382 



Forestry Quarterly. 



per acre of fully stocked forest is taken as the basis for calcula- 

 tion (being the average for the life of the trees to maturity for 

 all qualities of forest). This is expressed in cubic feet of stem 

 volume (not all of which is merchantable) got from the few 

 American yield tables (see Appendix, pp. 45-61) supplemented 

 by German yield tables, and weighted roughly according to the 

 species in the growing forests of each region. 



Table XIV.— Estimated Growth per Acre. 



In order to see how the density of our virgin forests compares 

 with the fully stocked forest of the yield tables recourse is taken 

 to a comparison of basal areas (area of tree cross sections). The 

 total basal area (see Appendix, pp. 62-63) for northern virgin 

 forests containing a large percentage of conifers ranges from 75 

 to 200 square feet, averaging about 120; the central hardwood 

 forests from 90 to 150, averaging about 117 square feet; the 

 southern pine forests 30 to 120, averaging 70 square feet; the 

 Rocky Mountain forests 30 to 130, averaging 80 square feet ; and 

 the Pacific coast forests 190 to 240, averaging 220 square feet. 

 These basal areas, when compared with Quality II 80-year white 

 pine in New England (see Appendix, p. 64, for normal yield table, 

 basal areas and increments), with 242 square feet per acre; paper 

 birch. Quality I, 60 years, in New England, with 120 square feet ; 

 loblolly pine in Texas, at 40 years, with 126 square feet ; second- 

 growth hardwoods in the Southern Appalachians, with 140 

 square feet. Norway spruce 120 years old, in Germany, with 288 

 square feet; beech with 192 square feet; and Scotch pine with 

 212 square feet, show that our virgin forests, even of the best 

 grades as selected and of much greater age than the normal forests 



