84 



NATURAL REGENERATION 



forester to have in mind the normal or average local number of trees per 

 acre for the different diameter classes; then by a comparison of the normal 

 with the actual stand it can be determined whether the forest has too 

 many or too few trees of the different size classes. Such data would be a 

 guide to determine from what diameter classes in a selection forest trees 

 should preferably be cut. The following table, compiled by Huffel, 

 shows average figures per acre for fir in different regions. 



TABLE 7.— AVERAGE FIGURES PER ACRE FOR FIR 



° Smaller trees are not calipered. 



Schaeffer ^ gives the follow^ing formula for the management of a 

 selection forest: 



"1. Establish a curve of a normal high forest, as has been indicated (see p. 214) 

 according to the existing stand. 



"2. Calculate the jdeld by any method (if you wish, even by the number of trees), 

 provided it is simple, taking care to adopt a figure less than the maximum yield which 

 has been determined. . . . 



"3. First cut the over-stocked age classes. 



"4. Arrange for periodic stocktaking in order to revise the yield and to make sure 

 that it approaches the type of forest desired." 



Spruce Selection Fellings. — Contrary to fir forests it is rare that ad- 

 vance growth is found under the parent spruce stand. Therefore, selec- 

 tion by groups or holes is always necessary, since it assures the regenera- 



8 Un Type de Futaie Jardinee, S. F. de F. C. et B., A. S. 



