GENETIC-VARIATION OF PINUS-CONTORTA VAR LATIFOLIA BREEDING MATERIAL IN SWEDEN

Genetic parameters were estimated, using the restricted maximum likeli hood method, for 1112 open-pollinated progenies of Pinus contorta Doug l. ex Loud. var. latifolia Engelm. plus trees selected from among 83 u ndisturbed stands in the interior of the Yukon and British Columbia, a nd five similar stands in Alberta. The progenies were grown in Swedish test plantations. Tree condition, height, and ramicorn whorl frequenc y were assessed at ages ranging between 8 and 12 years. On the harshes t sites, weather and fungal damage, e.g., caused by Gremmeniella abiet ina (Lagerb.) Morelet, were also assessed. Categorical data were trans formed into values on a normal score scale to improve the efficiency o f the evaluation. The genetic coefficients of variation in tree height ranged between 8 and 17%. The heritabilities for tree height, includi ng stand genetic variation, were estimated to range between 0.10 and 0 .54. Genetic correlations between tree height and trunk leaning were u sually high and positive, as were correlations between height and rami corn whorl frequency. At one site, heritability estimates for trunk in jury and (or) canker and fungal and (or) weather damage were 0.12 and 0.18, respectively.