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Published byFredrick Stabley Modified about 1 year ago

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Volume Determination

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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

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Board Foot How many board feet in a cubic foot?

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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

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

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Bored Feet

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Cubic Feet

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

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Roughly Half a Cord of Firewood

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Stem Form

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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’

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

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Extrapolate Top Diameter Given a Bark thickness, DBH and FC, you can calculate Diameter Outside Bark @17.3 feet. FC/100 = DIB/DBH DIB + 2XBark = DOB If bark =.5”, DBH = 20”, and FC = 80 DOB top = 17

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Common Local Form Classes

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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

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Factors affecting tree volume

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

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Standing Tree Volume Formulas

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Tree Volume Tables – Doyle (FC=78) Dbh (inches) Number of 16-Foot Logs 1/211-1/222-1/233-1/24 Board Feet 122030405060 143050708090100 16407010012040160180190 186010013016020022040160 2080130180220260300320360 22100170230280340380420460 24130220290360430490540600 26160260360440520590660740 28190320430520620710800880 302303805106307408409401,040 322704405907308609901,1201,220 343005106808501,0001,1401,3001,440 363505807809701,1401,3101,4801,640 383906608801,1001,2901,4801,6801,860 404307409901,2301,4501,6601,8802,080 Basically used by everyone except the US Government

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Tree Volume Tables – International (FC=78) Dbh (inches) Number of 16-Foot Logs 1/211-1/222-1/233-1/24 Board Feet 12306080100120 144080110140160180 1660100150180210250280310 1870140190240280320360400 2090170240300350400450500 22110210290360430490560610 24130250350430510590660740 26160300410510600700790880 281903504806007008109201,020 302204105506908109301,0601,180 322604706407909401,0801,2201,360 342905307309001,0601,2201,3801,540 363306008201,0101,2001,3801,5601,740 383706709101,1301,3401,5401,7401,940 404207401,0101,2501,4801,7001,9202,160

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

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

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Tree Volume Tables - Scribner Dbh (inches) Number of 16-Foot Logs 1/211-1/222-1/233-1/24 Board Feet 1228 48 667889 100 108 14407096116141160 170 178 165493129158191224248263 1872122168207248292325355 2090156212262317366415450 22111194262328392450510560 24137236319400470550620690 26165281381480565650740820 28195331450560670760860960 302273835206507708901,0001,110 322604406007408901,0201,1501,280 342945006808401,0101,1601,3001,460 363305657709601,1401,3101,4801,650 383656308601,0701,2701,4701,6601,840 404057009501,1801,4001,6301,8502,050

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Contrasting Tree Scaling Rules

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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.

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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.

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

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

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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

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