552 Forestry Quarterly. 



has the broadest crown of any German species with a diameter 

 of ten meters making 646 square meters to a group and fifteen 

 groups to a hectare. The felhng age is always equal to the 

 number of age-classes in each group multiplied by the number of 

 years intervening between successive returns to a group. For 

 pine under a rotation of 168 years and with a four-year return 



there are =42 age classes in each group and each of the seven 



4 

 clumps is six-partite. These six parts are arranged like the stories 

 of a building, the young under the older. The high yield of 15 

 festmeters per year and hectare (210 cubic feet per acre) can be 

 obtained in the productive twilight of such a stand. Practically 

 every tree cut in such a forest is mature and of high value, the 

 amount of small and cheap material being reduced ito a minimum. 

 The money return is large accordingly. Diiesberg without ap- 

 parent good reason expects gross yields of 600 marks instead of 

 100 and net yields of 540 marks instead of 50 to 60 per year and 

 hectare (i mark per hectare:=io cents per acre nearly). Poorer 

 sites can be managed on a lower rotation and with smaller yields 

 by reducing the number of parts in a clump and by lengthening the 

 period of return to a particular group. Thus for pine in four- 

 partite clumps and a return every fifth year we have twenty- 

 eight age classes in a group and a rotation of 140 years with an 

 annual production of 1.44 festmeters per hectare (20 cubic feet 

 per acre). Carefully considered and cletailed instructions are 

 given for converting existing, even-aged pure forests into this 

 form of selection forest, for their care and management and for 

 regulating their yield. 



Of course, the question keeps asserting itself: Should we ever 

 undertake to convert any large forest or the forest of any con- 

 siderable region as Diiesberg advises, will no new Diiesberg arise 

 in the course of the century or more necessary to make the 

 change, and, criticizing what we have already accomplished, ofifer 

 something better? This is the heel of Achilles common to all 

 methods of forestry and particularly characteristic of such as 

 Diiesberg's which so frankly rests on newly deduced principles of 

 biology and political economy, regarding them as the best. 



The question now arises : Is this policy Diiesberg so clearly 

 and enthusiastically proposes so well founded and free of fault 

 that every open minded forester will accept it as his guide, and 



