History of Forest Ecology 417 



shelterwood sj'stem were soon applied universally, even to the 

 northern pine forests. The result was that pure, even-aged, high 

 forests in many cases succeeded mixed forests. When the trans- 

 planting of conifers became general, about 1840, the clear cutting 

 and planting system was widely applied, especially in the pineries. 

 The result was, that since the middle of the 19th century the 

 common form of management in northern and central Germany 

 was the establishment of pure stands of even-aged, high forest. 

 The old masters, Hartig and Cotta, and those that followed them 

 brought about this management because it fitted very well the 

 conditions of the woodlands at that time and also because this 

 system was best from the standpoint of yield. 



The reaction set in during the last quarter of the century. 

 While the formation of pure stands was going on, investigations in 

 natural methods of reproduction lingered. On the other hand, the 

 old method of management became unexpectedly cut and dry and 

 inelastic. Moreover, the shelterwood system, which had been 

 developed according to the requirements of the beech was applied 

 to pine and spruce. When failures became evident, much opposi- 

 sition arose against the use of this system. Foresters began to 

 realize that the formation of large areas of pure stands was in many 

 ways antagonistic to the natural requirements of the trees. An era 

 then set in which brought modern forest ecology to the fore to show 

 the necessity of imitating nature's methods. Gayer, in 1878, set 

 forth the advantages of mixing species and later developed the 

 formation of uneven-aged mixed stands. In 1885, Borggreve 

 pointed out the evils of clear cutting and the advantages of natural 

 reproduction over the practice of planting. These men and others 

 advocated a change from the shelterwood system in hardwoods and 

 the clear cutting as applied to pines to the selection system and 

 from pure forests to mixed forests. 



Two schools of silvicultural management then sprang up 

 adhering to two opposite principles : the natural and the economic. 

 The former school favored natural reproduction, many-aged 

 stands, and the selection system; the latter school advocated the 

 greatest possible return, even-aged stands, and the clear cutting 

 and planting method. Without doubt modern European silvi- 

 culturists have been guided by the economic principle. As a 

 result, the natural principle which preserves the productive 

 power of the soil has been neglected. Even today the clearing 



