288 



CHAPTEPi YI. 



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 hring them out clearly, the 

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

 tration. 



1. Allotment of Increment during a Ilotation. 



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

 mencement of the rotation, the normal growing stock. Every 

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

 final annual yield, and this is replaced during the following 

 growing season by the laying on of the normal increment. 

 The latter is added, partly to 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 the total increment of one rotation is divided between 

 the two. 



Making the calculation for spring, the youngest age gradation 

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

 for ;• 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 y— 1 years during the first rotation, when it is cut 

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

 old growing stock ; but that laid on during the last year is not 

 cut, but goes over to the second rotation. The gradation, now 



