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:
All three samples above have exactly the same pattern of variation
Top sample has a growth rate less than that of the middle sample
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
:
There will be a vertical blue line marking the middle of your screen, as on the right
Put the ring that you wish to see better at the blue line
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
Comments to:
sheppard@ltrr.arizona.edu
Copyright © 1998, Laboratory of Tree-Ring Research, The University of Arizona
Revised -- December, 1998
URL:
http://tree.ltrr.arizona.edu/skeletonplot/relativescale.htm