88 ECONOMICS OF FORESTRY. 



as an economic factor, is by no means a mere col- 

 lection of trees, but an organic whole in which all 

 parts, although apparently heterogeneous, jumbled 

 together by accident as it were and apparently 

 unrelated, bear a close relation to each other and 

 are as interdependent as any other beings and con- 

 ditions in nature. 



Not only is there interrelation between plant 

 and climate and between plant and soil conditions, 

 but also an interrelation between the individuals 

 composing the forest growth .based on definable 

 laws, and finally an interrelation between the 

 arborescent growth and the lower vegetation ; the 

 whole being a result of reactions of plant life to 

 all surrounding influences and reciprocally of 

 influences on all elements of its environment. 

 Even the seemingly lawless mixture of species 

 which we find in the virgin forest is not altogether 

 fortuitous, but a result of such reactions. 

 ■ Out of these reactions and interrelations result 

 conditions which we call forest conditions, and 

 which not only distinguish the forest from other 

 collections of trees or woodlands, but also impart 

 a particular individuality and character to the 

 forest growth of each locality. Even the virgin 

 woodlands may lack what we conceive as ideal 

 forest conditions, when in the struggle for ex- 

 istence other forms of vegetation have still the 

 advantage over the arborescent growth and hence 

 forest purposes are imperfectly performed, or when 



