's learning experience. This includes:
NOTES AND DETAILED EXPLANATIONS regarding the research project: Your project may be conducted in pairs or individually. Each approach has advanatages and disadvantages which I probably do not need to explain here. Groups: you can collect and analyze more data, reach stronger conclusions and write different parts of the project up. However, I expect much more detail and reports twice as long as individual projects, so this means much more thoroughness in each section of the report. Individually, you will be limited by what a single person can do, but will have less coordination/difficulty in your project design. Your project may be conducted at the site of the field trip, or you may go elsewhere. The field trip is an excellent way to get your cores, because there will be enough people there to help with coring and deal with difficulties like stuck increment borers. This site will be an old Douglas-fir forest (~350 years old) with patches of bigleaf maple and an understory of shade tolerant western hemlock with cedars of various sizes and ages mixed in. There will large snags from individual tree deaths. There may be a stream within the site, as well. One rule with conducting research is that when you find a research topic and goal, you have to devise the way to get the best (and most) data to (help) answer the question. For this project, you must purposely limit your sample size so that your are not spending all of your time collecting data, but can work through other parts of the project. A second common rule is that research is a frustrating, extremely open-ended process, and that portions of the work are quite tedious. After your first three hours behind a microscope counting tree rings, you will realize that to be the case! Many people are driven away from research science because of this tedium, even though they have a great mind for science. I expect the projects in this class to be a simulation of a large research project. Your sample sizes are smaller nor will you have the time to do analyze everything that you do collect. Thus, there will be a deadline for your data sets well before the due date for the overall project. As with any science, one has to draw a line on when further data collection will not help answer the question, and it is time to start analyzing the numbers. For your project, your final data set is a cross-dated set of measured tree cores. Crossdating is supposed to be objective: a core is either properly dated or it isn’t. There is software that can help verify your dating. In reality, it is often not so clear if a core is dated correctly or not. It is totally fine if your cores are not all correctly crossdated. As long as you have made a good effort, found some common narrow rings, seen which cores fit the pattern and maybe remove some cores that refuse to crossdate. You can help each other through the process of cross-dating. There will be many tutorials on this at different times in the class. Class presentation (last week) We have two full class meetings for all of the presentations. I want these to be about 10-15 minute presentations of your results to date (your final paper is due later). People working as pairs should make a longer presentation. You can expect to get feedback from me at this time that will help you write your paper. This presentation is only 10% of your grade. The presentation should provide (at a minimum) 1) an introduction to your research question and predictions of what you expect to find and why you expect to find it (use text slides) 2) describe your study site, species and number of trees cored. 3) lab methods, what you found during the lab work (crossdating issues, for example) 4) graphs of the data summarized in ways that you think are meaningful to address your question. The final research paper requires an intro, methods, results, discussion (the typical science paper format as seen in many of the class readings). The length of the final paper should be at least 10 pages of double-spaced times new roman font, to describe everything, and include a discussion where you speculate on some of the causes of the patterns that you find. There should also be several pages of graphs. If you are working in pairs, you must each write two of the four sections (indicate the author of each section in the final paper), and the total paper must be 18 pages long. There is also this nice guide to the scientific paper format I strongly suggest reading: http://abacus.bates.edu/~ganderso/biology/resources/writing/HTWsections.html The only way your papers diverge from this guide is in that you are not doing “experiments” in the strict sense (OK, comparing sites may be somewhat of an experimental design, but in general retrospective studies like this are “natural experiments”. The words to use rather than “experiment” are “survey the growth of trees”, “examine patterns of growth to test the hypothesis that…”, etc. Some topics of students in years past: 1. Growth-climate relationship: differences between young trees and old trees (why might they differ?) 2. Growth of trees around canopy gaps (single tree falls) in old growth forest (which species responds best?) 3. Tree growth in riparian trees; relation to streamflow. 4. Early-wood width vs. late-wood width in Douglas-fir; why might the proportion of ring that is late wood vary among sites? 5. History of remnant oaks in Douglas-fir stands surrounding Eugene...what's the history of these stands? Department of Geography, University of Oregon Modified Apr 5, 2011 ![]() |
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