THE THEORY AND PRACTICE OF WORKING PLANS 13 



Hunger's formula is undoubtedly well adapted for selec- 

 tion forest. 



Fischer * has suggested the following modification of the 

 formula for normal growing stock when applied to reproduction 

 cuttings : 



wz) = (initial gr. stock+final gr. stock) X—^ — — ^- -X.5. 



The last figure varying according to the crown density. 



For example: A pine forest which contains, on one acre, 

 14,600 board feet at rotation age (160 years) is cut by shelter- 

 wood method so that 66 per cent of the volume is removed 

 during a twenty-year period of reproduction, whereby the density 

 is reduced to .5. Substituting: 



20 



W2; = (14,600 -f48i8)X — X.5 

 2 



= i9,4i8XioX.S 



= 194,180 X.5 



, 20 

 = 97,090 for — years 

 2 



= 9709 board feet for any one year, per acre. 



By formula: 



, ^14,600 

 . 160 X—^^- — 



nv=—= = 7300 board feet per acre. 



2 2 



TIT I \ 



Strzeleckis proposed f to figure nv = -\V — I — Vt\ where 



2\ 2 2 / 



r- = volume at \ rotation age and Fr = volume at rotation age. 

 2 



* AUgemeine Forst- und Jagd-Zeitung, March, 1914, pp. 100-102, briefed 

 For. Quart., Vol. XII, No. 2, pp. 279-280. 



t AUgemeine Forst- und Jagd-Zeitung, 1884, p. 88, p. 316. 



