VON mantel's method. 333 



3. Von ManteVs Method. 

 Von Mantel, in arranging for the speedy determination of 

 the yield of certain forests in Bavaria, laid it down, that this 

 should be done according to the formula — 



Annual Yield = I^eal Gr owing stock of the forest _ G^„, 

 Half the numl)er of years in the rotation r 



2" 

 This formula rests upon the same basis as Hundeshagen's 

 method, if for the latter the normal growing stock is calculated 

 with the final mean annual increment as in the Austrian 

 assessment method. Hundeshagen's formula — 



The cutting of the yield according to Von Mantel's formula 

 will gradually lead to the establishment of the normal growing 

 stock, as the following considerations will show : — 



Supposing the real growing stock, by which Von Mantel 

 understands that actually present in the forest, is equal to 

 the normal growing stock, then his formula goes over into — 

 rj<J 



r 

 "2 

 The formula gives, therefore, the correct yield, provided the 

 increment is normal. 



If the actual growing stock is smaller than the normal, say 



G,,„i = — x, then the 



A 



Yield = ^ = / - '^-^^ = / - -, 



r r J- 



2 2 



which means, that less than the increment is cut. 



y2 



