112 



TIMBER TRENDS ENT THE UNITED STATES 



cutting rates by diameter classes as estimated 

 from available survey measurements. Cutting 

 rates by diameter classes were derived in some 

 cases from permanent plots on which tallies 

 showed the proportion of tree sizes cut between 

 inventories. In other cases cutting rates were 

 obtained from stump counts taken at the time of 

 inventories, or from utilization studies on sample 

 logging operations. In addition to these vari- 

 ables the projection procedure requires estimates 

 of numbers of trees growing into the 2-inch 

 diameter class each year. 



This projection procedure also provided for 

 annual or periodic modification of these input 

 variables in response to prospective changes in 

 stand conditions resulting from the expected 

 development of stands or from changes in manage- 

 ment or cutting assumptions. Thus modifications 

 in net growth rates to reflect changes in prospec- 

 tive basal area, mortality, and ingrowth, for 

 example, were made throughout the projection 

 period. 



CUTTING ASSUMPTIONS 



The total volume of sawtimber cut each year 

 of the projection period was established for each 



section and region by a judgment allocation of 

 the projected "timber cut" for the United States 

 described in the section on The Outlook for 

 Timber Demands. These allocated cuts, shown 

 in tables 74 and 75, were based upon such factors 

 as past trends in output of timber products and 

 other considerations, as follows: 



(1) In the Pacific coast section, it was assumed 

 that the presently estimated allowable cut on 

 national forests and other public lands, and the 

 estimated prospective cut on private lands based 

 on past trends in cutting and anticipated changes 

 in growth and inventories, would be fully utilized 

 over the projection period. 



(2) In the Rocky Mountain section, it was 

 assumed that cutting on the national forests 

 would rise to about 90 percent of the prospective 

 allowable cut by 1980 and to 100 percent by the 

 year 1990. For other public and private lands 

 an estimate was made of the prospective cut 

 based on trends in cutting and available 

 inventories. 



(3) In the East, the projected cuts of softwoods 

 and hardwoods for all ownerships combined were 

 calculated as residuals by deducting the allocated 

 cuts for western sections from the total national 



Table 75. — Growing stock cut in the United States, by sections, 1952-2000 



[Billion cubic feet] 



Section 



1952 



1962 



Allocated cut 





1970 



1980 



1990 



2000 • 



Pacific coast: 



National forest 



0.5 



2.8 



1.2 

 2.4 



1.4 



2.7 



1.4 



2.8 



1.4 

 2.9 



1.5 



Other owner 



3.2 



Total 



3.3 



3.6 



4.1 



4.2 



4.3 



4.7 



Rocky Mountains: 

 National forest 



.2 

 .2 



.3 

 .3 



.5. 

 .3 



.7 

 .4 



.8 

 .4 



.8 



Other owners 



.4 



Total 



.4 



.6 



.8 



1.1 



1.2 



1.2 



South: 



Softwoods- 



3.1 

 2.0 



2.5 

 1.7 



2.7 

 1.9 



3.6 

 2.2 



5.1 



2.8 



7.4 

 3.7 



Hardwoods 



Total 



5.1 



4.2 



4.6 



5.8 



7.9 



11.1 



North: 



Softwoods 



Hardwoods ... 



.7 

 1.3 



.6 



1.1 



.5 



1.5 



.6 



2.0 



.9 

 2.6 



1.2! 

 3.4i 





Total.. 



2.0 



1.7 



2.0 



2.6 



3.5 



4.6. 





United States: 



Softwoods. _ . 



7.5 

 3.3 



7.2 

 2.9 



8.0 

 3.5 



9.4 

 4.3 



11.4 

 5.5 



14.4 



7.2 



Hardwoods 



Total 



10.8 



10.1 



11.5 



13.7 



16.9 



21.6 





