Cruising Timber
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Objectives
1. To evaluate the importance of
measuring timber.
2. To identify tools used in measuring
trees.
3. To understand how to measure trees.
4. To identify formulas used in
determining tree volume.
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Cruising Timber
• Is the practice of field measurement and estimation
of potential harvest volumes
• Is the process of measuring and recording the
diameter, height, species, product and grade of trees
• Is often used before timber harvest to estimate the
volume of standing timber to be harvested
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Standing Tree & Log
Volumes
• Are essential for a purchaser of timber
harvest products to determine the volume of
timber before purchasing
• Can be measured using a scale stick for the
following:
– tree diameter
– number of 16-foot logs
– length of pulpwood in a tree
– diameter and length of saw logs
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Terminology
• Diameter: the width of a circle
• Radius: the measurement of the exact
center of a circle or trunk to the outside
edge
• Circumference: the distance around a
circle or trunk
• π = 3.14 and is pronounced pi
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Standing Tree Measurement
Tools
• Include the following:
– diameter tape
• is a tape used to measure the diameter
of a tree
• when wrapped around the
circumference of a tree trunk it reads
the diameter directly
– Biltmore stick
• is similar to a yard stick
• is used to measure the height of a tree
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Standing Tree
Measurement
• Includes the following measurements:
– tree diameter
– tree height
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Tree Diameter
• Is the most important tree measurement
when cruising timber
• Is measured diameter at breast height, DBH
– is measured 4.5 feet from the base of the
tree
– can use either diameter stick or Biltmore
stick
– diameter tape should be tightly wrapped
around the tree
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Biltmore Stick
• Is also known as a cruiser’s stick
• Resembles a wooden yardstick with a diameter scale
stamped on the edge
• Measures tree diameter in the following ways:
– place stick crosswise against the tree 4.5 feet above
ground about 25 inches from your eye
– adjust stick so it looks like it extends to the left side
of the tree
– move your eye and look at the right side of the tree
and the number which intersects the stick is the
Tree Fact
trees diameter
25 inches from your eye is normally
arms length.
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Tree Diameter
• Can be measured without a diameter tape or
Biltmore stick
– measure the circumference of the trunk
– use the following formula to determine
diameter
• circumference ÷ π = diameter
nrcs.usda.gov
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Tree Height
• Is determined by using a clinometer
– measures the amount of rise in 100 feet
– first – user paces out 100 feet from the tree
– second – user sights the tree and the
stump and reads the scale on the
clinometer
• if uphill from stump, measure stump at
eye level and add the tree height
• if downhill from stump, measure stump at
eye level and subtract the tree height 11
Merchantable Tree Height
• Is the measurement from the stump to the point were
the tree is too small to be valuable
• Is measured with a Biltmore stick
– has Merritt Hypsometer on edge and calculates
the number of 16 foot logs
– first – user paces 66 feet away from the tree
– second – user holds the stick 25 inches from the
eye and lines the bottom of stick with stump
– third – user reads the number of logs or partial
logs on sticks
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Board Foot
• Board foot – a unit of volume for timber equal to 144
cubic inches.
• 1 foot Wide x 1 foot Length x 1 inch Thick
• 12 inches Wide x 12 inches Length x 1 inch Thick
• Width(inches) x Length(inches) x Thickness(inches)
144
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Stand Measurement
• Is measured for the following reasons:
– forest management planning
– forest health monitoring
– timber appraisal
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Stand Measurement
• Is normally measured in with sampling
techniques or small sample plots to
gather information about the forest
• Can be measured by a sampling
technique called a timber cruise which
is accurate when applied correctly
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Cruising Timber
• Includes the following steps:
– locate a good map of the forest
– be familiar with the variation of the timber
types
– establish sample points
• use around 10 percent of the stand
• draw grid lines on the map
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Establishing Grid Lines
• Includes the following:
– evenly place point centers on stands
– begin with 30 points and if stand is
variable add more points
– distance between the points will be based
on the scale of the map
– use a compass to move from one point to
another
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Cruising Timber
• Includes the following steps:
– collect data at sample point which includes
the following tools:
• compass
• measuring tape
• prism
• diameter tape or Biltmore stick
• hypsometer
• tally sheet
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Collecting Data
• Preformed by doing the following:
– at each point, hold prism over the point
and look through prism at trees in a circle
around the point
– if tree is within the prism, measure the
diameter, merchantable height and volume
– record the measurements on a tally sheet
– use a different tally sheet for each point
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Cruising Timber
• Includes the following steps:
– summarize data
• use formulas or tables to determine
the volume of forest per acre
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Volume Formulas
• Include the following for sawtimber:
– trees average one to two 16-foot logs
• (number of 16-foot logs in countable
trees × 650) ÷ number of point samples
= board feet per acre
– trees average 2.5 or more 16-foot logs
• (number of 16-foot logs in countable
trees × 600) ÷ number of point samples
= board feet per acre
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Volume Formulas
• Include the following for pulpwood or cords:
– (number of 8-foot sticks in countable trees +
number of countable trees) ÷ (2 × number of
point samples) = cords per acre
– trees average two to three sticks
• (number of 8-foot sticks in countable trees ×
0.7) ÷ number of point samples = cords per
acre
– trees average four sticks or more
• (number of 8-foot sticks in countable trees ×
0.6) ÷ number of point samples = cords per
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acre
Volume Tables
• Are provided by the USDA Forest
Service
– www.fs.fed.us
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Assessment
1. ____________________ is the practice of
field measurement and estimation of
potential harvest volumes.
2. Cruising timber is often used before timber
harvest to estimate the volume of standing
timber to be harvested.
a. true
b. false
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Assessment
3. _______________ is the width of a circle.
4. Name two tools which measure tree
diameter.
5. ________________ is the tool used to
measure tree height.
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Assessment
6. Tree diameter is measured at the base of
the tree close to the ground.
a. true
b. false
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References
• Measuring Standing Trees & Logs
www.ext.vt.edu
• Tree & Stand Measurement
extension.unh.edu
• Measuring Trees and Estimating Volume
learningstore.uwex.edu
• Using the Tree Measuring Stick
ohioline.osu.edu
• How to Measure Trees and Logs
extension.missouri.edu
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Acknowledgements
Production Coordinator:
Production Manager:
Brandon O’Quinn
Dusty Moore
Project Coordinator:
Meghan Blanek
Executive Producers:
Gordon Davis, Ph.D.,
Graphic Designer:
Jeff Lansdell
Ann Adams
© MMIX
CEV Multimedia, Ltd.
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