Rehfeldt, G. E. Adaptive variation in Pinus ponderosa from Intermountain regions. II. 

 Middle Columbia River system. Research Paper INT-373. Ogden, UT: U.S. Depart- 

 ment of Agriculture, Forest Service, Intermountain Researcii Station; 1986. 9 p. 



Seedling populations were grown and compared in common environments. 

 Statistical analyses detected genetic differences between populations for numerous 

 traits reflecting growth potential and periodicity of shoot elongation. Multiple regres- 

 sion models described an adaptive landscape in which populations from low eleva- 

 tions have a high growth potential while those from high elevations have a low growth 

 potential. Patterns of genetic variation reflect adaptation to a growing season of 

 variable length. Adaptive landscapes are used to construct guidelines for limiting seed 

 transfer in artificial reforestation. In general, seed from a single source should not be 

 transferred more than +200 m in elevation. 



KEYWORDS: microevolution, genetic differentiation, seed zones, seed transfer 



INTERMOUNTAIN RESEARCH STATION 



The Intermountain Research Station provides scientific knowledge and technology 

 to improve management, protection, and use of the forests and rangelands of the In- 

 termountain West. Research is designed to meet the needs of National Forest 

 managers. Federal and State agencies, industry, academic institutions, public and 

 private organizations, and individuals. Results of research are made available 

 through publications, symposia, workshops, training sessions, and personal contacts. 



The Intermountain Research Station territory includes Montana, Idaho, Utah. 

 Nevada, and western Wyoming. Eighty-five percent of the lands m the Station area, 

 about 231 million acres, are classified as forest or rangeland. They include 

 grasslands, deserts, shrublands, alpine areas, and forests. They provide fiber for 

 forest industries, minerals and fossil fuels for energy and industrial development, 

 water for domestic and industrial consumption, forage for livestock and wildlife, and 

 recreation opportunities for millions of visitors. 



Several Station units conduct research m additional western States, or have mis- 

 sions that are national or international in scope. 



Station laboratories are located in: 



Boise. Idaho 



Bozeman, Montana (in cooperation with Montana State University) 

 Logan. Utah (in cooperation with Utah State University) 

 Missoula, Montana (in cooperation with the University of Montana) 

 Moscow, Idaho (in cooperation with the University of Idaho) 

 Ogden, Utah 



Provo. Utah (in cooperation with Bngham Young University) 

 Reno, Nevada (in cooperation with the University of Nevada) 



