Units of Measure Commonly Used in Natural Resources

1
Units of Measure Commonly Used in Natural
Resources
2
Some Basic Measurements (a)

• 1 chain (ch.) 66 feet
• 1 mile 5,280 feet
• 1 acre (ac.) 43,560 sq. ft.
• 1 hectare (ha) 10,000 m2

3
Other Useful Conversions

• Chains to miles and vice versa (there are 80
  chains to a mile)
• Square chains to acres and vice versa (there are
  10 square chains to an acre)

4
Measuring Standing Trees Diameters
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DBH (c)

• Watch out for leaning trees !

Parallel to Ground is Incorrect
6
DBH (d)

• Watch out for leaning trees !

Perpendicular to the lean (or with the lean) is
Correct
7
DBH (e)

• Watch out for deformities at 4.5 ft. !

Incorrect
8
DBH (f)

• Watch out for deformities at 4.5 ft. !

Correct
9
DBH (g)

• Watch out for slopes !

From downhill side is Incorrect
10
DBH (h)

• Watch out for slopes !

From Uphill Side is Correct
11
Bark Thickness
DBHOB (2 x bark thickness) Inside Bark
Diameter
12
Diameter Class

• DBHs are often rounded to whole-numbered classes
• 1 classes
• Class DBHs in class
• 2 1.6 2.5
• 3 2.6 3.5 4 3.6
  4.5
• 10 9.6 10.5
  

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Diameter Class

• DBHs are often rounded to whole-numbered classes
• 2 classes
• Class DBHs in class
• 4 3.1 5.0
• 6 5.1 7.0 8 7.1
  9.0
• 14 13.1 15.0
  

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Basal Area

• Outside-Bark cross-sectional area (in sq. ft.) of
  a tree stem at 4.5 feet above ground.
• 0.005454 times DBH2

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Girard Form Class (a)

• Very important when figuring standing tree volume
  (addresses taper)!

16
Form Class Another Thought

• If you are having difficulty trying to figure out
  what form class actually represents try this
• Form class is the percentage of DBH that equals
  the inside bark diameter at the top of the first
  log.
• So for a form class of 82, the inside bark
  diameter at the top of the first log is 82 of
  the outside bark DBH.
• Clearly, then, the lower the form class, the more
  taper a tree stem has.

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Common QMD Formula (a.)

• We commonly express the number of trees on a per
  acre basis (to be covered in the inventory
  section of the course) and call it Trees per Acre
  or TPA
• We commonly express basal area on a per acre
  basis (to be covered in the inventory section of
  the course) and call it sq.ft. BA per Acre or BA
  (sq.ft.) per Acre

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Common QMD Formula (b.)

• With both the number of trees and basal area of
  trees expressed on a per acre basis, a more
  common QMD formula results

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Measuring Standing Trees Height
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Clinometer

• Be a set distance from the tree (usually 1 ch.)
• Sight the base of the tree (remember the number)
• Sight the top of the tree (remember the number)
• Be sure you are reading the numbers on the right
  hand side of the scale if you want to read feet
  directly

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Clinometer (c)
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Clinometer

• Subtract the first (bottom of the tree) number
  from the second (top of the tree) number to
  estimate height
• Note that most of the time the first number will
  be negative, so you will be subtracting a
  negative number when this occurs

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Clinometer

• First number negative, eyes are above the base of
  the tree, looking down to the base of the tree

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Clinometer

• First number positive, eyes are below the base of
  the tree, looking up to the base of the tree

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Clinometer
Clinometers use tangents !
26
Clinometer

• You can go just 33 feet away divide your
  measures by 2
• You can go 132 feet away multiply your measures
  by 2

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Volume Terminology
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Pulp sticks tend to be 100 inches in length in
WI, 8 or 10 feet elsewhere
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Some Terms (f)

• Topwood the pulpwood
• portion of a standing tree
• that occurs above the
• sawlog portion of a bole

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Some Terms (g)

• Scaling the process of estimating and/or
  determining the volume or weight of wood in a
  given log.

