Populations from areas peripheral to the central area of study were also included 

 in the present tests. The Okanogan Mountains in north central Washington (longitude 

 118.5°) were represented by two populations. Both populations were from relatively 

 high elevations (1,460 m) . Cold hardiness of these populations evidently approached 

 maximum values in mid-November. Unlike populations from farther east, hardiness in 

 populations from the Okanogan Mountains failed to develop greatly in response to the 

 cold temperatures of late November. On the other hand, populations from the Blue 

 Mountains in northeastern Oregon (longitude 118°) hardened similarly to populations 

 from northern Idaho. 



Current and previous studies on the hardiness of Douglas-fir populations have 

 direct application in delineating seed zones in northern Idaho and eastern Washington 

 that reflect adaptive variation in cold acclimation. In contrast with previous 

 results (Rehfeldt 1979) , present data provide no evidence that the cold Abies lasiocarpa 

 series of habitat types should represent a seed zone that is independent of elevation. 

 However, development of seed transfer guidelines associated with continuous variables 

 requires acceptance of a level of genetic similarity that minimizes risk of maladaptation 

 but that remains economically and administratively practical. For the present data, 

 a 50 percent genetic similarity implies that seeds transferred 1-1/2 degrees latitude 

 or 400 m elevation have a probability of only 0.5 of producing seedlings as cold hardy at 

 the alien site as seedlings derived from local seeds. Thus, it seems intuitively sound 

 biologically to limit seed transfer by 75 percent genetic similarity, even though the 

 associated probability of maladaptation is 0.25. However, it should be recalled that 

 the estimates of similarity derived by the techniques employed represent minimal estimates 

 (Morgenstern and Roche 1969). Consequently, probabilities of maladaptation are maximal. 



If a 75 percent genetic similarity limits seed transfer, seed for reforestation 

 of northern Idaho and northeastern Washington should not be transferred more than 1 

 degree latitude, 3 degrees longitude, or 200 m elevation. However, seed zones must 

 be based on numerous adaptational features. Consequently, this paper is one of a 

 continuing series on the ecological genetics of Douglas-fir in the Northern Rockies. 



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