THE THEORY AND PRACTICE OF WORKING PLANS 



timber, but it may also be used with reference to the density 

 of stocking, age classes, etc. 



The normal growing stock {nv) is theoretically attained 

 from normal age classes and normal increment, practically it 

 results from normal age classes and actual increment. 



The actual growing stock {v) is that which is present on a 

 given forest. This is obtained by timber estimating. 



The normal growing stock {nv) is obtained (i) by formula, 

 (2) from yield tables. 



Diagram B 



A, , , ^ ^ ^ ^ ^ ^ , , ^ ^ . ^B 



10 20 30 40 50 60 70 80 90 100 HO 120 130 140 

 Age ia Years 



(i) The normal growing stock is expressed by the formula: 



ri 



nv = — 

 2 



where wz; = normal volume of growing stock, r = rotation, and 

 i = the mean annual increment. 



(2) nv can also be determined directly from yield tables 

 constructed by measurements of fully stocked stands. 



nv then equaXs nla-{-b-\-c . . . + — ) 



