Heritability estimates for height for young interior spruce in British Columbia

Height growth for interior spruce (Piceaglauca (Moench) Voss and P. engelmannii Parry) after 3, 6, and 10 growing seasons was assessed in a progeny test of 174 wind-pollinated families at three test sites in north central British Columbia. Test sites had a major influence on the juvenile growth of interior spruce, reflecting differences in potential site productivity as well as the importance of good site preparation and subsequent brush control for spruce seedlings. Mean heights within and across sites differed among families. The 3- and 6-year family performances correlated with family performances at age 10. Family-site interaction was significant at the 1% probability level, but accounted for no more than a quarter of the family variance at the three assessment years. Performance of the top and bottom 25% of families was consistent across the three sites. The narrow-sense heritability estimates after the third, sixth, and tenth growing seasons were 0.52, 0.36, and 0.29, respectively. The corresponding family heritability estimates were 0.82, 0.73, and 0.67, respectively.