Ecological adaptations in Douglas-fir populations. II. Western Montana

Government Document

Transfer Guideline: Recommendation

Seedlings from 50 populations of Douglas-fir (Pseudotsuga menziesii var. glauca ) from Montana west of the Continental Divide were compared in nursery, laboratory, and shadehouse studies. Analyses of variance indicated significant differences among populations in six traits: bud burst, bud set, 3-year height, growth rate, cold injury, and flushing periods during the first or third growing season. Most traits were highly intercorrelated; thus, populations that expressed a high growth potential also set buds late, flushed twice, grew at a rapid rate, but were most severly injured by freezing. Consequently, adaptation of populations for numerous traits is viewed as a balance between selection of high growth potential in relatively mild environments and selection for cold hardiness in severe environments. Multiple regression analyses related genetic differentation of populations to geographic and ecologic conditions of the seed source. The regression model that best fit the data described adaptive variation according to two physiographic zones, elevation within each zone, and latitude within zones. Patterns of adaptive differentiation were used to develop seed transfer guidelines for reforestation and tree improvement.