The North American Forest 7 



complex and unalterable laws. Each tree does not 

 constitute an independent entity, but is affected in 

 every moment of its life by every other tree and 

 minor plant of the entire forest, and in turn itself 

 influences every other tree. The forest therefore 

 constitutes an organism, having a united life differ- 

 ent from, but dependent on, the life of its individ- 

 ual members. Within this organism, a never-ceas- 

 ing struggle is going on, tree fighting against tree, 

 species against species ; while the entire organism 

 carries on a warfare with other plant associations, 

 such as the prairie and the bog, in which it is some- 

 times vanquished, sometimes victorious. 



To the ingenuity of man, with the help of such 

 knowledge as he may acquire of the laws regula- 

 ting the life of the forest organism, it is possible to 

 make use of the various phases of this warfare for 

 his own purposes. By creating conditions favoring 

 some particular species of tree he is able to help it 

 to spread and flourish at the expense of its compet- 

 itors ; and similarly he may create conditions which 

 help the forest as a whole to maintain itself against 

 the aggression of other plant associations. No 

 small part of silviculture or the art of caring for 

 woodlands consists in just such interference in the 

 natural processes of forest development, rather than 

 planting and sowing. In order to understand the 

 relations of forestry to our national life, the reader 

 should have in his mind an outline at least of what 

 American forests are like, and also of how they came 

 to be what they are. 



