H4 Forests and Trees 



common, while along the coast are found the Douglas fir, 

 the giant cedar and the Sitka spruce, all of gigantic size. 

 This constitutes the most extensive and perhaps the most 

 valuable conifer forest in the world to-day. 



To one who thinks of the causes of things, it is a source 

 of constant wonder just how and why forests came to be 

 distributed as they are. Many guesses have been made 

 in attempts to explain particular instances, but only wide 

 knowledge combined with good judgment will prevent 

 mistakes. Such knowledge has been or is being gradually 

 built up. The geologist, by examination of impressions 

 of leaves and other such remains found in the rocks, can 

 tell us what plants have occupied any territory in past 

 geological ages. The botanist can tell what the natural 

 conditions must have been where these plants lived, and 

 the explorer can make plain the present conditions. Putting 

 all the facts together we are led to the conclusion that 

 existing forest conditions depend upon three main factors : 

 (i) The natural conditions, including climate, soil, moisture 

 and elevation; (2) The order in which species of trees 

 spread their seed to new areas and thus get possession; 

 (3) The power of species to contend with each other in the 

 struggle for existence. 



We now know that at one time it matters not to us- 

 how long ago or by what name the period is known 

 great forests of trees, very similar to those which now grow 

 much farther south, extended north beyond where forests 

 of any kind are now found. We know further that these 

 forests died out, and the northern part of the continent 



