Early realized genetic gains for coastal Douglas-fir in the northern Oregon Cascades

• Published in: Western journal of applied forestry Vol. 19; no. 3; pp. 195 - 201
• Main Authors: St. Clair, J.B, Mandel, N.L, Jayawickrama, K.J.S
• Format: Journal Article
• Language: English
• Published: Bethesda Oxford University Press 01.07.2004
• Subjects: analysis of variance; forest genetics; forest stands; forest trees; genetic improvement; least squares; progeny testing; Pseudotsuga menziesii var. menziesii; statistical analysis; tree and stand measurements; tree breeding; tree growth; tree yields; Oregon; Cascade Mountain region
• ISSN: 0885-6095; 1938-3770
• DOI: 10.1093/wjaf/19.3.195

Block-plot realized genetic gain trials were established for coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) at five sites in the northern Oregon Cascades. The long-term objectives of these trials are to explore the growth trajectories and productivity of genetically improved stands and their relationship to predicted genetic gains based on performance in progeny tests. Measurements 5 years after planting provide an opportunity for an early assessment of realized genetic gains as compared to predicted gains and provide data for determining the number of replicates needed to detect statistically significant differences between improved and unimproved populations using large block plots. Results indicate that progress from selection and breeding of Douglas-fir is readily achievable, and realized genetic gains 5 years after planting are similar to those predicted based on results from progeny tests. Realized genetic gains were about 6% for height, 8% for diameter, and 28% for stem volume, compared to predicted genetic gains of about 8% for height, 7% for diameter, and 25% for stem volume. Large numbers of replicates (30-50) are required to detect statistically significant differences in height and diameter between improved and unimproved populations given genetic gains expected in a typical tree improvement program.