MANAGEMENT PLANS — THE NATIONAL FOBESTS 15 



by an adjustment of tlie length of the first cutting cycle, or by a 

 modification oi" the methods of cutting during the cycle, or both. 



This method of calculating yield is crude indeed. It ignores a 

 number of factors usually taken into account and should not be used 

 if the necessary data for some more accurate method are available. 

 The results, though conservative, are sulliciently accurate, however, to 

 fill the needs of the sim})le plans that have been and are being made 

 in many national fore.sts, in which the ciiief concern is to set up a 

 safe cutting program for the next 10 years and get systematic man- 

 agement under way and headed in the right direction. 



For types that are cut clean, the cutting cycle coincides with the 

 rotation age, and the determination of a rotation age is of great 

 importance only for those types. Where partial cutting is used, the 

 important factor is that there be left, in any present cutting, enough 

 thrifty trees to produce a loggable cut of the desired products by the 

 end of the cutting cycle. The present age of such trees or their age 

 when they will be cut is relatively unimportant. If new even-aged 

 stands are to be grown, however, sustained yield can only be secured 

 by spreading the cutting of the present stands over the time required 

 to grow a new forest to maturity on the area tirst cut over. As a 

 general policy for the national forests, this rotation age will not be 

 less than that at which the mean annual growth culminates, figuring 

 the mean annual growth in terms of the chief product to be grown. 

 Thus if Douglas fir saw logs is the desired product, and for the aver- 

 age site in a working circle the mean annual growth is greatest when 

 the stands arc 125 years old, the rotation will be at least 125 years, 

 and plans must be made now to distribute the cutting of the existing 

 stands over that number of years. If the working circle is reason- 

 ably uniform in site quality, a simple division of the productive log- 

 gable area by the numl:)er of years in the rotation is often tiie first 

 step. Then multiplication by the average volume per acre for mature 

 stands gives an approximation of the allowable annual cut. Kefine- 

 ments of the method should be used if justified by the available data. 



TUVIBRR-SALE POLICY 



When the annual possibility of the working circle has been ascer- 

 tained and before decision is made as to when, where, and in what 

 sequence the 3'ield is to be harvested, it is in order to consider the 

 policy that is to be followed in making timber .sales; for only under 

 imusual circumstances will it be i)racticable to order the utilization 

 of timber stands solely in accordance with silvicultural needs. Acces- 

 sibility, as it afFects the cost of manufacture, qualit}' in its effect on 

 the value of the outimt. and policy as it relates to soimd business 

 practice as well as to public service, are and will be for many years 

 to come, ])otent factors bearing on the allocation of the cut. 



The statement of timl)(>i- sale policy to be enfereil in the plan should 

 be brief and to the point and should answer tlie following and simi- 

 lar questions: 



1. What types of operations are to be sotight : sawmill and logging, 

 logging alone, combination of nil conunodities, separate operations 

 for each commodity, etc.? 



2. What logging methods and I rnuspoi-tation systems are to be 

 required, encouraged, or forbidden? Is there need f<»r a progressive 



