582 JOURNAL OF FORESTRY 



thinnings represent, namely 28 to 40 per cent of the stock in 60-year 

 stands, and 12 to 15 per cent of the total increment in the loo-year 

 stands. 



The author also fears that by booking part of the thinnings as main 

 yield, the public interest (of communal forest owners) in a more in- 

 lensi^ e thinning practice would sufifer. 



In timber forest where stands can be differentiated by age classes, 

 the age of the stand furnishes the best basis for distinguishing the 

 character of the utilization as main or intermediate yield. Only in 

 the last third of the rotation doubts would occur; when regeneration 

 is the object, the cut will have to be considered as part of final yield, 

 so will forced fellings as consequence of storm and snow breakages, 

 insects, etc. Instead of summary estimates of thinnings, definitely 

 planned ones are suggested, as a percentage of the stock of the stand. 

 A table is given which, for spruce and beech, gives such percentages 

 for lo-year periods. For spruce in hill country, on the better sites, 

 these percentages in timberwood run for the decade mostly between 10 

 and 12 per cent. These represent the side stand which would die if 

 not utilized. 



Much stress is laid on the ascertainment of the stock on hand, which 

 is considered as more important than the area. The author is not 

 satisfied, as the German instructions are, with an ocular estimate using 

 yield tables and sample areas. In uniform and even-aged forest this 

 may do, and where the data of production have already for a long 

 time been controlled, and in State forest. But in Switzerland, with 

 68 per cent communal forest, a relatively small forest area and high 

 demand for wood, and lack of information of production, a more 

 exact knowledge of stock is needed. Especially knowledge of the com- 

 position of stock in diameter classes is needed to give insight and 

 answer to a number of important practical questions. Especially the 

 increment can hardly be ascertained without exact ascertainment of 

 stock. The cost of such careful ascertainment of stock is soon com- 

 pensated. 



An example is given, in which in three decadal revisions due to care- 

 ful stock measurement the annual felling budget was found to be 

 capable of a raise of nearly 50 per cent. And if a deficiency were dis- 

 covered, this would be just as important. 



For the sake of economy this careful measurement may be con- 

 fined to the stands in the second half of the rotation, for in a rotation 

 of 100 years the stands of 61 to 100 years represent 65 to 80 per cent 

 of the total stock of a management class ; and if diameter classes are 



