494 



TIMBER RESOURCES FOR AMERICA'S FUTURE 



ing demands of either medium or lower levels 

 until 2000, they are large enough to supply the 

 timber removal needed to meet medium level 

 demands through 1975 and lower level demands 

 through 2000. However, this would be at the 

 cost of inventory changes leading to limited sup- 

 plies and increasing difficulty in reaching needed 

 adjustments later on. 



Expected Trends in Quality 



Projections of the future timber supply are in- 

 complete if confined solely to consideration of 

 volume. Quality should also be considered, but 

 quality is more difficult to express in concrete 

 terms than volume. The reason is that (a) 

 standards of quality are numerous and vary 

 widely for the many products made of wood, and 

 (b) basic information on quality of current in- 

 ventory and growth is limited compared to 

 information on volume. Notwithstanding, sur- 

 veys in some regions and States have included 

 quality considerations that provide a basis for 

 general consideration of future trends. 



In the Lake States and South Atlantic regions, 

 and in Mississippi, surveys of the 1930's were 

 followed by similar surveys in the late 1940's and 

 early 1950's. The commercial forest land in 

 these three areas is 116 million acres or about 31 

 percent of all commercial forest land in the East. 

 In each area the proportion of sawtimber volume 

 in the smaller tree sizes increased between surveys. 

 This trend was contributed to by a concentration 

 of the timber cut on the larger, better quality trees 

 because of their higher values and lower operating 

 costs per unit of volume output. With some 

 exceptions, subsequent cutting has been done 

 prior to full replacement by growth of the previous 

 size and quality of trees. Thus, the larger and 

 better quality trees available at the time of each 

 subsequent cutting are smaller and of poorer 

 quality than previously. The result is harvest of 

 successively smaller sizes at each repeated cut. 



Current inventories of both eastern softwoods 

 and eastern hardwoods are characterized by large 

 volumes in small trees and poorer log grades 

 which have limitations for the production of 

 important end products. Many of these smaller 

 trees are free of defects and will improve in quality 

 if trends toward cutting successively smaller sizes 

 are modified. 



Another trend affecting the quality of forest 

 stands in some areas of both the East and the 

 West is the natural replacement of preferred 

 species by less useful species. Factors responsible 

 for these trends, operating singly or in combina- 

 tion, are fire, insects, disease, and cutting. Al- 

 though these factors sometimes affect species 

 composition favorably, available evidence indicates 

 a gradual trend toward reduced supplies of the 

 preferred species. 



Cull trees are a large overburden of useless 

 material in eastern hardwood forests. Character- 

 istically, they remain standing through successive 

 cuttings of sound trees, and continued retention 

 of them restricts future possibilities for both 

 volume and quality production. In contrast, 

 cull trees are much less prevalent in softwood 

 stands of both the East and West. 



The ctirrent inventory of western species, with 

 50 percent of the volume in trees 32 inches in 

 diameter and larger, still contains much high- 

 quality material. But trends toward smaller 

 sizes and poorer quality are present although less 

 pronounced than for eastern species gi-oups. 



Under medium level demand assumptions, re- 

 moval of eastern softwood sawtimber would be 

 slightly less than projected growth' in 1975 but 

 would greatly exceed projected growth later in 

 the century (table 295). This relation between 

 timber removal and projected growth in 2000 is a 

 strong indication that economic factors would 

 favor the continued cutting of successively smaller 

 trees, which would result in further declines in 

 quality. 



Under lower level demands, timber removal of 

 eastern softwoods would be less than projected 

 growth in 1975 but would be slightly greater than 

 projected growth in 2000. This comparison indi- 

 cates a decline in quality but at a much slower 

 rate than would occur under medium level 

 demands. With timber removal substantially 

 less than projected growth in 1975, some tempo- 

 rary halt in declining quality trends might occur. 

 Any temporary change, however, would not likely 

 add substantial supplies of quality timber, because 



Table 295. — Timber removal and projected growth 

 of sawtimber in 1975 and 2000, by levels of demand 

 and species groups 





1975 



2000 



Demand level and 

 species group 



Tim- 

 ber re- 

 moval 



Pro- 

 jected 

 growth 



Tim- 

 ber re- 

 moval 



Pro- 

 jected 

 growth 



Medium level: 



Eastern hardwoods. _ 



Eastern softwoods 



Western species 



Billion 



bd.-ft. 



18.4 



18. 1 



31.7 



Billion 



bd.-ft. 



22. 6 



20. 1 



15.9 



Billion 



bd.-ft. 



29. 4 



33.2 



42. 8 



Billion 

 bd.-ft. 

 12. 2 



(') 

 13.0 



All species 



68.2 



58.6 



105. 4 



25. 2 



Lower level: 



Eastern hardwoods. . 



Eastern softwoods 



Western species 



15.7 

 15.7 

 27.4 



24. 1 

 20. 7 

 16.3 



22. 2 

 24.9 

 32.2 



25. 6 

 23.0 

 18. 1 



All species 



58.8 



61. 1 



79.3 



ea 7 



Negligible. 



