PROJECTED TIMBER SUPPLIES 1970 LEVEL OF MANAGEMENT 



49 



Table 34. — Components of growing stock removals in the United States, 1952, 1962, and 1970, with projections 



to 2020 



[Percent] 





Component 



1952 



1962 



1970 



Projections 





1980 



1990 



2000 



2020 



Roundwood products 



SOFTWOODS 



85 



11 



4 



86 



10 



4 



87 



10 



3 



88 

 8 

 4 



89 



7 

 4 



90 

 6 

 4 



90 



Logging residue . . -- 



6 



Other removals 



4 









Total removals 



100 



100 



100 



100 



100 



100 



100 





HARDWOODS 





Roundwood products 



63 

 20 

 17 



57 

 14 

 29 



63 

 15 

 22 



81 



13 



6 



83 



12 



5 



85 



11 



4 



87 



Logging residue. ._ -- - - 



9 



Other removals 



4 









Total removals. . 



100 



100 



100 



100 



100 



100 



100 







percent by 2000 (table 32 and fig. 20). Under the 

 cutting assumptions outlined earlier, net growth 

 continues to exceed removals until reaching ap- 

 proximate balance in the year 1990. 



Xet growth of hardwood growing stock in- 

 creased in the 1952-70 period to 7.9 billion cubic 

 feet, a rise of 30 percent. However, because of the 

 heavy stocking attained in most hardwood stands, 

 projected net growth rises only 4 percent more by 

 1980. Xet growth in cubic feet is projected to 

 decline slightly thereafter as a result of heavy 

 stocking attained under the specific management 

 assumptions of this section and assumed loss of 

 forest land to other uses. 



Estimates of mortality, under the assumption 

 of 1970 levels of management, change relatively 

 little during the projection period. Mortality is in 

 considerable part a reflection of the inventory of 

 old-growth timber held over the projection period. 



For softwoods, mortality is projected to rise 

 slightly from 2.8 billion cubic feet in 1970. Hard- 

 wood mortality also is estimated to rise with 

 increasing stand densitv from 1.7 billion cubic 

 feet in 1970 (table 32). Mortality of softwood 

 sawtimber, amounting to 11.3 billion board feet 

 in 1970, is estimated to decline somewhat over 

 the projection period as old-growth timber stands 

 are harvested. 



Trees killed by destructive agents are for the 

 most part widely scattered, and it is assumed 

 that only a small portion of these losses will be 

 salvaged for roundwood products unless manage- 

 ment is substantially intensified. 



Supplies of Roundwood Products 



In addition to roundwood products cut from 

 growing stock, some logs and bolts also are pro- 



duced from other sources, including salvaged dead 

 timber, sections of rough and rotten trees, and 

 trees growing on noncommercial and nonforest 

 lands. Estimated volumes of roundwood products 

 in board feet also include an increasing volume of 

 saw logs from trees having smaller diameters than 

 specified in the standard definition of sawtimber. 

 Increased harvesting of such timber is anticipated 

 as thinning operations expand and new chipping 

 headrigs become more common in the sawmill 

 industry. 



Xongrowing stock sources provided 7 percent of 

 the total output of softwood roundwood products 

 in 1970, and 16 percent of all hardwood products 

 (table 32). Many of the trees available from these 

 sources are relatively high-qualitv trees of species 

 such as walnut growing along fence rows or in 

 narrow strips of forests along streams. 



In recent decades, volumes of softwood products 

 from nongrowing stock sources has partially offset 

 volumes of logging residues and other removals, 

 and consequently roundwood production has not 

 differed greatly from growing stock removals 

 (table 32). In the case of hardwoods, however, 

 roundwood production has been much less than 

 removals. 



Under the particular assumptions of these base 

 projections, estimates of available roundwood 

 supplies in cubic feet of softwoods rise 28 percent 

 between 1970 and 2000, from 9.0 billion feet to 

 11.5 billion cubic feet. For hardwoods, projected 

 volumes of available roundwood products that 

 could be harvested under the assumptions of this 

 section rise from 3.2 billion cubic feet in 1970 to 

 7.4 billion cubic feet by 2000 — a rise of 131 percent. 



In the case of sawtimber size material measured 

 in board feet, prospective increases in available 



