History of Forest Ecology 419 



(86) was inclined to differ from these men. He asserts that mix- 

 tures are better than pure stands, but that natural reproduction 

 is not ideal. His opinion is that after all is said and done the clear 

 cutting and planting method, judging from past performances, 

 has produced the best results. Dittmar (87) held that clear 

 cutting was unnatural and that natural reproduction was nearest 

 to nature's method. As early as 1901, Reuss wrote about the 

 detrimental effects of planting methods upon the future conditions 

 of the stands with partiular reference to the spruce. He called 

 the clear cutting method unnatural and considered its use mis- 

 management. Later, (85) in his splendid manual upon forest 

 reproduction, he established the golden rule : the simplest method 

 of producing a crop without sacrificing the soil was to be the sole 

 criterion between natural and artificial reproduction and between 

 pure and mixed stands. 



Duesberg (84) proposed a system which is probably the most 

 radical and at the same time the most thoroughly original one 

 that has been propounded. In a most thorough and painstaking 

 manner he seeks to break down the arguments which are in favor 

 of large, pure stands. In doing this, he brings into play a great 

 wealth of silvical observations and investigations. His thesis is 

 that Nature, unguided by man, produces a forest which is in 

 complete harmony with the soil and the plant and animal life in 

 the forest. Man should not interfere with Nature's work, but 

 should seek to understand the life-history of an unmanaged 

 forest and the natural laws which determine it. With this knowl- 

 edge he should decide upon the proper method of management, 

 try to improve upon Nature's method and direct the natiiral 

 forces to the production of economic values. Duesberg proposes 

 a simple type of selection forest, which recognizes every essential 

 of the uneven-aged forest, produces the highest yield and is most 

 simple to manage. This selection forest has for its unit small 

 areas of a size determined by the diameter of the crown of a full- 

 grown tree in the virgin forest. These areas differ with the dif- 

 ferent species and their typical shape is a regular hexagon. Seven 

 of these hexagons are termed a group, each one of the group being 

 a clump. 



Duesberg 's system impresses one as being too complex for 

 general introduction and certainly too difficult to instue its in- 

 auguration and success at the hands of the average forester. 



