Minimum Tree Size Characteristics

Product Pine Hardwood

Pulpwood 6” DBH to a minimum 6” DBH to a minimum3” top diameter 3” top diameter cord very low

Chip-n-saw 9-14” DBH to a not applicableminimum 6” top diameter cord low

Sawtimber 14” DBH to a minimum 16” DBH to a minimum8” top diameter 10” top diameter board foot high

Veneer log 16” DBH, clear/straight 18” DBH, clear/straightfirst log first log board foot high

Pilings various specifications not applicablebased on local markets board foot high

Estimating the Volume of a StandingTree Using a Scale (Biltmore) Stick

Distributed in furtheranceof the Acts of Congress

of May 8 and June 30, 1914.Employment and program

opportunities are offered toall people regardless of

race, color, national origin,sex, age, or disability. North

Carolina State University,North Carolina A&T State

University, U.S. Departmentof Agriculture, and local

governments cooperating.

The volume of wood in a tree and the type ofproduct made from the wood are based pri-marily on the tree’s height and diameter. Oneof the basic tools for estimating the height anddiameter of standing trees is a calibrated 25-inch scale stick, often referred to as a Biltmorestick or a cruiser’s stick. With practice, thisinstrument can be used to provide a reliableestimate of tree height and diameter, whichthen can be used to determine tree volume.This publication is for those interested inlearning how to estimate tree volume and thetype of product the tree may provide. Forinstructions on how to make your own scalestick, see page 3.

If you want to estimate tree volume inorder to sell timber, it is highly recommended

that you consult a forester for advice. Vol-ume alone does not determine value or theproducts that could be produced; tree qualityis also very important. Forestry consultantscan advise you on the types of wood prod-ucts that could come from your timber as wellas the quality of your timber. They also canprovide you with estimates of the volumeand value of the timber. In most cases theconsulting forester’s experience with timbersales and knowledge of current markets canincrease your revenues far in excess of theforester’s fees. For more information on con-sulting foresters, visit a county CooperativeExtension Center or North Carolina Divisionof Forest Resources county office.

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Table 1. Minimum tree size characteristics, volume units, and relative value by timber product.

VolumeUnit

RelativeValue

Crop Tree Management in North Carolina 2

Product Types and Measurement Units

Major products that can be produced from pine treesinclude pulpwood, chip-n-saw, sawlogs, veneer logs(also known as plylogs), and pilings or poles. Majorproducts produced from hardwood trees include pulp-wood, sawlogs, and veneer logs (also known as grade orexport logs). Each of these products must meet certainminimum size requirements (Table 1), and each varies invalue based on the product, tree quality, and markets.For example, a tree 14 inches in diameter (measured4½ feet above the ground) and with 50 feet of merchant-able height can produce any one of three products thatwill vary in value based on the product (Figure 1).

Standing trees or portions of trees sold for pulpwoodor chip-n-saw are measured in cord volume. A cord is astack of 4-foot long pieces of wood that is 4 feet high and8 feet long; it includes 128 cubic feet of wood, bark, andair space.

Standing trees sold for sawlogs or veneer logs aremeasured in board-foot volume. A board foot is 1 inchthick, 12 inches wide, and 1 foot long. To determine thecord or board-foot volume of a tree, first measure thediameter and height using a scale stick. Check thediameter at a point 4½ feet above the ground (diameterbreast height or DBH) on the uphill side of the tree and themerchantable height in increments of 16-foot and addi-tional 8-foot logs. With these two measurements, youcan determine the volume of the tree from various treevolume tables. Most scale sticks have the International

¼-inch, board-foot volume tables imprinted on them. Aset of volume tables for pines for all three log rules—International ¼-inch, Scribner, and Doyle—may be foundin Handy Tables for Measuring Farm Timber, Coopera-tive Extension Service publication AG-119.

In North Carolina, pine sawtimber volume is oftenestimated using the Scribner log rule, and hardwoodsawtimber volume is often estimated using the Doyle logrule. Tree volume estimates will differ based on which logrule is used because of differences in the way theestimates were formulated. Using the International ¼-inch rule as the basis for the volume, the Doyle log ruleprovides the lowest estimates for trees up to 30 inchesDBH, and Scribner provides intermediate estimatesacross all tree diameters (Figure 2). No matter which logrule is used to estimate volume, it is important to under-stand that timber prices also vary with log rules.

Figure 2. Relationships among three log rules in board-foot volume estimates for trees using the International¼-inch rule as a standard for comparison.

Figure 1. Relative value of a tree 14 inches in diameter DBH and 50 feet in merchantable height, based onvarious products that could come from it.

0%

20%

40%

60%

80%

100%

10 14 18 22 26 30

Tree Diameter (inches)

Per

cen

t

Doyle Scribner International 1/4-inchDoyle Scribner International ¼-inch

14 inchesDBH

50 feetmerchantableheight

Woodland Owner Notes

or

or

Potential Product Volume Relative Tree Value

Pulpwood $3.00

0.23 cord

Chip-n-saw $13.00

0.23 cord

Sawtimber $35.00

145 board feet

Crop Tree Management in North Carolina 3

Making a Scale Stick

Materials

• a yardstick, 1 inches wide• scissors• paintbrush• sandpaper• rubber cement or a waterproof,

clear household cement thatadheres well

• varnish

Steps

1. Cut out the three paper forms to theleft.

2. Glue Form 1 to the left edge of theyardstick, making sure that the leftedge of Form 1 is even with the leftend of the stick. The glue should beplaced on the stick.