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Units of Volume (a)

• Cubic feet
• 1 cubic foot 1 ft. x 1 ft. x 1 ft.
• 12 x 12 x 12 1,728 cu. in.
• Does not have to be a cube!!

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Units of Volume (c)

• Cunit
• 1 cunit 100 cu. ft. of wood fiber content
• 1 CCF (No bark or stacking space)
• Example 3,578 cu. ft. of wood 35.78 cunits

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Units of Volume (d)

• Board Feet
• 1 board foot (BF) 1 x 12 x 12 144 cu. in.
• Does not have to be a plank of these dimensions,
  but must be a sawn product (cut into boards)

Boards
1 MBF 1,000 BF 1 MMBF 1 million BF
Slabs
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Units of Volume (e)

• Cord (standard)
• 1 cord 128 cu. ft. of wood, bark, and space
• Origin is a stack of bolts 4 x 4 x 8 in size

There is less than 128 cu. ft. of wood content in
1 cd !!
128 cu. ft. of wood, bark, and space
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Cord equals 133 cubic feet of wood, bark, and
space in WI, 128 cu.ft. elsewhere
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Cubic Foot Volume Determination of Logs
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Inside-Bark Volumes in Cubic Feet
Employ 0.005454 x D2
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Needed Cross-Sectional Areas

• B cross sectional area (sq. ft.) at large end
  (large diameter) of the log
• B1/2 cross sectional area (sq. ft.) at midpoint
  of the log
• b cross-sectional area (sq. ft.) at small end
  (small diameter) of the log

Inside-bark small end diameter is called the
scaling diameter
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Needed Measurements
Log length in feet
b
B1/2
B
All cross sectional areas are inside bark and in
square feet!!
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Smalians Formula

• Cubic foot volume

Large End Cross-Sectional Area (inside-bark) in
sq. ft.
Log length in feet
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Hubers Formula

• Cubic foot volume

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Newtons Formula

• Cubic foot volume

Log length in feet
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Some Thoughts

• Smalians formula Easiest and least expensive
  to obtain, least accurate
• Hubers formula difficult and costly to obtain
  B1/2 ,
• more accurate
• Newtons formula extremely expensive to obtain,
• most accurate

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Board Foot Log Rules
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Board Foot Log Rules

• Doyle Log Rule(South/Southeast/Northeast)
• International ¼ Log Rule (Northeast/West)
• Scribner (Scribner Decimal C) Log Rule (Midwest)

Each describes board foot volume via tabled
values and/or formulas!
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Scribner Decimal C

• Scribner decimal C Scribner board feet
• rounded to the nearest 10 board feet, then
• divided by 10!

Example A log contains 354 Scribner Board
Feet To convert to Scribner Decimal
C, first round to the nearest 10, so 354 becomes
350. Then divide 350 by 10 (or just drop
the zero) to obtain 35 Scribner Decimal C

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Overrun vs. Underrun

• Compare total scaled board foot volume to total
  sawn volume (a collection of logs and not
  individual logs)
• Overrun lumber output is greater than scaled
  output
• (the result of much underscaling)
• Underrun lumber output is less than scaled
  output
• (the result of much overscaling)

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Percent Overrun or Underrun

• If a negative percentage, the mill has an
  underrun situation
• If a positive percentage, the mill has an overrun
  situation
• Must correct woodyard inventories for this factor
  !

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Log Weight Factors
Specific Gravity Moisture Content Bark
and other Foreign Material
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Specific Gravity

• Specific Gravity a unitless measure of mass
• Specific gravity (sg)
• sg typically varies from 0.35 to 0.81 for most
  commercial tree species

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Moisture Content (a)

• Moisture Content (MC) expressed relative to
  oven-dry weight or green weight
• MCd can exceed 100 !!

