46 THE FORESTS OF FRANC& 



may be obtained a constant supply of wood, the division 

 cut in the first year being ready again for the axe 

 in the twenty-first year of the operation, and again in the 

 forty-first year, while the other divisions follow in their 

 order. If the timber forest be one in which the trees may 

 profitably be felled after a growth of a hundred and twenty 

 years, by the forest being divided into a hundred and 

 twenty equal or equivalent portions, and these be treated, 

 as has been stated in regard to coppice woods, correspond- 

 ing results would be obtained. 



Advantages likely to follow such a method of manag- 

 ing forests suggest themselves at once, and as described 

 it seems to be one which must be of easy application 

 anywhere. But the practical forester who has given 

 attention to my statement may have remarked that I 

 have used the expression equal or equivalent portions. 

 Good will result from the adoption of divisions into equal 

 portions, much good, but with a large admixture of evil. 

 Equal portions are not necessarily equivalent portions, 

 and such is the variation in the productiveness of dif- 

 ferent portions of a forest, from variations in soil, in 

 exposure, and in adaptation to the growth of the kind 

 of tree which happens to be upon it, that it is very im- 

 probable that many portions equal in extent will be equal 

 in productiveness, if any at all happen to be so ; and 

 therefore the division of a forest into equal portions will 

 not yield advantages equal to what would be obtained 

 by the division of the forest into what I have called 

 equivalent portions. 



With the attempt to do this commences the difficulties 

 of the undertaking. Equivalent partitions cannot be 

 obtained by divisions founded on equality of superficial 

 areas, neither can they be obtained by divisions founded 

 on the number of trees growing in each, or even on the 

 cubic contents of these. The soil, the exposure, the kind 

 of tree growing in different localities, the adaptation of 

 the soil, and of the exposure, to the growth of the kind 

 of tree, or of trees, growing in each, the age or ages of 



