60 



THE THEORY AND PRACTICE OF WORKING PLANS 



maximum average volume production, or the maximum average 

 value production. 



The higher the average yearly production of a piece of 

 woodland, the greater, of course, will be its continuous produc- 

 ing value if cut over repeatedly. For example, in the second- 

 growth hardwoods in Connecticut * the average annual growth 

 in cubic feet and cords culminates as follows: 



Chestnut type: best sites end medium sites 35 years 



Chestnut type : poorest sites 40 



Oak-chestnut t>^e : best sites and medium sites 30 



Oak-chestnut t\T3e: poorest sites 35 



Oak t}"pe: best sites and medium sites 35 



Oak t>TDe: poorest sites 40 



These lengths of rotation are so nearly similar that it is safe 

 to place the cord wood rotation for second-giowth hardwood 

 stands at from thirty to forty years. To illustrate how silvi- 

 culture enters in as a limiting factor, the rotation for stands con- 

 taining much red, black, or scarlet oak should be thirty or 

 even twenty-five years in order to secure successful sprout 

 reproduction of these species. 



Another example of the economic rotation ma}- be taken 

 from Douglas fir on the Pacific Coast. According to published 

 tables t the economic rotation for cubic volumes and board- 

 foot volumes for best, medium and poor sites, in western 

 Washington and Oregon is as follows: 



* Bui. 96, Forest Ser\'ice, U. S. Dept. of Agri. Tables 30, 32, and ^^. 

 t For. Quart., Vol. XII, p. 447, table 6. 



