192 SELECriON-WOEltED JOEESTS TTNDEE TEANSfOEMAttON, 



easily recognised by the form of their boles which are clean up to a 

 great height ; and by the thickness and aspect of their annual rings. 

 It is the age of such trees, which have grown in a regular manner 

 and under average conditions of fertility, and which have besides 

 attained the dimensions correspondiug to the maximum of utility, 

 that ought to be adopted as the figure for the Rotation. 



The General Working Scheme gives the order in which the 

 various portions of the forest shall be taken up for transformation 

 during each successive Period of the Rotation. The Periods shoulds 

 as a rule, be long on account of the component species, which ia 

 with us generally the silver fir, and on account of the climatic con- 

 ditiops peculiar to high mountainous regions, The reason is evident 

 for in silver fir forests regeneration progresses very slowly, and in 

 order to obtain it in a completely successful manner, great caution 

 is necessary in the cultural operations. We do not estimate at less 

 than 25 years the period of time that must elapse between the 

 Primary and Final Fellings, and within this period at least one 

 Secondary Felling has to be made. 



The Periodic Blocks should all be of equal extent whenever the 

 ground permits of it, or, better still, of equal productive power. 

 Each of them should, as far as possible, form a compact mass bounded 

 by natural limits. The observance of this rule serves in the majority 

 of cases to indicate the proper number of Blocks to adopt, that 

 figure being no longer, as in regular forests, determined by the 

 number of the component age-groups, but by that of the natural 

 topographical divisions of the ground. In forests hitherto workeci 

 by Selection, it may be a matter of great importance to have the 

 successive Blocks of the same Working Circle following one another 

 on the ground in the order in which they shold be taken up and 

 in the direction opposite to that of dangerous winds. Indeed such 

 a disposition of the Blocks is seldom impracticable in the forests 

 under consideration. The Working Scheme is thus usually a very 

 obvious one, and is, in any case, always well-defined. 



The Special Scheme of Exploitations does not present thg 

 slightest difficulty as regards the nature of the cuttings to be pre- 

 scribed — Transformation Fellings in the Block under transformation. 

 Selection Fellings in all Blocks, the transformatioa of which has 



