Development of Silviculture. 67 



grower, was transplanted from the Alps (1730 in 

 Harz mountains), and its use was extended, as with 

 us, to conditions for which it was not adapted. 



It was principally a desire for novelty and perhaps 

 for better, especially foreign things, that led to the 

 planting of North American species in parks during 

 the first half of the 18th century. But, although 

 F. A. J. von Wangenheim's very competent writings 

 on the American forest-flora and on the laws of natu- 

 ralization (1787) stimulated interest in that direction, 

 the use of American species for forest planting was 

 not inaugurated till nearly 100 years later., with the 

 single exception of the White Pine (P. strobus), of 

 which large numbers were planted. 



7. Improvement of the Crop. 



Thinning of stands had been practiced early in the 

 16th century, not for improvement of the remaining 

 stand so much as to secure fence material, although in 

 1531 the observation was already recorded that thin- 

 ning improved and stimulated the remaining growth. 



In the 17th century, opposite views, or, at least 

 doubts as to its usefulness were expressed in the forest 

 orders, and sometimes thinning was even forbidden. 

 Even in the 18th century some of the prominent 

 foresters, Doebel and Beckman, were opposed to it, 

 and although others favored the operation, the prac- 

 tice of it remained limited. 



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 accentu- 



3a 



