スギ巣植林の生長(II)

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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.この報告は植栽後23年経過したスギ巣植林の生長を調べたものである.1) 巣間隔の広いA,C区は樹冠によって閉鎖されていないが,巣間隔の狭いB区は完全に閉鎖されていた.2)この10 年間に被圧のため多数の個体が枯死し,巣間の生存率の差が増大した.とくに6 本植えで枯死する個体が数多く発生した.塵間隔の狭いB 区では完全な6本植えはほとんど見られなくなった.3) 平均個体の大きさは巣本数が多いほど小さく, 1本植えと6本植えの差は増大している.一方,巣本数が増加しても,巣断面積の増加は頭打ちの傾向を示した.しかし巣間隔の狭いB区では頭打ちの傾向は見られなかった.4) 巣の最大個体は巣本数が増えると小さくなった.この現象は巣内の同種個体間のせりあいを示していると考えられる.5) 巣本数が多いほど,巣内の個体順位が固定しており,巣内における個体間の優劣は明らかであった.
九州大学の論文

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汰木達郎
九大

スギ巣植林の生長(II)

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