Figure 2. — In this western hemlock habitat in northern Idaho, Douglas- fir is a 

 relatively short-lived serai tree. It establishes more readily in exposed 

 situations (clearcuts) here than it does in other habitats, but later 

 growth is hindered by competition from better adapted species. 



Species Behavior 



Within a range extending more than 2,000 miles from north to south, Rocky Mountain 

 Douglas-fir grows in widely diverse environments (fig. 2-6). Environmental variety has 

 led to physiological and ecological diversity within the species. 



Frothingham (1909) suggested that, under moist conditions, Douglas-fir reproduces 

 better in the open than under drier conditions wnere it requires some protection by other 

 species, which it eventually replaces. Krajina (1965) recognized this for Douglas-fir 

 in Canada. Krauch (1956), working in the southern Rockies, found that shade favored 

 seedling establishment and early growth. In ecological terms, Douglas-fir is a serai 

 - species on moister sites and a climax species on somewhat drier sites. 



The Daubenmires (1968) classified the forest vegetation of eastern Washington and 

 northern Idaho into 22 habitat types, which they considered to be ". . .the basic 

 ecologic subdivisions of landscapes." Each habitat type has a distinct potential as to 

 sere and climax, and is recognized by a distinctive combination of overstory and under- 

 story at maturity. Three of these habitat types have Douglas-fir as the major climax 

 species. In five other more moist habitat tv'pes, it is a serai species. 



In central Idaho, preliminary forest habitat type work indicates that Douglas-fir 

 grows in 29 habitat types. It is a climax species in 14, a major serai species in 10, 

 and a serai species in certain parts of the range of the other 5 habitat types. 



Before we can confidently predict how Douglas-fir \\'ill respond to different treat- 

 ments, especially in the regeneration portion of the life cycle, we must first identify 

 differences in site conditions and then determine how the species responds to each par- 

 ticular set of conditions. Results of my field reconnaissance emphasize this point. 



4 



