THE CHANGING FOREST INVENTORY 



23 



lar significance is another aspect of the hardwood 

 problem: the replacement of more desired hardwood 

 species with less desired species. 



Current sawlog cutting shows a marked preference 

 for the higher-value species. Lower-value species are 

 cut only if they are of good quality, whereas high-value 

 species are cut heavily even in the lower grades. Such 

 differences in logging can only result in the displace- 

 ment of more desired by less desired species. 



Tree Size 



One of the most significant aspects of the changes in 

 volume which have occurred since 1932—35 is in tree 

 size. Small trees comprise an ever larger portion of 

 the total timber volume. The average size tree in the 

 growing stock (weighted by volume) is now 13 inches 

 for softwoods, 14 inches for hardwoods. 



Changes in tree size are illustrated in figures 22 and 

 23. In softwood species, 2- and 4-inch trees increased 

 a third; 6-inch trees increased about a fifth; 8-inch 

 trees held their own; and the numbers in all larger 

 classes declined. The rate of decline was sharper with 

 increasing diameter, up to 67 percent for 26-inch and 

 larger trees. In hardwood species the story is similar, 

 except that the small trees showed increases in all sizes 

 up through 14 inches and the decreases in larger sizes 

 were less severe than for softwoods. 



Current logging operations in pine stands tend to 

 reduce the stands to smaller tree sizes (fig. 24) . Cut- 

 ting of pine sawlogs, which accounts for 60 percent of 

 the total softwood drain, removes nearly all trees over 

 12 inches d. b. h., on the average operation, and almost 

 three-fourths of the volume in 10- and 12-inch trees. 

 Pulpwood logging, which accounts for 24 percent of 

 the total softwood drain, works down into smaller tree 

 sizes than sawlogs — the average operation removes 

 three-fourths of the pine volume in 6- and 8-inch trees. 



Cutting for pulpwood is apparently lighter in larger 

 tree sizes because most pulpwood chippers are not 

 designed to handle larger timber and because more 

 trees are earmarked for sawlog cutting. Products like 

 hewn ties and fuel wood are not cut so heavily as 

 sawlogs and pulpwood, although they are cut more 

 frequently from particular stands. Not only is the 

 typical pine cutting heavy in regard to volume re- 

 moved, but the bulk of the volume left standing is in 

 trees under 14 inches in diameter. 



Tree size in hardwood stands is being reduced at a 

 slower pace than in pine stands. Hardwood logging, 

 with the exception of fuel wood cutting, is heaviest in 



the large tree sizes; although, unlike pine logging, con- 

 siderations of quality and species lead operators to 

 leave many of the larger hardwood trees found in 

 stands. Nor does hardwood logging ordinarily extend 

 into such small diameters as does pine logging. For 

 example, cutting for sawlogs, veneer logs, and cooper- 



PERCENT 



OF 

 VOLUVE 



VENEER LOGS 



25 



o 





























M 



50 



25 







50 

 25 







GRADE GRADE GRADE 

 1 2 3 



SAWLOGS 

















- 



















■ 



1 2 3 



COOPERAGE BOLTS 











































1 



2 



3 







V::>!.j5S, ::■■■:,:. 



CUT 



H^l LEF- 



r 



















Figure 25. — Quality of timber in hardwood stands before 

 and after cutting for important products, 1947. 



