Cold‐Acclimation in Seedling Douglas‐Fir Related to Phenology and Provenance

Abstract

In October 1969, 1—year seedlings from 10 provenances growing at Corvallis were severely damaged by frost. Provenances came from eastern and western slopes of the Coast Ranges in western Washingon and Oregon. In the earliest provenance, bud set preceded frost by 5 weeks; in the latest, by 2.75 weeks. For each additional week by which bud set preceded frost, the proportion of frost—damaged seedlings decreased by 25%. For provenances setting buds in identical weeks, southern sources were more sensitive, the porportion damaged increasing by 4% per degree of decreasing latitude. Since southern sources generally set buds later and were at the same time more sensitive, they were much more severely damaged. The southernmost coastal source (Coos Bay) suffered 78% damage, the northernmost coastal (Soleduck) 10%.