760 Forestry Quarterly 



As regards rotation, or length of time for calculations, the 

 author claims to have found that 60 years give "the highest profits 

 from the use of the soil for private forestry, while 80 to 100 years 

 is more profitable for government forestry, working with lower 

 interest rates." 



The product of different sites varies more than is usually 

 realized. An extensive study by the Forest Service, unpublished, 

 brings out the fact that in Western Washington and Oregon, for 

 a 60-year rotation in Douglas fir, site I may be credited with 44 M, 

 site II with 32 M (75%), and site III with 16.5 M feet (nearly 

 40% of site I). 



In six tables, the costs for various conditions and ownerships 

 properly calculated are given, item by item, and in three tables 

 the possible reductions from costs due to thinnings are figtu^ed 

 for the three sites. All calculations are for Douglas fir. 



We can give only the totals, which for the six ownership classes, 

 as above, run per M feet : 



Site I 3.37 5.92 7.85 9.91 16.17 26.80 

 Site II 3.61 6.16 8.05 9.87 16.0 26.31 

 Site III 5.80 9.64 12.45 14.01 22.77 37.50 



The strange phenomenon that the cost on II site differs only 

 slightly from that on I site, and with high interest rates is even less, 

 is explained by the much lessened interest charge on the lower soil 

 value, so that costs are more reduced than yield, while on III site, 

 in spite of reduced cost on low soil values, the great decrease in 

 yield brings the cost far above the other sites. Natural regenera- 

 tion is here suggested as a way out (on sites on which natural 

 regeneration is probably difficult to manage? Rev.) 



Thinnings — and there is "very little doubt that all thinnings 

 from young stands originated now or hereafter may be utilized 

 because even now demands for pulp wood, ties, and mine timbers 

 are capable of using all this type of timber within easy reach of 

 transportation" — figure in quantity in the same proportionate re- 

 lation as the main yields (11:8:4), but the values, owing to smaller 

 sizes on the lower sites, will be less ; the total amounts on site II 

 being assumed as one half, on site III as one third of that on 

 site I. But the saving on cost due to thinnings per M feet figures: 



Site I 62 75 79 87 102 123 cents 

 " II 42 50 55 59 71 85 " 



" III 55 65 70 77 91 109 " 



