Tree
Measurements  Some stray thoughts 
Robert
Leverett 
May
30, 2007 12:10 PDT 
ENTS,
A few more thoughts on ENTS adopting the
new measure for big trees
that I just proposed. Firstly, our standard measures of full
tree height
and CBH are fine for the vast majority of trees that we measure.
Adding
maximum and/or average crown spread adds significantly to the
numeric
description of a tree, especially if teh crown spread is great.
But,
trees that are unremarkable, such as a 100foot, narrowcrowned,
forestgrown oak just don't warrant taking slew of extra
measures
unless we're doing scientific research that calls for added
measures.
However, the real giants across the landscape deserve more more
kinds of
measures. In particular, the CPA(n) concept makes sense for the
live
oaks that Larry Tucei Jr. measures because the huge ground area
they
cover and the proximity of the limbs to the ground, i.e. the
composite
limb architecture of the live oak is the hallmark of the
species. I
would propose for the big spreading trees the following
measures.
1. Full tree height (H)
2. Height to major point of branching (Hb)
3. Girth at breast height (GBH)
4. Girth at ground level (GGL)
5. Maximum spread (MS)
6. Average spread (AS)
7. Concave polygon area crown cover CPA(n)
Beyond these measures, there is trunk
and/or limb volume, but that
involves a mountain of work. So, the trees we volume model will
usually
be for specific research purposes. The Middleton Oak
demonstrated the
extreme effort required to volume model a big live oak.
We might establish thresholds for using
the above 7 measures, e.g.
all trees over 20 feet around would get the full treatment. Just
a
thought. Ed, what are your thoughts?
Bob
Robert T. Leverett
Cofounder, Eastern Native Tree Society

Re:
Some stray thoughts 
Edward
Frank 
Jun
03, 2007 07:52 PDT 
Bob,
Your list seems fine. I will leave the crown area and crown
volume to a
separate thread, but want to review the basic concepts presented
by your
first 6 measurements on the list. A fuller treatment is given in
the Tree
Measuring Guidelines of the Eastern Native Tree Society
document.
Bob Leverett wrote: "Firstly, our standard measures of full
tree height and
GBH are fine for the vast majority of trees that we measure.
Adding maximum
and/or average crown spread adds significantly to the numeric
description of
a tree, especially if the crown spread is great. But, trees that
are
unremarkable, such as a 100foot, narrowcrowned, forestgrown
oak just
don't warrant taking slew of extra measures unless we're doing
scientific
research that calls for added measures. However, the real giants
across the
landscape deserve more kinds of measures.. We
might establish thresholds
for using the above 7 measures, e.g. all trees over 20 feet
around would
get the full treatment. "
1. Full tree height (H): This is the most
critical measurement for many of
our research efforts. Measurements made using the distance from
the base of
the tree and the angle to the top are just not acceptable. The
mechanics of
using a laser rangefinder and a clinometer are pretty straight
forward.
First find a spot where you have a good view of the tree. Four
measurements
need to be taken.
a) Using the rangefinder find the highest point on the tree. For
a number
of branches at a similar angle, the branch that is farthest away
is the
highest branch. Write down the distance measured by the
rangefinder to the
top of the tree. This distance is most accurate when it is at
the point
where the distance number changes upward from one number to the
next higher
number.
b) Measure the angle to the same top point with the clinometer
and write
that number down.
c) Measure the distance to the base of the tree using the
rangefinder from
the same point that the top was measured, and write that number
down,
d) Measure the angle to the base of the tree using the
clinometer and write
that number down, noting whether the base of the tree is above
or below the
point from which it s being measured.
e) Use a pocket calculator to determine tree height. Here is an
example:
After the four measurements that have been taken., and say the
angel gle to
the tree top = 47 , distance to the top = 35 yards, angle to the
base = 7,
and distance to base = 23 yards:
1)First punch in the top angle [47],
2) press the sin button on the calculator [In this case the
number that
appears will be 0.73135],
3] press the multiplication key [X],
4) type in the distance to the top in yards [35],
5) press the multiplication key [X],
6) type in the number 3 [3 feet per yard],
7) press the = sign. This will give you the height of the top
above your
eyelevel. [76.8]
8) Write this number down, it is the height of the tree top
above eye
level.
Next calculate the "height" of the base of the tree,
using the same steps.
9) First punch in the base angle [7], Ignore at this step
whether the
number is positive or negative.
10) press the sin button on the calculator [In this case the
number that
appears will be 0.1219],
11] press the multiplication key [X],
12) type in the distance to the top in yards [23],
13) press the multiplication key [X],
14) type in the number 3 [3 feet per yard], this gives you 69
feet
15) press the = sign. This will give you the height of the top
above your
eyelevel. [8.4]
16) Write this number down, it is the height of the base of the
tree above
or below eye level. In almost every case the top of the tree
will be above
eye level, so it will be a positive number.
17) If the base of the tree is below eye level [negative angle],
add the
two numbers [from steps 8 and 16] together to get the height of
the tree.
18) If the base of the tree is above eye level, subtract the
base height
[step 16] from the top height [step 8] to obtain the height of
the tree.
2. Height to major point of branching (Hb): This is measurement
that is not
regularly obtained. Find the lowest point on the trunk where the
major
branching begins (ignoring epicormic sprouts, and so forth)
Using the same
methodology as described above for tree height, measure the
height of this
point above the base of the tree.
3. Girth at breast height (GBH): Girth is a dimension taken at a
point 4.5
feet above average soil level. If a burl or other atypical
growth formation
is encountered at this point the least distorted girth below
this point is
used; or just above breast height as appropriate.. When a tree
is growing on
a slope the girth is taken at a point that is the average of the
highest
point and the lowest point the tree trunk appears to contact the
soil (Mid
slope). This midslope rule is used to follow the American
Forests
guidelines for measuring champion trees. In all cases the girth
is taken
perpendicular to the axis of the trunk at BH, not parallel to
the soil.
4. Girth at ground level (GGL): Again this is not a standard
measurement.
The base of the tree will flare outward and have many hollows
and ridges
leading to the underlying root structures. In
this case the girth would be
measured from ridge to ridge around the periphery of the trunk.
To do
proper volume measurements a footprint map of all the hollows
and ridged
would need to be made, but this detail is not necessary for GGL
5. Maximum crown spread (CSM): This is the maximum horizontal
distance from
branch tip to branch tip through the central mass of the crown.
It is
generally measured by finding the a point directly underneath
each of these
points on the ground and then measuring the horizontal distance
between
these two points.
6. Average crown spread (CSA): This is the numerical average of
the maximum
crown spread as described above and the shortest spread measured
at right
angles to the CSM through the central mass of the tree crown.
Edward Frank

