CHAMONIX WORKING PLAN 259 



M. Schaeffer's argument based on these figures is given in full since 

 it illustrates the judgment — or, if you like, guesswork — which enters 

 into the final yield analysis and answer. 



"The 312 trees (bored) together take 6,742 years to pass from one (2-inch) diameter 



class to another or an average of -^^ = 21.6. If one glances at the preceding table 



(see curve) it is evident that for the diameter classes between 8 and 28 inches the time 

 it takes to pass is about constant. . . . One can conclude also that the length of 

 the period fixed at 20 years by the working plan of 1890 should be considered as a 

 mmimum and that the rotation of 200 years adopted in the present study is not too 

 high when it takes the average seedling 194 years to pass from a diameter of 6 inches 

 to 24 (21.6 X 9 = 194). This conception of the average length of time (to pass from 

 one class to another) establishes, in a way, an index of the forest. For the forest of 

 Houches, where situated in a valley ... the average time was 19.4 (Chamonix 

 21.6). This difference of two years shows that the forest of Chamonix is less favorably 

 situated than its neighbor, and it might be said this inferiority amounts to 10 per cent. 

 The rotation of the forest of Houches has been fixed at 180 years; that of Chamonix, 

 therefore, ought to be normally 200 (as it is). 



"In evening off this growth per cent graphically (see curve; . . . several inter- 

 esting deductions can be made. To start with it is noticeable that in the lower classes 

 where the measurements were numerous, the evened off curve follows the actual curve. 

 It might be stated also that beginning with 24-inch diameters the growth per cent 

 falls normally below 1 per cent. This merits the conclusion that the reservation of 

 trees of higher diameters should be the exception. If the evened off growth per cent 

 is multiplied by the total volume (on the entire forest) as given in the recent stock- 

 taking, the probable production of the forest as it stands is obtained: 2.54 X 30,437 



-1- 2. X 43,951, etc. (for each class), with the following total = — ' = 4,511 cubic 



meters. The average per cent would then be _ ' _-_ = 1.54 per cent. If it is possible 



to conclude that 1.54 is the maximum growth per cent under actual conditions, and 



given the yield reduced to 1.03 per cent then 0.51 per cent (of the growth) or about 



one-third will be saved each year. 



"There are other methods of valuing the probable production of the Chamonix 



forest. Taking for granted that the figure of 1,800 hectares represents the area actually 



292 777 

 forested, it might be argued that the average stand is - ' ., = 160 cubic meters 



IjoUO 



roughly. By referring to the table (of average production for Savoie) ... it 

 appears that when it takes 22 years (to pass from one diameter class to another) and 

 the stand per hectare is 160 cubic meters then the growth is 2.5 cubic meters per hec- 

 tare; the total growth then is 1,800 X 2.5 = 4,500 cu. m., a figure which exactly agrees 

 with that obtained (by multiplying the volume by the growth per cent). It is, more- 

 over, confirmed by the comparison of the compartments calipered twice; those 20 

 years ago had a volume of 218,980 cubic meters (calculated by the present volume 

 table) and to-day 278,360. Since about 26,000 cubic meters (by same volume table) 

 was cut, the production has been 278,360 + 26,000 - 218,980 = 85,380 or 4,269 per 

 year, a figure which is also in accord with the preceding when it is considered it applies 



to only about 1,700 hectares (i.e., ^j^^^J^ = 4^519). 



"Finally if we use the formula of the whole yield, that is to say, if we take count of 

 the growth of 'old wood' and a third of that of the 'average wood' (remembering that 



