206 THE THEORY AND PRACTICE OF WORKING PLANS 



to the formula — , where z = the mean annual increment. The 



2 



number of years in which the excess or deficit of the growing 

 stock is to be equalized is determined for each individual case 

 according to the particular circumstances. The cutting cycle 

 (period between cuts) is not to be placed too high: usually 

 seven to nine years. 



Planting and Road Plans are to form a part of every working 

 plan. The planting plan embraces not only the methods of 

 artificial reproduction, of nursery practice, and the source of 

 plant material, but also the care of cutting areas and of young 

 plantations. 



Revisions of the Working Plan are to take place in the middle 

 of the twenty-year period. The kind and degree of the revision 

 to be undertaken follows from the demands made on the plans 

 and the changes which, through the methods of management 

 pursued or through outside influences, have occurred during the 

 first half of the working period (ten years). At the end of the 

 working period (twenty years) an entirely new working plan 

 is drawn up. 



The essential points to be considered in revision are: Changes 

 in area, the actual annual cut as compared with the allowed 

 annual cut as regulated, the comparison of the volume yield of 

 stands cut over with the estimated volume thereof, the unfore- 

 seen cuttings not provided for in the plan, the yield from thin- 

 nings, the execution and cost of planting and seeding, the 

 changes in servitudes, the relation of by-products to the scheme 

 of management, the completion of road and trail buildings, etc. 



An interesting feature is the instruction that a financial 

 valuation of the forest must be made when a new working plan 

 is prepared or an old one reiised. The data for local yield 

 tables are to be gathered by establishing carefully chosen, typical, 

 permanent sample plots to serve as " index stands." 



