匹見演習林における天然スギの研究(II) : 天然スギの更新に関する研究(第1報) : 伏条椎樹の生育状態について

In the western part of the Chugoku range, natural Sugi trees (Cryptomeria japonica) can generally be found over many of mountains.
To collect data for a study on reproduction of them, the writers made some preliminary investigations in the Shimane Agricultural College Forest of HIKIMI from 1956 to 1960.
Results investigated were as follows :
1. Pure forests of natural Sugi were found growing mainly on the ridge more than 1000 m above the sea.
2. In mixed forests natural Sugi trees were found mostly with some broad-leaved trees, such as Buna, Ryobu, Kaede and Musikari.
3. Generally speaking, the young trees of natural Sugi were found often in the mixed forests than in the pure forests, and on the ridge and the mid-slope than in lower areas.
4. Young trees of Sugi were reproduced by layers, i.e. twigs of mother trees.
5. Layers were very slow in growth under a closed stand ; their mean annual growth measured 2.7～3.6 cm in height and only 0.5～0.8 mm in diameter.
6. The natural Sugi which were cut down in 1960 had been liberated from suppressed condition twice ca. 70 and 40 years ago. And many layers began better growth at those times, but few fell again into suppressed condition after some years and then they recovered their power of growth when next chances was given.
7. The writers found a trend that the layers taller than 1.5 m could recover their power of growth after liberation. Whereas the shorter ones couldn't perhaps because of their suffering from drought due to their shallow and limited root system.