12 X. H. Agr. Experiment Station [Bulletin 318 



becoming available within this period. This quantity depends largely 

 on the merchantable timber standing at the beginning of the period, the 

 growlh rate of the particular species present, the site, and to a very 

 small extent the management practices followed. 



Such an estimate of production can be made by applying Von Mantel's 



formula J annual cut = ' :r^ — —~^ I to the total merchant- 



[ % rotation J 



able volume of the existing growing stock. The annual cut so calculated 

 tends to be conservative when a long rotation is used. 



By applying the above method and using a rotation period of 120 years 

 for all species except pine and paper birch which would have rotation 

 periods of 80 years, the annual cut for the area surveyed on a sustained 

 yield basis is shown in Table 3. 



Table 3. — Annual cut on sustained yield basis for the area surveyed, 



by types 



Type Good quality Fair quality Total 



M bd. ft. M bd. ft. M bd. ft. 



Pine 1,397 982 2,379 



Other softwood 1,047 678 1,725 



Hardwood 343 783 1,126 



Total 2,787 2,443 5,230 



15--" 



This table indicates that approximately five million board feet can be 

 taken from the area each year without depleting the foundation stock. 



In making the division between good and fair, it is assumed that in tlic 

 relatively short period under consideration, new management practices 

 instituted at present would not greatly affect the quality of tinibci- har- 

 \'ested. 



Tlierefore, it is probable, provided the annual cut is properly distrib- 

 uted, that the quality harvested each year might be expected to be 



roughly in the same ratios as indicat- 

 ed in Table 1. 



Data presented in the preceding 

 section are summary and include all 

 .•inticijiated gi'owth in the area studied. 

 The picture is not complete without 

 some information on what proportion 

 of the total annual growth takes place 

 on tracts accessible for logging oper- 

 ations and under the control of per- 

 sons willing to dispose of woodland 

 products. A. factor which sometimes 

 tends to limit the supply available in 

 a gix'en year is the shortage of log- 

 ging equipment such as teams and 

 tractors. 



I ..urti ss III \\ hit I- Ml. N'.il. l'"ni<si. 



Tractor logging in a lowland soft- 

 wood area. 



