Methods of Forest Organization. 65 



especially in moimtain districts, produced very unequal 

 felling budgets. To overcome this inequality, Jacobi, in 

 Goettingen (1741) introduced proportional felling areas, 

 making the felling areas on poor sites permanently 

 larger. 



Similarly, v. Langen and Zanthier attempt equal 

 annual returns, without slavishly holding to the geomet- 

 ric division, only seeing to it that the total area be cut 

 over in the predetermined rotation. 



The first attempts to introduce a regulated manage- 

 ment by malring a volume division the basis is recorded 

 in the Harz mountains in 1547. This method based on 

 very crude estimates, although upon very fair forest de- 

 scription, was continued into the 18th century. 



In the last half of the 18th century all these crude 

 methods were improved and applied on extensive areas. 



In 1785 Zanthier combined area and volume division, 

 determining the felling budget on each felling area by 

 counting and estimating the trees and calculating how 

 many trees could be used annually under a sustained 

 yield management; the area division being used only as 

 a check or means of control. 



A very considerable advance was made by Oettelt, 

 (who surveyed and regulated the Weimar forests in 

 1760) in the elaboration of details and establishment of 

 proper principles for regulating the felling budget. 



In his forest description he introduces for the first 

 time periodic age classes, usually six, but of uneven 

 length : Young growth below twelve years, thicket twelve 

 to twenty-four years, polewood twenty-four to forty 

 years, clear timber forty to fifty, medium timber fifty to 

 seventy-five, mature timber seventy-five and over. 



