Measures and yields of products and residues 521 y 



individual components, groups of components, and the complete tree or shrub is 

 essential, but Young (1978b) points out that all the field and lab work for a single 

 species' tables can be done by two men in 6 weeks or less. 



CONVERSION TABLES 



The foregoing paragraphs describe the content of logs and trees in terms of 

 cords, board feet, cubic feet, and pounds. Since all of these units of measure are 

 in widespread use, conversion data are useful; some tables for this purpose 

 follow. 



Cords to cubic feet.— Tables 13-21, 13-24, 27-1, and 27-22 provide data to 

 convert cords to cubic feet. 



Cords to board feet log scale. — Cordwood volume should not be expressed 

 in terms of board foot log scale unless the cordwood is comprised of bolts large 

 enough for lumber manufacture, i.e. , more than 6 inches in diameter. According 

 to the Service Foresters Handbook (U.S. Department of Agriculture, Forest 

 Service 1970, p. 6), the following conversion factors permit cords to be approxi- 

 mately expressed in terms of board foot log scale. 



Cords per Mbf/log scale 

 Tree dbh 



Inches 



8 



9 

 10 

 11 

 12 

 13 

 14 



Worley (1958) computed cord-to-board-foot ratios by tree diameter, form 

 class, and merchantable length, as scaled by three log rules (table 27-102). He 

 chose form class 75 and 80 as typical of small hardwoods and gave separate 

 values for short and tall trees because the upper portions of tall trees will yield 

 fewer board feet per cubic foot than the lower or butt section of the tree. Thus, 

 for 8-inch trees of form class 75, it takes 2.8 cords from tall trees to equal 1 Mbf 

 International !/4-inch scale but only 2.6 cords from short trees. 



Cord to board foot ratios can also be based on bolt diameter. For short bolts 

 (26 to 72 inches long) of yellow-poplar, sweetgum, and oak, Redman (1957) 

 found that the conversion factors ranged from 5.30 cords per 1 Mbf Doyle scale 

 for 8-inch bolts to 2.14 cords per 1 Mbf for 18-inch bolts (fig. 27-8). 



Barrett et al. (1941) tallied the board-foot content of long cords (160 ft"*) of 

 peeled mixed oak (table 27-103). He noted that the ratio of cords to board feet 

 varies with bolt diameter, length, and taper. For his table, average log taper was 

 assumed, and bolts were 5 feet long; factors for obtaining the board-foot content 

 for standard cords of 4-foot wood (rough or peeled) are given in table 27-103. 



Cords to board feet lumber scale. — To make this conversion, it is first 

 necessary to convert cord volume to cubic foot volume as previously explained. 



