TABLE OF AGE CLASSES. 285 



It is always useful to prepare this table, as it enables the 

 forester to calculate the total yield capacity of the area. In 

 this table each working section must be recorded separately, 

 as the yield capacity depends on the species, sylvicultural 

 system and rotation. 



The Saxon Tables (p. 388, App. D) give the following 

 mean production per acre for Scotch pine woods, under a 

 rotation of 80 years : 



For the V. Class (lowest) = 19 cubic feet. 

 IV. = 44 



HI. = 70 



II. = 96 



I. (best) =122 



The mean annual increment, or the yield capacity, of the 

 area shown in the above table, would therefore be : 



Yield capacity = 29 x 19 + 49 X 44 + 67 X 70 + 50 X 96 + 22 X 122 



= 14,881 cubic feet, 

 or average yield capacity per acre = = 69 cubic feet. 



This figure represents the normal yield ; the real, or actual, 

 yield depends on the quality of the growing stock and the ages 

 of the several woods. Assuming that the age classes are 

 represented in normal proportion, and that the mean quality 

 of all woods was equal to '7, the actual yield would be equal to 



14,881 x -7 = 10,417 cubic feet, 

 or 48 cubic feet per acre and year. 



5. Table of Age Classes. 



This table is of great importance, as it gives a correct idea 

 of the proportion of the different age classes, which affects the 

 determination of the yield in the immediate future. It maybe 

 prepared in the following form : 



