TIMBER SUPPLY OUTLOOK 



477 



time expand the above concept of growth capacity. 

 For example, growth can no doubt be greatly 

 increased by forest genetics and by application of 

 growth-increasing substances which are still in 

 experimental stages. Thus, ultimate capacity 

 cannot yet be clearly foreseen. 



A more realistic rung on the ladder of growth 

 capacity results from the concept of "realizable 

 growth." This is the total national growth that 

 could be attained if the present area of commercial 

 forest land in each region were placed under the 

 better forest management in effect today in each 

 region. Being a more practical concept of ca- 

 pacity, realizable growth is useful in judging the 

 possibility of supplying mounting future demands 

 for timber and in determining sources of needed 

 growth by species groups. 



Realizable growth of saw timber is 100.7 billion 

 board -feet (table 281). This is about twice the 

 net growth of 47.4 billion board-feet for 1952. 

 Realizable growth of growing stock is also about 

 double the net growth of 1952. Thus, realizable 

 growth occupies a position on the ladder of 

 growth capacity well above current growth but 

 considerably below the estimates resulting from 

 the concepts first discussed. 



Eastern softwoods account for 40 percent of 

 the realizable growth of saw timber with eastern 

 hardwoods and western species each producing 

 about 30 percent. About 70 percent of realizable 

 growth of sawtimber consists of softwood species. 

 In terms of growing stock, eastern hardwoods 

 account for 37 percent of realizable growth, eastern 

 softwoods 35 percent, and western species 28 

 percent. 



Table 281. — Realizable growth and 1952 growth 

 oj sawtimber and growing stock, by species 

 groups, United States and Coastal Alaska 





Realizable 

 growth 



1952 

 growth 



Species group 



Saw- 

 timber 



Grow- 

 ing 

 stock 



Saw- 

 timber 



Grow- 

 ing 

 stock 



Eastern hardwoods 



Eastern softwoods 



Western species ' 



Billion 



bd.-ft. 



30. 5 



39. 6 



30. 6 



Bil- 

 lion 

 cu. ft. 

 10. 2 

 9.7 

 7. 6 



Billion 



hd.-ft. 



19. 1 



17.0 



IL 3 



Bil- 

 lion 

 cu. ft. 

 7.0 

 4. 4 

 2.8 



All species 



100.7 



27.5 



47. 4 



14.2 



■ Realizable growth includes 0.5 bilHon board-feet of 

 hardwood sawtimber and 0.3 billion cubic feet of hard- 

 wood growing stock; 1952 growth includes 0.3 billion 

 board-feet of hardwood sawtimber and 0.1 billion cubic 

 feet of hardwood growing stock. 



TIMBER GROWTH AND INVENTORY 

 NEEDED TO SUSTAIN PROJECTED 

 DEMANDS 



The volumes of live sawtimber and growing 

 stock that must be cut to supply the various 

 levels of demand in 1975 and 2000 were presented 

 in the section Future Demand for Timber. The 

 next step in exploring timber outlook is to estimate 

 the growth and inventory needed to sustain 

 lower and medium projected demands on a 

 permanent basis. Before introducing these 

 estimates, however, the concepts of "timber 

 removal" and "needed growth" and their rela- 

 tionship will be discussed as an aid in the inter- 

 pretation of later comparisons. 



Timber removal includes the timber cut from 

 the live inventory to supply estimated demands 

 and a margin to allow for natural catastrophes 

 and other contingencies. Needed growth and 

 inventory are those quantities needed to perma- 

 nently sustain timber removal. On a national 

 basis, timber removal and needed giowth are 

 synonymous. But when species groups are con- 

 sidered separately, timber removal and needed 

 growth are different quantities because ability to 

 support removal throughout the projection period 

 differs from growing capacity". For example, 

 western species with 70 percent of the national 

 sawtimber inventory and 30 percent of realizable 

 growth capacity are capable of supplying, for the 

 next half century, a higher proportion of the total 

 timber removal than of needed growth. 



National total timber removal of hardwoods 

 and softwoods is apportioned separately to 

 eastern hardwoods, eastern softwoods, and M'estern 

 species in accordance with the ability of each 

 species group to support removal during the next 

 half century with least impairment of prospects 

 for future growth. Needed growth is determined 

 by an apportionment of the same national timber- 

 removal estimates in accordance with realizable 

 growth of the species groups. 



Timber Cut Accounts for Most of 

 Timber Removal 



The timber cut needed to supply estimated 

 demands accounts for most of the timber that 

 would be withdrawn from inventory. However, 

 there are additional withdrawals not considered 

 in other calculations in this report that must be 

 recognized. For example, since 1900 the average 

 annual loss from natural catastrophes has been 

 2.3 billion board-feet, 13 percent of which was 

 salvaged. Although some progress may be made 

 in salvaging future catastrophic losses, the diffi- 

 culty of recovering substantial amounts before 

 spoilage means that net withdrawals are to be 

 expected in the future. 



