3330 Chapter 27 



ing log size, ranging from 33 percent for 7-inch logs to 14 to 17 percent for large 

 logs (table 27-150). The study sample was 230 saw logs from 47 yellow-poplar 

 trees 12 to 28 inches in dbh cut in western North Carolina. Stems were bucked 

 into 8- to 16-foot logs with a minimum scaling diameter of 8 inches inside bark. 

 After debarking in a rosserhead debarker, logs were sawn into 4/4 lumber in a 

 conventional hardwood mill with a 3/16-inch-kerf band headsaw and in-line 

 edger and trim saws. Predicted residue yields are given by log size in table 27- 

 151 and by tree size in table 27-152. 



PULP CHIPS 



Pulp chip yield per Mbf log scale, per Mbf lumber scale, per log, and per tree 

 can be estimated from data in the preceding sub-section: SLABS, EDGINGS, 

 AND TRIM. 



Dry yield of wood and bark per green ton of whole- tree chips. — In a study 

 of small hardwoods ( 1 to 5 inches in dbh) growing in the Georgia Piedmont and 

 North Carolina mountains, Phillips and McClure (1976) computed the yields of 

 dry wood and bark that could be expected from one green ton of chips for each 

 species (table 27-153). Yellow-poplar yielded about 850 pounds of dry wood 

 and bark out of 2,000 pounds of green wood and bark; hickory yielded about 

 1,250. The other species were intermediate in yield, with values of 1,000 to 

 1 ,250 pounds. (Details on the sample trees used in this study are given in tables 

 7-3 and 16-7). 



Wood and bark content of whole-tree chips. — Whole-tree chips from abo- 

 veground, foliage-free portions of northern red oak and yellow-poplar trees are 

 about 84 percent wood and 16 percent bark (Clark 1978). Bark content of whole- 

 tree chips of other species can be approximated from data in sections 1 3-3 and 

 16-1. 



Chip bulk density. — See tables 16-44 and 16-44 A with related discussion in 

 section 16-3. 



SAWDUST 



Circular saws produce more sawdust than handsaws, which have thinner 

 kerfs. For example, when yellow-poplar was sawn into 4/4 lumber with a 3/16- 

 inch-kerf band headsaw, sawdust averaged 12 to 13 percent of log green weight, 

 regardless of log size (table 27-150). Similarly, black oak of all diameters sawn 

 with a thin-kerf band headsaw yielded 10 to 12 percent sawdust (table 27-147). 

 However, when mixed oak logs were processed with a circular saw, sawdust 

 percentages were 17 to 22 (Massengale 1971). 



Sawdust yields from processing trees 10 to 24 inches in dbh are given in tables 

 18-57 through 18-62 for red maple, black oak, chestnut oak, northern red oak, 

 white oak, and yellow-poplar. 



