Hybrid Poplar Cooperative Spacing Trials (EP 1181)


Hybrid poplars are characteristically fast growing and yield high quality fiber on short rotations.  However, there is little local information on the growth, yield and development of intensively managed hybrid poplar plantations established at varying planting densities and different planting configurations. This project uses a non-systematic (“plaid”) design that allows inter-tree spacing to be varied in two dimensions on a factorial basis with constant number of trees per plot. In the design, the distance between rows and the distance between trees within rows are considered as two independent factors associated with each spacing treatment. The row-spacing factor (A) and the column-spacing factor (B), have ‘a’ and ‘b’ levels, respectively. The a x b factorial treatment combinations are randomly allocated to the plots of unequal sizes and shapes which are grouped into rectangular blocks; each block constituting a complete replicate.


The primary objective is to determine the effects of initial density and configuration (rectangularity) on the growth, development and yield of hybrid poplar plantations. A secondary objective is to test the utility of the “plaid” design for studies of this nature.


Originally, this study was established at three separate locations in British Columbia: (1) near Menzies Bay on Vancouver Island, (2) on Carey Island in the Fraser River, and (3) at the Kalamalka Research Station in Vernon. Plantations were planted in the spring of 1995. Four spacings (1.5, 2.25, 3.0 and 4.5 m) using a single clone were planted on the “plaid” design, resulting in a broad range of initial densities of from 494 to 4444 trees/ha and within/between row ratios (rectangularities) of 1:1 to 3:1.n Each 7x7 tree measurement plot was buffered by two guard trees.  The Menzies Bay installation was subsequently abandoned because poor clone selection resulted in very heavy mortality and very poor growth.


1181.02 Carey Island was last measured and released in 2011.  EP1181.03 Kalamalka was last measured and released in 2015. 


  • Johnstone, W.D. 2008. The effects of initial spacing and rectangularity on the early growth of hybrid poplar. West. J. Appl. For. 23(4):189–196.