3. Glue Form 2 to the stick. Make surethe left edge of Form 2 butts againstthe right edge of Form 1, which ismarked by two arrows. The glueshould be placed on the stick.

4. Glue Form 3 to the stick by aligningthe left edge of Form 3 with the rightedge of Form 2, which is marked bytwo arrows. The glue should beplaced on the stick.

5. After gluing the three forms to thestick, trim and sand the corners ofthe stick so that the edges aresmooth. Then cover the stick withclear water repellent (such as aclear varnish) to protect the stickduring use.

¼8

Crop Tree Management in North Carolina 4

Figure 4A. Measuring merchantable height with a scale stick.

Scale stick at stump height.

Scale stick indicating amerchantable tree height oftwo 16-foot logs.

Measuring Diameter

Tree diameter is the most important measurement ofstanding trees. Trees are measured 4½ feet aboveground-level, a point referred to as diameter breastheight or DBH. Diameter breast height is usually mea-sured to the nearest inch; but where large numbers oftrees are to be measured, 2-inch diameter classes areused.

To measure DBH, stand squarely in front of the treeand hold the scale stick 25 inches from your eye in ahorizontal position against the tree at 4½ feet above theground. Shift the stick right or left until the zero end of thestick coincides with the left edge of the tree trunk.Without moving your head, read the measurement thatcoincides with the right edge of the tree trunk. Thismeasurement is the tree’s DBH, including the tree’s bark(Figure 3). On sloping ground, measure from the uphillside. Two measurements at right angles to each otherand averaged will give a more accurate reading sincemany trees are not perfect cylinders.

Measuring Merchantable Height

Merchantable height refers to the length of usable treeand is measured from stump height (1 foot above ground)to a cutoff point in the top of the tree. The cutoff height willvary with markets, with the product being produced, andwith the presence of excessive limbs. The scale stickhas been calibrated so that if you stand 66 feet from thetree being measured and hold the stick 25 inches fromyour eye in a vertical position, you can read the numberof merchantable logs from the stick. It is important not tomove the stick when taking a measurement; tilt yourhead back slightly so that you do not have to move yourhead when reading from stump point to cutoff height(Figures 4A, 4B).

20170295400480

18

2

135235315375

16105180240285

Merchantableheight is 216-foot logs

Figure 4B. Reading merchantable height from a scale stick.

Estimating the Volume of a Standing Tree Using a Scale (Biltmore) Stick

Cutoff point

Line of sight

Line of sight

Stand 66 feet from the tree and hold the scale stickvertically, 25 inches from your eye.

Stump height 12 inches–>

Figure 3. Measuring diameter with a scale stick.

Line of sight

25" distance

Line of sight

Zero end of stick

Eye

Stump height

3630

283456158501025

52093513051590

324057209901200

46082511501400

3438

40730133018702295

590106514851815

655118516702040

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1Merchantableheight is two16-foot logs

Crop Tree Management in North Carolina 5

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Which Price Do You Use?

Timber prices per board foot vary, based on which log rule is used to estimate timber volume.Here are conversion factors for the various log rules:

Log Rule Conversions (Dollar Values)

Doyle to Scribner (26% difference) 0.75 Doyle to ScribnerScribner to Doyle 1.33 Scribner to Doyle

Doyle to International ¼-inch (39% difference) 0.62 Doyle to International ¼-inchInternational ¼-inch to Doyle 1.60 International ¼-inch to Doyle

Scribner to International ¼-inch (20% difference) 0.83 Scribner to International ¼-inchInternational ¼-inch to Scribner 1.20 International ¼-inch to Scribner

For Example: You know that pine sawtimber is selling for $300 per 1,000 board feet(Scribner log rule). What is the price equivalent for the International ¼-inch log rule?

$300 per 1,000 board feet (Scribner log rule) X 0.83 = $249 per 1,000 board feet(International ¼-inch log rule)

Estimating Volume

To estimate the board-foot volume of a tree using the volume table (International ¼-inch rule)imprinted on the scale stick, you need an estimate of the tree’s DBH and merchantable height.With these two measurements, the board-foot volume of the tree is estimated by reading first thetree’s DBH and then the number of 16-foot logs (Figure 5). For example, a tree that is 10 inchesDBH with a merchantable height of two 16-foot logs would have a volume of 60 board feet,International ¼-inch rule. See the box below for instructions on converting to Doyle or Scribner.

Figure 5. Estimating volume using the volume tableimprinted on the scale stick.

Woodland Owner Notes

Crop Tree Management in North Carolina 6

Prepared by

Robert E. Bardon, Extension Forestry Specialist

Published by

NORTH CAROLINA COOPERATIVE EXTENSION SERVICE

4/02—5M—DSB WON-05

E02-39054

Things to Remember

• Seek professional forestry advicebefore selling your timber.

• The products that could be madefrom a tree vary based on minimumsize requirements and tree quality.

• In general, product value increaseswith tree size.

• Timber prices differ, based on whichlog rule is used.

• Tree volume estimates vary, basedon which log rule is used.

• When reviewing tree volume andprices, be sure that the price usedto estimate value is for the log ruleused to estimate volume.

• To ensure accuracy, hold the stick25 inches from your eye when mea-suring.

• To measure tree height correctly,stand 66 feet from the tree.

5,000 copies of this public document were printed at a cost of $1426.00 or $.29 per copy.

Woodland Owner Notes