114 



THE THEORY AND PRACTICE OF WORKING PLANS 



The distribution of the age classes (see age-class table, 

 Chapter I, Section 2) shows a considerable abnormality, as 

 follows : 



The rotation is 160 years; the total area 710 acres exclusive 

 of natural blanks, and the protective belt of selection forest 

 (see foot-note p. 113). 



Despite the abnormality, the annual cutting area is here 

 calculated for the sake of an example, e.g., by method No. i, 



A V TO 



variation I, the annual cutting area = — = -^=4.43215 acres. 



r 100 



For ten years = 44.3125 acres. 



The cutting for the next ten years would, therefore, be con- 

 fined entirely to compartment gb. 



But where stands are so irregular in age classes, site quality 

 and density of stocking, it is not well to resort to area as the 

 regulating factor, but rather to use some volume method, such 

 as Heyer's, of comparison with the normal growing stock 

 (method No. 9). 



This would give: 



z (increment) = 5,840 M. feet of spruce X (say) .007 =40,880 ft.b.m. 

 970 M. feet of fir X .01= 9,700 ft.b.m. 



Total, 50,58c feet. 



r = i6o 

 ri 



wz' = — = 4,046,400 feet b. m. 

 2 



v= 6,810,000 feet b. m. 

 v> nv by 2,763,600 feet b. m. 



