image of tree rings

Geography 423/523: Advanced Biogeography
Topic for Spring 2011: Dendrochronology

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.

Meeting times: Tuesday and Thursdays 10:00-11:20 in 206 Condon.

Instructor: Daniel Gavin (dgavin@uoregon.edu)
GTF: Ian David Crickmore (crickmor@uoregon.edu)
Office: 110 Condon Hall; Phone: 346-5787
Office Hours: 3-4 Wednesdays in 110 Condon

Photos from old growth fieldwork on April 16!


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/

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:
  • Two exams (20%, 20%).  The first exam is in-class.  The second exam is a take-home exam (24 hours) and is not very long.
  • An individual research project, involving all the major steps of conducting a research project (50%).  Please see below the schedule for a detailed description of the project.
    • Devising a research question
    • Developing sampling methods
    • Conducting field sampling and laboratory analyses
    • Analyzing results using the proper data graphics and statistics
    • Writing a research paper (Introduction, Methods, Results, Discussion)
    • Students enrolled in Geog 523 will be required to analyze their results using sophisticated statistical methods and write a report using the primary scientific literature.  Students in Geog 423 will also be required to conduct statistical analyses and write a scientific report, but expectations for using the primary literature and the level of statistical analysis will be lower.
    • Grade broken down as follows: 
      • Assessment of consistent progress through course (meets three due dates for project development: 15%)
      • Quality of data collection and analysis (25%)
      • Clarity of writing and presentation of research question (30%)
      • Background research: presenting the context for your question and the connection of your results with other studies (30 %)
  • A 10-minute in-class presentation of your research findings & class participation. (10%)
Each student will be responsible for organizing field work and collecting data for their projects.  I encourage you to work in groups for this part of the project, so that you are in the field collecting data together.  Cores collected for one project may be used for another project if the sampling designs permit such sharing. However, everyone will be working on their own project with unique research questions.  

  • These steps must be completed through the term to make adequate progress on your project.  Turn in hard-copy versions of each of these:
    1. Initial project idea, due April 7th.  This should be a note that contains a questionthat you wish to address in your project (i.e., phrase it as a question).  A few rules:  First, a good question is succinct and addresses a process, not just a simple fact.  Second, a good question is not so broad it is unanswerable, and you have the constraint that you have limited amount of time to do all parts of the project.  Easily obtainable data are 1) the ages of a common forest tree, and/or 2) growth rates of those trees.  Many good, workable, questions involve forest dynamics, including canopy gap dynamics.  I won't list any here to leave the full spectrum of possible topics untouched!  Also, include a few sentences on where sampling will occur and sample size.  I will provide feedback within a few days.
    2. Final project idea, due Apr 14th.  Same as above.  However, also include a few sentences on how the data will be analyzed.  I will again provide feedback.  If you want to work outside of the field trip area (old growth Douglas-fir forest), you should obtain permission from landowners or managers for coring and obtain cores as soon as possible.
    3. Project data summaries, due May 21st.  A list of 1) trees and core samples taken, and 2) cross-dating results (COFECHA output).  Any other ancillary information would be appreciated.
You will also be responsible for obtaining access and permission for working on the lands you wish to sample. Prof. Gavin will have some suggestions on where to begin.

Standard stuff here: During lecture please be respectful of everyone's learning experience.  This includes:
  1. No talking amongst each other.  Please leave your social conversations for outside the classroom.  However, questions during lectures are encouraged.  If you have a question, raise your hand or catch me after class.
  2. Please don't leave in the middle of lecture. It is distracting for many people, including me. If you need to leave, then let me know before the lecture starts, then sit near an exit.
  3. Do not have your laptop open to surf the web.  Note-taking on laptops is OK.
  4. Cheating.  Cheating, such as copying material from other students on tests, will result in failing the test at a minimum and I will pass the information on to the Dean of Students.  In serious cases, you will flunk the class or be expelled from the university.
  5. Plagiarizing.  Plagiarizing occurs when you copy materials from other sources without citing the source (i.e., taking credit for someone else’s work), or copy someone else’s lab.  All students should be familiar with the material in this guide on avoiding plagiarism.
All readings are mandatory.  Many lectures will have a lab component to be done in 217 Pacific.  These are listed in parentheses.
Week Date Topic Readings (NOT FINAL!).
1 Mar 29
Overview of the course.  What are tree-rings? Speer Chapter 1
Mar 31
A survey of applications of tree-ring analysis.
Speer Chapter 2
Apr 3 (Sunday) Coring field trip, western Cascades. 12-4 Phipps
2 Apr 5
A brief history of the use of tree-ring analysis  (Core mounting)
Speer Chapter 3
Apr 7
Tree-ring anatomy – softwoods & hardwoods (Surface prep and ring counting)
Due: initial project idea
Speer Chapter 4
Hoadley 1-16; 20-22; 28-34
3 Apr 12
Site selection
Pattern recognition and crossdating (Crossdating practice)
Graph paper for skeleton plots
Schweingruber
Stokes 47-57
Yamaguchi
Apr 14
Tree growth dynamics I (Crossdating practice)
Due: final project idea
Kozlowski 1-30
April 16 All day field trip to collect project data, western Cascades.
4 Apr 19 Tree growth dynamics II (measurement using a slide micrometer)
Apr 21 Tree growth dynamics III
Crossdating: statistics (in class: using COFECHA)
Note: Your cores should be glued and sanded by April 26th
COFECHA manual
also this link
5 Apr 26
Lab day in Pacific 217 (crossdating your cores)

Apr 28
Standardization and climate reconstruction (guest lecture by Aquila Flower) Cook 97-108 (?)
6 May 3
Exam I 
May 5
Climate reconstruction II (in class: using ARSTAN and/or dplR) Hughes
7 May 10 Dendroclimatology applications: drought and streamflow Cook
Woodhouse
May 12
Dendroecology – forest dynamics Poage and Tappeiner
8 May 17
Dendroecology – insect outbreaks / tree-line dynamics Swetnam: GTR report
Lloyd and Fastie
May 19
Dendroecology – air pollution, forest declines
Due: project data summaries
Gavin
9 May 24
Dendroecology – fire history
Dendrogeomorphology – glacier fluctuations, fluvial processes
Swetnam: PAGES newsletter
Wiles
May 26
Exam 2 (take-home exam)
10 May 31
Project presentations
Jun 1
Project presentations
Jun 8 Project reports due

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
Document made with Nvu