40 PRACTICAL FORESTRY IN 



and filled the blanks between them. Perhaps destruction was 

 not so complete and surviving trees made the process a swifter 

 one. Except in the very oldest forests, where remains of the 

 original stand have entirely rotted away, the history in either 

 case may be read in ancient snags and fallen logs. 



Suppose, however, that fire had not come to aid the fir in 

 perpetuating itself ? This, too, we can answer from the signs 

 today. Every Northwestern woodsman knows tracts of vary- 

 ing size (usually small because fire has been almost universal) 

 covered with big old hemlock, white fir and cedar, with here 

 and there a dying giant fir, perhaps, but mainly showing fir 

 occupancy only by rotting stumps and logs. No sign of fire 

 is seen. When this fir forest was approaching middle age, 

 the shade bearing species began to appear beneath it. As 

 the firs began to crowd themselves out, the later comers shot 

 up with the increased light and filled the open places. Ac 

 last the even-aged fir forest was completely transformed into 

 a selection forest of other trees, which will remain until some 

 accident again gives fir a chance if any survives near enough 

 to reach the spot with seed. 



Douglas fir is not the only Western tree which usually 

 grows in even-aged stands. Lodgepole pine has the same 

 habit, often supplanting yellow pine after fire or logging. 

 Western white pine is perhaps more tolerant than Douglas fir, 

 hence more likely to hold its own without artificial aid, but 

 is also more certain to compete successfully if it has such aid. 

 The same is true of tamarack. 



NATURE AS A MODEL 



We thus see that if economic reasons suggest it, we may 

 use the selection system as a basis for artificially managing 

 the shade bearing species such as hemlock, white fir, cedar, 

 spruce, and even Western yellow pine. We may cut the 

 largest and oldest trees and still have a well started second 

 crop. If there is not much young growth to leave, even a lit- 

 tle is valuable. It mav be decided! v best to leave medium 



