8 Forest Management 



ranged in "cutting series." By "proper cutting series" is understood a 

 number of adjoining age classes, sloping roof-like from the older to the 

 younger, toward the windward side. If the cutting series are improper, 

 then sacrifices must be made, hypermature wood must be left, and im- 

 mature wood must be cut unless the mistake originally at hand is 

 allowed to be perpetuated. In the latter case, the losses of the future 

 are apt to be greater than the sacrifices voluntarily made with a view 

 to the establishment of proper cutting series. Cutting series must be 

 isolated one from the other, if need be, by "severance cuttings." 



PARAGRAPH III. 



NORMAL GROWING STOCK. 



The normal growing stock is at hand where the age gradation of the 

 various woods composing the forest and their respective volumes are 

 normal. A forest, however, might have the normal volume without 

 having the normal age gradation, when a deficiency of one age class is 

 offset by a surplus in another age class. The normal growing stock, 

 during summer, has the volume 



r'Xi 



2 



wherein r represents the rotation, and i the average annual increment 

 of a mature age class. 



Illustration: A spruce forest covers 2,000 acres. The rotation is 100 

 years. The mature wood, 100 years old, contains normally 120 cords 

 per acre. Under these conditions, the area of an age class is 20 acres; 

 the average annual increment of the mature age class is 24 cords; and 

 the normal growing stock is 



100 X ioo X 24 



= 120,000 cords. 



2 



The volume of poles and trees predestined to be cut and removed prior 

 to maturity (by way of thinnings) is not included in the volume given 

 by the formula. 



Whilst one normal growing stock is removed, in the course of a ro- 

 tation, another normal growing stock its exact counterpart is raised 

 on the very same area. 



If the original growing stock is abnormally deficient, the foresters, 

 by cutting less than the increment of the forest and thus adding to the 

 original volume, may succeed in gradually establishing the "normal 

 growing stock." 



Normality of the growing stock is that condition required in an 

 "ideal forest," which the foresters would find it rather easy to pro- 

 vide. In the virgin woods, frequently the actual growing stock is 

 larger than the normal growing stock, owing to the preponderance of 

 mature and hypermature age classes. 



