Effects of residual tree density (stems per hectare, stems ha⁻¹) on the density of balsam poplar regeneration one year after treatment (2004) (A), density of balsam poplar regeneration 5 y post-treatment (2008) (B), and maximum height (C) of balsam poplar regeneration in 2008 in Lac La Biche (LLB) and Peace River (PR). Bars represent the least square means; error bars represent the 95% confidence interval of the mean values. Different letters indicate significant differences according to Tukey’s multiple comparison test (p < 0.05); lowercase letters represent comparisons for LLB and uppercase for PR.