40 THE PRINCIPLES OP HANDLING WOODLANDS 



duction and growth, and these are subject to great va- 

 riation under different conditions of soil and climate. 

 Stands vary enormously in composition, form, density, 

 and thriftiness. The forester must know the habits and 

 requirements of the different species, and must be able 

 to diagnose the needs of any given stand, in order to 

 handle it in such a way as to secure the results desired. 



Every measure of practical silviculture is, however, 

 subject to local conditions of markets and logging. The 

 owner desires as high a production as possible, but the 

 question of cost will always shape the method of apply- 

 ing his operations. Not only may the market and log- 

 ging conditions determine the system of silviculture; 

 they will always be a great factor in determining the de- 

 gree of intensity of the work, and govern the details of 

 operation. 



In the discussion of the various systems of silviculture, 

 repeated references will be made to the different factors 

 which modify the working out of details on the ground. 



Choice of Species 



In reproducing a forest, one aims to establish the 

 species which will best meet the objects of management. 

 In artificial reproduction there is, theoretical h', a choice 

 among all species adapted to the local climate and soil. 

 In practise, it may be possible to secure trees or seed of 

 only a limited number of species. 



When natural reproduction is used, choice is restricted 

 to the species already growing on the ground. In a mixed 



