416 Forestry Quarterly 



and especially of natural reproduction he makes use of aU modern 

 ecological development. Mayr's work treats silviculture in the 

 light of the various habitat factors which affect tree growth. His 

 contribution to forestry is his recognition that climate is the basis for 

 biological differences not only in industrial trees and tree formations 

 but also in silvicultural practice. His dicta are suggestive working 

 hypotheses upon which the future superstructure of silvioilture 

 might be reared. Duesberg's book is not merely a scientific treatise 

 on silviculture but it is a philosophy of the forest. He has developed 

 rules and principles with due regard to historical, economic, legal, 

 ethical, and aesthetic relations in nature and society. By a critical 

 investigation of the interrelation of forest and soil he shows how 

 the even-aged high forest outrages nature and that mixed, uneven- 

 aged forests are the ideal towards which silviculturists must work. 

 Every paragraph contains shrewd observations and a wealth of 

 detail, every one of which is supported by whatever facts scientific 

 investigators have contributed either to support or contradict. We 

 have in this work the modern principles of ecology applied par 

 excellence. Wagner's latest book deals largely with silvicultural 

 systems and its discussion will be relegated to the next section. 



The Influence of Modern Forest Ecology upon Silvicultural 

 Management 



Before the experiment stations came into being, pure, even-aged 

 stands were the rule in many parts of Germany. Shortly after 

 these stations were established, the investigative attitude began to 

 pervade every branch of forestry. It was due largely to this new 

 investigative point of view that a reaction set in in silvicultural 

 management. The return to mixed selection stands was advo- 

 cated by many foresters who saw in this purely formal treatment 

 of the forest the violation of many fundamental natural Idws. In 

 the protest against the old system which ensued, forest ecology 

 was again brought into play and in the general controversy that 

 followed, quite often the ecological discussions waxed so hot that 

 the main issue of the discussions was lost sight of, much to the 

 advantage of forest ecology. 



Natural reproduction methods were chiefly employed until 

 almost the middle of the 19th century. The selection and coppice 

 systems were used until Hartig and Cotta brought the shelterwood 

 system into favor. Hartig's eight rules for the application of the 



