Abstract
We analyzed the growth patterns of pure even-aged plantations of four North American hardwood species, yellow poplar (Liriodendron tulipiferd), black birch (Betula lento), pin oak (Quercus palustris), and north catalpa (Catalpa speciosd), in Iwate Prefecture, Japan. Yellow poplar plantations showed more vigorous height growth than natural hardwood stands in high-quality sites in Iwate Prefecture. The periodic annual volume increase in all the plantations except those of black birch in 2004 exceeded the simultaneous mean annual volume increase. The stand volume of yellow poplar plantation with a planting density of 1000 trees/ha was 476 m^3/ha when the stand was 28 years old; this was 2.4-4.2 times as much as the stand volume of the other three species in plantations with planting densities of 1000-2500 trees/ha and ages of 28-31 years.
