The effects of severe soil compaction and whole tree harvesting plus forest floor removal (referred to as forest floor removal) on trembling aspen (Populus tremuloides) and white spruce (Picea glauca) growth, foliar δ¹³C and δ¹⁵N, and plant cover and species composition were investigated in a boreal forest long-term soil productivity (LTSP) site near Dawson Creek, British Columbia. Soil compaction reduced aspen maximum height by 35% without forest floor removal and average height by 20% regardless of forest floor removal. Forest floor removal reduced aspen maximum height by 66 and 52% in the compacted and non-compacted treatments, respectively, and average height by 60 and specific leaf area by 18% regardless of soil compaction. Without forest floor removal, soil compaction reduced white spruce specific leaf area, unit leaf weight, and height increment by 29, 33, and 58%, respectively. In the non-compacted treatment, forest floor removal reduced white spruce specific leaf area, unit leaf weight, and height increment by 29, 32, and 35%, respectively. Aspen foliar δ¹⁵N was reduced by soil compaction without forest floor removal. Forest floor removal reduced aspen foliar N content but increased foliar δ¹⁵N. Our results indicate that water availability was not limiting for tree growth in the year the study was conducted while nutrient acquisition by aspen had been affected by soil compaction and forest floor removal. Plant total cover was highest in the compacted and forest floor removed treatment, due to increases in moss and shrub cover. Soil compaction and forest floor removal shifted the plant community composition. The four-year data analyzed in this paper indicate that soil compaction and forest floor removal can reduce aspen and white spruce growth, understory community structure, and soil N cycling processes.