Log rules employed 



The factors applying to board- foot volumes are based on 

 Scribner Decimal-C log rule. Cubic-foot log vol\imes were determined 

 from the cubic volume tables in the I'ational Forest Scaling Handbook. 

 Deductions for defects were made in accordance with the National 

 Forest Scaling Handbook, 



Any log that was more than 50 percent cull xi^as considered all 

 cull in board-foot computations, and any log that was more than 75 

 percent cull in cubic feet was considered all cull in cubic-foot 

 computations. Any inconsistencies in the ratio of cubic to board- 

 foot percentages may be accounted for in part by the fact that shake 

 was regarded as a defect in making board- foot deductions j but not as 

 causing loss of cubic volume of wood. Some inconsistency may be 

 charged to making no cubic-foot deductions from saw kerf, short 

 lengths, and trimming. 



CAUSES MD TYPES OF CULL 



Cull in living trees is largely due to decayed wood, but some 

 may be due to sound defect from such causes as shake, crook, and 

 si-xeep. Shake (fig, 2) is the only sound defect that contributes 

 appreciably to cull in the stands of Southeast Alaska, Loss of vol- 

 ume from burning, as found in large fire scars in other regions, is 

 inconsequential in this rain forest. Sound cull from shake caused 

 a loss of board-foot volume but was not considered a loss in cubic 

 vol\mie . 



Most board-foot cull and all cubic-foot cull was due to 

 decayed wood. Decayed wood is of two types: "brown rot" and "white 

 rot," In brown rot the causal fungi attack primarily the cellulose 

 fibers (fig. 3); in white rot, the lignin content of the wood (fig, 

 5). Likewise, tvro general stages of decay were recognized in this 

 study analysis. They are the early, or incipient, stage of decay 

 (fig. k) and the late, or typical, stage (figs, 3 and 5). 



In the incipient stage the affected wood is usually discolored 

 and firm, but often somewhat softened and weakened. Lox>r grades of 

 lumber may be manufactured from such wood. This wood may also be 

 used in pulp making, though some weakening of fiber results when 

 incipient decay of the brown rot type is used, ^food in the typical 

 stage of decay x^^.ll not make lumber, even of low grade, and the typi- 

 cal stage of brox'm rot makes wood unsuited for pulp of any kind. 

 Part of the wood containing typical decay of the white rot type, 

 however, may be used in pulp making but with considerable loss of 

 yield. 



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