Genecology of Bud-Burst Phenology in Douglas-Fir: Response to Flushing Temperature and Chilling

摘要: We studied the process by which bud burst of coastal Douglas-fir (Pseudotsuga menziesii var. [Mirb.] Franco) is synchronized to seasonal cycles. Seedlings from 23 populations were treated in 12 growth-chamber combinations chilling periods and flushing temperatures. Bud-burst rates increased approximately logarithmically with temperature. Rates also depended on duration chilling, temperature coefficients (Q10) increasing 2.7 after 11 days 3.5 77 days. The annual cycle, moisture relation, latitude, elevation, distance ocean site origin a population influenced rate under controlled conditions. adaptive significance these responses discussed terms Levins's dormancy strategy hypothesis.