21( 



THE NORMAL AGE CLASSES. 



Immediately before cutting, the arrangement would be as 

 follows : — 



It will be seen, that a normal coppice with standards forest 

 must have an overwood, which consists of f X r = H age 

 gradations ranging from 1 year up to li years old. 



Example. — A forest of 200 acres, worked under a rotation of 

 20 years for the underwood, and 100 years for the overwood, 



has -— - = 5 overwood classes. On the 10 acres which are 



zo 



about to be cut, will be found — 



Underwood = 20 years old 



Overwood = 20, 40, 60, 80 and 100 years old. 



The next oldest coupe contains — 

 Underwood := 19 years old 

 Overwood = 19, 89, 59, 79 and 99 years old. 



The youngest coupe contains — 

 Underwood = 1 year old 

 Overwood = 1, 21, 41, 61 and 81 3'ears old. 



The appended figure, 47, illustrates the distribution of the 

 several age gradations over the area. 



The area occupied by each overwood class can be determined 

 only by assuming, that each gradation occupies an equal 

 extent of ground ; hence, the youngest gradation will have most 

 trees and the oldest least. Imagining now, that the age classes 

 of the overwood were not intermixed, but that the trees of each 



