320 DETERMINATION OF THE YIELD. 



from the other, the error is to a great extent elimi- 

 nated. 



(2) As the yield is determined by a formula, the method, if 

 applied rigidly, may lead to absurd results : for instance, 

 it may happen that a full increment takes place, that 

 the real growing stock is equal to the numerical normal 

 growing stock, and yet there may not be a single mature 

 wood in the forest fit to cut. 



If the method is applied judiciously, that is to say, if: 



(1) the real growing stock is taken as that actually existing 



in the forest, and the normal growing stock calculated 

 from a suitable yield table ; 



(2) the yield as calculated with the formula is modified to 



suit the special conditions of each forest ; 



then the method is one of considerable merit. It enables the 

 forester to arrange the grouping of the age classes in the most 

 desirable way, and to do justice to all other sylvicultural 

 requirements, since it leaves him an entirely free hand in the 

 selection of the woods to be cut. 



The method is applicable to all sylvicultural systems, but 

 the determination of the increment and growing stock involves 

 much labour. Under it a forest is gradually led over into the 

 normal state, though perhaps not for a considerable period of 

 time ; the difference between the real and normal state will, 

 after the first rotation is passed, be so small that it can be 

 neglected. 



The sample working plan given in Appendix C, p. 364, has 

 been based upon the formula of this method. 



2. Hundeshageri's Method, 

 a. Description of the Method. 



Hundeshagen's method of determining the yield is based 

 upon the idea that the real yield must bear the same pro- 

 portion to the real growing stock as that existing between the 

 normal yield and normal growing stock ; he thus obtains the 

 equation : 



