Volume Determination

Definitions  Log = 8 or more feet long (usually 16 feet)  Bolt or Stick = less than 8 feet long  Scaling = the process of estimating or measuring wood volume

Board Foot How many board feet in a cubic foot?

 1 board foot equals 144 in 2  1 cubic foot equals 12 board feet  However, if timber is scaled in cubic feet – 12 board foot per cubic foot isn’t realized in lumber  This is due to…  Kerf  Slabs  Trim waste

Kerf – wood lost as sawdust Why 12 board foot of lumber isn’t actually what a cubic foot of wood yields

Bored Feet

Cubic Feet

Cord Assume 80 cubic feet of solid wood due to air space

Roughly Half a Cord of Firewood

Stem Form

Girard Form Class  Ratio of the inside-bark diameter at the top of the first 16 ft. log to dbh. Defines the rate of taper in a tree.  Stump height (1 ft.) and a trim allowance (0.3 ft.) are factored in, making the upper measurement at 17.3 ft. above ground.  Example: diameter inside bark at 17.3 feet: 14.3 inches  dbh: 17.8 inches  Girard Form Class: (14.3 / 17.8) = 0.803, or 80 percent  drawback: getting the inside-bark diameter at 17.3 feet. Can measure bark thickness, double it and subtract from DOB at 17.3’

Girard Form Class Diameter inside bark 17.3 feet Divided by Diameter Breast Height (DBH) (outside 4.5 feet) times 100 DIB top X 100 = FC DBH

Extrapolate Top Diameter  Given a Bark thickness, DBH and FC, you can calculate Diameter Outside feet.  FC/100 = DIB/DBH  DIB + 2XBark = DOB  If bark =.5”, DBH = 20”, and FC = 80  DOB top = 17

Common Local Form Classes

Historic Local Form Classes Appalachian Softwoods:  White PineFC=79 HemlockFC=78 SprucesFC=82 CypressFC=78 Hardwoods:  White OakFC=78 Red oaksFC=78 Yellow PoplarFC=78 CherryFC=82 BasswoodFC=80 WalnutFC=78 BeechFC=84 MaplesFC=79 BirchesFC=78 Upland ashesFC=82 Red & black gumFC=78 HickoriesFC=78 Cottonwood & willowFC=78 Other hardwoodsFC=78 Central States Softwoods:  White PineFC=80 HemlockFC=78 SprucesFC=78 Hardwoods:  White OakFC=78 Red oaksFC=78 Yellow PoplarFC=78 CherryFC=82 BasswoodFC=78 WalnutFC=78 BeechFC=82 MaplesFC=79 BirchesFC=78 Upland ashesFC=82 Red & black gumFC=80 HickoriesFC=78 Cottonwood & willowFC=78 Other hardwoodsFC=78

Factors affecting tree volume

Geometric forms of portions of tree Newton’s Formula: V = h/6(A b + 4A m + A u )

Standing Tree Volume Formulas

Tree Volume Tables – Doyle (FC=78) Dbh (inches) Number of 16-Foot Logs 1/211-1/222-1/233-1/24 Board Feet , ,1201, ,0001,1401,3001, ,1401,3101,4801, ,1001,2901,4801,6801, ,2301,4501,6601,8802,080 Basically used by everyone except the US Government

Tree Volume Tables – International (FC=78) Dbh (inches) Number of 16-Foot Logs 1/211-1/222-1/233-1/24 Board Feet , ,0601, ,0801,2201, ,0601,2201,3801, ,0101,2001,3801,5601, ,1301,3401,5401,7401, ,0101,2501,4801,7001,9202,160

Change the form class a little… Rule of Thumb: Change of one form class = ~3% volume change

Derivation of Merchantable tree volume  Refer to previous slide See how form class defines the volume estimates for upper logs

Tree Volume Tables - Scribner Dbh (inches) Number of 16-Foot Logs 1/211-1/222-1/233-1/24 Board Feet ,0001, ,0201,1501, ,0101,1601,3001, ,1401,3101,4801, ,0701,2701,4701,6601, ,1801,4001,6301,8502,050

Contrasting Tree Scaling Rules

Scaling Timber by Weight  Sometimes trees are sold by weight instead of volume. Certain species, uses, and regions specifically.  Weights are subject to influence by multiple factors. Some of these include species, logging practices (how long it stays in the field after felling), season, climatic conditions, growth conditions, age, live/dead, etc.  Example – salvage cuts, ‘fire break’ cuts, clear cuts, where all trees are to be removed regardless. Saves time/money – don’t have to scale trees before cut.

Development of Weight Factors  When selling by weight, a weight to gross cubic volume factor must be determined.  Weight factors must be specific to species or species groups.  At least 10 observations with < 15% sampling error at the 95% confidence level.

Traditional Log Scaling  Historical information (species and product of load, gross cubic volumes, net load weights) from traditionally scaled logs

Xylodensimeter the mean of at least 3 heartwood cores are taken at DBH, must be analyzed before losing moisture

Chunk Scaling <8’ pieces volume calculated with Smalian’s formula and weight recorded to develop factor, chunks summed for each tree Large Chunk Scaling – 1 st piece is stump to DBH, other are 8’ pieces, whole tree volume and weight used for factor