104 



THE THEORY AND PRACTICE OF WORKING PLANS 



to grow from one class to the next are found by working up the 

 increment borings.* The complete data are as follows: 



D. B. H. Class 

 (Inches.) 



9 



12 



15 



i8 



Volume per Tree. 



Board Feet. 

 (Table 9. Bui. 11.) 



42 U) 



293 w 



Number of Trees per 



Average Acre. 



(Table 4, Bui. 11.) 



.9l(«i) 

 .87(«2) 

 • 33(»3) 

 . 2o{ni) 



Years Required to 



Grow from One Class 



to Next. 



27(«2-ai) 

 32(03-0-2) 

 35(04-03) 



cc = at—a3 

 = 35 years 



Applying the formula, y, the annual cut, 



—^ — i;4=—X 293 = 1.674 board feet per acre, 

 «4-a3 35 



+25r5,%3 = :i3xi72= .637 " " " " 



«4-<J3 35 



.1i=^,,^-^x 93 = 1-569 



^3-^2 32 



32 

 .04, 



. n\—n2 -^tvx c 



-\ vi=—^X 42= .062 



fl2 — fll 27' 



Total 



= 3-942 



It K (( 



a li (( 



II (( ee 



^2_^ 168.48 bd. ft per ac. of surplus ^^3^^ ^^^^^ ^^^^ ^^^^^ 



cc 35 years, the cutting cycle 



Total annual cut 



= 8.756 



(( iC (( 



or, for the 1730 acres in this type = 16,117 board feet of hemlock. 

 Comparing this with the results obtained from similar 

 data by method No. 4, the annual cut does not appear exces- 

 sive. If, however, the result were much higher than those 



See " A Practical Application of Pressler's Formula," F. Q., XIV, No. 2. 



