222 THE THEORY AND PRACTICE OF WORKING PLANS 



was 3008 hectares, or approximately 1.5 the normal of 2031 

 hectares. 



The rotation age is determined on the basis of highest net 

 annual income (forest rent) unless there are cogent reasons, such 

 as legal constraints, logging or market conditions, for keeping 

 a higher rotation. Stands are usually considered mature, 

 i.e., of proper cutting age, whose index per cent has sunk below 

 the adopted interest per cent on the investment and whose 

 cutting will not interfere with the proper development of the 

 cutting series. 



In addition to the stands thus mature, the cuttings of the 

 ensuing working period are to include all very open, stands and 

 stands with unsatisfactory increment whose reproduction is 

 obviously desirable; and also such stands as must be sacrificed 

 to the proper progress of the cutting series. 



The aim is, obviously, to approach a normal distribution of 

 the age classes. The length of time required in this approach 

 to normal is fixed tentatively. To aid in this and in the fixa- 

 tion of the decade cutting area the results of past cuttings are 

 re\'iewed, especially in their effect on the development of the 

 proper age-class distribution; this last is shown graphically 

 for decades past. 



Based on these considerations the decade cutting area is 

 finally fixed and the volume thereon, increased by adding the 

 increment to the middle of the decade, constitutes the allowed 

 cut for the decade. 



In the selection forest of the protective belt, everything is 

 subordinated to the protective function and hence no sustained 

 annual cut is determined, but the allowed cut merely approxi- 

 mated from experience. 



Control and revision of the working plan which is docu- 

 mented in bound form and called an " Operat." — The following 

 current records are kept: 



(i) The memoranda book (" Gedenkbuch ") wherein all 

 changes other than those changes which result from the cuttings 

 prescribed in the working plan are entered. Changes in sur- 



