476 



TIMBER RESOURCES FOR AMERICA'S FUTURE 



likely to be as reliable as those that appraise the 

 current situation. This is because there are gaps 

 in the knowledge of how timber growth is affected 

 by a given degree of forestry effort, and profes- 

 sional judgment and estimation must be relied 

 upon m projecting net growth. Timber cut, too, 

 introduces uncertainties since it has been projected 

 on the basis of assumed trends in population, gross 

 national product, degree of utilization, etc. These 

 uncertainties become much greater when applied 

 to individual species or to States or regions than 

 when applied to national totals. 



Because the projections are suitable for general 

 rather than detailed interpretation, the data from 

 them are presented in broad classifications. For 

 example, species and locality are combined in the 

 following; eastern hardwoods, eastern softwoods, 

 western species. Projections of inventory, net 

 growth, and timber cut are presented for those 

 three groups rather than for softwoods and hard- 

 woods bj' State and region. 



The elimination of detailed classifications still 

 leaves problems of unusual complexity. For ex- 

 ample, projection requires consideration of two 

 future benchmarks in time — 1975 and 2000. Two 

 levels of demand are compared — medium, and 

 lower. The four important comparisons intro- 

 duced by the time element and by demand are 

 multiplied many times by consideration of (a) the 

 three species-geographic groups; (b) two broad 

 size-class groups, gi-owing stock and sawtimber, 

 each with a different unit of measure; and (c) net 

 growth and inventory in terms of amounts needed 

 to support demand and also in terms of amounts 

 available if demands continue to be met. Thus, 

 presentation of the timber outlook even in broad 

 perspective involves a complicated pattern of 

 estimates and comparisons. 



The following estimates are presented here : 



1. The capacity of the 489 million acres of com- 

 mercial forest land in this country to grow timber. 



2. The volume of timber which would be re- 

 moved from inventory each year to meet medium 

 and lower levels of projected demand plus an 

 allowance for removals due to catastrophes, and 

 conversion of commercial forest land to other uses 

 and unanticipated new uses for wood, none of 

 which have been accounted for elsewhere. This 

 is called "timber removal." 



3. The growth necessary to sustain timber 

 removals in 1975 and 2000 is also estimated; it is 

 referred to as "needed growth." 



4. The volume of live standing timber necessar}^ 

 to produce the "needed growth" is also presented 

 and is called "needed inventory." 



5. The net growth expected in 1975 and 2000 

 if (a) the timber removals of each year increase 

 steadily to meet the rising demand and (b) forestry 

 efforts continue to increase as indicated by recent 

 trends. This is called "projected growth.' 



6. The inventory expected in 1975 and 2000 if 

 (a) the timber removals of each year increase 

 steadily to meet the rising demand and (b) forestry 

 efforts continue to increase as indicated by recent 

 trends. This is called "projected inventory." 



7. The timber removal that could be sustained 

 if an approximate balance between removal and 

 gi'owth was reached and maintained. This is 

 referred to as "sustained removal." 



These estimates are used for comparisons be- 

 tween the supplies of timber needed to meet 

 future requirements and the supplies likely to be 

 available if demands are met every year and if 

 forestry progresses as indicated by recent develop- 

 ments. The supplies needed in the future and 

 those expected to be available are also compared 

 with 1952 supplies to provide additional perspec- 

 tive on trends. These estimates and comparisons 

 give a basis for judgment as to the relative ease or 

 difficulty of supplying demands in the years ahead. 



Projections of supply for the upper demand 

 level are omitted. Later discussion in this section 

 shows that if only the medium projected demands 

 were actually supplied each year to 1975, inven- 

 tory and gi'owth would decline so far that de- 

 mands at this level could no longer be met late in 

 the century. The intensity of forestry needed to 

 prevent this downward supply trend and to build 

 up the growth and inventory needed to sustain 

 medium projected demands is far beyond the 

 intensity expected from continuation of recent 

 forestry trends. Consequently, projections of 

 growth and inventory in relation to upper de- 

 mands would add little from a practical standpoint 

 to the outlook presented by projections at the 

 medium and lower levels. 



GROWTH CAPACITY MUCH HIGHER 

 THAN CURRENT GROWTH 



Benchmarks of the growth that our commercial 

 forest lands could produce are useful in appraising 

 the possibilit}^ of supph^ing needed growth. 



Growth capacity for the United States and 

 Coastal Alaska may be viewed as a series of 

 levels, like the rungs of a ladder, the uppermost 

 of which can be perceived only dimly. For 

 example, if the average growth of the most pro- 

 ductive timber stands known today for each 

 forest type and site were extended to all com- 

 mercial forest land in each type and site class, 

 with appropriate consideration given to distribu- 

 tion of age classes, an annual growth of 50 billion 

 cubic feet, including 200 billion board-feet of 

 sawtimber, might be attained. This concept of 

 growth capacity is highl}^ theoretical, and it 

 results in an estimated volume of growth that 

 is probably not attainable under present limita- 

 tions in forestry knowledge. On the other hand, 

 new scientific developments may at some future 



