Individual tree data for seedling height and diameter at root collar were checked for normality using the SAS
Univariate procedure (SAS Institute Inc., 2002). Plot means (i.e., the average of all trees from a given family within a replication) improved the normality of data for both traits at the different ages, as mentioned Jansson and Danell (1993). Therefore, plot means were employed for both traits at the different ages in subsequent analyses, in order to improve the normality and on the basis that this decision does not affect the precision with which any parental breeding value is predicted (White and Hodge, 1989).