Southern Red Cedar tape-drag error   Jess Riddle
  Jan 08, 2006 11:14 PST 


Over the holidays I attended a friend's wedding on St. Simons Island
on the Georgia coast. To my surprise, I recognized the chapel
grounds. The avenue of Spanish moss draped live oaks could be found
at many sites along the coast, but the presence of the state champion
southern red cedar (Juniperus silicicola) confirmed the site as the
one I remembered.   The tree's massive spreading limbs produce a
memorable image and support a broad crown with an undulating upper
surface, similar to the adjacent Intercoastal Waterway on a rough day.
That structure produces many tops of similar height, and several of
those tops are laterally greatly displaced from the base, a leading
cause of height errors. Contrastingly, the site offers excellent
measuring conditions; the ground is flat, and the open grounds offer
completely unobscured views of the crown from multiple directions.
While the tree definitely has a single stem, the branches emerge low
enough to swell the trunk at 4.5', another source of potential error.

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Georgia Champion Southern Red Cedar 16'5" circumference at three feet above ground, 41.7' tall.

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Georgia Champion Southern Red Cedar 16'5" circumference at three feet above ground, 41.7' tall. Previously measured as being 52' tall.

A plaque beside the tree states a local garden club (?) now looks
after the tree's health, and declares the southern red cedar the
second largest in the state and second largest in the country. The
national champion in Florida has only slightly more points, but the
tree remains on the Georgia list as the state champion. The plaque
also indicates the tree has been measured by foresters three times:
first in 1976, once in the 1980's, and most recently in 2004. The
dimensions listed on the plaque, presumably from the most recent
measurement, are 16.6' circumference, height 52', and spread 80'.
Measuring at the 3' high waist, I got a circumference of 16'5", pretty
close. However, the highest live top I could find was 41.1', and a
recently killed top was 41.7'. Another top a foot higher might be
hiding within the crown, but the height certainly does not approach

epworthc.jpg (544807 bytes)
At the same site, a 4'9" cbh grape vine growing on a live oak.

Even under these good conditions, purported experts failed to
measure the tree's height accurately. A tape and clinometer certainly
could have been used to accurately measure the tree's height; if the
position on the ground below the high point were located, dragging the
tape from that point would have yielded an accurate height.   This
situation is another example showing that for a clinomter to enable
accurate height measurements is not a sufficient condition for
accurate height measurements. In broad usage, people cannot be
assumed to use them correctly.

Jess Riddle