190 



Studies in Forestry 



[CHAP. IX, 



I. In the first instance, that of a thirty-seven-year-old crop 

 of Spruce, raised by planting, the data 1 were : 



Previous to thinning: 



During the thinning there were removed 



In consequence of the thinning, the arithmetical mean 

 diameter at breast-height (4^ ft.) of the stems that were left 

 was found to be 



On area I, 5-12 inches ; 



On area II, 5-68 inches; 



On area III, 5-84 inches; 



whilst five years later , just before another thinning was to take 

 place, it was found to have increased 



On area I to 5-48 inches, or an average diametral increment 

 of 0-36 inches per stem. 



1 These and the following data are, by permission, excerpted from 

 Dr. M. Behringer's prize thesis Ueber den Einfluss wirthschafflicher 

 Massregeln auf Zuwachsverhaltnisse ^lnd Rentabilitdt der Waldwirthschaft, 

 1891, pp. 19 et seq. 



