Spacing Trial of Douglas fir (EP 534)


The experiment was established by George Warrack of the B.C. Forest Service to provide growth and yield information of planting densities on a steep side-hill site, at 550 - 600 m elevation. Due to an accidental juvenile spacing of the experiment at 18-years, the objectives were modified to determine the rate of growth within the spaced plots, the effect of suppression on the unspaced plots, and the growth response  of the spaced plots relative to the growth of the trees planted at the wider spacing.


To determine the rate of growth within juvenile-spaced plots and the effect of suppression on their growth response relative to the growth of trees at the wider spacing.


There are 2 components to this experiment:

EP 534-01, established in 1959 at 16 Creek near Cowichan Lake. The experiment consists of three blocks of 4 plots each; the plots in one block are of fixed-area (0.2 ha) and those in the rest of the blocks are of variable-area. The planting espacement levels are: 1.8m x 1.8m, 2.4m x 2.4m, 3.7m x 3.7m, and 4.6m x 4.6m. The plots were planted with Douglas fir 2+0 stock. Plot sizes for two of the blocks are 7 trees by 7 trees for 49 trees per block and the third block has its four 0.2023 ha plots running with the long axis up the slope. In 1975 plots 1-12 were accidentally spaced to 3.7m (except the 4.6).

EP 534 – 02 series A, established in 1963 in the same area as unit 534-01 on order to replace the initial plots that were accidentally spaced. An area 18.6 ha was divided in to 4 blocks (of approximately same size) and planted respectively with Douglas fir at 2.4m x 2.4m, 3.0m x 3.0m, 3.7m x 3.7m, and 4.6m x 4.6m spacing. EP534–02 series B, were established in 1983 with plots 25-34 given the same spacing as the series A plots.


EP534-01(12 plots) was last measured and released in 2001. EP534-2A (24 plots) was last measured and logged in 2011. EP534.2B is Active.