METHOD OF 1883 237 



be a submultiple of a third of the rotation; (2) the number of compart- 

 ments be about equal to the years in the period; (3) the local forester 

 be free to allot the amount of the cut in each compartment according 

 to local requirements at the time of cutting; (4) the yield be revised at 

 the end of each felling period. 



Disadvantages. — (1) To be exact the number of years in each class 

 should be varied in accordance with the number of years of growth 

 actually consumed. (2) Unless there is some other check on the nor- 

 mality of the old wood and average wood besides the proportion of 5 

 to 3 it is insufficient because an acre might contain 5 board feet of old 

 wood and 3 board feet of average wood without being normally consti- 

 tuted. There must be some conception of total volume. (3) Trees 

 must be tallied down to one-third the rotation (exploitable size). 



The advantages are: (1) The yield is in accordance with the condition 

 of the stand. (2) The tendency is to work toward normal diameter 

 classes. (3) A sustained yield is secured and the growing stock is being 

 continually built up. (4) The method has worked fairly well in practice. 



Illustration.^^ — The merchantable size is 24 inches corresponding to 

 a rotation of 180 years. The old wood is 17 inches and over, the average 

 wood 9 to 16 inches inclusive, and the young wood 1 to 8 inches. 



A sample inventory is shown on the following page. 



(A) According to the inventory the normal proportion exists, the 

 average wood totaling 3,000 M and the old wood 5,000 M — therefore 



the cut is ' = 83 M per year or if the old wood were growing at the 



^ ^ X 5,000 X 0.02 X 60 „ , , , , , , , , 

 rate of 2 per cent per year — ^ or 3 M would be added 



making the cut 86 M. 



(B) Suppose the volume of the old wood = 6,200 M and the volume 

 of the average wood = 1,800 M. Here the old wood exceeds the normal 

 proportion so the old wood diameter classes should be examined to see 

 if they can be transferred to the average wood group and held over a 

 period equal to 60 years — one-third the rotation. If there is no objec- 

 tion to this transfer the trees in the 17 and 18-inch diameter classes, 



35 An exact adaptation of an oiBcial French illustration of the method and as illus- 

 trated by the Chamonix Working Plan, by A. Schaeffer. American units have been 

 substituted. The art of French regulation imder such an expert as Schaeffer rests 

 chiefly on a thorough, intimate knowledge of the local conditions rather than on the 

 organization of methods that differ fundamentally from what has already been accepted. 

 Schaeffer knew the selection conifer forests of the Savoie region so well that he could 

 probably estimate ocularly the growth per cent on any forest within one-half of 1 per 

 cent by simply making a reconnaissance on foot. Such insight into the growth of a 

 forest is similar to the knowledge of stands per section obtained in the West by seeing 

 what the timber on sections of land (640 acres) looks like, and then learning what they 

 cut out under given methods of logging. 



