Spacing effects on seedlings of northern red oak and yellow-poplar

Seedlings of northern red oak (Quercus rubra L.) and yellow-poplar (Liriodendron tulipifera L.) were grown at spacings of 10.8/m2 (1 per square foot), 26.9/ m2 (2.5 per square foot), and 53.8/m2 (5 per square foot) for 2 years. Spacing had no significant effect on first-year growth of either species, but increasing density significantly reduced second-year growth. Compared to the 53.8/m2 spacing, 2-year-old seedlings of northern red oak were 3 times larger at 10.8/m 2, and 2-year-old seedlings of yellow-poplar were 4.8 times larger at 10.8/m2