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Moisture Content (b)

• Moisture Content (MC) expressed relative to
  oven-dry weight or green weight
• MCg cannot exceed 100 !!

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MCd Another Thought

• If you are having difficulty trying to figure out
  what MCd represents, try this
• When MCd 100, what you are weighing contains
  an equal amount of wood and water (on a weight
  basis)
• When MCd lt 100, what you are weighing contains
  more wood than water (on a weight basis)
• When MCd gt 100, what you are weighing contains
  more water than wood (on a weight basis)

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Density (a)

• Density weight per cubic foot
• Relates moisture content and specific gravity
  for a given species and/or log

There are 62.4 lbs in 1 cubic foot of water
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Density (b)

• Density is expressed in lbs. per cubic foot !
• Density is a function of specific gravity and
  moisture content
• Specific Gravity is unitless !
• Specific gravity is a feature of oven-dry weight

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Terminology

• Density (Bulk Density)
• Inside bark weight divided by inside bark volume
• Scaling Factor (Weight Scaling Factor)
• Outside bark weight divided by inside bark volume

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Measuring Standing Trees Volume and Weight
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Importance of Merch. Height (a)

• Sawlog merchantable heights determine the number
  of sawlogs that can be cut from a standing tree
• Remember minimum scaling diameters !
• Allow 1 for the stump
• Allow an extra 0.3 per log or half-log for
  bucking

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Importance of Merch. Height (b)

• Butt (lowest) log usually must be 16, can count
  ½ logs (8) above that.
• Top of first sawlog is 17.3 above ground
• Top of the second full log, if present, is 17.3
  16.3 33.6 above ground

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Importance of Merch. Height (c)

• Pulpwood sticks (whether on a pulpwood tree or
  topwood) are about 8 long
• Need to count pulpwood sticks above last sawlog
  in a sawtimber tree

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Example
A sawtimber tree
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Example
Where is the sawlog top?
40.5
Find the location (height) of the minimum scaling
diameter for sawlogs!
How many logs fit under that location?
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Example
Is there a half log above the last full log?
(Need to go another 8.3 feet up, we are now 41.9
feet above the ground)
Allow 1 foot for the stump
Remember first log needs to be 16.3 feet long
(top of first log is 17.3 feet above ground)
This is a two log tree
49.9
40.5
41.9
Is there a second full log? (Need to go another
16.3 feet up, we are 33.6 feet above the ground)
Actual sawlog top is 33.6 feet above ground, even
though sawlog merchantable top was 40.5 feet
33.6
Is there a third full log? (Need to go another
16.3 feet up, we are 49.9 feet above the ground)
17.3
Topwood, then, starts at 33.6 feet, NOT 40.5 feet
above ground
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Example

• Calculate number of sawlogs from the sawlog
  merch. height identified.

40.5 feet minus 17.3 feet (the first log) 23.2
feet of bole remaining
23.2 divided by 16.3 1.42 whole logs, so there
is a second whole log, but not a third whole log.
23.2 feet minus 16.3 feet 6.9 feet of bole
remaining
This is less than the 8.3 feet required for a
half log, so this is a two log tree
40.5 feet minus 6.9 feet 33.6 feet, which is
the actual sawlog top (where topwood begins)
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Example

• Place logs on the tree until you cannot fit any
  more counting the logs as you go

33.6
Defects and/or knots tend to limit actual sawlog
heights more than minimum scaling diameters!
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Example
68
68 feet minus 33.6 feet 34.4 feet of bole
34.4 / 8 4.3, so there are 4 sticks of
pulpwood (as topwood)
33.6
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Another Example
Allow 6 inches (0.5 feet) for the stump
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Find the pulpwood merch. top
Determine how many sticks of pulpwood fit above
the stump and below the top height
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Another Example
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50 feet 0.5 feet 49.5 feet of bole
49.5 feet divided by 8 6.16
This tree has 6 sticks of pulpwood