112 Forestry Quarterly 



them, but offers some provisory ones collected by the Swiss 

 Experiment Station on six experimental areas in spruce and fir, 

 each representing characteristic types. 



"How large the ideal or normal stock to be attained should be 

 in order to produce the quantitatively and qualitatively highest 

 sustained increment, we do not dare decide." "The methode du 

 controle assumes for the main stand (over 8 inch), say 6,100 cubic 

 feet total wood per acre or 5,000 cubic feet timberwood, of which 

 20 per cent, of 8-14 inch, 30 per cent, of 16-22 inch, 50 per cent, of 

 24-inch and over." Whether, when and how far this is correct, 

 is still open to question. Comparing with the experimental areas 

 we find that 50 per cent, of stoutest wood is attainable only on 

 best sites. Stands on poor sites cannot come up to this require- 

 ment even with the highest practicable rotation. On medium 

 sites, the experimental areas show about 29, 50, 21 per cent, for 

 the three sizeclasses, and if the five sizeclasses as above are taken 

 the percentages run Z.Z, 10, 28.7, 45, 13, showing very much higher 

 percentages than the 120-year spruce forest in the stouter size- 

 classes. 



If these figures represent what normally shoidd be in the normal 

 stock of the selection forest, the reviewer would conclude that it 

 is capital-expensive, but the author does not draw such conclusion, 

 declaring merely that the selection forest is characterized by sawlog 

 and stoutwood production and that "even on poor sites the selec- 

 tion forest can produce percentically as much or more stoutwood 

 as the best spruce forest in even-aged timberforest," which may 

 be readily granted. 



Finally, the author exhibits the error in the formula of the use 



per cent. p=100 — , which by substituting n'X:^ for ns becomes 



p = . This would mean that the use per cent, is equally large 



for all species, which cannot be right, since the different species 

 differ in the rate of increment, so that even with the same rotation 

 the relation of ri to ns varies from species to species. But by 



100 



substituting ns = riXcr, formula becomes p = — which takes 



care of the specific character of each species. 



From the tabulation of use per cents, figured in this way we 

 see that for spruce, fir and beech for 100-120-year rotation the use 



