250 INCREMENT, GROWING STOCK AND YIELD. 



m 2 

 and out of this 



~"2"~~wT 



and 



a 

 m = 



Y- I 



2 



Example : Table at page 190. 



A wood of 10 acres, now 80 } r ears old, is to be regenerated 

 during the next 20 years ; what will be its annual yield during 

 that period ? 



.20 -5 



2650 x 20 = 53,000, or per acre = 5300, 



which is the same as the wood should have had when 90 years 

 old, if no cuttings had been made. 



Again, supposing the yield has been fixed at 2,650 cubic 

 feet a year, the 10 acres in question will furnish that yield 

 for 



=20years 



2650 - 



3. Relation between Normal Yield and Normal Increment. 

 The normal final yield is equal to 



(a.) The volume of the oldest age gradation ; 



(6) The mean annual final increment of all gradations ; 



(c) The total current annual increment of all gradations. 



Example : Table at page 190. 



Area of a normal forest = 100 acres 

 Rotation = 100 years. 



