Comparison of Experimental Designs for Clonal Forestry Using Simulated Data

Various alternatives for the design of clonal field trials in forestry were studied using simulated data to identify “optimal” or “near-optimal” scenarios for the estimation of genetic parameters. The simulated field site consisted of a rectangular grid on which 256 clones with 8 ramets each were installed. Estimates of genetic parameters were compared for (1) single-tree and four-tree row plots; (2) several experimental designs (completely randomized, randomized complete block, incomplete blocks of various sizes, and row–column); (3) no mortality versus 25% mortality; and (4) different patterns of environmental variability (only patches, only gradients, and both patches and gradients). Use of single-tree plots, on average, increased the correlations between true and predicted clonal values by 5% over four-tree row plots and increased genetic gain from selection. Starting with a parametric broad-sense heritability (HB 2 ) of 0.25 for a completely randomized design, the experimental designs resulting in the highest HB 2 were row–column designs for single-tree plots and incomplete blocks with 32 blocks per replication when four-tree row plots were used. These designs increased average heritability 10% and 14% over a randomized complete block design, respectively. The only effect of 25% mortality was an increase in the variability of some variance component estimates. FOR. SCI. 52(1): 108–116.