Abstract
In the forest stand consisting of only 14-years-old Hinoki (Chamaecyparis obtusa (Sib. et Zucc.) Endl), rooting-up occurred in February 1996. Around the seven gaps caused by the rooting-up, residual trees were trimmed, and artificial gaps with different sizes and different cumulative amounts of relative solar radiation were made. The nursery stocks of Keyaki (Zelkova serrata (Thumb.) Makino) were planted in each gap, and the effect of the cumulative amount of relative solar radiation on their height growth was examined by comparing the growth in each gap. The height growth of Keyaki was markedly influenced by the cumulative amount of relative solar radiation that varied with the position of planting. That is, the higher the cumulative amount of relative solar radiation, the greater the height growth of Hinoki. In the gaps surrounded by partly opened canopy, the cumulative amount of relative solar radiation did not vary so much with the position of planting, and even the Keyaki trees near the edge of the forest stand grew well. This suggests that smallarea afforestation is possible even in the gaps, depending on the shape of the gap.
