Forest Management 9 



PARAGRAPH IV. 



NORMAL INCREMENT. 



The normal wood at the age of maturity has imbedded in itself the 

 increments of a wood, one, two, three, etc., years old; consequently, it 

 represents all of the increments taking place annually over the entire 

 area of a normal forest containing the age classes, one, two, three, etc. 

 Since only a few trees, however, reach maturity a rule fails to be en- 

 tirely correct which reads: "The normal increment of a forest equals 

 the normal volume of its oldest age class." 



Generally speaking, since the same causes must have the same ef- 

 fect, the actual increment, in tons of wood fibre, normally formed on 

 an acre of ground, fully stocked, depends solely on climate and soil, 

 wood fibre being "solidified atmosphere." The forester's aim should 

 be to concentrate the increment into the smallest number of trees, 

 without losing any increment, so as to grow the biggest logs in the 

 shortest rotation. 



In America, soil is cheap; hence there seems to be no need to force 

 every square inch of soil into the harness of tree production. We 

 should keep in mind, however, — 



1. That woods poorly stocked are apt to yield knotty timber; 



2. That the outlay for taxes, protection and administration de- 



pends more on area than on density of stand; 



3. That the logging expenses per 1,000 feet b. m. are small 



where the stumpage is heavy; 



4. That investments for roads and other permanent improve- 



ments, per 1,000 feet b. m., are relatively small in well 

 stocked forests; 



5. That the fertility of forest soil suffers under a loose canopy 



overhead. 



The main sylvicultural measures leading to a normal increment are: 

 Weeding. 



Improvement cutting. 

 Thinning. 

 Afforestation. 

 Reinforcing. 



PARAGRAPH V. 



FINANCIAL CONSIDERATIONS. 



Three kinds of increment compose the latent gross revenue obtain- 

 able from any wood which is left to itself or which is placed under 

 forestal care: 



I. The quantity increment, depending solely on the amount of wood 

 fibre formed. 



