CLEAR CUTTING IN HIGH FOREST. 



Now r x i = volume of oldest age gradation and also 

 = to increment of all gradation in one year, which may be 

 placed = J, then : 



r@ n = L x r + 7 . This is for autumn. 



2 2 



For spring there would be : 



r rxri ri Ixr I 



a2 a 3 - 



For summer, the arithmetical mean of the two : 



G.-1" 



The normal growing stock is, therefore, equal to the volume 

 of the oldest age gradation multiplied by half the number of 

 years in the rotation, or equal to the total increment of one 

 year multiplied by half the number of years in the rotation. 



Example. Data as above ; rotation = 100 years, then : 



For autumn O. = - -+ = 281, 790 cubic feet. 



4 A 



5580x100-5580 Or7 /. -m 

 spring G n = -- - -- -__ = 276,210 



n 5580 x 100 Or70 nAr1 



,, summer G n = -- =279,000 



The forest treated under a rotation of 80 years would 

 have : 



For summer *>G n = 495 X 8Q x ^ = 247,500 cubic feet, 

 & oO 



or less than above. 



It will be seen that the normal growing stock calculated by 

 the mean annual increment is smaller than that calculated 

 from a yield table. This is, however, by no means always the 

 case. Taking, for instance, the data in the table at page 190, 

 and calculating the normal growing stock for various rotations, 

 and a number of acres equal to the number of years in the 



