THE THEORY AND. PRACTICE OF WORKING PLANS 77 



Xj = 3 .032 board feet per acre 

 Yi = 2 .214. 

 Zi= .232 



Xi-\-Yi-\-Zi = 5. 4^8 



Then CC= =^ — ^ = 5^ years, and the annual cut 



Xi-\-Yi-{-Zi 5.478 



= ^^ = ,^^ = 5478 board feet per acre, or, for the 1730 



acres in this type, =9477 board feet of hemlock.* 

 Eliminating Z and Zi in figuring CC: 



CC = ^i-— — — = -^^-^ = 26 years, and the annual cut = — '^^~ 

 Xi-VYi 5-246 CC 



= - — ^ = 11.797 board feet per acre, or for the 17^0 acres in 

 20 



this type = 20,409 board feet of hemlock. 



(c) Value and Application. — This method is well adapted to 



finding the allowed annual cut in a selection forest. It should 



be used, however, in conjunction with some other methods, 



such as Method 12, Var. II, Method 2, and the area check as 



indicated for selection forest in Method i. 



* By Von Mantel's method, the cut of hemlock figures out 9965 board feet. 

 The cut by the Swiss method for the other species in the stock table is as follows: 

 Beech, above 16 inches d.b.h. = 10.878 board feet per acre; 18,819 board feet for 



1730 acres. 

 Birch above 16 inches d.b.h. = 29.183 board feet per acre; 50,487 board feet for 



1730 acres. 

 Maple above 16 inches d.b.h. = 17.345 board feet per acre; 30,007 board feet for 



1730 acres. 

 Others above 16 inches d.b.h. = 14.610 board feet per acre; 25,275 board feet 



for 1730 acres. 



For further details see, " A Practical Application of Pressler's Formula," 

 F. Q., XIV, 2. 



