Normal and Actual Forest, Etc. 



159 



For sake of simplicity the following premises are assumed: 



area 1,200 acres; rotation 120 years; period of return 20 



years; principal reproduction at once, i. e., during one year; 



average yearly growth 500 ft. B. M. and Y^., i. e., 1 acre of trees 



120 years old would cut 60 M. ft. B. M. That these trees are 



scattered among the younger growth need not disturb the con- 



• 1 • T. , , 1200 



sideration. Each year's cut would cover =60 acres and we 



might divide this forest into 20 equal tracts of cutting areas 

 of 60 acres each. The following diagram v/ould then indicate 

 the order and the year of cutting each of these cutting areas. 



From this table it appears that: The cut comes to each lot 

 every 20 years. Reproduction of the cleared spots and with 

 this a new growth on any lot every 20 years. For the whole 

 forest the cut is a yearly cut, reproduction is a yearly affair and 

 the age classes are all fully represented just as much as if the 

 trees of different ages were on separate areas in pure, even-aged 

 stands; there are r age classes and the triangle diagram applies 

 here as well as in the usual case. 



If the V70rking is done right, as is here asstmied, then we may 

 think of the trees on any one cutting area separated, i. e., collected 

 on separate areas, and we then would have the following conditions 

 of age classes on the different cutting areas: 



In the fall of the year with the oldest or ripe timber in Lot 1 

 ready to cut : 



