In case that we examine the establishment of avalanche prevention forest or the planting method of general forest in the heavy-snow area, we must not ignore the effect of the snow pressure upon trees. For that reason, it will be important to make clear, by what kind of life form, the natural trees are comform to snowy enviroment and to learn about it. This investigation was done with the point of view described above. The species used is White fir (Abies sachalinensis). The result are summarised as follows : 1) The natural young trees growing under heavy-snow environment, not only on the slope but also the flat ground, take a form of the stem-bending near the ground inevitably as shown in Fig. 2-(1). 2) As the basal diameter becomes about 0.2〜0.3 cm (the tree height about 10〜15 cm), the stem-bending becomes gradually remarkable and several adventitious roots come out of stems which are in contact with the ground (Fig. 1 and Fig. 2-(2)). 3) With a development of the basal diameter (1.0〜1.5 cm), the growth of adventitious roots become vigorous (Fig. 2-(3)). The adventitious root which is developing conspicuously as Fig. 3-(1), seems to play an important role to fix the part of the stem-bending on the ground firmly (Fig. 2-(4)). 4) A development of the adventitious roots promote a growth of basal diameter as in Fig. 4. The adventitious roots and the stem near the ground grow as shown in Fig. 6. 5) As for above mentioned, it appears to be clear that the natural young trees are forced to form the stem-bending by the snow pressure but they are growing with a moderate balance against it.

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[in Japanese]

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