CHAPTER XVn 

 DOUGLAS FIR 



General Conditions. — Altho the Douglas or red fir is one of our 

 most widely distributed timber trees and is found throughout 

 the Rocky Mountain and Cascade ranges from Northwestern 

 Texas to British Columbia it is not the dominant species over 

 wide areas except in the extreme northwestern part of the 

 United States. There it occurs in nearly pure stands with high 

 yields. In California the type occupies the middle slopes of the 

 west side of the Cascades between the sequoia and sugar pine 

 types. All of western Oregon is covered with it from the sununit 

 of the Cascades to the Pacific Ocean except the valley of the 

 Willamette River, a sheltered basin lacking in precipitation. 

 Northward in Washington there are no such dry valleys and the 

 type js the dominant vegetation west of the Cascades. 



Altitudinally the type may occur anywhere between o and 

 6000 feet above sea level but in accordance with the laws of 

 cUmate is only abundant at sea level in Washington. South- 

 ward in Oregon and California it is commonly forced to keep to 

 the mountain slopes by tree sp>edes like the sequoia which are 

 better adapted to .the warmer, drier climate and even on these 

 slopes it prefers the cooler north slopes. 



With a north and south extent of 500 miles and an east and 

 west width of 1 50 miles there is naturally considerable variation 

 within the type in climate. The north and south extent is less 

 important, however, than the distance from the Pacific Ocean. 

 The moisture laden winds come from there and ascend the 

 steep slopes of the Cascade Range. At the point where they are 

 cooled down to the temperature at which they give off their 

 moisture freely the Douglas fir type is most vigorous. While 

 it can exist with an average annual precipitation of 50 inches it 



does better where the total annual rainfall is 50 to 100 per cent 



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