Spatial patterns of tree height variations in a series of Douglas-fir progeny trials: implications for genetic testing

Spatial variation patterns of tree heights at ages from 6 to 12 years in a series of Douglas-fir (Pseudotsuga menziesii (Mirb.) France) progeny trials that were conducted on 66 test sites over southern coastal British Columbi a were examined with conventional statistics and geostatistical techniques. It was found that there were large variations in tree height over the year s within and among the 66 test sites. The estimated proportions of the with in-site variance explained by family, row, column, patchiness, and within-p lot were on average 11, 7, 5, 12, and 47%, respectively, plus 7% due to unk nown factors, and the applied blocking removed about 5% of the within-site variance. Significant gradients in row and column directions were observed in more than 44 test sites, and the estimated slopes ranged in average from 0.33 to 1.52 cm/plot, Patch sizes varied greatly over the test sites and r anged in:average from 5.21 to 6.47 (plots), indicating that the average pat ch size for these trials was 18 m across. Temporal variations were large fo r family variance but not much for those variance proportions explained by row, column, patchiness, and within-plot. More gradients and larger patch s izes were found with older trees. Implications of these results are discuss ed for forest genetic testing.