fre;nch fir management in the vosges 541 



per solid cubic meter standing- averaged from 1892 to 1900 that given 

 in column 3 of Table i. With this data and by means of the compound- 

 interest formula A=a (i.ox)"^, where ^ = final capital, a = initial 

 capital, ;r = interest rate, and w = number of years, one can calculate 

 at what rate of interest (x) the amounts representing the values of the 

 trees of each class yields. Table i gives the results of the calculations. 

 It is evident from this table that the rates . . , decrease very rapidly 

 as the sizes of the trees increase. 



As we shall see later on, in adopting an exploitable size of 50 cm. in 

 diameter, the rate of interest in money for the whole forest, reckoning 

 from the passing to the 20 cm. size of the wood not mentioned, the 

 value of the soil, fixed charges, etc., is 3.05 per cent, and that obtained 

 with the wood which does not exceed 50 cm., because it takes 19 years 

 to pass from 50 cm. to 55 cm. ; but if ... it appears that they can 

 pass from 50 cm. to 55 cm. in much less time, it would be best to hold 

 them until they do not bring the yield to less than 3.05 per cent ; one 

 could keep a few of the best trees, 50 cm., 55 cm., and even 60 cm. and 

 above. 



2. Normal Stand 



Knowing the normal exploitable size, what will be the composition 

 of a stand in trees of all sizes to assure the permanence of the forest 

 and to obtain the largest return with the smallest possible growing 

 stock ? 



The solution of this question depends on knowing (a) the growing 

 space per hectare which it is necessary and sufficient to give to each 

 tree diameter class; (b) the number of trees of each class which must 

 be raised in this space. 



(a) In default of exact data on this question and until better ones 

 are found, one can admit, as most foresters do, that it is necessary to 

 give to each diameter class equal space. It is the fundamental principle 

 of the treatment of the regular high forest ; it is also explicitly ad- 

 mitted by the French administration for the calculation of yield in the 

 selection forests ; it is also admitted for the management of the Saxon 

 forests. 



It is possible that it would be well to allot a larger area to the large 

 wood than to the younger age classes. If in reality a large tree is re- 

 moved, the area freed (of timber) is occupied, first, by the bordering 

 crowns which become larger; secondly, by the seedlings which develop 

 in the center of the opening. These seedlings do not entirely occupy 

 the area covered by the large tree. 



