Reflected-Light Image Analysis in Dendrochronology

The basis for applying reflected-light image analysis to measurement of conifer tree rings is as follows: surface brightness is directly related to the cell lumen:wall ratio, which is inversely related to ring density, which is then inversely related to surface brightness.  Thus, ring brightness variables may be easily measured and then analyzed dendrochronologically as ring density.

components of reflected-light image analysis system Image-Analysis System: Here are the components, which are all standard off-the-shelf items, of my reflected-light image analysis system.  The tree-ring sample is an increment core or cross-section as used normally in dendrochronology.  The sample is illuminated with plain white light, which is reflected diffusely back to the microscope, which focusses the image to the ccd video camera.  Commercial software on the computer processes the image, which is displayed on a monitor for the user to see and measure.  Other specialized software converts images to data files typically used by other dendrochronological programs.
picture of two conifer rings with associated brightness scanImage with Brightness Scan: The brightness scan (top) is a composite of all radial files within each ring (below) without effects of blemishes such as resin ducts.  Ring boundaries and earlywood-latewood boundaries are determined computationally and verifiable by the system user.  Ring 1 has dark (dense) latewood and a low minimum latewood brightness value, while Ring 2 has lighter (less dense) latewood and a higher minimum latewood brightness value.  This approach also provides other brightness variables (marked on scan for Ring 2) and the usual width variables, as well as odder variables such as area beneath the scan (marked for Ring 2).

Sheppard, P.R. and L.J. Graumlich. 1996. A reflected-light video imaging system for tree-ring analysis of conifers. Pp. 879-889 in Proceedings of the 1994 International Conference on Tree Rings, Environment, and Humanity (Tucson, AZ), J.S. Dean, D.M. Meko, and T.W. Swetnam, editors. Tucson: Radiocarbon, Department of Geosciences, The University of Arizona.

Sheppard, P.R., L.J. Graumlich, and L.E. Conkey. 1996. Reflected-light image analysis of conifer rings for reconstructing climate. The Holocene 6(1):62-68.

Paul R. Sheppard 
Laboratory of Tree-Ring Research 
The University of Arizona 
Tucson, AZ 85721 USA
office: (520) 621-6474
fax: (520) 621-8229
Revised -- October 1, 1997; Copyright © ±1997, Paul R. Sheppard
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