CHAPTER II. 



CHOICE OF EXPLOITABILITY. 



SECTION I. 

 Principal Kinds of Exploitabilitt. 



From one and the same forest very different results are obtained 

 according to the age at which the timber is felled. This age, which 

 may vary between very wide limits, sometimes even between 20 and 

 200 years, determines the interval of time, at the end of which the 

 exploitations, after successively passing through the rest of the 

 forest, come back to the point whence they started. There is 

 nothing analogous to this either in agriculture or the manufactures. 

 Thus a question of an entirely special character presents itself to us 

 here : to resolve it, we must go back to the fundamental principles 

 of forest economy. 



All ownei-s of forest property find it to their advantage to exploit 

 their timber when it has attained its maximum utility. Whether 

 we speak of a single tree or a canopied collection of trees, the timber 

 is now said to be EXPLOITABLE, and the peculiar conditions it offers 

 constitute what wo will call its EXPLOITABILITT. This state of the 

 timber, which always corresponds to its maximum usefulness, de- 

 pends above all on the nature of the services required of it. 



The utility properly so called, i. e., the technical utility, of wood 

 varies with the species yielding it and with its properties, and 

 increases in direct proportion to its size. A given quantity of 

 timber is, as a rule, all the more useful for being composed of treea 

 of large girth. The principal reason for this is that it can thereby 

 serve a greater variety of purposes, and can in consequence be 



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