Measuring Notable Trees
The Connecticut Botanical Society uses a tree measurement system that produces a single score, which we call points. This champion tree points system was developed as part of the National Champion Tree Program, launched in 1940 by the American Forestry Association (now American Forests) and now administered by the University of Tennessee, Knoxville.
The formula adds together:
- +Trunk circumference at 4.5 ft above ground (inches)
- +Tree height (feet)
- +¼ of the average canopy spread (feet)
Circumference
With a tape measure, find the circumference (not diameter) at 4 feet 6 inches above ground level. If the tree is growing on a slope, measure from the center of the slope. If branches begin to swell the trunk at or below 4.5 feet, measure the smallest circumference below that point. If the tree is multiple-stemmed and forks above ground, measure the smallest circumference below the fork and also measure each stem at 4.5 feet. If multi-stemmed into the ground, measure each stem separately. Convert feet and inches to inches for the calculation.
Height
We do not use estimates for trees which are contenders for largest of their kind. Most measurements have been done with a clinometer, accurate to one or two feet in 100. This device is held in the hand while the treetop is sighted through it; a scale gives height in feet when you are exactly 100 feet from a point directly below the sighted branch. Various optical and electronic instruments are also available for measuring heights. Use the height in feet for the calculation.
Average Spread
Measure the greatest branch spread from one side of the canopy to the other. Then measure a second spread perpendicular (90°) to the first. Average the two measurements and divide by 4 for the points calculation.
Reporting Notable Trees
Information about potentially notable trees in Connecticut can be sent to notabletrees@conncoll.edu or by mail to:
Connecticut College Arboretum
270 Mohegan Avenue
New London, CT 06320
Please include the name of the tree if at all possible, the circumference at 4.5 feet above ground, and the name, phone number, and address of someone who can show us the tree if we decide it merits a complete measurement.