Cruising TimberCruising Timber

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ObjectivesObjectives

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 TimberCruising 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 Standing Tree & Log VolumesVolumes

• 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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TerminologyTerminology

• 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 Standing Tree Measurement ToolsTools

• 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 Standing Tree MeasurementMeasurement

• Includes the following measurements:

– tree diameter

– tree height

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Tree DiameterTree 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 StickBiltmore 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 trees diameter

25 inches from your eye is normally arms length.

Tree Fact

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Tree DiameterTree 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.gov10

Tree HeightTree 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

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Merchantable Tree HeightMerchantable 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 FootBoard 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 MeasurementStand Measurement

• Is measured for the following reasons:

– forest management planning

– forest health monitoring

– timber appraisal

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Stand MeasurementStand 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 TimberCruising 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 LinesEstablishing 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 TimberCruising 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 DataCollecting 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 TimberCruising Timber

• Includes the following steps:

– summarize data

• use formulas or tables to determine the volume of forest per acre

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Volume FormulasVolume 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 FormulasVolume 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 acre

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Volume TablesVolume Tables

• Are provided by the USDA Forest Service

– www.fs.fed.us

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AssessmentAssessment

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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AssessmentAssessment

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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AssessmentAssessment

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

Project Coordinator:

Meghan Blanek

Production Manager:

Dusty Moore

Executive Producers:

Gordon Davis, Ph.D.,

Jeff Lansdell

Production Coordinator:

Brandon O’Quinn

Graphic Designer:

Ann Adams

© MMIXCEV Multimedia, Ltd.

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