WHITE PIKE UNDER FOREST MANAGEMENT. 23 
Table 6. — Yield per acre in lumber of even-aged second-growth white-pine stands. 
Age. 
Lumber yield per acre. 
Age. 
Lumber yield per acre. 
Quality Quality 
1 
Quality 
III. 
Quality 
I. 
Quality 
H. 
Quality 
III. 
Years. 
20 
25 
30 
35 
40 
45 
50 
55 
60 
Boardft. 
4,500 
8.400 
Boardft. 
Boardft. 
Years. 
65 
70 
75 
80 
85 
90 
95 
100 
Boardft. 
65, 100 
Boardft. 
51.600 
Boardft. 
38,100 
5.400 
69, 900 56. 100 
42,300 
13,900 
22,500 
32,800 
41,800 
49,100 
55,000 
60,200 
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 
74,100 
77,850 
81,400 
84,800 
88,000 
91,200 
60.200 
64,000 
67,500 
70,900 
74,000 
77,000 
46. 300 
50, 100 
53,700 
57,000 
60,000 
62, 800 
In 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. 
