To measure a prospective champion, you will need
some basic tools. Below, you will find the accepted methods for measuring
trees. All measurements will be accepted, but they will need to be
verified before champion status will be given. The latest
measuring techniques can be found at the Eastern Native Tree Society website:
Valley Forge Park Hackberry
State Champion Southern Catalpa, Wycombe
Big Tree Formula
Circumference at breast height - Also known as CBH,
this measurement is made in inches at a point on the tree trunk, 4 1/2 feet above the ground.
If the tree is growing on a slope, the 4 1/2 feet is determined at
mid slope. This is the point halfway between the high and low
points where the trunk meets the soil. If the tree branches
under 4 1/2 feet (single pith at ground level), has abnormal swelling,
or a burl, the measurement is to be taken at the narrowest point below 4 1/2 feet,
and the height of measurement is to be noted. If a tree is multiple
stemmed, and they originate at ground level (several separate piths
at ground level) the largest stem is to be measured at 4 1/2 feet,
or above the co joined stems. One point is given for
each inch of circumference.
Height- The height of a tree is the distance from the
ground line at mid-slope of the tree trunk to the tallest part of the tree.
Height is often the
measurement that is calculated incorrectly. The most
common errors come from not being able to see the top of the tree,
mistaking the visible edge of the canopy as the top, and the top not being
directly over the base of the tree . Each can lead to height measurement errors.
information on this subject, please visit the Eastern Native Tree Society
ENTS methodology uses a laser range finder and clinometer to measure
tree height. Both of these most common problems are
avoided using the Eastern Native Tree Society laser/clinometer
methods. There are other less technological ways to get
an estimate close to the actual height of the tree. One method
and requires only a straight stick or yardstick and a tape.
First, measure the distance from your eye to the joint of your
thumb and index finger (arm is stretched out). Next, hold the stick straight up and down at arm's length in front
of you and make sure the portion above your hand is the same as what
you measured from your eye to your hand. Step backwards until the tree's base appears to rest on the top of
your fist, while the top of the stick appears to touch the top of
the tree. At this exact point, the height of the tree is equal to
the distance from the base of the tree to you. Place a stake in the ground and measure (in feet) from the trunk
of the tree to the stake to find the height! Another method involves the use of a clinometer. If you
can see the top of the tree at 100', a clinometer will tell you the height of
the tree on the right side of the instrument. A longer explanation
of various tree measurement procedures is provided here.
One point is given for each foot of height.
The last two measurements needed
are for average crown spread. This is a horizontal measurement, from
leaf tip to leaf tip, of the shortest spread, and the longest spread of the
tree. Adding the two numbers together, and then dividing by two will
give you the average crown spread.
The Pennsylvania Big Tree program
collects both average crown spread information for use in the
American Forests Big Tree Program and maximum crown spread for the
Pennsylvania big tree list. Maximum crown spread receives a quarter
point for every foot of average spread. You can obtain the points by
multiplying the average spread by .25.
Pennsylvania Big Tree Points = Height (feet) + Circumference Breast Height (inches) + 1/4
Maximum Crown Spread
Adding these three measurements together will give you your