134 THE COPPICE WITH STANDARDS METHOD 



the several age classes of standards which will be present. If, 

 for example, 0.5 of the area is allotted to standards and there 

 are five age classes of standards on a rotation of 120 years, 

 with a coppice rotation of 20 years, then o.i of the area 

 should be occupied by the standards of each age. Each age 

 class of standards occupies the same area as it increases in 

 age throughout the rotation. As a necessary corollary each age 

 class of standards must contain more trees when first estab- 

 lished than at the end of the rotation, because each indi- 

 vidual tree occupies more space with increase in age. In 

 order to keep the area occupied by standards of a given age 

 approximately constant, it is necessary to reduce their num- 

 ber occasionally. (See Fig. 50.) 



This is done at the time the coppice is cut clear. Where 

 standards are in dense groups overtopped, intermediate or co- 

 dominant trees may be cut in a thinning without decreasing 

 the area filled by the age class, but in addition other standards 

 must be cut, which will actually reduce temporarily the area 

 occupied by that class. 



The relative number of standards at different ages must be 

 worked out for each species and situation. The following 

 illustration for oak in a European forest is cited by Graves^: 



Number of Standards 



100 years old i 



80 years old 2 



60 years old 3 



40 years old 12 



20 years old 20 



A uniform distribution of standards over the area need not 

 be attempted. They may be left singly, wherever desirable 

 trees for standards occur among the coppice, or in groups. 



