|
The western redcedar genetic resource management program includes genetic conservation, genecology, tree breeding, and technical support.
The following activities occurred over the last year: Approximately 100 new parents from southern Oregon were cloned and established in the gene archives at Cowichan Lake Research Station. Besides contributing to the ex situ gene pool, these parents will also be included in the breeding and testing programs. Ten-year measurements of the open-pollinated progeny trials were collected and are currently being analysed. Seed was collected from approximately 300 polycross families from last spring's breeding, for a total of 750 families to date. An additional 250 coastal U.S. sources will be bred over the next two years. To date, 25 progeny test sites have been established including over 450 polycrossed families. An additional 300 families will be established into trials over the next two to three years. All sites were maintained to minimise competing vegetation and deer browsing. Four nutrient-poor sites were fertilised last spring. The first series, established in 1998, was measured for 5-year heights. Breeding values have been officially released for 150 parents. The redcedar program has several additional genetic support studies which are of great interest, as it has several unique biological features not present in other tree species. A total of 80 provenances from the interior portion of the species’ range in B.C. and the U.S. have been collected and will be used to test adaptation and develop seed transfer guidelines for the ICH zone. So far the first series of trials has been planted, and additional series are planned for subsequent years. Selfing studies Field trials comprising 15 F1 families and corresponding S1 and S2 families from 30 random and 30 select lines were established on three coastal sites. The study was designed to evaluate growth and adaptation differences due to genetic selection and inbreeding, and thus the feasibility of utilizing S1 and S2 families in a recurrent selection program. Stand volume originating from various proportions of selfed seed in a seedlot were simulated for different stacking and site indices. On average, for every 10% reduction in selfed seed, stand yield at 60 years is improved by 0.8%. These results will help to assign genetic worth to seedlots with reduced selfing.
Wood durability Western redcedar trees were tested for enhanced natural durability by analysing wood cores for tropolones, in particular the thujaplicins, and correlated to weight loss in soil block tests. It is anticipated that wood durability measures will be developed for 300 clones by the end of this project. Mammal browse resistance Ungulate browse damage to redcedar seedlings costs $20-25 million in BC per year at a cost of $5-6/tree for physical protection. Browse damage levels in the field are directly related to foliar monoterpene concentrations. These defence chemicals naturally occur in a wide range of plants and much is known about their biochemistry and genetics. Monoterpene level is a heritable trait, with concentrations increasing as seedlings age, but with consistent expression allowing selection by age 1. We have selected and bred redcedar populations for high and low monoterpene concentrations. With a 2-year breeding cycle, results are achieved quickly. Western redcedar shows no trade-off between monoterpenes and growth: deer-resistant seedlings grow just as tall as susceptible seedlings.
Before browse-resistant seedlings are made available, we are gathering information on how best to deploy it. Planting 100% resistant redcedar stock would effectively force deer to forage on that where no alternative food source is available, and they may change their foraging behaviour. Ensuring a mixture of susceptible and resistant material, in combination with other suitable species, is important to reduce the long-term risk of mammals acclimatizing to high-terpene seedlings. Climate change research: adaptation and forest health Studies on projected impacts of climate change show little effects on coastal populations from the maritime zone. However, the submaritime zone shows significant trends with cold hardiness and latitude. Increasing minimum temperatures and changes in timing of the growing season and frost-free period may lead to mortality in natural populations in this zone.
A study examining potential impacts of climate change on forest health showed that the fungal leaf blight Didymascella thujina (Keithia) was expected to increase in severity with warming in some sites. As higher-elevation populations experience climates more characteristic of lower sites, their lower natural resistance compared to low-elevation sources can lead to more severe disease outbreaks.
Ministry Contact: Alvin Yanchuk |
 |
| |||||||||||||||||
