THE PACIFIC NORTHWEST 41 



sized trees, which otherwise we would cut, because they are 

 still growing rapidly. 



On the other hand, we see that this, method would not be 

 of any advantage at all in insuring a second crop of Douglas 

 fir, for there is no young growth of this species to protect. 

 The small and medium sized trees, instead of being immature, 

 are merely stunted specimens of the same age as their larger 

 brothers and unlikely to gain in size if left. Selection cutting 

 here would save for future use only such understory of shade- 

 bearing species as may exist. Unless this is an object, the 

 best plan is to cut clean and get all we can. If we leave any 

 fir at all it is for the purpose of reseeding, not to secure bet- 

 ter utilization of the trees themselves, and whether we do so 

 depends, theoretically at least, upon whether it is better than 

 artificial seeding or planting. In short, selection cutting har- 

 vests the ripest trees of a perpetual forest, while clean cutting 

 destroys the forest in order to start an entirely new and more 

 rapid growing one. 



Clean cutting is therefore necessary as well as natural in 

 dealing with intolerant trees. But it does not follow that the 

 selection system, although natural to tolerant species, is the 

 only one adaptable to them. While the one class demands 

 light, the other does not demand shade. It is merely capable 

 of enduring it. Indeed, except for the greater susceptibility 

 of some species to extreme heat and dryness when very young, 

 as a rule shade bearing trees grow much better if they do 

 have ample light supply. Consequently clean cutting may be 

 the best system for these also under certain economic condi- 

 tions. 



Besides its influence upon the occurrence of species in the 

 forest, light practically governs the physical form of the in- 

 dividual tree. If grown in an opening and not artificially 

 pruned, a tree will have a conical trunk and living branches 

 almost down to the ground. The denser and consequently 

 darker the forest, the more cylindrical the trunk, the smaller 

 the crown of branches and the greater the clear length. The 

 individual tree has no object in assuming a desirable com- 



