THE AUTHOR 



G. E. REHFELDT is a plant geneticist at the Inter- 

 mountain Research Station's Forestry Sciences 

 Laboratory in Moscow, ID. He has been studying the 

 ecological and quantitative genetics of Rocky Mountain 

 conifers since 1968. 



RESEARCH SUMMARY 



Genetic differentiation of 60 populations of Pinus 

 contorta primarily from eastern Idaho and adjacent 

 Wyoming was assessed in three studies involving (1) 

 growth and development in field environments, (2) the 

 periodicity of shoot elongation in the greenhouse, and 

 (3) freezing tolerance in the laboratory. Genetic 

 differentiation between populations was observed for 

 traits that included 3-year height, leaf length, freezing 

 tolerance, and the pattern of shoot elongation. Regres- 

 sion models related as much as 83 percent of the vari- 

 ation between populations to the elevation and geo- 

 graphic location of the seed origin. Elevational ciines 

 were particularly steep. Consequently, if maladaptation 

 is to be controlled in artificial reforestation, seed 

 transfer should be restricted severely for elevation but 

 geographically may be relatively liberal. Detailed prac- 

 tical guidelines will be presented separately. 



