Tatsuro Yuruki

The Development of Momi and Tsuga Forest : The Influence of Broad-leaved Trees on the Growth of Two dominant Conifers, Momi and Tsuga Trees

The influence of broad-leaved trees on the growth of two conifers, Momi arid Tsuga trees was explained by the changes of individual ranking, including that of broad-leaved trees, from an early stage in the development of the community. 1) Judging from the age structure, it was considered that Momi and Tsuga trees, and broadleaved trees on the surveyed plots had developed in gaps or openings in the forest. 2) Momi and Tsuga individuals established earlier in gaps or openings in the forest were superior to broad-leaved trees in competition from an early time in the development of the community and became stable in a superior position. 3) 011 the other hand, most of the Momi and Tsuga trees established later stagnate in a subordinate position as a result of oppression from the upper trees. This phenomenon indicated that the occurrence period, i, e., the time of establishment, affected the growth of individuals. 4) Momi and Tsuga individuals were ranked in three classes-superior, medium and subordinate in a Momi and Tsuga forest, but when broad-leaved trees outnumbered Momi and Tsuga trees, those of the latter in the medium class were few. 5) Broad-leaved trees CO-existing with Momi and Tsuga trees were composed of a large number of middle-sized and small trees, and a small number of large trees. It was considered that the paucity of large broad.leaved trees also prolnoted the superiority of Momi and Tsuga trees in a natural forest.