Development of Silviculture. 63 



In 1761 we find the first good statement of the theory 

 of thinnings by Berlepsch, who advised taking out the 

 suppressed trees when the sound poles were clear of lower 

 and middle branches; he also accentuated the financial 

 argument of earlier returns and increased value of the 

 remainder. 



About the same time Zanthier recommended two thin- 

 nings, namely, for conifers in the thirtieth to fortieth 

 year first and again in the fiftieth year, for broadleaf 

 forest first in the forty-fifth and again in the eightieth 

 to ninetieth year. 



In 1765 the financial gain from thinnings is figured 

 by Oettelt, and the possible reduction of the rotation due 

 to thinnings is recognized by Leubert in 1774. 



Just as the thinning in polewoods arose from the need 

 of utilization, so the weeding of young growths was done 

 for the purpose of getting material for withes to bind the 

 grain, etc. 



The removal of coppice shoots in oak plantings was 

 practiced in Prussia in 1719, and the thinning of too 

 dense sowings was advised by Carlowitz in 1713. Yet 

 much later even such an intelligent man as Oettelt 

 inveighed against the weeding out of the birch in spruce 

 sowings because "nature prefers variety, with which 

 preference it is not good to iuterf ere." 



This was ia opposition to v. Langen (1745), who pre- 

 scribed for the first time regular cleaning or weeding, 

 especially the removal of the softwoods, aspen and birch, 

 and of coppice shoots from seedling forest. 



It was also known that this weeding is best done "in 

 the full sap," in order to kill the stocks. 



