| 内容注記 |
-
Other
10年生および11年生の幼齢林と68年生の高齢林において, 樹冠内で起こる光減衰の程度を表わす光減衰係数を算定した。光減衰係数は, どの林分でも入射角が50°以上になると著しく増大し, 両者の関係は双曲線で近似されるが, 幼齢林で大きく高齢林で小さい値を示す。これは, 高齢林では幹から分岐する1次枝の立ち上がりが急であること, そして1次枝に着生する葉が先端部に著しく集中することによると考えられる。また, 1次枝の本数密度, すなわち一定の長さの幹から分岐する1次枝の本数も, 光減衰係数に影響するようである。以上, 本報では, 枝葉の着生と結びついた樹冠の構造上の性質が, スギ林の光合成生産機構に深くかかわることを指摘した。
The extinction coefficient of light, suggesting the degree of light interception by the crown components, was calculated for three sugi, Japanese cedar (Cryptomeria japonica D.DON) stands, 10,11,and 68 years old. In each stand, it showed a marked increase at incident angles above 50° where the relationship was well-defined as a hyperbola. Compared with the two younger stands, the oldest one had significantly smaller values. This is supposed to be due to the fact that the primary branches coming from the stem extend upward more steeply, and furthermore, the leaves are not distributed evenly from the tips to the bases of the primary branches but are clustered at the tips in the old stand. The branch density, the number of primary branches originating along a constant length of the stem, also seems to influence the extinction coefficient of light. Thus, this paper points out that the crown's spatial arrangement of the leaves and branches plays an important role in the photosynthetic production processes of a sugi stand.
|
