﻿WHITE PINE UNDER FOREST MANAGEMENT. 23 



Table 6. — Yield per acre in lumber of even-aged second-growth while-pine stands. 



Age. 



Lumber yield per acre. 



Age. 



Lumber yield per acre. 



Quality 



Quality 

 II. 



Quality 

 III. 



Quality 



Quality 

 II. 



Quality 

 III. 



Years. 

 20 

 25 

 30 

 35 

 40 

 45 

 50 

 55 

 60 



Boardft. 

 4,500 

 8.400 

 13,900 

 22,500 

 32,800 

 41,800 

 49,100 

 55, 000 

 60,200 



Boardft. 



Boardft. 



Years. 



65 



70 



75 



80 



85 



90 



95 

 100 



Boardft. 



65, 100 

 69, 900 

 74,100 

 77, 850 

 81, 400 

 84,800 

 88,000 

 91,200 



Boardft. 

 51,600 

 56, 100 

 60.200 

 64,000 

 67,500 

 70, 900 

 74,000 

 77,000 



Boardft. 

 38,100 

 42, 300 

 46, 300 

 50,100 



" 53,700 

 57,000 

 60,000 

 62,800 



5.400 

 9,600 

 15,900 

 23.500 

 30,600 

 36,600 

 42,000 

 46,900 





5,300 

 9,300 

 14, 200 

 19,200 

 24,100 

 29,000 

 33,600 



111 using the yield tables it should be borne in mind that, since they 

 are based upon fully stocked stands, they represent better conditions 

 than usually exist in natural stands except over small areas. For 

 this reason, and also to allow for crooked and defective trees, it is 

 advisable to discount the values given by an amount suggested by the 

 conditions in each individual case. A discount of from 10 to 15 

 per cent of the board-foot yield will usually be ample. 



The rate at which average stands increase in volume may be easily 

 determined from the yield tables by dividing the yield at any desired 

 age by the number of years. The average annual growth thus ob- 

 tained is of use in comparing the rate of growth of stands of different 

 ages or in contrasting the growth of stands of the same age but in 

 different qualities of site. Table 7 gives the average annual growth 

 in cubic and board feet at 5-year intervals for average stands of three 

 qualities. The point where growth culminates (indicated in the table 

 by heavy figures) in general occurs earliest in the best sites. There- 

 fore to secure continuously the greatest yield from successive crops of 

 white pine, the final cutting would have to be made at an age when 

 the average annual growth is greatest. That this age does not always 

 coincide with that at which the money income is greatest is brought 

 out under " Rotation/' page 36. 



