# Relative Scale of Skeleton Plots

Trees living within a homogeneous stand or forest:
• Usually exhibit the same relative pattern of growth variation through time, BUT
• Often have absolute growth rates that differ substantially due to living in different microsites:
• Difficult to compare the ring-growth variation of two or more specimens from actual wood samples
• For example, see figure:

1. All three samples above have exactly the same pattern of variation
2. Top sample has a growth rate less than that of the middle sample
3. Middle sample has a growth rate less than that of the bottom sample
Problem: Because of different growth rates, it's impossible to align the common pattern of variation using the actual wood samples

Solution: Dendrochronologists can make skeleton plots to standardize scales:
• Represent growth variation of samples onto separate strips of graph paper
• Equalize the absolute scales ring growth
• Easily compare growth variation of two or more specimens
Note the three skeleton plots of the figure above:
• Have the same relative scale
• Easy to compare to one another
• Clearly show the same pattern of variation of each sample:
When you try skeleton plotting for yourself, you can move the virtual core left and right:

<==== Move core left or right ====>
• Put the cursor anywhere on the core above
• Click and hold the mouse button
• Move the mouse left or right
• Don't worry that the core goes off the edges -- it always comes back!

Note: The virtual core comes with every 10th ring prenumbered -- which won't be true in real life, so number your wood carefully!

When you try skeleton plotting for yourself, you can change the scales of the graphics:
• There will be magnification circle buttons, as on the left
• You may enlarge or reduce the virtual core to see rings better
• Choose between 1x, 2x, or 3x
• Hint for magnifying a ring:
1. There will be a vertical blue line marking the middle of your screen, as on the right
2. Put the ring that you wish to see better at the blue line
3. Then magnify -- at 3x magnification, narrow rings are apparent
• You may also enlarge or reduce the graphs
• Choose between Large, Medium, and Small

Previous Page | Next Page
Introduction | Dendrochronology Applications | Crossdating Application | Ring-Growth Anomalies
Sensitivity-Complacency | Skeleton Plotting | Relative Scale | Master Chronology
Pattern Matching | Finding the Dates | Absent/False Rings | Try Skeleton Plotting for Yourself!
Laboratory of Tree-Ring Research

Paul R. Sheppard
Laboratory of Tree-Ring Research, The University of Arizona
Tucson, Arizona 85721 USA
office: (520) 621-6474, fax: (520) 621-8229