Copyright © 2013 by Kevin Martin from his forthcoming book, Big
Trees of New Hampshire: Short Hikes to the Biggest Trees in New
Hampshire from the Seacoast to the North Country. Courtesy of
Peter E. Randall Publisher, LLC. www.perpublisher.com
Once you find a new tree, it is measured [Or say "measure it"?] to compare it to
others on the list. You need a flexible tape measure to check the circumference of the
trunk; measure it 4 ½ feet up from the ground. If the ground at the trunk is sloped,
measure from between the high and low spot at 4 ½ feet. Just measure around the trunk at
that 4 ½ feet, or “breast height,” to find its circumference breast height, or CBH.
A diameter tape (relatively expensive) gives you the circumference and the diameter
with one measurement, but a regular 25-foot tape will work if you do not plan to do much
measuring. If you find a tree that's a potential candidate, you can call in a measuring
team, and they can compare the size of this tree to other champions on the list.
The measuring team will recheck the CBH and any other measurements taken. (Most
will just measure the CBH.) Then, with a 100-foot tape, they will measure the crown
(how wide the branches spread out from the tree) at the widest point, and then take
another crown measurement at a right angle to the first one. The crown sizes are then
added together and divided by 2 to get the average crown spread, or ACS.
[The circumference is measured 4 1/2 feet up from the ground (per the above text),
but this drawing shows 5 feet. Is this apparent discrepancy OK? BFR] The drawing is for
the height measurements. There is another for circumference
[[Insert diagram of tree – line drawing – Figure 2]]
Then the height of the tree is checked[Or say "Then check the height of the tree . .
." since you, not someone else, are doing the measuring?] with a clinometer, a
Copyright © 2013 by Kevin Martin from his forthcoming book, Big
Trees of New Hampshire: Short Hikes to the Biggest Trees in New
Hampshire from the Seacoast to the North Country. Courtesy of
Peter E. Randall Publisher, LLC. www.perpublisher.com
calibrated instrument that is quite accurate if read correctly. Measure out from the tree
100 feet and then look through the clinometer, which gives a reading of the height from
your eye to the top of the tree. Then sight the bottom of the tree and add or subtract this
measurement from the tree height, depending on whether you are higher or lower than the
base of the tree at 100 feet away. What you end up with is the vertical height, or VH. A
GPS reading is then taken, and the tree is checked over[Or say "Then take a GPS
reading, and check the tree over . . ."?] to report the condition as excellent, good, fair,
or poor.
The tree is then scored with a point system and compared[Or say "Then score the
tree with a point system and compare it . . ."?] with others on the list. The total points
are determined by adding the circumference in inches to the height in feet, then adding
one-quarter of the average crown spread in feet. So a tree with 75 inches CBH, 100 feet
VH, and 60 feet ACS is scored as 75 + 100 + 15 = 190 total points.
Keep in mind that some types of tree do not grow very large. You may not be very
impressed by a champion gray birch or an American chestnut unless you have some idea
of what an average-size tree of the species looks like.
While you are out measuring, be sure to look at the surrounding trees. If you come to
a grove that consists of mostly one type of tree, be sure to look for the largest one. Then
when you do see the champion of that type, you will appreciate it a bit more.
Be sure to check the New Hampshire Big Tree web site at
http://extension.unh.edu/Trees/NH-Big-Tree-Program for updates on the trees listed in
this book.