Measuring Trees

Where we are headed
 Map reading and compass use
 Species identification (FOR 219)
 Tree measurement (diameters and heights)
 Defect recognition and determination
 Quality determination (grading)
 Use of timber cruising tools
 Traverses
 Elementary use of aerial photography
 Compass and GPS
 Loggers tape
 Dendrometer and Hypsometer
 Increment Borer
 Flagging and Stakes
 Maps, Aerial Photos, Cruising plan
 Axe and paint
 Data recording device (electronic or manual)
 Prism
 Calculator
 Boots
 Chaps
 First aid kit
 Hard Hat
 Safety glasses
 Vest
 Radio
 Water supply
Part 1 - Diameter
 An instrument used to measure trees
 Diameter Breast Height
 Average diameter at 4.5 feet (1.4 meters)
 Easiest to measure, less taper, not height of cut
 Outside bark
 Uphill side of tree
Circumference:  =  
Radius:  = /2
Area:  =  2
Basal Area(ft2)= .005454 DBH2
basal area of a forest stand can
be found by adding the basal
areas of all of the trees in an
area and dividing by the area of
land in which the trees were
measured. Basal area is
generally expressed as ft2/acre
Held 25” from eye
 One-inch diameter class examples
 5-inch class = 4.6 to 5.5 inches
 9-inch class = 8.6 to 9.5 inches
 Two-inch diameter class examples
 12-inch class = 11.0 to 12.9 inches
 14-inch class = 13.0 to 14.9 inches
 Can average DBH for stand and/or by species
 After calculating Basal Areas for all trees. You can
average the BA for the stand and/or by species
 The square root of the mean BA/.005454 is the
quadratic mean diameter or the diameter of the tree of
mean basal area.
 Needed for tree form, taper, and volume.
 Can determine merchantable height.
 Need to be able to do this easily, quickly and safely.
To use the one-half diameter method, make
two marks opposite each other on the stem at 4.5
feet. Measure the distance between the marks
with the diameter tape and double the
measurement to determine DBH. Repeat the
process for the other tree.
If these measurements are at equal distance
from 4.5 feet, average A and C to arrive at DBH
If point A and point C are at unequal distances
from 4.5 feet, interpolate the distances to
arrive at DBH measurement
a. Measure diameter above DBH
where shape is normal, point A in
diagram at right.
b. Measure height to the point where
DBH was taken.
c. Determine average taper from
comparable trees of the same
species in immediate area.
d. Interpolate DBH measurement "C"
based on diameter measurement
"A", the estimated average taper,
and length "B".
 For split trees, measure
DBH with calipers or use
the one-half diameter
technique. Make two
marks opposite each
other on the stem at 4.5
feet. Measure the
distance between the two
marks with a diameter
tape and double the
measurement to
determine the diameter
Since DBH includes bark
you must estimate what
the measurement would
be including the missing
If all bark is missing, try to
get a measure from similar
nearby trees.
-- Diameter tape (D-Tape).
Adjust the tape at a normally
rounded position to allow for the
catface portion missing. If the tape
is not adjusted but is pulled tight,
the tape will be straight across the
missing portion and the diameter
read will be less than it should be.
-- Calipers. Measure DBH at right
angle to catface.
-- One-half Diameter
Technique. Use this technique on
trees growing together.
Crown Width
 Highly correlated to tree vigor and other measurable
 Helps predict response from silviculture treatments
like thinning or fertilization
 Useful in ecological studies
1. Average of Maximum and
Minimum diameters
2. Average of Maximum diameter
and the one perpendicular to
that axis
3. Average of some random width
and the perpendicular axis
4. For highly irregular crowns
more than 2 measurements
may be averaged
How, What, Where, Why
 Easily seen from a distance
 Type of mark may be distinctive for type of tree (i.e.
diagonal line for boundary, horizontal line for pulp
tree, etc.
 Boundary trees marks visible from three sides.
 Boundary trees visible from each other.
 Survives after operation
 Downhill side
 Remove loose bark, etc first
 Paint into bark furrows and between root swellings
 Include tree and soil
 Law enforcement ramifications
 Black paint used first to hide old paint
 All forest service paint contains tracers - Thus USFS
paint requires tight supervision, inventory, security.
 May be used when need to identify this tree is
temporary or short lived.
 Cruise ID number painted on tree
 Cruiser initials also
 Paint applied towards plot center if part of sample

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