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Low Elevation (<650m) Maritime Hemlock Hemlock is the most under-planted, but still widely used species for regeneration in B.C. It is hoped that this will be rectified as higher gain seed becomes available to support planting improved material over natural regeneration. Since genetic worth of first generation orchard seedlots has now levelled off at around 16% gain, further improvements will depend on moving to the next generation of selections.
To date, 220 trees have been chosen from advanced generation HEMTIC (Hemlock Tree Improvement Co-operative) trials based on age 5 height. The tests incorporate the best parents from first generation programs in Washington State, Oregon and B.C. Age 10 results are now analyzed, and about half of these early picks will be culled based on the results. The advantage of selecting broadly, then roguing parents that underperform, is to have sizeable grafts on hand as soon as the age of selection is reached, saving several years in the breeding cycle. Briefly, parents from northern Washington State have a slight edge in performance in south coastal B.C. Oregon material has sub-standard performance, though when crossed with B.C. parents can be quite comparable to local sources. The heritability of growth for individual trees was low, as was expected for this ecologically plastic species. This means that the value of the selections relies more heavily on their family performance than on that of the individual within the family. To remedy this for later advanced generation tests, clonal trials are established and assessed, containing several copies of each individual to allow for effective within family selection. In 2005 three clonal test sites were planted. In the meantime, methods of producing a desirable balance of male and female strobili with young selected material in small pots are being optimized to begin breeding with the new material as soon as the age 10 data are evaluated. Note: Participation in HEMTIC by the BC Ministry of Forests has been terminated. As per the Memorandum of Understanding with which the Co-op was established, age 5 data from the HEMTIC tests has been sent to the co-operators, thus securing MFR access to all HEMTIC improved material. Continued co-operation with the current members is planned, in the hope that further exchanges of data (age 10) can be arranged. High Elevation (>650m) Hemlock The advantages of hemlock over other high elevation species include faster growth than yellow-cedar and better wood quality than Pacific silver fir. The species plan requires first generation testing of about 300 parents to achieve 15% genetic gain in growth traits. We have results from 240 parents, of which 212 have new breeding values. The last series, testing a further 110 poly-cross families, has recently been established after overcoming nursery cultural problems.
Ministry Contact: Alvin Yanchuk |
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