"Build a Tree" Dendrochronology Activity

"Build a Tree" Dendrochronology Activity

The interactive diagram below demonstrates a very simple model of tree ring growth.

  1. Select This Year's Temperature (Cool, Normal or Warm) and This Year's Precipitation (Dry, Normal or Wet).
  2. Next, click the Add Yearly Growth button.
  3. A cross-section of your tree's trunk will appear, simulating the first year of growth of your virtual tree.
  4. Repeat these steps to add more rings to the cross-section while varying the temperature and precipitation.

Which of these factors has a stronger influence on the growth of this tree?

  • Use the New Game button to start over.
  • The Show Specimen Tree button displays a cross-section of an "actual" tree.

Try to figure out how temperature and precipitation varied during each year of this tree's life by selecting the correct temperature and precipitation to match your diagram with the specimen (The "answer" is listed near the bottom of this page).

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Click here to download a copy of the Tree Rings software. (On a Windows PC, right-click on the link, then "Save as..." to save the file to your local hard drive; on a Macintosh computer, hold down the Control key while clicking the link, then "Save as...")

This interactive was built using Flash, so you will need the Flash plugin from Adobe installed in your browser to view the interactive.

Some Limitations of this Tree Ring Model

Photo of Tree Rings"All models are wrong... some models are useful." - George E.P. Box

  • Real tree ring cross-sections are not perfectly circular (and centered), or even symmetric, like the ones in this model.
  • Different types of trees have different responses in their growth rates to temperature and precipitation. Some thrive in warm conditions, while others grow quickly when it is especially wet.
  • Other variables (besides temperature and precipitation) influence growth rates of trees.
  • Real trees have a central section called the "pith"; this model starts right in with the first annual ring instead.

The Answer: Climate History of the Specimen Tree in the Interactive

The annual climate sequence for the "specimen" tree in the interactive model, starting with the tree's first year of its 15-year life, is:

  1. normal & normal (temperature & precipitation)
  2. warm & normal
  3. normal & normal
  4. warm & normal
  5. warm & dry
  6. warm & dry
  7. normal & dry
  8. normal & normal
  9. warm & normal
  10. normal & normal
  11. cool & wet
  12. normal & normal
  13. warm & normal
  14. warm & wet
  15. warm & wet
© 2005 UCAR