Potential pollen contamination effects on progeny from an off-site Douglas-fir seed orchard: 9-year field results

To evaluate the potential effects of seed orchard pollen contamination from surrounding background sources, we made control pollinations with outside orchard pollen and inside orchard pollen on trees of a Douglas-fir (Pseudo tsuga menziesii (Mirb.) Franco) coastal–interior transition zone seed orchard. The resulting progeny were tested on a transition zone and a coastal site. After nine growing seasons, survival was above 90% on both sites for both pollen sources, and the trees height differences due to pollen source were statistically nonsignificant. Wildstand operational seedlots, used as controls, were 17% shorter than the "contaminated" seedlings. Orchard management implications of these results are discussed.