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Ready, Set, SCIENCE!, by the National Research Council, focuses on K-8 science classsrooms. Check out the other publications in our online store, as well as classroom materials.

# "Build a Tree" Dendrochronology Activity

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

Select a temperature range (Normal, Cool, or Warm) and a precipitation amount (Normal, Dry, or Wet) for the coming year. Click the "Add Yearly Growth" button. The tree (which you are viewing a cross-section of the trunk of) grows one year's worth, adding a new ring.

Add some rings while varying the temperature and precipitation. Which of these factors has a stronger influence on the growth of the type of tree being modeled here?

Use the "Reset" button to start over.

The "Show Specimen Tree" button displays a section of an "actual" tree specimen. Can you model the annual climate during each year of the specimen tree's life, matching your diagram with the specimen, to determine the climate history "written" in the rings of the specimen tree? (The "answer" is listed below, lower down on this page).

### Some Limitations of this Tree Ring Model

 Real tree rings are much messier than the ones in this simulation, but the same principles apply. Credit: UCAR

"All models are wrong... some models are useful." - George E.P. Box

• Real tree ring cross-sections are not so nice and 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 really like warm conditions, while others are happiest 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"; our model starts right in with the first annual ring instead.

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

Please refer to our Changing Planet: Survival of Trees Classroom Activity and Video for more on tree rings.

#### Shop Windows to the Universe Science Store!

The Winter 2009 issue of The Earth Scientist, focuses on Earth System science, including articles on student inquiry, differentiated instruction, geomorphic concepts, the rock cycle, and much more!

## Cool It! Game

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## Climate Change Teacher Resources

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## Earth's Greenhouse Gases

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## Space Missions to study Earth's Atmosphere & Climate

Television weather forecasts in the space age routinely feature satellite views of cloud cover. Cameras and other instruments on spacecraft provide many types of valuable data about Earth's atmosphere...more

## Modeling the Future of Climate Change

Predicting how our climate will change in the next century or beyond requires tools for assessing how planet responds to change. Global climate models, which are run on some of the world's fastest supercomputers,...more

## Effects of Climate Change Today

The world's surface air temperature increased an average of 0.6° Celsius (1.1°F) during the last century according to the Intergovernmental Panel on Climate Change (IPCC). This may not sound like very...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information.