Studies on the Growth of a Sugi (Cryptomeria japonica) Stand Planted in Clumps (II)

A 23-year-old Sugi stand planted in clumps was surveyed. 1) Because of the wide clump spacing, plots A and C were not closed by tree crowns. However, plot B with narrow clump spacing was completely closed. 2) A large number of trees had died due to oppression by adjacent trees over the previous ten years and the difference in survival rates increased among the clumps. An especially large number of trees had died in the clumps of six trees. Almost the whole clump of six trees had disappeared from plot B with narrow clump spacing. 3) The greater the number of trees per clump, the smaller the individual mean became. The difference between the individual mean for the clumps of single trees and that for the clumps of six trees was increased. Even if the number of trees per clump increased the basal area per clump showed a tendency to reach a ceiling, but this trend was not observed in plot B with narrow clump spacing. 4) The greater the number of trees per clump, the smaller the largest tree in the clump became. It is considered that this phenomenon demonstrates intraspecific competition. 5) The greater the number of trees per clump, the more steady the individual ranking was fixed. The difference between the superior and inferior trees was obvious in the clumps of several trees.