86 PRACTICAL FOREST MANAGEMENT. 



It will be seen that the proper spacing of sal of 4^' girth is 75 

 trees to the acre and that a crop of 5' trees will average 60 to the 

 acre. It is therefore evident that in order to preserve the coppice, 

 if this is a sine qua non of the management, the number of 

 standards must at some stage in the rotation be reduced to about 

 30 per acre so as not to occupy more than half the crown space of 

 the canopy. 



The following are the essential points which must be attended 

 to by the management :- 



(1) The maintenance of the balance between the standards 



and the coppice, both being considered as of equal 

 importance. Consequently the area occupied by the 

 spread of the crowns of the standards should not exceed 

 half the crown space available. 



(2) The correct distribution of the age classes of the standards. 



The rotation of the'standards is a multiple of that of the 

 coppice and each age class of standards should occupy 

 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 established 

 than at the end of the rotation, because each indivi- 

 dual tree occupies more space with increase in age. 

 In order to keep the area occupied by the standards of 

 a given age approximately constant, it is necessary to 

 redilbe their number occasionally. 36 



(3) It may be necessary to start with a large number of 



standards as a protection from frost. If so, these must 

 be reduced to the normal number indicated above as 

 soon as they have fulfilled their object of a forest 

 protection overwood. In certain oases standards are 

 principally retained as a frost protection as in the 

 Nawadia Working Circle of Pilibhit, in which latter case 

 they are removed altogether after 10 years. 37 



36 Practice of Silviculture HAWLEY. 



17 Working flan for 'Pillthii dioiiion HALL. 



