236 THE NORMAL YIELD. 



On these 50 acres, the following material is cut : — 



(1.) All trees which have reached the age of 100 years. 



(2.) A certain proportion of trees in the younger age classes, 

 so as to reduce their number gradually to that, which should 

 reach maturity at the age of 100 years. 



These cuttings should give, theoretically speaking, the same 

 yield, as if the area were treated under the clear-cutting 

 system. 



(1. ( 'oiipiri' and Coppire ivith Slanihtrds. 



The normal yield of coppice woods is calculated in the same 

 way as for clear cutting in high forest. In this case, the 



annual cutting area is = - and the volumetric yield is com- 

 posed of the material standing on that area, plus thinnings in 

 the younger age gradations. 



In coppice with standards, the annual cutting area is 

 the same as in simple coppice. The normal annual yield 

 consists of : — 



(1.) The underwood on the oldest age gradation, less those 

 trees which are left to grow into standards. 



(2.) The contents of the oldest, B years old, age gradation of 

 the over wood. 



(3.) The thinnings amongst the younger age gradations of 

 overwood standing on the annual coupe and occasionally hi 

 the younger underwood gradations. 



Example : — 



Taking the data given at page 231, the yield in overwood is 

 as follows : — 



40 trees (mature) 100 years old, each = 50 c' = 2,000 



40 „ 80 ,, ,, ,, = 80 c' = 1,200 



50 „ 60 „ „ ,, - 15 c' = 750 



70 „ 40 „ „ „ = 2 c' = 140 



Total = 4,090 c', 

 to which the volume of the underwood has to be added. 



