232 



A NATIONAL PLAN FOR AMERICAN FORESTRY 



TABLE 23. Theoretical future growth under the hypothetical allocation of areas 

 to types of management given in table 22 



The growth rates used in this calculation were derived from detailed 

 consideration of present growth and future yield capacities for the 

 principal timber types in each region. The areas relatively unfavor- 

 able for forestry as a rule are characterized by poor growing condi- 

 tions. Nevertheless, in recognition of the fact that some may become 

 a factor in timber supply, a nominal growth rate was applied. The 

 present average growth of 21 cubic feet per acre for the 432 million 

 acres of present commercial forest land now in productive condition 

 was applied to those relatively favorable areas allocated to simple 

 protection. In the areas allocated to extensive forestry the growth 

 rate averages about 42 cubic feet per^acre, while on the intensive 

 forestry area the average rate for all regions is about 67 cubic feet. 



The estimated future annual growth for the entire 508.6 million 

 acres, on the basis of the assumed allocations to the several types of 

 management is 17,755 million cubic feet. The distribution of this 

 growth, in comparison to present growth, is shown in figure 19. The 

 saw timber equivalent of this total growth is estimated to be about 

 60 billion board feet. 



Among the requisites for attaining and maintaining such a yield 

 is the establishment of forest growing stock adequate in character 

 and amount. The minimum growing stocks which would be required 

 to sustain a yield equal to the growth shown in table 23 on a saw- 

 timber basis, with uniform rotations as assumed in table 21, is 

 presented in table 24. As a matter of interest there is also included 

 in table 24 the total volume of the existing stands. 



