24.5 



CHAPTER VL 



RELATIONS BETWEEN INCREMENT, GROWING STOCK AND YIELD. 



BETWEEN the increment, growing stock and yield of a normal 

 forest relations exist, which are of great importance in deter- 

 mining the yield. In order to bring them out clearly, the 

 system of clear cutting in high forest will be used as an illus- 

 tration ; it will, in the majority of cases, also be assumed that 

 the current annual increment is equal to the final mean annual 

 increment. 



1. Allotment of Increment during a Rotation. 



Every normal series of age gradations contains, at the com- 

 mencement of the rotation, the normal growing stock. Every 

 year the oldest age gradation is cut over, which gives the normal 

 annual yield, and this yield is replaced during the following 

 growing season by the laying on of the normal increment. 

 The latter is laid on partly on the old growing stock, and re- 

 moved with it during the first rotation ; but partly it accumu- 

 lates on the cleared areas, forming a new growing stock, which 

 is carried over into the second rotation. The question then 

 is, how much of the total increment of one rotation is added 

 to the old growing stock, and how much to the new. 



Making the calculation for spring, the youngest age gradation 

 is years old, and the oldest r 1 years. The former grows 

 for r growing seasons, and is cut over during the last winter of 

 the first rotation, so that all its increment is removed during 

 the first rotation ; hence, all goes to the old growing stock, 

 and nothing to the new stock. The gradation now one year 

 old grows for r 1 years during the first rotation, when it is 

 cut over. All the increment laid on during these years goes 



