186 THE THEORY AND PRACTICE OF WORKING PLANS 



It is to be remembered, however, that too many divisions 

 of the working unit make the plan unwieldy and difficult of 

 execution, hence only considerable differences are to be taken 

 into account. 



The instructions for determining the rotation age are a 

 declaration of principles for the new Bavarian forest policy. 

 The rotation age is to be governed by the objects of manage- 

 ment: " Without violating the sustained yield and with the 

 regard to rights of user, to secure the highest possible produc- 

 tion of those classes of timber best suited to the needs of the 

 community and of the country as a whole. In addition, the 

 administration is bound to manage the state property entrusted 

 to it in an economic manner, and from the management to 

 secure the highest possible money revenue. 



" According, therefore, as a forest is not exclusively or pre- 

 ponderatingly intended to satisfy servitudes or to be a protection 

 or a recreation forest, the management must aim at the largest 

 possible production of most demanded timber and at the 

 economic securing of a maximum money revenue." 



The rotation age must be determined from this standpoint. 

 This determination is not to be confined to the other stands, 

 but must extend to the younger classes whose origin and growth 

 are often different from that of the older timbers; * for in fixing 

 the rotation age, the period of years required for these younger 

 stands to reach maturity is the most important. 



The possible rotation period is bounded on the lower side 

 by the merchantability of the sizes secured, on the upper side 

 by the age at which the forest rent ceases to increase. The 

 time of maximum forest rent is therefore the extreme rotation 

 age. As a rule the rotation is to be fixed at that age which 



* This difference is well illustrated by the Western yellow pine. Measure- 

 ments made by the author near Flagstaff, Arizona, in 1907, show that the mature 

 yellow pine, when in the " blackjack " form, grew much slower than the present 

 " blackjack " of the same size; e.g., at 100 years of age the present " yellow pine " 

 were 13.2 inches diameter breast high; the present "blackjack" 17.95 inches 

 diameter breast high. See Forest Service Bulletin loi, " Western Yellow Pine 

 in Arizona and New Mexico," tables 9 and 10. 



