THE THEORY AND PRACTICE OF WORKING PLANS 



71 



III. HuFNAGL variation: Hufnagl multiplies the annual 



, ., average age 

 cutting area by the — ^-. 



For example, if the stand shows the following distribution 

 of the age classes: 



Total, 2160 93,500 



93.5oo-i-2i6o = 43 years = the average age. 



Area =2160 acres. 



Rotation = 80 years. 



Average age = 43 years. 



•. the annual cutting area = 



2160. ,43 



80 



X^^=2Q acres. 

 40 



(c) Value and Application. — The area method is the oldest 

 of regulation, dating from the sixteenth century. It enables 

 the transition from mere exploitation to a conservative manage- 

 ment. 



Its great advantage is simplicity. 



Its great disadvantages are: 



I. The rotation is assumed as a fixed value, whereas in 

 reahty it is a mere approximation and varies with the interior 

 (management, accidents, etc.) and exterior (markets, desires of 

 owner) changes to which every forest is subjected. 



