Orchard pollen contamination: joint estimation of realized levels on current growth and future effects on volume and value at rotation in coastal Douglas-fir in British Columbia |
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| Authors: | Michael Stoehr Joe Webber |
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| Institution: | 1. British Columbia Ministry of Forests, Lands and Natural Resource Operations, Tree Improvement Branch, Saanichton, Canada;2. Retired.;3. Formerly in the former Research Branch at the former British Columbia Ministry of Forests, Salt Spring Island, Canada. |
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| Abstract: | Pollen contamination was evaluated using control-pollinated seedlings pollinated with polymixes of orchard pollen and pure wildstand and wind-pollinated orchard seedlings. At age 7, seedlings pollinated with contaminate pollen were the shortest across all four sites, but had survival levels (83%) similar to open-pollinated (84%) and pure orchard seedlings (86%). Open-pollinated seedlings had intermediate heights while pure orchard seedlings were tallest. The level of pollen contamination in open-pollinated seedlots was estimated to be 26%. Survival for all pollen sources combined was similar at the two high-elevation sites (84%) and low-elevation sites (86%). Using a yield model to compare volume/ha at rotation age for open-pollinated orchard seedlings and pure orchard seedlings, differences were small and increased due to site index (SI; from 3 to 6?m3/ha) but not due to planting density. Equivalent discounted benefits at rotation were 27 vs. 54 C$/ha at the two extreme site indices (18 vs. 25), respectively. These projected reductions due to pollen contamination are magnified by the large area that is regenerated annually with orchard seed of coastal Douglas-fir and contamination can cause a reduction in benefits of up to C$748,500 per year at the highest SI at a planting density of 1111 trees/ha. |
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| Keywords: | Pseudotsuga menziesii A-class seed progeny testing growth and yield modelling |
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