History of Forest Ecology 403 



G. L. Hartig summarized and systematized what science and 

 practice had developed up to the end of the 18th century in the 

 realms of thinning a,nd improvement cuttings. He was the first 

 to use the word Durchforstung (thinnings). He emphasized the 

 idea that only the dead and suppressed trees should be removed, 

 and that the crown cover should remain unbroken. Cotta at 

 first also believed in light thinnings, but later went to the other 

 extreme. Pfeil was of the opinion that it was impossible to gen- 

 eralize, but that thinning practice should be regulated according to 

 the needs of the species and site. Carl Heyer is responsible for the 

 terse instruction: "early, often, moderate." 



The true scientific basis for thinnings, however, was not devel- 

 oped until the forest experiment stations came into being. Before 

 this, numerous attempts were made to explain the biological basis 

 for thinnings, perhaps the earliest of which was the observation 

 by Spaeth in 1802 that the soil is not capable of furnishing food 

 materials for all the individuals of a young stand. The physiologi- 

 cal and ecological reasons for the practice of thinning were particu- 

 larly advanced by the botanists Goeppert and Robert Hartig and 

 by the foresters Kraft, Lorey, Borggreve and Wagener in the latter 

 part of the 19th century. 



Previous to 1800, perhaps the only silvicultiu^al works worthy of 

 mention are Carlowdtz's Silvicultura Oeconomica (1713) and the 

 encyclopaedic works of the Cameralists. The former was the first 

 book which divorced forestry from hunting. The Cameralists 

 deserve credit for having collected in large volume the empirical 

 knowledge of the so-called " holzgerechte Jaeger." The 19th 

 century saw a reaction to monographic writings, although at first 

 the tendency was to treat the subject as the Cameralists did. The 

 works of the old masters Hartig, Cotta, Pfeil, Heyer and Hunde- 

 shagen should be mentioned here, since they began to put silvi- 

 culture upon a scientific basis. In 1855, appeared Burkhardt's 

 book Sden und Pflanzen, sl volume which had great value in the 

 development of artificial reproduction by planting. Fuerst's 

 Pflanzenzucht im Walde, which appeared in 1882, was a similar 

 work. Between 1880 and 1885 Gayer, Wagener, Borggreve and 

 Ney contributed modern works on general silviculture. 



The transition from silvicultural practice based upon empiricism 

 to that based upon the fundamental sciences and experimental 

 forestry ecology is a very gradual one. In fact, it covers a period of 



